This document provides information on the structure and function of various cell types including plant, animal, bacteria and human cells. It also summarizes cellular processes like photosynthesis, respiration, diffusion, genetics and inheritance. Some key points covered include: - The main organelles in plant and animal cells and their functions. - Differences in cell structure between plant (algal and yeast), bacteria and human cell types. - The process of photosynthesis including the role of chloroplasts and limiting factors. - Aerobic and anaerobic respiration and their roles in providing energy to cells. - Cell division through mitosis and meiosis and their roles in asexual and sexual reproduction. - Basic concepts of genetics including DNA

1. Structure of a
cell:
•Nucleus- To
control the cells’
activities.
•Cytoplasm-
Chemical
reactions take
place.
•Cell
membrane-
Controls the
movement of
material’s in and
out of the cell.
•Mitochondria-
Where Energy
released
during aerobic
respiration.
•Ribosome-
Where Protein
synthesis takes
place.
Algal Cells:
• Cell Wall- Made of cellulose (carbohydrate
molecule) that supports the cells.
•Chloroplasts- Found in green parts of the
plant.
They are green as they absorb green substances
such as chlorophyll (absorbs light energy to
make food).
•Permanent Vacuole- Space in the
cytoplasm which is fill with cell sap. This keeps
the cells rigid.
Bacteria Cells:
•Each bacterium cell is a single cell.
•It is made up of cytoplasm, cell membrane and cell wall.
•Bacteria does not have a nucleus so the Genetic
material (The DNA that carries the instruction
For making new cells) is carried in the cytoplasm.
•They contain plasmids ( small bits of DNA) which contains
extra genetic information.
•Some bacteria’s have 1 flagellum(a long protein strand). This
Is used to move themselves.
Yeast Cells:
•Each yeast contains a nucleus, genetic material,
Cytoplasm, cell membrane and call wall.
•Yeast is produced by asexual budding. (New yeast
growing out from the original cell.)
•Yeast uses aerobic respiration using oxygen. The
Oxygen is used to breakdown sugar to provide energy
for the cell. They produce water and carbon dioxide.
•Yeast can also use anaerobic respiration. When the
yeast breaks down sugar they produce ethanol and
carbon dioxide. (Fermentation).
Fat Cells:
•When you eat more food than your body
needs you to then your body stores the food
Into fat cells.
•This will help you when your body runs out
of food.
•They have a small amount of cytoplasm.
•It has a large amount of fat.
•They have a small amount of mitochondria
as
it needs a small amount of energy.
•They can expand.
Cone cells:
•The cone cell are in the light sensitive layer
of your eye.
•The cone cells allow you to see colours.
•Outer segment contains special chemicals which
changes the colour of the light to change it back
to its original colour you need energy.
•The middle segment is full of mitochondria and
this releases energy needed to reform the pigment.
•Last part of the cell has synapses that connects to
the optic nerve.
Root hair cells:
•This helps take water in.
•They are close to the xylem tissue carries
Water and mineral ions up into the rest of
plant.
•The root hair increases the surface area of
the for the water to move into the cell.
•It has a large permanent vacuole which
speeds up the of the water.
Sperm Cell:
•It has a long tail which whips side to
side which allows the sperm to move
towards the egg.
•The middle part is full of
mitochondria which gives energy for
the tail to move.
•The acrosome stores digestive
enzymes for breaking down the
outer layers of the egg.
•Nucleus contains the genetic
information.

2. Diffusion:
•Diffusion is the spreading of the particles of a
substance in a solution.
• The net movement is from an area of high
concentration to an area of lower concentration.
It takes place because of the random movement
of the particles.
•If there is a big difference in the concentration
between two areas the diffusion will take place
quickly.
•If there is a small difference in the concentration
Between the two areas the net movement by the
diffusion will take place slowly.
•The greater the difference in concentration the
faster the rate of diffusion.
•An increase in the temperature causes particles
in a gas/liquid to move quickly the diffusion takes
place rapidly.
•Amino acids that breakdown proteins in y our
gut also pass through cell membranes by diffusion.
The net movement= particles moving in-particles moving out.
Concentration Gradient= Difference between two areas of
concentration.
Tissues:
•Tissue is a group of cells with a
similar structure /
function to work together.
•Muscular tissue=Contract to bring
movement.
• Glandular tissue= Contains secretory
cells which produces enzymes and
hormones.
•Epithelial tissues= Covers your
outside body.
•Epidermal Tissues= Cover the
surfaces.
•Mesophyll Tissues= Contains
chloroplast/ carries
out photosynthesis.
Organs:
•Organs are made up of
tissues.
•Muscular Tissues= Chums
the food and digestive
juices of the stomach.
•Glandular
Tissues=Produces digestive
juices that breaks down the
food.
•Epithelial Tissues= Covers
inside and outside of the
organs.
Digestive System:
•A muscular tube squeezes your food through it.
•It starts from the mouth and finishes with your anus.
•The Salivary Gland releases digestive juices which contains
enzymes to break the food down.
•Enzymes break down the large insoluble food molecules
into smaller soluble ones.
•Small intestine is where the soluble food molecules are
absorbed into the blood once it gets transported into the blood
stream.
•Muscular walls of the gut squeezes the undigested food into
the large intestine. This is where water is absorbed into your
blood. Material left as faeces and passed out from the anus.

