biology term 3

TOPIC 14: TAXONOMY AND BIODIVERSITY (14)
14.1 Taxonomy
(2)
Candidates should be able to:
(a) explain the importance of taxonomy in biological sciences;
(b) explain the concept of species, and relate how a species is classified into
higher categories in a taxonomic hierarchy.
14.2 Diversity of
organisms
(6)
(a) describe the morphological characteristics of the following phyla in the
respective kingdoms: Protoctista (Chlorophyta and Zoomastigina), Fungi
(Zygomycota), Plantae (Bryophyta, Filicinophyta, Coniferophyta and
Angiospermophyta) and Animalia (Porifera, Cnidaria, Platyhelminthes,
Mollusca, Arthropoda and Chordata).
14.3 Biodiversity
in Malaysia (2)
(a) describe the different levels and examples of biodiversity in Malaysia,
namely ecosystem or community diversity, species or taxonomic diversity
and genetic diversity;
(b) explain the importance of biodiversity in Malaysia.
14.4 Threats to
biodiversity (2)
(a) explain the natural and man-made factors that threaten biodiversity in
Malaysia;
(b) explain the steps and efforts taken by various agencies and
organisations to address the threats.
14.5
Conservation of
biodiversity
(2)
(a) describe the various measures taken to conserve the different levels of
biodiversity including in situ and ex situ conservation in Malaysia.
Topic: 14 Taxonomy and Biodiversity (14)
14.1 Taxonomy (2)
Learning outcome
(c) Explain the importance of taxonomy in biological sciences;
(d) Explain the concept of species, and relate how a species is classified into higher categories
in a taxonomic hierarchy.

Teacher’s Guidance
1. Definition, concept and the importance of taxonomy
- Taxonomy is the study of classification
- Involved the naming of prganisms and the systematic placing of organisms into
group or taxa.
- On the baiss of certain relationship between organisms.
Importance of taxonomy
- to formulate a universally accepted name or nomenclature for the organisms to avoid
confusion caused by regional names
- to classify all the organisms systematically : enable the characteristics of an individual
or groups of organisms to be easilyidentified and compared
- to show evolutionary relationships
- to identifyeasilynew species
2. Taxonomic hierarchy (7 taxon / rank)
- All systems of classification are hierarchical: each successive group containing more and
more different kinds of organisms.
- Taxonomic hierarchy is used in Linnaeus’s system of classification (1707 -1778)
- Has the followingfeatures:
 Consists of a series of groups within groups from the most general (kingdom) to the
most specific(species)
 No overlapping between the groups,i.e there is no organism that is part amphibian
and part reptile: its either in one group or the other
 The groups are based on shared features. The most specific the group, the more
shared features there are.
- Linnaeus’s system of classification uses seven taxonomicrank(taxon)
- Taxonomic rank/taxon: a group or level of organization within the
hierarchy/classificatorygrouping.
3. Classification of species into higher categories in a taxonomic hierarchy.
The seven taxonomic rank (fromsmallest to largest are):
 Species
 Genus
 Family
 Order
 Class
 Phylum/Division
 Kingdom

Taxon Definition
Kingdom The largest and most inclusive grouping e.g plants, animals, fungi
Phylum Consists of several different classes
Includes many differentorganisms that share important
characteristics
Class Composed of similar orders within a phylum
Order Composed of similar /apparently related families
Family Consist of closely related genus, whichshare many characteristics
Genus Consist of closely related species whichare grouped together
Species Basic unit of classification
A group of organisms whichhave numerous physicalfeatures in
common
Are normally capable of interbreeding and producing viable
offspring.
- Example of taxonomy hierarchy forplants and animals
Taxonomic
rank
Organisms (common name)
maize Flame of the forest rat human
Kingdom
Phylum
Class
Order
Family
Plantae
Angiospermophyta
Monocotyledoneae
Glumiflorae
Maydae
Plantae
Angiospermophyta
Dicotyledoneae
Caesalpinoidales
Caesalpinoideae
Animalia
Chordata
Mammalia
Rodentia
Muroideae
Animalia
Chordata
Mammalia
Primates
Hominidae

Learning Outcome:
(a) describe the morphological characteristics of the following phyla in the
respective kingdoms: Protoctista (Chlorophyta and Zoomastigina), Fungi
(Zygomycota), Plantae (Bryophyta, Filicinophyta, Coniferophyta and
Angiospermophyta) and Animalia (Porifera, Cnidaria, Platyhelminthes,
Mollusca, Arthropoda and Chordata)
Genus
Species
Zea
mays
Delonix
regia
Rattus
rattus
Homo
sapiens
4. Construction of dichotomus key
5. Concept of species and ways in defining species
6. Naming of an organism based on binomial system
14.2 Diversity of Organisms
1. Morphological characteristics of the kingdom and phyla given with their example.

Content
Morphological characteristics at kingdom level
MORPHOLOGICAL CHARACTERISTICS
KINGDOM CELL
ORGANIZATION
ORGANISM MODE OF
NUTRITION
PROTISTA or
PROTOCTISTA
Eukaryotes Unicellular
Multicellular
Photoautotroph
Heterotroph
(Holozoic)
FUNGI Eukaryotes Mostly
Multicellular
Heterotroph
(Saprophytic,
Parasitic)
PLANTAE Eukaryotes Multicellular Photoautotroph
ANIMALIA Eukaryotes Multicellular Heterotroph
(Holozoic)
Morphological characteristics at phylum level
KINGDOM and PHYLUM MORPHOLOGICAL CHARACTERISTICS
KINGDOM:
PROTISTA or PROTOCTISTA

- Divided into two group:
i. Algae
ii. Protozoa
- Algae is divided into phylum:
Chlorophyta
Contoh: Spirogyra
- Protozoa divided into phylum:
Zoomastigina
Contoh: Chlamydomonas
Characteristics of algae
 Eukaryotic unicellular @ multicellular organisms
 Photosynthetic
 Photosynthetic pigments: chlorophyll a & other
accessory pigments
 Classification is based on pigment composition
 Habitat: aquatic
 Considered as plant-like but without true plant
structures (no roots, stems & leaves)
FUNGI

PLANTAE
ANIMALIA
1. Kingdom Protoctista (Chlorophyta and Zoomastigina)
 Morphological characteristics
- Unicellular @ multicellular organisms
- Autotrophs, heterotrophs, or both
- Habitat: aquatic (most live in water)
- Protistan nuclei contain multiple DNA strands, though the total number of nucleotides
is significantly less than in more complex multicellular eukaryotes.
 ALGAE: phylum Chlorophyta
 Unique Characteristics:-
 ‘Green algae’
 Similar to green plants in cell structure & biochemistry
 Chlorophyll a & b, carotenoids
 Stored food: starch
 Cell wall : cellulose
 Single-celled / filamentous / colonial
 Most are fresh water inhabitants
 Eg: Chlamydomonas ( unicellular )

 KINGDOM PROTISTA:ALGAE:
 phylum CHLOROPHYTA- Chlamydomonas :
 Unique characteristics:
 Unicellular with 2 flagella
 Has Chloroplast: single, cup-shaped that contain pyrenoid ( a structure where starch
is synthesized )
 Has a red pigmented eye spot (stigma): sensitive to
light, necessary for photosynthesis


 KINGDOM PROTISTA:ALGAE: phylum CHLOROPHYTA- Chlamydomonas :
 Unique characteristics:
 May reproduce asexually: by mitosis
 May reproduce sexually: when condition is unfavorable
 - Involves the formation of gametes in unicellular gametangia
 - Type of sexual reproduction: isogamous*
 * ( Isogamous: reproduction involves gametes which are identical in size & shape)

 KINGDOM PROTISTA:ALGAE: phylum PHAEOPHYTA - Fucus sp:
 Unique characteristics:-
 ‘Brown algae’
 Chlorophyll a & c, carotenoids including fucoxanthin
 Stored food: laminarin
 Multicellular ( largest & most complex of all algae )
 Most are marine
 Eg: Fucus

i. Unique kingdom among the five classification kingdom
ii. It contains a divers collection of eukaryotic organisms that are generally regarded
as identical or similar to the ancestors of modern plants, animals and fungi
iii. Most organisms in this kingdom consists of colonies or filaments of cells.
iv. Some are very simple with the cells almost identical to each others, certain cells
and regions have become specialized and interdependent
v. This kingdom is divided into two groups:
o Algae
o Protozoa
vi. Algae is divided into phylum:
o Chlorophyta: Spirogyra

o Phaeophyta
o Rhodophyta
vii. Protozoa divided into phylum:
o Rhizopoda
o Ciliophora
o Zoomastigina: Chlamydomonas
viii. Algae and protozoa are adapted for aquatic habitats
2. Kingdom Fungi (Zygomycota),
 Generallymulticellular eukaryotes
 Heterotrophic:
 i. Some are saprophytic ( saprobes )
 ~ Cells release digestive enzymes & absorb nutrient molecules from dead organic
substances
 ii. Some are parasitic
 ~ Absorb nutrients from living hosts
 iii. Several have mutualistic relationships


 Mutualistic relationships:
 *Lichens
 ~ Association between fungi and green algae or cyanobacteria

 ~ Fungi absorbs nutrients from the algae / cyanobacteria
 ~ Fungi also provides suitable environment for growth of the algae / cyanobacteria
 ~ Both can live in areas of extreme conditions & contribute to soil formation

 Fungi are different from plants:
 ~ Lack chloroplasts
 ~ Cell wall contains chitin
 ~ Energyreserve is glycogen
 Vegetative structure: hyphae
 Reproduction:produce spores ( asexually or sexually )
 Classification based on type of sexual reproductive structure

 Vegetative structure
 - Filamentous body plan
 - The filaments called hyphae
 - Hyphae: - long, branched & threadlike, may absorb nutrients
 - form a mass called mycelium

 - Types of hyphae:
 Coenocytic ( nonseptate )
 hyphae not divided into cells, multinucleated
 2. Septate
 hyphae are divided, by cross walls called septa, into individual cells containing
one or more nuclei

 reproduction of fungi
 Most reproduce by forming spores
 Spores are produced on specialized aerial hyphae or in specialized spore-forming
structures ( eg: sporangium )
 Spores will germinate, forming new hyphae
 Spores produced sexually or asexually
Phylum Zygomycota
Sexual spores Zygospores
Sexual reproductive
structure
Zygosporangium

