The document provides information about biology topics including plant and animal cell structure, diffusion and osmosis, photosynthesis, respiration, enzymes, genetics, and homeostasis. A typical plant cell contains a cell wall, cell membrane, nucleus, vacuole, cytoplasm, and chloroplasts. A typical animal cell contains a nucleus, mitochondria, cell membrane, and cytoplasm. Diffusion is the passive movement of particles from an area of high concentration to low concentration, while osmosis is the diffusion of water through a selectively permeable membrane. Photosynthesis requires carbon dioxide, water, chlorophyll, and sunlight to produce glucose and oxygen. Respiration uses glucose and oxygen to produce energy, water, and carbon dioxide. Enzymes are

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Biology 2Biology 2
AQA Additional ScienceAQA Additional Science

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A typical plant cell:A typical plant cell:
Cell wall – made
of cellulose which
strengthens the cell
Cell membrane
– controls what
comes in and out
Nucleus – controls
what the cell does and
stores information
Large vacuole –
contains sap and
helps support the
cell
Cytoplasm –
Chemical reactions
happen here
Chloroplasts (containing
chlorophyll) – this is needed
for photosynthesis

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4)
1)
5)
3)
A Typical Animal CellA Typical Animal Cell
Ribosomes – protein
synthesis happens here
Mitochondria -
energy is released
here
Cell Membrane –
controls what
comes in and out
Cytoplasm - this is
where the reactions
happen and these are
controlled by enzymes
2) Nucleus –
controls the
cell’s activities

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More specialised animal cellsMore specialised animal cells
Red Blood Cell
Carriesoxygen around thebody
No nucleusand largesurface
area
I.D:
Function:
Features:
White blood cell
Egg cell (ovum)
Ciliated
epithelial cell
Nerve cell
(neurone)

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DiffusionDiffusion
Diffusion is when something travels from an area of high
concentration to an area of low concentration. For example,
consider the scent from a hamburger…
The “scent particles” from
this hamburger are in high
concentration here:
Eventually they will
“diffuse” out into this area
of low concentration:
Oxygen passes into cells by diffusion

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Diffusion SummaryDiffusion Summary
Diffusion is when particles spread from an area of high
concentration to an area of ___ concentration. The particles
move along a “concentration _____” and this process takes no
_____ (it’s a “passive” process”). Diffusion can be accelerated
by increasing the _______ of the particles, which makes them
move _______.
Words – faster, low, gradient, temperature, energy

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OsmosisOsmosis
Osmosis is a “special kind of ___________”. It’s when water
diffuses from a __________ area to a less concentrated area
through a partially permeable _________ (i.e. one that allows
water to move through but not anything else):
Water Sugar solution
In this example the water
molecules will move from
left to right (along the
concentration ______) and
gradually _____ the sugar
solution.
Words – membrane, concentrated, dilute, diffusion, gradient

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Strong
sugar
solution
Medium
sugar
solution
Weak
sugar
solution
Potatocells

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Travels up
from the roots
WATER
CARBON DIOXIDE
Enters the leaf through small
holes on the underneath
SUNLIGHT
Gives the plant energy
CHLOROPHYLL
The green
stuff
where the
chemical
reactions
happen
Photosynthesis – the 4 things you needPhotosynthesis – the 4 things you need

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Leaf StructureLeaf Structure
Palisade
cells

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Carbon dioxide + _____ glucose + _____
6CO2 + 6H20 C6H12O6 + 6O2
Sunlight
Chlorophyll
Sunlight
Chlorophyll
The GLUCOSE produced by photosynthesis is used by the
plant for _______ (through ____________). It is stored
in the plant as ___________.
Words – respiration, starch, water, oxygen, energy
Photosynthesis equationsPhotosynthesis equations

12. 04/25/16Three factors can affect photosynthesis:Three factors can affect photosynthesis:
1. Temperature – the best temperature is
about 300
C – anything above 400
C will slow
photosynthesis right down
2. CO2 – if there is more carbon dioxide
photosynthesis will happen quicker
3. Light – if there is more light
photosynthesis happens faster

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Drawing graphs of these factorsDrawing graphs of these factors
1. Temperature
Photosynthesis is controlled by
enzymes – these are destroyed
at temperatures above 400
C
2. Carbon dioxide
3. Light
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or CO2
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or light

