life sciences

1. UNIT 11

2.  Biodiversity refers to the total number of
species found in an area.
 Includes the large variety of species, different
ecosystems and genetic differences.
 Endangered species: species in danger of
extinction
 Threatened species: species likely to become
endangered in the near future

3. ENDANGERED
SPECIES
THREATENED
SPECIES
GOPHER
TORTOISE
BALD
EAGLE
GRAY
WOLF
BLACK
BEAR
HAWKSBILL
SEA TURTLE
ARMOURED
SNAIL
SNOW
LEOPARD

4.  Ecologists describe biodiversity as an
attribute of three other levels of biological
organization:
◦ Genetic diversity: variation among members of a
population, higher genetic diversity – higher chance
of survival.
◦ Community diversity: community composition,
increases the levels of biodiversity.
◦ Landscape diversity: a group of interacting
ecosystems within one landscape.

5.  Biodiversity not
evenly spread
throughout
biosphere
◦ Protecting some areas
will save more species
than protecting other
areas
 Regions of the world
are called
biodiversity hotspots
◦ Contain unusually large
concentrations of
species
CAPE REGION

6.  INDIGENOUS
SPECIES
 Occurs in a place
naturally
 Native
 A species can be
indigenous to a
number of places at
once
 ENDEMIC SPECIES
 Occurs naturally
only in that place.
 Native to an
exclusive or limited
area.
 Not widely
distributed – won't
be found naturally
anywhere else.
e.g. Madagascar Flying Fox
endemic to Madagascar

7.  More than a million species of living
organisms discovered and described
◦ Estimated ±30 million species still to be discovered
 Scientists involved in describing species are
called taxonomists

8.  Plant & animal species identified exhibit great
deal of variation
◦ In form, structure, mode of life & other aspects
 Plants & animals need to be divided into
discrete groups based on the differences
◦ In order to study them.

9.  Classification: the scientific practice of
identifying, naming and grouping of living
organisms.
 Branches of biology that deal with
classification:
◦ Taxonomy deals with describing and naming
organisms.
◦ Systematics deals with grouping and arranging the
described taxa into a hierarchical classification.

10.  Makes studying living organisms convenient.
 Helps in specific identification of an organism.
 Study of a few representatives from each distinct
group helps to integrate idea of life as a whole.
 Reveals relationships among various groups of
organisms.
 Provides information about plants and animals
occurring in specific geographical regions.
 Indicates evolutionary relationship
◦ Establishing gradually increasing complexity of form and
structure in different groups of organisms.

11.  ARISTOTLE (Greek philosopher)
◦ 1st to classify organisms
◦ Either as plants or animals
◦ He formulated the 2 kingdom system = Plantae
and Animalia
◦ Plant group subdivided into 3 smaller groups:
shrubs, herbs, and trees.
◦ Animals subdivided into groups according to
where they lived: on land, water or in the air.

12.  Ernest Heackel
 Proposed adding a third kingdom = Protista
 Robert Whittaker (1969)
 Expanded the classification system to five
kingdoms
 Organisms were placed in these kingdoms based
on type of cell, complexity, and type of nutrition
 All prokaryotes were placed in the monera
kingdom.
◦ Organisms without a membrane bound nucleus

13.  Carl Woese (1970)
 Proposed 2 groups of prokaryotes after
researching the rRNA
◦ Bacteria
◦ Archaea
 These also fundamentally different from each
other
 Should be assigned to separate domains
◦ (higher classification category than a kingdom).
 Thus formulated a 3 domain system =
Bacteria, Archaea and Eukarya

15. Linnaeus’s System
 Carolus Linnaeus (Swedish Botanist)
developed a method of classifying organisms
properly.
 Based on classifying according to physical &
structural similarities.
◦ E.g. he might use the similarities in flower parts as
a basis for classifying flowering plants.
 Became foundational way for today’s modern
classification systems.

16.  Modern classification systems use a two-word
naming system called Binomial Nomenclature
◦ Bi: two
◦ Nomial: associated with a name
 Species is given a unique and stable name
 Meant that each species is composed of two
Latinised words (similar to name & surname)
1. Genus
2. species

17.  First word identifies the genus name of the
organism.
 A genus (plural form = genera) consists of a
group of similar species.
 Second word, the species, often describes a
characteristic of the organism.
 Scientific name = the Genus name + species
name

18.  Example: Homo sapiens (wise man)
 Note:
 Genus name begins with capital letter
 Species name begins with lower case letter.
 Both names are always italicized or
underlined
 Example: Sutherlandia frutescens or
Sutherlandia frutescens

19.  Latin is the language of scientific names
 Many organisms have common names just
like you might have nicknames.
 Example:
◦ Sutherlandia frutescens (scientific)
◦ Cancer bush / Kankerbos (common)
 Accepted by speakers of all languages
 Each name applies only to one species
 Each species has only one name

20.  A Kingdom is the largest group in the
classification system
 Encompasses all the related species
 Living organisms are subdivided into 5 major
kingdoms:
◦ MONERA
◦ PROTISTA
◦ FUNGI
◦ PLANTAE
◦ ANIMALIA
◦ (Organisms cannot belong to more than one)

21.  Kingdom Monera
 Consists of all bacteria – simple, single celled
organisms with no nucleus

22.  Kingdom Protista
 Consists of single celled or simple multi-
cellular organisms
 Some obtain energy by photosynthesis –
algae.
 Some ingest other organisms
 Some absorb molecules through the cell
membrane
 E.g. Amoeba, Euglena.

23.  Kingdom Fungi:
 Single celled –e.g. yeast- to multi cellular
organisms
 Body composed of very fine threads –
saprophytic nutrition

24.  Kingdom Plantae:
 Plants
 Multi cellular terrestrial organisms
 Cells have cell walls, obtain energy through
photosynthesis
 Kingdom Animalia:
 Animals
 Multi cellular, aquatic and terrestrial organisms
 Cells have no cell wall, feed on other organisms