Hyphae Coenocytic
Type of reproduction Asexual and sexual
Asexual reproduction Non motile spores formed in
sporangium
Common types Black bread molds
 Importance of fungi
 Decomposers – recycling materials
 ii. Symbionts ( eg: lichens – contribute to soil formation )
 iii. Disease-causing pathogens ( eg: causing ringworm, athlete’s foot )
 iv. Commercial importance in food production ( fermented food )
( eg: yeasts, mushrooms, truffels )
 v. For medical purpose / pharmaceutical ( eg: production of penicillin from Penicillium
)
 vi. For biotechnology ( eg: Neurospora ) & biological control of pests


consists of fine threads called hyphae

3. Kingdom Plantae (Bryophyta, Filicinophyta, Coniferophyta and Angiospermophyta)
4.
 Multicellular; eukaryotic
 Autotrophic ( photosynthetic )
 Cell wall consists of cellulose
 Food storage: starch
 Show adaptations to terrestrial living
 Show alternation of generations in the life cycle

 During the life cycle, 2 multicellular body forms alternate, each form producing the other
 2 forms: gametophyte & sporophyte
 Gametophyte represents haploid (n) generation
 Sporophyte represents diploid (2n) generation
• Gametophyte is named for its production of gametes
• Sporophyte is named for its production of spores by meiosis

– Spore is haploid reproductive cell
–
• There are 4 main groups of land plants:
1. Bryophytes
2. Pteridophytes
3. Gymnosperms
4. Angiosperms

Characteristics of the phylum BRYOPHYTES
• The most primitive land plants ~ terrestrial adaptations
• Nonvascular seedless plants
• Small-sized

• Vegetative structure: don’t have true roots, stems or leaves
• Most don’t have waxy cuticle layer
• Inhabit moist habitats, most grow close to the ground
• Need water for sexual reproduction & growth
• Gametophytes are the most conspicuous, dominant phase of the life cycle
• Sporophytes are smaller and depend on the gametophytes for water and nutrients
• Gametophyte is more adapted to terrestrial living; sporophyte is very dependent on the
gametophyte
• Habitats must be moist or near to water source
• Most grow close to the ground
• Root-like rhizoids function to absorb water
• Form the zygote & embryo within the female gametangium, ensuring the early stage of
sporophyte is protected
•
• Plantae:gymnosperm:phylum coniferophyta, eg: Pinus
• Various sizes & habitats
• Non-flowering, vascular, seed-bearing plants
• Naked seeds ( exposed & unprotected; lack ovaries )
• Most: xylem without vessel elements;phloem without companion cells
• Sporophyte: dominant
• Gametophyte: very much reduced & not independent
• Reproductive organ on sporophyte: staminate cone / strobilus or ovulate cone /
strobilus
• Most: heterosporous
• No external water needed for fertilization
CONIFEROPHYTA
Shape of
leaves
Needle-like leaves
( & some scale-like
sporophylls form
the cones )
Reprod.
organ
Cones
Xylem No vessel
elements

Phloem No companion
cells
Sporophyte
(type of sex)
Monoecious
•
quest
ans

5. Kingdom Animalia (Porifera, Cnidaria, Platyhelminthes, Mollusca, Arthropoda and
Chordata)




22.1.1 Kingdom Protoctista
i. Chlorophyta: oneexampleof
unicellular and oneexample of
filamentous
Zoomastigina: Euglena

14.3 Biodiversityin Malaysia
Learning outcome:
(a) Describe the different levels and examples of biodiversity in Malaysia, namely ecosystem
or community diversity,species or taxonomic diversity an dgeneticdiversity
(b) Explain theimportance of biodiversity in Malaysia.
Content/Notes/Sources/Description
1. Ecosystem diversity, species diversity, taxonomic diversity with example
a. Ecosystem /community diversity
 The different habitats, that support species (eg: National Park, tropical land
forest, rivers, streams, etc)
 Terrestrial ecosystem, mangrove swamps, aquatic ecosystem
 Ecosystem consists of living and non-living organisms which interact with each
other.
b. Species /taxonomic diversity
 The number of different species present in a community.
c. Genetic diversity
 The heritable variation among members of a population
 Genetic variation arises by gene and chromosome mutations or by sexual
reproduction
2. Importance of biodiversity in Malaysia
a. Natural resources for food
b. Source of industrial products, medicines and timber.
c. Reservoir of genetic information
d. Maintain recycling water and nutrient.
e.Stabilising the weather
f. Cleaning the air and water
g. Maintain sol fertility
h. Aesthetic value for recreation.
Question
1. Explain the importance of mangrove forest to the human.
2. Explain the difference levels of diversity in Malaysia

14.4 Threats to biodiversity
 Explanation of the natural and man-made factors threatening local biodiversity
 Explanation of the steps and efforts taken by local agencies and organisation to address
the threats
Prior knowledge: The students should have learnt about greenhouse effects and thinning of
the ozone layer.
Useful references:
1) Campbell, N.A. and Reece, N.A., 2005. Biology. 7th edition. San Francisco: Benjamin/
Cummings.
2) Taylor, D.J., Green, N.P.O. and Stout, G.W., 2003. Biological Science 2: Systems,
Maintenance and Change. 3rd editon. Cambridge: Cambridge University Press.
Notes:
Natural factors
 Global change
- This includes change in climate, atmospheric chemistry, and broad ecological
systems that reduce the capacity of Earth to sustain life.
i) Acid precipitation, eg. acid rain (with pH less than 5.2)
- The burning of wood and fossil fuels and volcanic eruption releases oxides of sulfur
and nitrogen that react with water in air, forming sulfuric and nitric acids. The acids
eventually fall to Earth’s surface, including Malaysia, harming some aquatic and
terrestrial organisms.
ii) Increase in greenhouse gases such as CO2
- Greenhouse gases increase in global temperature and cause global warming
- Global warming causes climatic change and natural disasters like flood and drought,
this affects the distributions and survival of organisms
iii) Depletion of atmospheric ozone
- Decreased ozone levels in the stratosphere increase the intensity of UV rays reaching
Earth’s surface. The consequences of ozone depletion for life on Earth may be severe
for plants, animals, and microorganisms
iv) Natural disasters
Natural disasters like flood and drought may threat the survival of local species
Learning Outcome
(a) Explain the natural and man-made factors that threaten biodiversity in
Malaysia
(b) Explain the steps and efforts taken by various agencies and organisations to
address the threats

Man-made factors
1) Destruction of habitat:
i) Conversion of land for
- agriculture, eg. large areas of forests are cleared for oil palm plantation, shifting
cultivation
- housing, eg. forests are clear for housing development
- construction, eg. hydroelectric dam, resorts and industries
- aquaculture, mangrove swamps are destroyed for fish and prawn culture
ii) Mining, eg. tin-mining destroys natural habitats of many species
2) Over-exploitation of biological resources
i) Overlogging and illegal logging
ii) Excessive hunting and poaching
iii) Overfishing and fish bombing
3) Pollution
i) Pollution from industries and agriculture into the aquatic environment
ii) Air pollution from industries and vehicles may cause acid rain
4) Introduction of new species
New species may displace the original species because the new species are not subject
to population-controlling mechanisms
Steps and efforts taken by various agencies and organisation to address the threats
1) Malaysian laws or enactments
i) National Forestry Act 1984
- Provides for classification of the forests as protected in the country.
- Logging should be selective and sustainable.
ii) Environment Quality Act1974
- An environmental impact assessment has to be done for activities affecting the forests.
iii) Protection of Wildlife Act 1972
- Provides for the establishment of wildlife reserves or sanctuaries for protection of the
flora and fauna.
iv) Fisheries Act 1985
- Provides for the conservation, management and development of fishing and fisheries in
Malaysia.
2) Education
- Educating the public on the need to protect the environment and the ways to save the
environment.
- Having campaign like ‘reduce, reuse and recycle’ to lessen the impact of wastes on
biodiversity.
3) Sewage and industrial wastes treatment

- The wastes should be treated before dischanging them into rivers or seas
4) Avoid the excessive use of pesticides and fertilisers
- Biological control, eg. using owls to control rats in oil palm plantation
- Reduce harmful chemicals from contaminating the water systems
5) Local Agenda 21
- To involve communities to work towards sustainable development at local level.
- Commits to maintain green areas within urban districts.
- Green areas help educate the public on the importance of conservation, provide resting
and watering places for migrating birds, help maintain urban air quality and temperature
and provide important rest and recreation areas to relieve the stress of urban life.
- A successful example is the Kota Kinabalu City Bird Sanctuary.
6) University and research institutions
- play an important role in acquiring more scientific knowledge about rainforests, the
marine environment and the interactions between different species.
- Build up the capacity of the country in the training of biologists and others professionals.
eg. Forestry Research Institute of Malaysia (FRIM) and MARDI
7) Non-Governmental Organisations (NGOs)
- Provide alternative viewpoints to development plans.
- Implementation of environmental legislations.
- Environmental management and conduct vital public awareness and research work.
eg. Malaysian Nature Society (MNS), World Wide Fund (WWF), Malaysian
Environmental NGOs (MENGO)
8) Regional initiatives
- Protect ecosystems and wild life regardless of political boundaries.
Example 1: A number of Transboundary Conservation Areas (TBCA) has been
undertaken by ASEAN member countries.
Example 2: Lanjak-Entimau Wildlife Sanctuary in Sarawak and Betung Kerihun
National Park in West Kalimantan was proposed as a transboundary conservation
area.
9) ASEAN Heritage Parks
- All ten ASEAN Member Countries are signatories to the ASEAN Declaration on
Heritage Parks. This provides a framework for concerted action toward protected areas
in the ASEAN region.
10) Convention on International Trade in Endangered Species of Wild Fauna and Flora
(CITES)
- To ensure that international trade in specimens of wild animals and plants do not
threaten their survival.
Questions
1. A decrease in Malaysian biodiversity is caused by humans directly or indirectly. Explain.
2. As a leader of Malaysia, explain what would you do to reduce the various threats to the
biodiversity in Malaysia.

14.5 Conservation of biodiversity
Learning Outcome:
a) Describe the various measures taken to conserve the different levels of biodiversity
including in situ and ex situ conservation in Malaysia.
Content/Notes/Sources/description
Teacher Guidance
Introduction
In situ conservation is a way to conserve the flora and fauna in their original habitats by setting
up natural parks, sanctuary and reserves in which they are managed to prevent the
deterioration of the environment.
Referens: Ministry of Education Malaysia(2003), Teaching Courseware
Campbell at.all (2011) Biology, Ninth Edition.