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What is the glucose used for?What is the glucose used for?
Glucose (sugar) can be used to make long chains of starch…
Glucose
molecules
Starch
molecule
This glucose is then used by the plant as a store of _____ and
some of it may be used for _________. The energy released
from respiration can be used to make ______ acids or to build
up fats and _____ as a food store in a _____.
Words – seed, amino, glucose, respiration, oils

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2 common nutrients…2 common nutrients…
Nitrates:
 Used to make proteins
 Lack of it leads to stunted growth
Magnesium:
 Used to make chlorophyll
 Lack of it leads to yellow leaves

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Food chainsFood chains
A food chain shows where the energy goes in a food chain (in
other words, “what gets eaten by what”):
Cabbage Rabbit Stoat Fox
The arrows indicate where
the energy is going
Plants convert the
sun’s energy into food

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Pyramids of biomassPyramids of biomass
In this food chain we can see that the mass of organisms in
each stage is less than in the previous stage:
Cabbage Rabbit Stoat Fox
We can draw a “Pyramid of Biomass” to show this pattern:
Mass of cabbages
Mass of rabbits
Mass of stoats
Mass of foxes

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Energy flow in a food chainEnergy flow in a food chain
Consider the energy flow in this food chain:
Cabbage Rabbit Stoat Fox
100% 10% 1% 0.1%
Clearly, not all of the ___’s energy that becomes stored in the
_______ will end up in the fox. Only around ______ is passed
on to the next stage in each food chain.
Energy is lost at each stage because of a number of reasons:
1) Each organism has to ____, keep warm etc
2) Energy is lost through faeces (______)
Words – 10%, move, sun, waste, cabbage

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Sankey Diagrams for animalsSankey Diagrams for animals
Cold blooded animal Warm blooded animal
Faeces
Movement
Heat
Faeces
Movement
Heat

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Improving the efficiency of a food chainImproving the efficiency of a food chain
Clearly, food chains aren’t very efficient. How could the
efficiency of a food chain be improved?
1) Reduce the number of stages in the chain:
Cabbage Rabbit Stoat
2) Limit an animal’s movement
or keep it warm:
Fox
3) Use plant hormones to
regulate the ripening of fruit

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Farming MethodsFarming Methods
There are basically two types of farming method; “intensive”
and “organic”:
Intensive Organic
Cost
Produce
Fertilisers/
food
Space

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Recycling ourselvesRecycling ourselves
Microbes are the key to this – they break down waste and
dead bodies so that the products can be used by plants for
growth. Microbes work best in warm, moist conditions where
there is plenty of oxygen.
Eating
Waste
Death
Broken
down
Absorption

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The Carbon CycleThe Carbon Cycle
CO2 in air
1. CO2 is taken in
by plants for
photosynthesis
and turned into
carbohydrates
2. Plants release
CO2 through
respiration
3. The carbon
taken in by plants
is then eaten by
animals
5. Animals (and plants)
die and their remains
are fed on by microbes
and detritus feeders
6. These
microbes also
release CO2
through
respiration
4. Animals
release CO2
through
respiration

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Introduction to EnzymesIntroduction to Enzymes
Enzymes are biological catalysts. They help the reactions
that occur in our bodies by controlling the rate of reaction.
An enzyme is basically a protein molecule
made up of long chains of amino acids. These
molecules are then “folded” to create a
certain shape:
The enzyme’s shape helps another
molecule “fit” into it:
This shape can be destroyed by
high temperatures or the wrong
pH:
Enzyme Substrate

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Enzyme use in natureEnzyme use in nature
Cells use glucose to generate
energy – this process is called
“respiration”. Respiration
happens in mitochodria and is
catalysed by enzymes.
Photosynthesis is
catalysed by enzymes
in the cells.

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(Aerobic) Respiration(Aerobic) Respiration
Words – breathing, energy, grow, respiration, food
All living organisms have to move, _____, reproduce etc. Each
of these life processes needs ENERGY. ___________ is the
process our bodies use to produce this energy:
Glucose + oxygen water + carbon dioxide + ENERGY
The glucose we need comes from ______ and the oxygen from
_________. Water and carbon dioxide are breathed out.
The MAIN product of this equation is _________.