3. Photosynthesis:
•The cells in algae are full of green particles called chloroplasts.
•Chloroplast contains a green substance called Chlorophyll.
•Light energy is absorbed during photosynthesis by chlorophyll
In the chloroplast.
•The energy made is converted into carbon dioxide from the air
and water from the soil into glucose. (Also creates oxygen).
•Glucose is made and converted into insoluble starch.
•When testing to see whether photosynthesis has taken place
in a plant you use iodine (yellow /brown liquid) which turns dark
blue when reacted with starch.
Leaf Adaptations:
•Most leaves are broad which gives them a bigger
surface area for light to fall on.
•They also contain chlorophyll in the chloroplasts
to absorb the light energy.
•They have air spaces which allows carbon dioxide
to get to the cells and oxygen to leave. (By
diffusion)
•They have veins which bring water to the cells.
Limiting
Factors=
Factors that
limit the
rate of
reaction.
Light:
•Light affects the rate of photosynthesis.
•The brighter the light the faster the rate
of photosynthesis.
Temperature:
•The higher the temperature the rate for
photosynthesis increases as the reaction
rate speeds up.
Photosynthesis is controlled by enzymes so
if the temperature is too high the enzymes
are denature.
Carbon dioxide:
•Plants use carbon dioxide to make glucose.
•Increasing the carbon dioxide level will increase the rate
of photosynthesis.
•At night the carbon dioxide levels increase around near
the plant as the plant respire but doesn’t photosynthesise.
Glucose:
•Glucose is produced during photosynthesis by the cells.
•Glucose is used for respiration to provide energy for cell
function.
•Glucose is broken down by oxygen to provide energy for
the cells.(Carbon dioxide and water are the waste products
produced).
•Energy released is used to build small molecules into big
molecules.
• Some glucose is turned into starch.
•Plant/ Algae build up glucose from photosynthesis to
make amino acids by adding nitrate ions and mineral ions
from the soil. (Amino acids build up into proteins).
• Glucose from photosynthesis and energy from respiration
build up to fats and oils.
Starch:
•Plants convert some of the glucose into starch.
•Starch is insoluble water. It will have no effect
of the water balance of the plant. This means
that plants can store large amount of starch in
their cells.
The Garden
Greenhouse:
•In the green house within the
glass/ plastic
the environment is more
controlled than outside.
•Atmosphere is warmer inside
than outside this
means that this affects the
photosynthesis rate
and this will help the plants
grow quickly.
Technology:
Hydroponics system helps the plants grow in water
with perfect balance of Mineral ions instead of soil
so nothing
slows down their growth.
Carbon Dioxide+Water Glucose +Oxygen.

4. Factors affecting
Living organisms.
Temperature:
Temperature is a limiting factor for photosynthesis
and therefore growth in plants.
Nutrients:
The level of mineral ions available has a big
impact on the distribution of plants.
Amount of light:
•Light limits photosynthesis.
•Most plants need a lot of light to grow well.
•Some plants need less light as they may have
more chlorophyll/big leaves.
Availability of water.
Availability of oxygen and
Carbon dioxide.