15 Ecology (22)
15.1 Levels of ecological
organisation (3)
(a) explain the concept of hierarchy in an ecosystem and the
interaction between the biotic and abiotic components.
15.2 Biogeochemical
cycles (3)
(a) describe the biogeochemical cycles (carbon, phosphorus and
sulphur), and explain their importance.
15.3 Energy flow (3) Candidates should be able to:
(a) describe the energy flow and the efficiency of energy transfer in
terrestrial ecosystem (tropical rain forest) and aquatic ecosystem
(lake).
15.4 Population ecology
(6)
(a) explain population growth (S and J growth curves), biotic
potential, natality, mortality, migration and survivorship;
(b) explain the characteristics of populations that show Type I, Type
II and Type III survivorship curves, and K-strategies and r-
strategies.
15.5 Carrying capacity
(3)
(a) explain what is meant by carrying capacity and sustainable
development;
(b) explain the factors limiting the population size and distribution.
15.6 Quantitative
ecology (4)
(a) describe the use of quadrat and line transect sampling methods
and explain the advantages and disadvantages of using these
methods;
(b) calculate the various sampling parameters (frequency, density,
cover and their absolute and relative estimations) and estimate
the population size of organisms;
(c) explain the pattern of distribution of organisms in an ecosystem.

TOPIC15: ECOLOGY (22)
15.1 Levels of Ecological Organisation (3)
Learning outcomes
(a) explain the concept of hierarchy in an ecosystem and the interaction between the biotic
and abiotic components
Teacher’s guidance
 explain the concept of hierarchy in an ecosystem
 defining an ecosystem and describe the biotic and abiotic components of ecosystem
 distinguish between biotic and abiotic components(climatic, edaphic and topographic
factors)
 the interaction between the biotic and abiotic components

15.2 Biogeochemical cycles (3)
Learning outcomes
(a) describe the biogeochemical cycles (carbon, phosphorus and sulphur), and explain their
importance
 Describe the carbon cycles and explain their importance
 Describe the phosphorus cycles and explain their importance
 Describe the sulphur cycles and explain their importance

15.3 Energy flow (3)
Learning outcome
(a) Describe the energy flow and the efficiency of energy transfer in terrestrial ecosystem
(tropical rain forest) and aquatic ecosystem (lake).
The two laws of thermodynamics and relate them to energy transfer
 Energy flow through the biosphere and how the energy is lost in each level.
Diagram of food chain and food web in terrestrial ecosystem (tropical rain forest) and
aquatic ecosystem (lake)
 Ecological pyramid (pyramid of number, pyramid of biomass, and pyramid of energy)
that describes the feeding or reflects energy relationship through the biotic component in
an ecosystem
 Interpret the energy flow diagram through different trophic levels of a food chain in
terrestrial ecosystem (tropical rain forest) and aquatic ecosystem (lake)
 Describe and calculate the trophic efficiency of energy transfer in terrestrial ecosystem
(tropical rain forest) and aquatic ecosystem (lake). (gross primary production GPP, net
primary production NPP and secondary production)

15.4 Population ecology (6)
Learning outcome:
(a) Explain population growth curve (S and J growth curves), biotic potential, natality,
mortality, migration and survivorship;
(b) Explain the characteristics of populations that show Type I, Type II and Type III
survivorship curves, and K-strategies and r-strategies.
Teacher’s Guidance:
 meaning of population size, population density, biotic potential, natality, mortality,
migration and survivorship
 explain population growth curve (S / logistic growth curve and J/exponential growth
curves)
 biotic potential related to J growth curve
 Survivorship curves; explain the characteristics of populations that show Type I, Type II
and Type III.
Type I; K selected species related to K-strategis,
Type III; r-selected species related to r-strategies
 Identify K selected species and r-selected species; K-strategies and r-strategies.
 Populations grow, shrink, or remain stable, depending on rates of birth, death,
immigration, and emigration.
growth rate = (crude birth rate + immigration rate) – (crude death rate + emigration rate)

15.5 Carrying capacity (3)
Learning outcome
(a) Explain what is meant by carrying capacity and sustainable development;
(b) Explain the factors limiting the population size and distribution
 Meaning of carrying capacity related to population size
 meaning of environmental resistance and sustainable development; (sustainable
forestry, sustainable agriculture and sustainable fisheries
 explain the factors limiting the population size and distribution
Density-dependent factors that account for the logistic growth curve
(a) Intraspecific competition
(b) Interspecific competition
(c) Predation
(d) Disease
(e) Fire (for a population of fire prone plant)
(f) Parasitism
Other factors occur regardless of density and are density-independent factors.
(a) Floods
(b) Drought
(c) Extreme temperatures
(d) Pollution
(e) Fire
(f) Salinity

5.6 Quantitative Ecology (4)
Learning outcome
(a) Describe the use of quadrat and line transect sampling methods and explain the
advantages and disadvantages of using these methods;
(b) Calculate the various sampling parameters (species frequency, species density, species
coverage and their absolute and relative estimations) and estimate the population size
of organisms;
(c) Explain the pattern of distribution of organisms in an ecosystem.
 Quadrat sampling method
(a) Types and size of quadrat ; frame and point quadrat
(b) Random or systematic sampling
 The purpose of using quadrat and line transect methods
 Quadrat and line transect procedure
 The advantages and disadvantages of using quadrat and line transect methods;
 Sampling parameters (species frequency, species density, species coverage, relative
species frequency , relative species density and relative species coverage) and estimate
the population size of organisms;
 Three distribution pattern of organisms in an ecosystem.
(a) Random
(b) Uniform / regular
(c) Clumped
Notes
1. Distribution pattern differs across biomes
2. Distribution pattern is determined by abiotic factors e.g. amount of rainfall, temperature,
latitude and soil factor.
3. The three distribution patterns:
Clumped : due to patchy resources, social factors, parental care and mechanism against
predator .
Regular: due to territorial behavior, nutrient distribution and man-made activities
Random: due to homogenous environment, consistent environmental condition and
uncontrollable factors

TOPIC 16: SELECTIONAND SPECIATION
16.1 Natural and artificial selection
Learning Outcome:
b) Describe continuous and discontinuous variation in relation to selection and speciation;
c) Explain the modes of natural selection(stabilising, directional and disruptive) and their
consequences;
d) Describe with example, sexual selection and polymorpism;
e) Explain the importance of artificial selection (gene bank, germplasm bank and sperm
bank).
Teacher Guidance
1. Comparison between continuous variation and discontinuous variation.
2. Comparison between modes of selection
3. Relate between sexual selection and polymorphism
4. Importance of artificial selection
Introduction-Variation
The differences between individual of a plant or animal of the same species are called
variation. These differences may be the result of genetic differences, the influence of the
environment or a combination of genetic and environmental influences.
Variation causes some individual in a population to be better adapted for survival than others.
Variation also enables a population to inhabit a larger range of habitat and niche.
There are 2 major types of variation
In a natural population, two types of variation occur,
• Discontinuous variation
• Continuous variation
Continuous variation
• A characteristic which shows a complete gradation from one extreme to the other
without any break.
• Differences between individuals are slight & grade into one another so that individuals
often do not fall into distinct categories.

• The frequency distribution for a characteristic exhibiting continuous variation is a normal
distribution curve.
• Most of the organisms in the population fall in the middle of the range with approximately
equal numbers showing the two extreme forms of the characteristic
Discontinuous variation
• Discontinuous variation produces individuals showing clear cut differences with no
intermediate forms between them.
Comparison between continuous variation & discontinuous variation
Continuous variation Discontinuous variation
• Show quantitative inheritance.
Quantitative character can be
measured or graded on a scale
• Show qualitative inheritance. Qualitative
character cannot be measured or
graded
• Characteristic exhibiting are produced
by the combined effects of many
genes (polygenes) and environmental
factors.
• Are usually controlled by one or two
major genes. The phenotypic
expression is relatively unaffected by
environmental conditions.
• Normal distribution curve. • Discrete distribution curve
• Eg: Weight, height & skin colour • Eg: eye colour, ear-lobe, blood group in
0
20
40
60
80
100
Can rool tongue cannot roll tongue

human, tongue rolling & curly/straight
hair and sex in animals and plants.
Sources of variation
Variation within a population can be increased by the process of Genetic and environmental
factors
Genetic factors causes of variation
• A population which breeds sexually will produce varied individuals because sexual
reproduction involves the random processes of meiosis followed by random fertilisation
of gametes. This can occur in two way, Independent/random assortment and Crossing
over.
• Other genetic causes of variation include choromoseme mutation, gene mutation,
polygenes, dominant and recessive genes/alleles and hybridisation.
Sexual Reproduction
• During gametogenesis, male and female gametes are formed. Each gamete may differ
from each other. This is due to crossing over and random assortment of homologous
chromosomes during meiosis.
Random fertilisation
• Random fertilisation between the male and female gametes will lead to genetic variaton
in the offspring.
• Any egg could combine with any sperm (in humans) so that there is even more different
combination possibilities.
• This takes place when two gametes fuse to form a zygote. Each gamete has a unique
combination of genes, and any of the numerous male gametes can fertilise any of the
numerous female gametes. So every zygote is unique
• For example, one sperm may carry the allele for haemophilia and the other may not.
Whether the offspring is haemophiliac or nor will depend on the allele of the egg and
which sperm is involved in fertilising this egg.
Random assortment
• This happens at metaphase I in meiosis, when the bivalents line up on the equator. Each
bivalent is made up of two homologous chromosomes, which originally came from two
different parents (they’re often called maternal and paternal chromosomes).
• Since they can line up in any orientation on the equator, the maternal and paternal
versions of the different chromosomes can be mixed up in the final gametes.