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Uses for this energyUses for this energy
Animals and plants have many uses for the energy they
generate from respiration:
1) To perform the life processes, such as moving, _____ etc
2) To build up body _______
3) To maintain a constant body ___________ (warm-blooded
mammals only)
4) To build up sugars, ________ and other nutrients in plants
5) To build up amino acids and ________
Words – nitrates, tissue, proteins, respiration, growing

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Enzymes in digestionEnzymes in digestion
Enzymes can be produced by the body to help _______. When they come
into contact and react with food they break it down into ______ pieces
which can then pass into the ______:
Carbohydrase (produced in the mouth,
pancreas and small intestine) breaks
_______ (a carbohydrate) down into
glucose:
Protease (produced in the stomach,
pancreas and small intestine) breaks
_______ down into amino acids:
Lipase (produced in the pancreas and
small intestine) breaks fats (_____)
down into fatty acids and glycerol:
Words – blood, lipids, proteins, digestion, starch, smaller
Bloodstream

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Bile and The LiverBile and The Liver
Bile is a chemical produced in the
liver and stored in the gall
bladder. It has 2 functions:
1) It neutralises stomach acid
and produces alkaline
conditions for enzymes to
work in
2) It emulsifies (“breaks down”
fats:
Fat
globules
Fat
droplets

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Enzymes are
denatured
beyond 40O
C
EnzymesEnzymes
Enzymes work best in certain conditions:
Enzyme activity
Temp pH pH400
C
Could be
protease (found
in the stomach)
Could be amylase
(found in the
intestine)

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Industrial uses of enzymesIndustrial uses of enzymes
1) Enzymes are used in washing powders
to help digest fats and proteins in food
stains. Biological washing powders will
only work on 400
C or lower.
2) Enzymes are used in baby foods to
“pre-digest” the proteins.
3) Enzymes are used to convert starch
into sugar which can then be used in
food.
4) Conversion of glucose into fructose
– glucose and fructose are “isomers”
(they have the same chemical formula),
but fructose is sweeter.

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HomeostasisHomeostasis
Homeostasis means “controlling internal conditions”:
Waste products that need to be removed + how
CO2
Urea
Internal conditions that need controlling + how
Temperature
Ion content
Water content
Blood glucose
Produced by respiration, removed via lungs
Produced by liver breaking down amino acids,
removed by kidneys and transferred to bladder
Increased by shivering, lost by sweating
Increased by eating, lost by sweating + urine
Increased by drinking, lost by sweating + urine
Increased and decreased by hormones

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Controlling Body TemperatureControlling Body Temperature
Wow it’s hot!
Also, temperature sensors in the skin
detect the heat and send information
to the brain.
The thermoregulatory centre in the
brain detects “warm blood”.
When the brain detects the high
temperature it takes two main steps....

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Maintaining Body TemperatureMaintaining Body Temperature
Cold Hot
Vasodilation
Vasoconstriction

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Controlling Blood Sugar levelsControlling Blood Sugar levels
We need glucose in our bodies to help our cells to respire and
produce energy. What happens if we have too much glucose?
If blood sugar is too high the
pancreas releases insulin
The liver then converts
glucose into insoluble
glycogen and is removed
from the blood

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DiabetesDiabetes
Diabetes is a ________ in which a person’s blood sugar
(i.e. glucose) level may rise to a _______ level. This is
because the ______ doesn’t produce enough _________.
Diabetes can be treated by __________ carefully or by
injecting extra insulin when needed. Diabetics have to
test their blood sugar level before they decide how much
insulin to _______ themselves with.
Words – insulin, disease, inject,
dangerous, eating, pancreas

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Modern GeneticsModern Genetics
Guten tag! My name is Gregor Mendel.
I am the father of modern genetics
because of the work I did on pea plants
in 1865…
Take two plants; one which is
pure-bred for tallness and one
pure-bred for shortness, and
cross them:
X
Mendel’s experiment:

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Modern GeneticsModern Genetics
All the plants produced
were tall.
Now cross two of these plants…
3 out of every 4 plants
were tall, leading Mendel
to hypothesise that “for
every characteristic
there must be two
determiners”

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Modern GeneticsModern Genetics
Achtung! Unfortunately, nobody knew
about chromosomes or genes when I
published my findings so no one believed
me until after my death, when more
powerful microscopes were available.

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MitosisMitosis
Each daughter cell has
the same number of
chromosomes and genetic
information as the parent.