• In this simple example with 2 homologous chromosomes (n=2) there are 4 possible
different gametes (22
). In humans with n=23 there are over 8 million possible different
gametes (223
). The number of possible offspring pruduced from two parents is (8 miliion
x 8 milion).
Crossing over
• In the prophase of the first meiotic, the homologous charomosomes (comprising two
chromatids each) are in pairs and in close contact with each other.Crossing over occurs
when all four charomatids are at synapsis. The non-sister chromatids may break and
rejoin at certain points called chiasmata. Parental gene combination are replaced by
recombinants. This is a major source of genetic variation.
Chromosomal mutation
• There are two forms: Change in the number of chromosomes and change in the
structure of the chromosomes.
Hybridisation
• Occur when an organism obtains genes from two different species. The organism is
called a hybrid. The hybrids have different phenotypes and genotypes compared to their
parents
Polygenes/polygenic Inheritanc
• In polygenic inheritance, the character of an organism is controlled by more than one
gene. Variations to a polygenic trait can be clearly observed in a population. They are
slight different between group of individuals in a population for a polygenic trait. E.g. in
human are height, weight, eye colour, skin colour & intelligence

Environmental factors causes of variation.
• Environmental variation is not that much important in evolution since it only affects the
phenotype rather than genotype of an organism.
• So genetic variation can be passed on from one generation to generation while
environmental variation cannot be passed on. However it still important to determine the
phenotype. Some example :
Growth of identical twins.
• Both of the twins have the same genotype since they emerge from the same embryo,
however they do not show the same physical appearances.
Appearance of the arrowhead plant.
• The terrestrial form has large arrowhead shape leaves while the aquatic form has needle
like leaves
Appearance of the Himalayan rabbit
• Himalayan rabbit normally has white fur. Its long ears, nose, tail, and lower leg limbs
have black hair because these extremities are cooler as they tend to lose heat faster.
The Himalayan rabbit’s fur grows as either black or white depending on localised
temperatures
• Appearance of hydrangea flower.
Hydrangea produces different coloured flowers depending on the acidity or alkaline of
the soil.
The Importance of genetic variation
• According to Darwin, genetic variation plays an important role in evolution. It acts as the
raw material for the process of natural selection. The choosing of the group of individuals
with better traits and survivality occur all the time and important in the environment
where changes happen regularly.
• A population without variation might have become extinct when there were abrupt
changes in the environmental condition, and this has been proved by fossil records.
• Variation allows a population to overcome the problem of unstable environmental
condition for survival.
16.2 : Selection
Introduction
Selection is a process that determines which alleles are passed on the next generation by virtue
of the differential advantages they exhibit when expressed as phenotypes. Selection operates
through the process of differential mortality and differential reproductive potential.
In his theory of evolution, Darwin states that evolution is brought about by a process which he
called natural selection. Genetic variation provides the diversity on which natural selection can
act.
Selection can also occur in the form of artificial selection whereby humans select the traits
which are desirable in plants and animals and breed only those individuals possessing the
desired traits.
Natural Selection
Natural selection is defined as a process by which individuals’ inherited needs & abilities are
more or less closely matched to resources available in their environment, giving those with

greater “fitness” a better chance of survival & reproduction. Natural Selection also refers the
tendency of organisms that possess favourable adaptations to their environment to survive and
become the parents of the next generation.
• In natural selection, favourable genes are selected & unfavourable genes are eliminated
from a population.
• Therefore, unfavourable genotypes are eliminated because the phenotypes do not have
favourable characters for survival & reproduction in the existing environment
• Natural selection favours organisms who are most adaptable in the existing
environment.
• These selected organisms will produce the most number of offspring, thereby
contributing the most to the gene pool.
There are three kinds/modes of natural selection:
• Stabilising selection
• Directional selection
• Disruptive selection
To explain these 3 modes of selections, we need to refer to the normal distribution curve for
continuous variation in a population.In a normal distribution curve, we can identify 3 groups of
phenotypes (2 extreme groups & one intermediate group).The ‘min’ in the curve symbolises the
phenotype most adaptable to the existing environment as long as the environmental conditions
are stable.For a natural population, the environment determines the type of selections.
Min
Intermediate
group
Extreme
group

NORMAL DISTRIBUTION CURVE
a) Stabilising selection
• Stabilising selection favours the intermediate phenotype and tends to eliminate the
extreme phenotypes (extreme groups) from the population.
• Environmental pressure act to eliminate the two extreme groups. The intermediate
group is selected.
• This will cause the normal frequency distribution curve to become narrower.
• Stabilising selection happens in a population that is well adapted to its environment.
When a species adapt itself to the specific environment and the environment does not
change, then stabilizing selection will act to maintain that species. It does promote to
maintain phenotypic stability within the population from generation to generation.
eg. 1: Human birth weight .Based on extensive data from hospitals, it has been
determined that infants born with intermediate weights are more likely to survive.
• The majority of human birth weights are in the 3-4kg range. For babies much smaller or
larger than this, infant mortality. Infants at either extreme (that is, too small or too large)
have higher death rates.

• When infants are too small, their body systems are immature, whereas infants that are
too large at birth have difficult deliveries because they cannot pass as easily through the
birth canal.
• Stabilizing selection operates to reduce the variability in birth weight so that it is close to
the weight with the minimum mortality rate.
eg. 2: Stabilising selection in a forest. The tallest plants are easier to fall when blown
by the wind, while the lowest plants have a problem of getting sunlight. Finally the trees
with the average height will be favoured in a forest.
b) Directional selection
• Direction selection favours individuals on one end of the phenotypic extreme and
results in a shift of the min either to the right or to the left.
• It occurs in response to changes in the environment. Environmental changes favor
the selection of more suitable phenotypes, causing the normal distribution to shift.
eg: 1. Industrial melanism for Biston bitularia (peppered moth).
• White and black peppered moths are a classic example of natural selection in
action.
• The case has been documented in England since 1850.

• The tree trunks in a certain region of England were once white because of a type of
fungus, a lichen, that grew on them.
• The common peppered moth was beautifully adapted for landing upon these white
tree trunks because its light color blended with the trunks & protected it from
predacious birds.
• At that time black moths were rare.
• Then the industrial revolution came along in the 19th century.
• Airborne pollution in industrial areas mottled the birch tree bark with soot, and now
the mutant black-peppered moths blended better against the darkened bark, while
the white variety became much more vulnerable to predators.
• Over time the mutated black peppered moths were naturally selected to survive and
became far more numerous in urban areas than the pale variety.
eg.2 : The long neck of the giraffe is thought to have evolved in this way. Probably
when food was in short supply, only the tallest individuals could reach enough food
to survive. They passed on their genes to the next generation.
c) Disruptive selection
• Disruptive selection is a form of natural selection in which the two extreme types are
selected but act against the intermediate group.
• Disruptive selection occurs when environmental conditions fluctuate between 2
opposite extreme values (eg: weather fluctuation between very cold & very hot
conditions).
• The fluctuation favours both the extreme groups.
• This causes the presence of two distinct groups or the existence of polymorphism

• Environmental changes favor the selection of more suitable phenotypes at both
extremes of the normal distribution, causing a split
Eg: Limited foods supply during a severe drought caused a population of Galapagos
finches to undergo disruptive selection.
• The finch population initially exhibited a variety of beak sizes & shapes.
• Two distinctly different beak sizes occur in the population. Small-billed individual feed
mainly on soft seeds, whereas large-billed birds specialise in cracking hard seeds.
Natural selection select against intermediate sized bills, which are inefficient at
feeding both types of seeds.
Sexual selection and polymorphism
Sexual selection
Sexual selection, a form of selection in which individuals with certain inherited characteristics is
more likely than other individuals to obtain mates. Sexual selection is a special kind of natural
selection that acts on trait that help an animal increase its chances of mating and therefore
passing on its genes to future generations.There are several ways.
 Intersexual selection: also called mate choice, individuals of one sex (usually the
females) are choosy in selecting their mates from the other sex. In many cases, the
female’s choice depends on the showiness of the male’s appearance or behavior.
 Males may compete by
• ‘song’
• Displays of prominent features.
• Defending/fighting
 Intrasexual selection: meaning selection within the same sex,individuals of one sex
compete directly for mates of the opposite sex. In many species, intrasexual selection
occurs among males. For example, a single male may patrol a group of females and
prevents other males from mating with them.

eg: Peacock where the females choose males with the most interesting mating behavior
(peahen)/hens choose roosters with bright eyes and large red combs and wattles.
Polymorphism
Refer to the many different phenotypes found in a population. The condition in which a species
exists in two or more different forms within the same population is called polymorphism. The
different forms are genetically distinct from one another but are contained within the same
interbreeding population.
There are two types of polymorphism
 Balanced polymorphism
• Occurs when two or more alleles of a gene are maintained in a population
because each is favored by a separate environmental force.
• Example: the alleles for normal (H) and sickle-cell haemoglobin (h) are
maintained by selection against both homozygotes.Heterozygotes reproduce the
most, thereby keeping both alleles in the population. In areas where malaria is
endemic, people with normal haemoglobin are more susceptible to the disease.
• HH – dies of malaria
Hh – lives and reproduces
hh- dies of sickle-cell anaemia
 Transient polymorphism
• The occurrence of two (or more) forms of a species or genes (alleles) within a
population while one form is being replaced by another.
• Example: In England, there are two morphs of the moth, Biston betularia
• One form has-spotted wings and the other has black wing (melanic wings)
• In 1948, most of the Biston betularia in Manchester, England were reported to be
of the white-spotted form. During this era, the area was not polluted and the
trunks of trees had lichens growing on them. The white-spotted moths had better
camouflage when resting on tree trunks and were not spotted by predators.

• In 1995, it was reported that 98% of the moth were of the melanic form. This was
a result of the changing climate condition. Manchester had became industrialized
and pollution killed the lichens. The tree trunks were more dark and the melanic
form was better camouflaged and as such survived.
Artificial Selection
• Artificial selection involves a breeding procedure.
• The breeding procedure involves selective crosses to obtain the desired genotypes &
phenotypes.
• Man is the selection agents.
• The purpose is to produce desirable phenotype.
• Artificial selection is practiced in live-stock breeding & agriculture.
• Artificial selection is like natural directional selection. It results in changing the
frequencies of the alleles & genotypes.
• Favorable genes & genotypes are selected & their frequencies are increased.
• Artificial selection can produce new sub-species of plants & animals.
• As shown below, farmers have cultivated numerous popular crops from the wild
mustard, by artificially selecting for certain attributes.
• These common vegetables were cultivated from forms of wild mustard. This is evolution
through artificial selection

Dog Breeds: An Example of Artificial Selection
• Selecting for different traits over hundreds of years of breeding has caused different dog
breeds to have distinctive characteristics.
(d) Importance of Artificial Selection (Gene bank,Germplasm bank and Sperm bank)
Gene Bank/Germplasm Bank
• Gene bank is a storage in low temperature which preserves genetic material.
• In plants, the storage can be seed and tissue banks.It is possible to unfreeze the
material it and new plant is produced.
• In animal, the storage can be sperm and egg banks. A living female is required for
artificial insemination.
• There are many types of gene banks (seed bank/tissue bank/cryobank/pollen bank/field
gene bank).
Sperm Bank
• Animal sperm bank is the storage of sperm from animals of proven genetic stock and
used for controlled breeding.
• The sperm is collected from studs and deep frozen in liquid nitrogen.
• A human sperm bank is the storage of human sperm, usually operated by hospitals to
inseminate wives whose husbands are sterile. Therefore, the human sperm bank create
a lot of controversies.
Importance of Artificial Selection
• The evolution of plants can be studied through artificially bred crops
• It was used by Darwin and many scientists to show that artificial selection could be use
as evidence for evolution

• Artificial selection is used in selective breeding and development of crops and
domesticated animals.
• From artificial selection, scientists have used biotechnology and recombinant technology
to engineer specific plants and animals.
Question

16.2 Speciation
Learning Outcome:
a)Explain the processes of isolation, genetic drift, hybridisation and adaptive radiation;
b)Explain the importance of speciation in relation to evolution.
Teacher Guidance
1. Processes of isolation, genetic drift, hybridization and adaptive radiation
2. Importance of speciation
Speciation
Speciation refers the natural condition & producing fertile offspring. Speciation is the formation
of new species from pre-existing species.
• A species consist of one or more population whose members are capable of
interbreeding under natural condition & producing fertile offspring.
• Each species has a gene pool that is separate from that of other species, & reproductive
barriers restrict each species from interbreeding with other species
Mode of Speciation
• Allopatric Speciation-Due to geographical isolation
• Speciation that occurs when one population becomes geographically separated
from the rest of the species & subsequently evolves by natural selection and/or
genetic
• Allopatric speciation is thought to be the most common method of speciation, &
the evolution of new species of animals has been almost exclusively by allopatric
speciation.
• Sympatric Speciation
• From the Greek, ‘sym’: together & ‘patri’: native land.
• Although geographical isolation is an important factor in many cases of evolution,
it is not an absolute requirement.
• When a population forms a new species within the same geographical region as
its parent species, sympatric speciation has occurred.
• Sympatric speciation is especially common in plants.
• There are at least 2 ways in which sympatric speciation can occur:
• A change in ploidy ( the number of chromosome sets making up an
organism’s genome)
• A change in ecology.

Factors involved in the formation of new species(speciation).
(a) Processes formation of new species can be caused by various factors as follows:
Geographical Isolation
• A large population in broken up into two smaller population by geographical barrier
such as river, dessert or mountain.
• The two smaller populations (demes) are prevented meeting and breeding each
other.There is complete isolation with no gene flow between the two
demes.Differential selection pressure and random mutations will result in the
formation of new genotypes in each deme.
• After a long period of time, they are no longer able interbreed to produce fertile
offspring even when brought together
Isolation can be in many forms.
• Reproductive isolation occurs due to reproductive barriers that prevents two
species from producing fertile hybrids, thus contributing to reproductive isolation.

• There are several reproductive barriers & most species are separated by a
combination of more than one of these barriers.
Most occur before mating or fertilization (prezygotic), whereas others occur after
fertilization has taken place (postzygotic).
Prezygotic barriers include:
• Temporal isolation
• habitat isolation
• behavioral isolation
• mechanical isolation
• gametic isolation
Postzygotic barriers include:
• Hybrid inviability
When prezygotic barriers are crossed & hybrid zygote are formed, genetic
incompatibility between the two species may abort developing of the hybrid at
some embryonic stage.
e.g: nearly of the hybrids die in the embryonic stage when the eggs of a
bullfrog are fertilized artificially with sperm from a leopard frog.
• Hybrid sterility
If a interspecific hybrid does live, it may not be able to reproduce.
There are several reasons for this;
Hybrid animals may exhibit courtship behaviors incompatible with those of
either parental species & as a result, they will not mate.
e.g: A "Jaglion", (a Jaguar/Lion hybrid)
One more cause of this barrier is a failure of meiosis to produce normal
gametes in the hybrid if chromosomes of the 2 parent species differ in
number or structure.
e.g:Mules are interspecific hybrids formed by mating a female horse with a
male donkey.Although the male exhibits valuable characteristics of each of its
parents, it is steril

• Hybrid breakdown
In some cases when species cross-mate, the first generation hybrids are
viable & fertile, but when these hybrids mate with one another or with either
parent species, offspring of the next generation are feeble of sterile.
e.g: different cotton species can produce fertile hybrids, but breakdown
occurs in the next generation when offspring of the hybrids die in their seeds
or grow into weak & defective plants
Genetic drift
• Genetic drift is a random process by which the allele frequencies in the population
change over time.
• In large population, genetic drift is not noticeable. But in small subpopulation, a small
change in the gene composition of the gene pool will result in drastic changes in
gene & genotype frequency their effect is called genetic drift.

Hybridization
• Hybridization refers to offspring that are produced when two genetically different
parents mate.
• Sometimes, hybridization is followed by a doubling of the chromosome number. The
resulting organism is called a polyploidy.Hybrid are usually infertile.
Adaptive radiation
• The cases where, a species gives rise to many new species in a relatively short time,
this process is called adaptive radiation.
• It occurs when populations of a single species invade a variety of new habitats &
evolve in response to the differing environmental pressures in those habitats.
e.g: The adaptive radiation of the Galapagos finches (Darwin’s Finches)
The Galapagos Archipelago were formed from volcanic explosion (about 900km west
of Ecuador).In the beginning, there were no plants & animals on these islands.
Then later on, plants & animals from the mainland colonized these islands.
• The plants & animals changed gradually along different lines of inheritance in
evolution to become new species which basically looked similar to the plants &
animals in the mainland, but were different in certain characters.
Darwin's finches share similar size, coloration, and habits. Their salient difference is
in the size and shape of their beak

(b) Importance of Speciation in Evolution
• Isolation is the separation population either physically or reproductively.It cuts gene
flow and in the long terms results in speciation
• Hybridisation is the crossing of two different species. It creates new species straight
away after chromosome doubling.
• Adaptive radiation is the formation of new species based on the changes of
homologous structures as a result of mutations. It result in divergent evolution that fill
species to different niches
• Speciation is a non-stop process to improve adaptation of organisms for survival. It
continues after a new species is formed.
• Speciation produces biodiversity i.e more species are formed.
Question

TOPIC 17: INHERITANCE AND GENETIC CONTROL
17.1: Types of genetic crosses and breeding system
Teacher’s guidance
Assumed prior knowledge
Students should already :
 understand the meaning of chromosomes, homologous chromosomes, chromatids,
gene, allele, genotype, phenotype, dominant, recessive, homozygous dominant,
homozygous recessive and heterozygous.
 learned how homologous chromosomes and chromatids are distributed in meiosis I and
meiosis II respectively.
 learned that a dominant allele is represented by a capital letter such as R and a
recessive allele of the same gene is represented by a small letter, r.
 understand that a genotype of a homozygous dominant individual is represented by two
capital letters (RR), the homozygous recessive of the same gene by two small letters (rr)
and the heterozygous by one capital and one small letters (Rr).
 learned that the genotype of two traits are represented by different letters such as
RRWW and rrww for the double homozygous dominant and double homozygous
recessive respectively.
 know the basic principle of a monohybrid cross
Content/notes/sources/description
Learning Outcome:
a) Explain the Mendelian inheritance pertaining to the phenotypic and
genotypic ratios
b) Describe the types of crosses (test cross, backcross, reciprocal cross and
selfing) and explain their importance
c) Describe pure breeding, outbreeding, inbreeding, selective breeding, and
explain their importance

Genetic terminologies
1.Mendelian genetics
‘Transmission of genetic information from parent to offspring’
2. Character
Heritable feature (eg: flower colour)
3. Trait
Each variant for a character (eg: purple or white colour for flower)
4. Gene
A segment of DNA that serves as a unit of heredity (eg: gene for flower colour). Each
gene resides at a specific locus on a specific chromosomes
5. Alleles [alel]
- Alternative version of a gene
- One of two or more molecular forms of a gene that arise by mutation and code for
different versions of the same trait.
- Eg: a pea plant may have the purple-flower allele [P] & white-flower allele [p]
6. Locus [Lokus]
- Position of a gene on a chromosome.
- A particular gene or allele is located at a specific site within a specific chromosome.
7. Dominant allele [Alel dominan]
- An allele which affects the phenotype of a heterozygous organism just as much as
when the organism is homozygous for this allele.
- Can be expressed in homozygous or heterozygous conditions.
8. Recessive allele [Alel resesif]
- An allele which only affects the phenotype of an organism when the dominant allele
is not present
- Can only be expressed in homozygous condition.
9. Homozygous
- Having 2 identical alleles for a certain gene ( eg: PP ~ dominant homozygous; pp ~
recessive homozygous ).

10. Heterozygous [heterozigot]
- Heterozygous having two different alleles (one dominant, one recessive) of a gene
pair (eg:Pp)

Heterozygous alleles
Homozygous
dominant alleles
Different genes
11. Homologous chromosomes [kromosom homolog]
Term for the pair of chromosomes in the parental cell
12. Phenotypes [fenotip]
- Physical appearance for a certain character of an organism
- Total appearance of an organism, determined by interaction during development
between its genetic constitution and the environment
13. Genotype [Genotip]
- Genetic constitution for a certain character of an organism
- Genetic constitution of a cell or individual, as distinct from its phenotype.
Loci
Homozygous recessive
alleles

Genotype Phenotype
PP Purple flower
Pp Purple flower
pp White flower
14. Genetic constitution (for the axial flower is AA and aa, for the terminal flower) of an
organism with respect to the allele under consideration is termed as genotype. If both
alleles are dominant, AA it is termed as homozygous dominant and the other plant
homozygous recessive when both alleles are recessive, aa.
15. Parental, P1 [Induk, P1]
Parental generation in breeding work. Their offspring constitute the F1 generation
16. First filial, F1 [Filial pertama]
The first generation of hybrid offspring resulting from a cross between parents from two
different true-breeding lines
17. Second filial, F2 [Filial kedua]
The second filial generation (offspring produced from a cross between F1 individuals)
18. Back cross [kacuk balik]
Crossing between an F1 individual with one of the parents ( or with individual that has
same genotype as the parents )
Backcross
The cross of a hybrid with either of its parents (or a genetically equivalent individual)
19. Self cross
Cross involving individuals of same generation (eg: F1 x F1)
20. Monohybrid cross [kacukan monohybrid]
A cross involving parents which are heterozygous for one trait. Average ratio for all
traits studied in the monohybrid crosses is 3:1, dominant to recessive respectively
21. Hybrids [Hibrid]
A cross-bred, heterozygotic organism or cell, an individual from any cross involving
parents of differing genotypes.
22. Pure breeding[Pembiakbakaan tulen]
A group of identical individuals that are bred for many generations from members of the
same strain and always produce progeny of the same phenotype when intercrossed.