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MeiosisMeiosis
Each daughter cell has half
the number of chromosomes
of the parent.

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Mitosis vs. MeiosisMitosis vs. Meiosis
Mitosis:
1. Used for growth and repair of
cells
2. Used in asexual reproduction
3. Cells with identical number of
chromosomes and genetic
information are produced
Meiosis:
1. Used to produce gametes for
sexual reproduction
2. Each daughter cell has half the
number of chromosomes of the
parent

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Sexual ReproductionSexual Reproduction
The human egg and
sperm cell
(“GAMETES”) contain
23 chromosomes each
and are created by
meiosis.
When fertilisation happens the
gametes fuse together to make a
single cell called a ZYGOTE. The
zygote has 46 chromosomes (23
pairs) and continues to grow through
mitosis.

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Boy or Girl?Boy or Girl?
X Y X
XX XY
Girl Boy
“Allele”

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Father
Mother
Son
Daughter
Boy or Girl?Boy or Girl?

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Key wordsKey words
Gamete
Zygote
Allele
Dominant
Recessive
Homozygous
Heterozygous
•This allele determines the development of a
characteristic
•This is formed when an egg is fertilised by a sperm
•This allele will determine a characteristic only if
there are no dominant ones
•This word refers to a pair of chromosomes being
made of two different alleles of a gene
•An egg or a sperm are called this
•This word refers to a pair of chromosomes being
made of two of the same alleles of a gene
•An alternative form of a gene

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Genes, Chromosomes and DNAGenes, Chromosomes and DNA

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Some facts:
- Made up of paired bases
- Contain instructions on what a cell does, how the organism
should work etc
- The instructions are in the form of a code
- The code is made up from the four bases that hold the
strands together
- The bases represent the order in which amino acids are
assembled to make proteins
- Everyone (apart from identical twins) has different DNA
and people can be identified by “DNA finger printing”
How genes workHow genes work

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Eye colourEye colour
In eye colour the brown eye allele is dominant, so we call it
B, and the blue eye is recessive, so we call it b:
bbBB Bb
Homozygous
brown-eyed
parent
Heterozygous
brown-eyed
parent
Blue-eyed parent
What would the offspring have?

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Eye colourEye colour
Example 1: A homozygous
brown-eyed parent and a
blue-eyed parent:
Example 2: 2 heterozygous
brown-eyed parents
BB bbX Bb BbXParents:
Gametes:
Offspring: Bb Bb BbBb BB Bb bbbB
B B bb B bB b
(FOIL)
All offspring have brown eyes 25% chance of blue eyes

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Eye colourEye colour
Example 3: A heterozygous brown-eyed
father and a blue-eyed mother:
Bb
Bb Bb bbbb
bb
b bB b
Equal (50%)
chance of
being either
brown eyed or
blue eyed.

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B b
b
b
Another methodAnother method
Example 3: A heterozygous brown-eyed
father and a blue-eyed mother:
B b
b Bb bb
b Bb bb
Father
Mother

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Example questionsExample questions
1) In mice, white fur is dominant. What type of offspring
would you expect from a cross between a heterozygous
individual and one with grey fur? Explain your answer with a
genetic diagram.
2) A homozygous long-tailed cat is crossed with a homozygous
short-tailed cat and produces a litter of 9 long-tailed kittens.
Show the probable offspring which would be produced if two
of these kittens were mated and describe the characteristics
of the offspring (hint: work out the kitten’s genotype first).

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Inherited diseasesInherited diseases
1) Cystic fibrosis – a disease that causes thick and sticky
mucus to coat the lungs, gut and pancreas. It’s caused by
recessive alleles:
2) Huntingdon's disease – a disease of the nervous system
that causes shaking and eventually dementia. It’s caused by a
dominant allele:
Embryos can be screened for alleles that cause
these diseases before birth.
Ff FfX
Cc ccX

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Stem CellsStem Cells
A while ago we considered examples of specialised cells:
White blood cell
Egg cell (ovum)
Ciliated
epithelial cell
Nerve cell
(neurone)
A “stem cell” is a cell that hasn’t yet become specialised and
can be found in embryos or bone marrow. These cells can be
used to treat certain conditions but the use of these cells is
very controversial.

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Research tasksResearch tasks
Task
Present an argument concerning one of these two topics:
1) Use of stem cells from embryos in medical research
2) The use of embryo screening to identify deformities