23. Cross-pollination
24. Cross-fertilised
25. Mendel’s experiment
- In a typical breeding experiment, Mendel would start by crossing 2 true breeding
individuals as P1 [eg of true breeding plant: a plant with purple flowers that produces
offspring which all have purple flowers through self-pollination]
- Mendel then tracked the heritable characters for 3 generations.
- Mendel did 2 types of crosses:
i. monohybrid cross
ii. dihybrid cross
26. Mendel’s experiments genetics on monohybrid cross
- ‘A genetic cross that takes into account the behaviour of alleles of a single gene at
a single locus’.
- The cross tracks the inheritance of only a single character

a. Mendel forwarded a hypothesis that a plant inherited two factors or alleles about
a trait, one from each parent
b. He crossed pure breeding white-flowered plants and pure breeding purple-
flowered ones. These strains are the parental, P1.
c. The progeny from such a cross are designated the F1, or first filial generation.
d. The F1 generation inherited two factors or alleles about flower colour. The
purple colour was dominant and masked the allele for white in the F1 plants.
e. Alleles are alternate forms of a gene which is the basic units of heredity
f. The F1 hybrid received a dominant allele (P) from the purple-flowered plant
(PP) and a recessive allele (p) from white-flowered (pp) one. All F1 plants were
purple-flowered (Pp)
g. When F1 generation was self-fertilised, the white trait that disappeared in F1,
reappeared in F2. The result showed ¾ of the plants had purple flowers and ¼
had white. The phenotypic ratio of purple to white is 3:1. This cross is a
monohybrid cross.
h. Mendel suggested that different alleles of a given gene segregate
independently of each other
i. On the basis of this he formulated his first law, the Law of Segregation and
restated in modern term.

- Phenotypic ratio of F2 (when heterozygous F1 plants were self-crossed) is 3:1 while
genotypic ratio is 1:2:1
- A Punnet square can be used to determine the combination of alleles in a
monohybrid cross

27. In a monohybrid cross an individual can receive only one allele from each parent.
28. - Based from the monohybrid cross, Mendel proposed the law of segregation:
‘the two alleles for a heritable character separate during gamete formation and
end up in different gametes’
29. Law of Segregation [Hukum Segregasi]
Mendel’s first law, stating that allele pairs separate during gamete formation, and then
randomly reforms as pairs during the fusion of gametes at fertilization. A certain
characteristic of an organism is determined by an internal factor which occurs in pairs.
Only one of such factor is received by a gamete. In modern terms: the law stated as “A
certain characteristic of an organism is determined by a gene which occurs as a pair of
alleles on a pair of homologous chromosomes. During meiosis, the two alleles separate
or segregate independently and only one allele is received by a gamete.
30. This corresponds to the distribution of homologous chromosomes to different gametes
in meiosis

31. Mendel went one step further by considering how two traits are inherited relative to
each other. He performed dihybrid crosses between plants that differed in two
characteristics and proved experimentally that different characters are inherited
independently of one another.
32. Mendel used a test-cross in which a plant of unknown genotype is crossed to a
homozygous recessive for the trait in question.
33. Testcross [kacuk uji]
- Experimental cross to determine whether an individual of unknown genotype that
shows dominance for trait is either homozygous dominant or heterozygous.
- Crossing between an individual of unknown genotype with a homozygous recessive
individual.
- Done to determine the unknown genotype
- Eg: Genotype for a tall pea plant may be TT or Tt
Test cross is used to determine the unknown genotype
If test cross is done on an individual which is heterozygous for one character
(eg: Tt), phenotypic ratio for the offspring will be 1:1
Alleles of the same gene

34. Reciprocal cross [kacuk salingan]
- Using male and female gametes from two different parents, alternating the source
of gametes
- A reciprocal cross involves a cross-fertilisation done twice, using the opposite
gametes.
- Both crosses in a reciprocal cross produced equal numbers of dominant and
recessive forms of trait studied
- The inheritance of the trait is thus not due to the types of gametes used but on the
alleles present in the gametes.
35. Dihybrid cross [Kacukan dihibrid]
- A genetic cross that takes into account the behaviour of alleles of genes at 2
different loci.

- The cross tracks the inheritance of 2 characters
36. Recombinants [Rekombinan]
An offspring whose phenotype differs from that of the parents
37. Mendel’s Experiments genetics on dihybrid cross
a. In a dihybrid cross Mendel studied two traits of the pea plant, such as round
yellow seeds and wrinkled green seeds
b. The round (RR) yellow (YY) seed is a homozygous dominant while the wrinkled
(rr) green (yy) seed homozygous for the recessive
c. The loci for gene R and gene Y are on different homologous pairs of
chromosomes
d. Cross-fertilization of parental plants with round yellow (RRYY) seeds and plants
with wrinkled green (rryy) may produced F1 plants all with round yellow seeds,
with a heterozygous genotype of RrYy.
e. The F1 plant receives an allele R and an allele Y from the homozygous
dominant parent and an allele r and allele y from the homozygous recessive
parent
f. When the F1 plant (RrYy) was self-fertilised the possible combination of
genotypes in the gametes were RY, Ry, rY and ry
g. In this dihybrid cross the ratio of the phenotypes in the generation was 9:3:3:1
for round yellow, round green. Wrinkled yellow and wrinkled green respectively

38. On the basis of the four phenotypes produced in F2 generation, alleles for colour and
shape of seed which have segregated independently, Mendel formulated his second
law, the Law of Independent Assortment which states: Each of a pair of contrasted
traits may be combined with either of another pair. The law could be rewritten as: Each
member of an allelic pair may combine randomly with either of another pair.
39. Genes are packaged into gametes in all possible allelic combinations, as long as each
gamete has 1 allele for each gene
This occurs as 2 pairs of homologous chromosomes can be arranged in 2 different
ways at metaphase I

40. Law of Independent Assortment [Hukum pengisihan bebas]
The genetic principle noted by Gregor Mendel, that states that the alleles of unliked loci
are randomly distributed to gametes
41. Mendel’s experiments show that a trait is determined by one gene (locus) which
consists of two alleles, one completely dominant to the other. Each individual receives
two genes (loci), one from each parent. These condition together with the random
segregation of alleles into gametes, led to the classic Mendelian 3:1 and 9:3:3:1 ratios.
42. Test cross for dihybrid
- Genotype for a tall pea plant with purple flowers may be TTPP or TTPp or TtPP or
TtPp
- Test cross is used to determine this
- If test cross is done on an individual which is heterozygous for both characters (eg:
TtPp), phenotypic ratio for the offspring will be 1:1:1:1

Question:
1. (a) Mendel discovered that the unit of heredity occurs in pairs and it segregates at meiosis.
What are these units now called?

(b) State Mendel’s first law.
(c) (i) Using appropriate symbols , what are the possible genotype of a pea plant with purple and
white flower?
(ii) Which of the above genotypes are homozygous? Heterozygous?
(iii) What gametes will each type produce?
2. Brown eyes (B) are dominant to blue eyes (b). Show genotypic and phenotypic ratios of
children from the following parental types :
(i) BB x bb
(ii) Bb x Bb
(iii) Bb x bb
3. The table below shows four traits of F2 generation of monohybrid crosses.

(a) Calculate the phenotypic ratio of the dominant to the recessive forms and determine the
average ratio.
(b) If Y represents the allele for yellow seed colour, what are the possible genotype for the
(i) Yellow seed
(ii) Green seed
4. The diagram below shows a parental cross between pea plants with green pod and yellow
pod. The yellow pod is recessive to the green.

(a) Fill in the circles 1 to 4 with the appropriate letter or letters to represent each genotype.
(b) (i) What is process L and M?
(ii) What is the phenotype of the F1 generation which is represented by P?
(c) Show the cross between the F1 generations. What is the genotypic and phenotypic ratio of
the F2 generation?

Topic 17: Inheritance and Genetic Control
17.2: Non-Mendelian inheritance
Assumed prior knowledge :
 Students should already know :
 common genetic terminologies
 Mendel's monohybrid and dihybrid ratios
 Mendel's first and second laws.
 Know the various terms used in genetics such as genes, alleles, dominant alleles,
 recessive alleles, homozygote, heterozygote, phenotypes and genotypes.
 Know the concept of monohybrid and dihybrid crosses.
 Know the ratios of monohybrid and dihybrid crosses.
Common genetic terminologies
1. Codominance [kodominan]
Condition in which two alleles of a locus are expresses in a heterozygote.
2. Quantitative variation [variasi kuantitatif]
Variation measured on a continuum (height in human beings) rather than in discrete
units or categories. The existence of a range of phenotypes for a specific character,
differing by degree rather than by distinct qualitative differences
3. Polygenes [Poligen]
Genes, at more than one locus, variations of which in a particular population have a
combined effect upon a particular phenotypic character (said to be determined
polygenically, or to be a polygenic character)
4. Autosome [Autosom]
Any eukaryotic chromosome that is not a sex chromosome; autosomes are present in

the same number and kind in both males and females of the species.
5. Carrier [Pembawa]
An individual heterozygous for a recessive character and who does not therefore
express it, but half of whose gametes would normally contain the allele for the character.
6. Pedigree analysis [Analisis Pedigri]
The study of inherited trait in a group of related individuals to determine the pattern and
characteristics of the trait, including its mode of inheritance, age of onset, and
phenotypic variability
For Mendelian inheritance, each character is determined by 1 gene, each consists of only 2
alleles (dominant & recessive). But these conditions are not met by all heritable characters such
as those involving:
i. incomplete dominant allele
ii. codominant allele
iii. multiple alleles
i. Codominance is the distinct phenotypic expression of both alleles of a gene
 An example of codominance is seen in the MN blood group in humans (M and N is an
antigen type)
• 2 alleles are codominant when both alleles are fully expressed in heterozygous
• Eg: inheritance of human MN blood group
- 3 blood groups : M, N & MN
- M individuals are homozygous for allele M
- N individuals are homozygous for allele N
- MN individuals are heterozygous (MN)
• Phenotypic ratio for F2 (when heterozygous F1 individuals are self-crossed) is 1:2:1
 Codominance produces an F2 generation exhibiting a 1:2:1 ratio for both genotype and
phenotype

ii. Incomplete dominance is the expression of an intermediate phenotype caused by a pair of
allele where neither is dominant
 An example of incomplete dominance can be seen in the inheritance of flower colour in
snapdragons (Antirrhinum). When snapdragons are crossed with white snapdragons, all
the F1 offspring show an intermediate pink coloured flower.
 Incomplete dominance produces an F2 generation exhibiting a 1:2:1 ratio for both
genotype and phenotype (as there is no dominance, the phenotypic ratio is identical to
the genotypic ratio)

iii. Multiple alleles occur when a gene (locus) has more than two alternative alleles
 An example of multiple alleles is the ABO blood group in humans where the alleles IA.
IB
,
and i produce four blood groups: A, B, O and AB.
o Allele IA
causes production of antigen A on red blood cells
o Allele IB
causes production of antigen B on red blood cells
o Allele i causes no production of antigen on red blood cells

o Allele IA
and IB
are codominant and i is recessive to both

 Mendel’s research was able to identify that monohybrid crosses produced a phenotypic
ratio of 3:1 and dihybrid crosses produced a phenotypic ratio of 9:3:3:1
 However, in other investigations, the ratio obtained differ from the expected ratios.
Studies shown that these deviation can be due to linked genes, sex-linked genes, lethal
genes, epistasis and polygenes
 Mendelian Genetics does not always govern the inheritance of characteristics from one
generation to another
 Lethal genes
 Lethal genes occur when a combination of alleles in an individual result in its death
before or shortly after birth
 An example of a lethal gene can be seen in the allele for yellow fur colour in mice where
YY individuals die before birth
 2 types:
- dominant lethal gene (cause death even in heterozygous condition)
- recessive lethal gene (cause death only in homozygous condition)
• Eg: inheritance of coat colour in rodents
- Y allele : dominant for coat colour (yellow) but it is also a recessive
lethal gene
- y allele : recessive for coat colour (grey)
- when yellow-coated rodents are self-crossed, phenotypic ratio for F1 is 2:1

 Clear-cut differences in allele expression which show no intermediate form and no
overlap between the phenotypes is known as discontinuous variation
 In contrast, continuous or quantitative variation in allele expression results in numerous
forms ranging from one extreme to another
 Continuous variation is often a result of control by polygenes, i.e. many genes
 Although polygenes show continuous variation, the individual genes are inherited in
accordance with Mendelian laws.
 The characters studied by Mendel showed independent assortment because they were
determined by genes located on different chromosomes
 Chromosomes are made up of linear sequences of genes linked together, which cannot
behave or segregate independently of one another in their inheritance
 Genes (Loci) which are found on the same chromosome are said to be linked genes
 Crossing over is a process of exchange between homologous chromosomes, which
gives rise to new combination of traits and it is the only way in which linked genes are
separated

 In many organisms such as humans and other mammals, the sex (male or female) of an
individual is determined by specific chromosomes known as sex chromosomes, the X
and Y chromosomes
 Most parts of each sex chromosome contain genes which have no corresponding alleles
on the other type of sex chromosome
 Genes located on the sex chromosomes are known as sex linked genes and the
inheritance pattern they display is known as sex-linkage
 The inheritance of sex-linked genes is different from the inheritance of genes on the
autosomal chromosomes
 Examples of sex linkage are white eyes in Drosophila and haemophilia in humans
i. inheritance of body colour & wing size in Drosophila
- genes for both characters are linked
- allele for grey body : B and black body: b
- allele for normal wings: V and vestigial wings : v
 Epistasis
 Epistasis is a form of genetic interaction in which a gene at one locus masks or
suppresses the expression of another gene at a different locus
 The different coat colour in mice, agouti, black and albino, is due to the interaction of two
gene loci. One gene controls the distribution of melanin pigment, the other determines if
melanin is produced at all
 When at least, one dominant allele of this second gene is present (CC or Cc), the agouti
and black phenotypes can be expressed. When the second gene is in the homozygous
recessive form (cc), no pigment is formed and the mice are albino.
 Pedigree analysis
Construction of family tree in order to study the genetic interrelationships of parents and
children across the generations
Useful to study the inheritance of genes in humans as - generation span is about 20
years
- produce relatively few offspring
- well-planned breeding experiments are impossible
Symbols are used to represent different aspects of pedigree

 (www.ncbi.nlm.nih.gov/booksNBK21257/)

17.3 : Genetic mapping
Assumed prior knowledge :
 Students should already :
 Understand the concept of linkage of genes
 Know the sequence of events that takes place in meiosis
 The discovery of linked genes and recombinant due to crossing-over, led to a method for
constructing genetic maps, an ordered list of genetic loci along a particular chromosome.
 The frequency of recombinant gametes is directly related to how far apart two genes are
on the chromosome.
 Recombination = Number of recombinants
frequency Total number of offspring
 Genes that are further apart, have a greater chance of a cross-over occurring between
them during meiosis. This is reflected in a higher frequency of recombinant gametes.
Learning Outcome:
(a) explain
(i) incomplete dominance (flower colour in snapdragon),
(ii) codominance (MN blood group in humans),
(iii) multiple alleles (ABO blood group in humans), and calculate the
genotypic and phenotypic ratios;
(b) explain lethal genes (sickle-cell in human/coat colour in mice/chlorophyll
production in maize), polygenes (height in humans), linked and sex-linked
genes (Drosophila eye colour and haemophilia in humans), and epistasis
(coat colour in dog and capsule shape in shepherd’s purse plant);
(c) explain the pedigree analysis.
X 100

 A relatively large percentage of recombinant offspring in a testcross indicates that the
genes are relatively far apart on the chromosome.
 A low percentage of recombinant offspring in a testcross indicates that the genes lie
close together
 The distance between genes can be expressed in ‘map units’. One map unit is
equivalent to a 1% recombination frequency.
 Chromosome maps are constructed by directly converting the cross-over value or
frequency (COV) between genes into hypothetical distances along the chromosome.
 Cross-over value or frequency (COV) will not only indicate the distance between two
genes, it also indicate the linear sequence of the genes.
 In practice, it is usual to determine cross-over values of at least three genes at once in
order to establish a linear sequence.
 To calculate the sequence and distances between the genes, a line is drawn to
represent the chromosome and the following procedure is carried out:
1. Insert the position of the genes with the least COV in the middle of the
chromosome
2. Examine the next largest COV, and insert both possible positions of
the new gene on the chromosome, relative to the gene in the middle of
chromosome.
3. Repeat the procedure for the next largest COVs, until all the positions
relative to one another limited to only one possibility.
 Example:
Offspring from a test cross done on Drosophila with gray body & normal wings :
- gray body-normal wings : 965
- black body-vestigial wings : 944
- gray body-vestigial wings : 206
- black body-normal wings : 185
Recombination frequency = 391 x 100
2300
= 17 %
:.Distance between the gene for body colour and gene for wing size is 17 map
units or 17 centimorgans

• Using recombination data, we can map numerous genes in linear arrays
[ but it does not accurately portray the precise locations of the genes ]
• Eg: P, Q, R & S genes are linked
- recombination frequencies for pairs of genes:
P and Q = 35%
P and R = 5%
R and Q = 40%
Q and S = 10%
R and S = 30%
- sequence for the genes would be:

When Drosophila flies with normal wings and grey bodies (WwGg) were crossed with flies with
vestigial wings and ebony bodies (wwgg), the progeny were as follows:
normal wing, grey body 586
vestigial wing, grey body 106
normal wing, ebony body 111
vestigial wing, ebony body 465
1. (a) What is the cross over value (COV)? Show your working.
(b) What is the distance between genes W and G on the chromosome?
2. The COV can be used to locate the relative positions of genes on chromosomes. By
convention, 1% COV is equivalent to one map unit. Below are the results of breeding
experiments involving three genes A, B and C:
COV
A and B 14%,
A and C 20%
B and C 6%. 
Draw a linkage map to show the position of genes A, B and C on a chromosome.
Answer:

17.4 : Population genetics
Assumed prior knowledge:
Students should already:
. Know the concept of genes, alleles, and gametes, Punnett square.
. Know the concepts of Mendelian genetics such as segregation, independent
assortment, dominant and recessive traits, linked and sex-linked traits.
Content/notes/sources/description:
 A population is a group of individuals of the same species living in a particular habitat.
 In population genetics, the gene is considered as the unit of evolution
 The sum total of all the genes in a population at a given time is known as gene pool
 Gene pool concept:
o Studies the change of frequencies of alleles within a population
o Population - a group of individuals of the same species that live in a habitat &
may interbreed to produce fertile offspring
o - shares a same gene pool
o Gene pool - total aggregate of genes in a population at any one time
Learning Outcome:
(b) describe the concept of gene pool, gene/allele frequency and genotype
frequency;
(c) explain Hardy-Weinberg equilibrium(p2 + 2pq +q2 = 1 and p + q = 1), and
calculate the gene/allele and genotype frequencies;
(d) explain the conditions for Hardy-Weinberg equilibrium to be valid;
(e) describe changes in genotype frequencies in relation to evolution.

o - consists of all alleles at all gene loci in all individuals of the
population at a given time
o For a diploid species, each locus is represented twice in the genome
(homozygous / heterozygous)
o Eg: - A study was done on 10,000 rats, focusing on the fur colour
(determined by dominant allele A & recessive allele a)
- Data: AA individuals = 6,000
Aa individuals = 2,000
aa individuals = 2,000
:. Total number of alleles for fur colour
= 2(6000) + 2(2000) + 2(2000)
= 20000
o Each of the allele types has a relative frequency in the gene pool
o Allele frequency: ratio of any given allele in a population, relative to all the other
alleles of that gene at the same locus
o Eg: - Using the previous data, calculate the allele frequencies for A&a
in the gene pool
- Total of A alleles = 2(6000) + 1(2000)
= 14000
- Total of a alleles = 2(2000) + 1(2000)
= 6000
- Frequency for A alleles = 14000 / 20000
= 0.7
- Frequency for a alleles = 6000 / 20000
= 0.3
o For a gene locus where only 2 alleles occur in a population, allele
frequencies can be calculated using this equation :
p + q = 1
p = frequencyof the dominant allele
q = frequencyof the recessive allele
If q = 0.3, p = 1 – 0.3 = 0.7
o Allele frequencies in a gene pool determine the genetic change for a
population
o Naturally, the composition of a gene pool may change over time due to
certain factors
Change in allele frequencies

Change in gene pool
Change in genetic composition of population
Evolution
o If no change in allele frequencies from one generation to the next, the gene
pool is considered static
o This shows that the gene pool is in genetic equilibrium
o HARDY-WEINBERG Law
o Describes a population in genetic equilibrium
o The frequencies of alleles and genotypes in a population’s gene pool
remain constant over the generations with assumptions that:
i. Population size is large
[ for a small-sized population, fluctuations in the gene pool
can cause genotypic frequencies to change over time]
ii. There is random mating / fertilization
[ if individuals choose mates only with certain traits,
frequencies of certain alleles may change ]
o This law describes a non-evolving population
o Naturally, the conditions for the law of Hardy-Weinberg are rarely met
o Related to allele frequencies are the genotypic frequencies
o Genotypic frequency is the ratio of individuals with certain genotype in a
population
o Hardy-Weinberg equations are used to estimate the frequencies of alleles &
genotypes in a population which is in genetic equilibrium
o Related to allele frequencies are the genotypic frequencies
o Genotypic frequency is the ratio of individuals with certain genotype in a
population
o Hardy-Weinberg equations are used to estimate the frequencies of alleles &
genotypes in a population which is in genetic equilibrium
o The equations:
p2
+ 2pq + q2
= 1 and p + q = 1
p2
= genotypic frequencyof homozygous dominant
2pq = genotypic frequencyof heterozygous
q2
= genotypic frequencyof homozygous recessive
p = frequencyof dominant allele
q = frequencyof recessive allele
o Question 1

o Resistance toward a type of pesticide for a population of rats is controlled
by dominant allele, R. 64% of the rat population show the resistance.
o a) Calculate the frequency for R allele.
o Assume that the population is in genetic equilibrium and
o p2
+ 2pq + q2
= 1 while p + q = 1
o 36% of rat population are homozygous recessive (rr).
o Genotypic frequency for homozygous recessive (rr), q2
= 0.36
o Frequency for recessive allele (r), q = √0.36
o = 0.6
o Frequency for dominant allele (R), p = 1 - q
o = 1 – 0.6
o = 0.4
o
b) Calculate the number of rats with genotypes RR, Rr and rr for a
population of 200 rats.
o It is already known that p = 0.4 and q = 0.6
o Genotypic frequencyfor homozygous dominant (RR), p2
= (0.4)2
o = 0.16
o Number of rats with genotype RR = 0.16 x 200
o = 32
o Genotypic frequencyfor heterozygous (Rr), 2pq
o = 2(0.4)(0.6)
o = 0.48
o Number of rats with genotype Rr = 0.48 x 200
o = 96
o Genotypic frequencyfor homozygous recessive (rr),
o q2
= 0.36
o Number of rats with genotype rr = 0.36 x 200
o = 72
o Question 2
o For a population of Shorthorns, the following data was obtained:
o
o Calculate the frequencies for alleles CM
and CP
.
o ans:
o Total number of individuals for the population = 308
o Frequencyfor allele CM
= 2(110) + 150
o 2(308)
o = 0.6
o Frequencyfor allele CP
= 2(48) + 150
o 2(308)
o = 0.4

 The genotype frequency is the fraction, usually expresses as a decimal, of a given
genotype in a given population
 It is customary to describe the gene pool of organisms in terms of gene or allele
frequencies
 Evolution is considered as a permanent change in allele frequencies within a population
 The frequency of the dominant allele is represented by the letter p and the frequency of
the recessive allele is represented by the letter q:
p + q = 1
 Using the equation developed by Hardy and Weinberg, the allele frequencies can be
calculated.
 The Hardy-Weinberg equation is
P2
+ 2pq + q2
= 1
Where,
P2
is the frequency of homozygous dominant individuals in the population
2pq is the frequency of heterozygous individuals
q2
is the frequency of homozygous recessive individuals
 The allele frequencies can be calculated from the number of homozygous recessive
individuals in the population. The number of homozygous recessive individuals gives us
q2
.
 From this, q is obtained by taking the square root of q2
and this gives the frequency of
the recessive allele. The frequency of the dominant allele, p, can be obtained by
substituting the value of q into the equation p + q = 1
 Genotype frequency can be obtained by using the Hardy-Weinberg equation.
 Hardy-Weinberg equilibrium states that the frequencies of dominant and recessive
alleles will remain constant from generation to generation provided certain conditions are
met.
 These condition are:
i. large population size
ii. random mating
iii. no migration
iv. no mutations
v. no natural selection
 If any of these conditions are not met, the population will experience deviations from the
stability predicted by the Hardy-Weinberg equilibrium. In other words, evolution occurs.
Question:
1. Define the terms below.

(a) Population
(b) Gene pool
(c) Genotype frequency
(d) Gene
(e) Evolution
(f) Allele frequency
(g) Gene flow
2. (a) (i) There are two equations involved in population genetic. Describe briefly
these two equations.
(ii) State the use of these two equation
(b) (i) State the Hardy-Weinberg equilibrium
(ii) List down the conditions in which the Hardy Weinberg equation can be
applied.
(iii) Predict what would happen to the population if any of the conditions in (b)
(ii) is not met.
3. (a) In a human population, there are 60% gene H and 40% gene h. Calculate the
percentage of HH genotype.
(b) In a stable population, 64% individuals have rr genotypes. Calculate the
frequency of R gene in their parental population.
(c) In a human population, the frequency of the homozygous recessive genotype is
0.09. Calculate the frequency of the homozygous dominant individuals.
(d) In a population of ladybirds, the genotype and phenotype for body colour are as
follows :

Genotype Phenotype Number of individuals
RR red 200
RW orange 300
WW  yellow 100
Calculate the frequencies of R and W alleles.
(e) In a human population one person in 3000 suffers from cystic fibrosis. The condition is
controlled by a single gene with two alleles. People who have the dominant allele F, do not
suffer from this condition. People with the genotype ff suffer from cystic fibrosis. If one in 3000 is
a sufferer, then one in 3000 must have the genotype ff.
(i) Calculate the frequency of the recessive allele and the dominant allele.
(ii) Calculate the frequency of the genotype in the population.
ANSWER:
1. (a) Population is a group of the same species living in a particular habitat.
(b) Gene pool is the sum total of all the genes in a population at a given time.
(c) Genotype frequency is the fraction of a given genotype in a given population.
(d) Gene is considered as the smallest physical unit of heredity encoding a molecular
cell product.
(e) Evolution is considered as a permanent change in allele frequencies within a
population.
(f) Allele frequency is the relative proportion of the particular allele in a population.
(g) Gene flow is the transfer of alleles due to the movement of individuals or gametes
into or out of a population
2.(a) (i)The first equation applies to alleles : p + q = 1.0 
Where, the letter p represents the frequency of the dominant allele, whereas q
represents the frequency of the recessive alleles. 1.0 represents the total frequency of
all alleles of this gene.
The second equation applies to genotypes : p
2
+ 2pq + q
2
= 1

Where; p
2
= frequency of the homologous dominant individuals.
2pq = frequency of the heterozygous individuals.
  q
2
= frequency of the homozygous recessive individuals.
1.0 = the total population
(ii) The two equations can be used to find out the frequency of both alleles and
genotypes in a stable population.
(b) (i) The Hardy-Weinberg equilibrium states that the frequency of dominant and
recessive alleles in a population will remain constant for generations provided
certain condition exist.
(ii) - The population is large
- No mutation are occurring
- Mating is random
- No migration is taking place
- No natural selection  
(iii) The population will experience deviations from the state of equilibrium. In other words,
evolution will occur.

Title : Taxonomy and Biodiversity
14.3 Biodiversityin Malaysia
Learning outcome:
(c) Describethedifferentlevelsandexamplesof biodiversityin Malaysia,namelyecosystemor
communitydiversity,speciesortaxonomic diversity andgeneticdiversity
(d) Explaintheimportanceofbiodiversityin Malaysia.
1. Ecosystem diversity, species diversity, taxonomic diversity with example
a. Ecosystem /community diversity
 The different habitats, that support species (eg: National Park, tropical land
forest, rivers, streams, etc)
 Terrestrial ecosystem, mangrove swamps, aquatic ecosystem
 Ecosystem consists of living and non-living organisms which interact with each
other.
b. Species /taxonomic diversity
 The number of different species present in a community.
c. Genetic diversity
 The heritable variation among members of a population
 Genetic variation arises by gene and chromosome mutations or by sexual
reproduction
2. Importance of biodiversity in Malaysia
a. Natural resources for food
b. Source of industrial products, medicines and timber.
c. Reservoir of genetic information
d. Maintain recycling water and nutrient.
e. Stabilising the weather
f. Cleaning the air and water
g. Maintain sol fertility
h. Aesthetic value for recreation.

Question
1. Explain the importance of mangrove forest to the human.
2. Explain the difference levels of diversity in Malaysia
Title:17 InheritanceandGeneticControl
17.5 DNAreplication
Learning outcome:
(a) ExplaintheexperimentstoproveDNAisthe
geneticmaterial(Avery,MacLeodandMcCartyexperimentandHersheyandChaseexperiment)
(b) ExplainthethreemodelsofDNAreplication,and interprettheexperimentofMeselsonandStahl to
provethesemi-conservativemodelofDNA replication
(c) ExplainthemechanismofDNAreplication,and theroleoftheenzymesinvolved.
1. Griffith’s transformation experiments
Question : Can a genetic trait be transmitted from one bacterial strain to another?
Hypothesis : The ability of pneumococcus bacteria to cause disease can be transmitted from
the virulent strain (smooth, S cells) to the virulent strain (rough, R cell)
Experiment : Griffith performed four experiments on mice, using the two strains of
Pneumococcus

Griffith's experiment discovering the "transforming principle" in pneumococcus bacteria.
Griffith's experiment, reported in 1928 by Frederick Griffith,[1]
was one of the first experiments
suggesting that bacteria are capable of transferring genetic information through a process
known as transformation.[2][3]
Griffith's findings were followed by research in the late 1930s and
early 40s that isolated DNA as the material that communicated this genetic information.
Pneumonia was a serious cause of death in the wake of the post-WWISpanish influenza
pandemic, and Griffith was studying the possibility of creating a vaccine. Griffith used two
strains of pneumococcus (Streptococcus pneumoniae) bacteria which infect mice – a type III-S
(smooth) and type II-R (rough) strain. The III-S strain covers itself with a polysaccharide capsule
that protects it from the host's immune system, resulting in the death of the host, while the II-R
strain doesn't have that protective capsule and is defeated by the host's immune system. A
German bacteriologist, Fred Neufeld, had discovered the three pneumococcal types (Types I, II,
and III) and discovered the Quellung reaction to identify them in vitro.[4]
Until Griffith's
experiment, bacteriologists believed that the types were fixed and unchangeable, from one
generation to another.
In this experiment, bacteria from the III-S strain were killed by heat, and their remains were
added to II-R strain bacteria. While neither alone harmed the mice, the combination was able to
kill its host. Griffith was also able to isolate both live II-R and live III-S strains of pneumococcus
from the blood of these dead mice. Griffith concluded that the type II-R had been "transformed"
into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S
strain bacteria.
Today, we know that the "transforming principle" Griffith observed was the DNA of the III-S
strain bacteria. While the bacteria had been killed, the DNA had survived the heating process

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