5. Proteins:
Proteins carry out many different
functions in your body such as:
•Structural components
(muscles).
•Hormones (Insulin).
•Antibodies to destroy
pathogens.
•Catalysts in the form of
enzymes.
Enzymes:
•Chemical reactions are controlled by enzymes in your body.
•Enzymes are large protein molecules.
•Long chains of amino acids are folded to produce a molecule
with a specific shape. (Active site allows other molecules to fit
into the enzyme protein.
•They build large molecules from lots of small ones.
•Changes the molecule into another one.
•Breaks down the large molecules into small ones.
•Different enzymes catalyst specific types of reactions.
•Enzymes in bacteria breakdown protein structures.
•The rate of enzymes controlled reactions increases as the
temperature increases.
Different enzymes have different pH levels.
•Chemical breakdown is controlled by enzymes.
•Digestive enzymes work outside your cells. (Produced in the
Gland and on the lining of your gut).
•Carbohydrases are enzymes that break down carbohydrates.
(This is done by turning it into sugars into your moth and into
your small intestine this is done by an enzyme called amylase.
•Amylase is produced in the salivary gland.
•Protease enzymes are produced by your stomach and they
breakdown the amino acids.
Lipase enzymes are made in your pancreas and they break
down the fatty acids.
pH level:
•Keeping the pH in your gut at ideal level is not easy
because
the enzymes work best at different pH levels.
•Your enzymes work best in an acid Ph.
•Your stomach produces a concentrated solution of
hydrochloric
acid from the same glands.
•Stomach also produces a thick layer of mucus which
coats stomach walls and protects them from being
digested by the acid and the enzymes.
•Your food moves into your small intestines so in your
small intestine some of the enzymes that catalyse
digestion are made in your pancreas.
•Acidic liquid that comes from your stomach becomes an
alkaline mix in your stomach.
•Liver makes a greenish/ yellow alkaline liquid called
Bile which is stored in your gall bladder until needed.
•When food is coming into the small intestine bile is
squirted onto it so it can neutralise the acid from the
stomach.
Advantages: Disadvantages:
Effective at cleaning at low
temperature.
Triggers allergies.
Less electricity is used.
Cheap/ Good for environment.
Biological
Powders:

6. Aerobic Respiration:
Glucose+Oxygen Carbon Dioxide +Water(+Energy)
Mitochondria:
•They are tiny rod-shaped parts that are found in
plant/animal cells.
•They have a folded inner membrane.
•Provides a large surface area for the enzymes to be
involved in aerobic respiration.
•Number of mitochondria in a cell show how active
the cell is.
Respiration:
•Living cells build up large molecules from smaller
ones to make new cell materials. Most of the energy
is released in respiration.
•In animals energy from respiration is used to make
muscles contract.
•Mammals and birds keep their bodies at a constant
temperature .
Exercising:
•Muscle tissues are made up of protein fibres.
•Muscle fibres need a lot of energy to contract. They
contain mitochondria to carry out aerobic respiration and
supply energy.
•Muscles also store glucose as the carbohydrates glycogen.
This can back to glucose by exercise.
•Muscular activity increases your heart rate and the arteries
supply blood to your muscles.
•Also your breathing rate increases and you breathe deeply
as more oxygen is brought into your body and picked up by
your red blood cells.
Anaerobic Respiration:
•When you exercise you increase your hear rate and
breathing rate and sometimes blood cannot supply
oxygen to the muscle fast enough so this causes the
muscle cells to get energy from glucose. (Anaerobic
respiration).
•Glucose is not broken down in this process so lactic
acid is produced instead of carbon dioxide and water.
•When using your muscle the muscle fibres become
fatigued (stop contracting efficiently).
•Anaerobic respiration is not as efficient as aerobic
respiration this because the glucose is not broken down
completely.
Anaerobic Respiration:
GlucoseLactic Acid(+Energy)

7. •Each cell has a nucleus which has a gene.
•A gene carries information that controls your
characteristics.
•Alleles are different forms of the same gene.
•Genes are grouped together on chromosomes.
•Each body has 46 chromosomes in the nucleus of a body
cells. (23 pairs)
•One of each pair is inherited from your father and one
from your mother.
Mitosis:
•Cell division in a normal body cells produce two
identical cells. (Mitosis).
•Asexual Reproduction the cells of the offspring are
produced by mitosis from the cells from the parents. This
is why they contain the same alleles as their parents with
no genetic variation.
•Before a cell divides it produces new copies of the
chromosomes in the nucleus so when the cell divides
once to form two genetically identical cells.
Differentiation:
•Cells are specialised as different cells do different jobs.
They have differentiated.
•Undifferentiated cells are formed at active regions of the
stems and roots. (Mitosis takes place in these areas).
Meiosis:
•Meiosis results in sex cells called gametes with only half the
original number of chromosomes.
•Gametes are formed by meiosis. (Female –egg and Male-Sperm).
•When the a cell divides to form gametes the chromosomes are
copied so there are four sets of chromosomes. Cell divides twice
quickly to form four sets of gametes which each have a single
chromosomes.
Fertilisation:
•When two sex cells join together during fertilisation the single new
cell formed has 46 pairs chromosomes in 23 pairs. This because in
the egg cell it contains 23 and the sperm also contains 23.
•Once fertilisation is done the new cell divides by mitosis.
Variation:
•In asexual reproduction the offspring are produced as a result of
mitosis from the parent cells. So they contain the same
chromosomes and the same genes as their parents.
•In sexual reproduction the gametes produced by meiosis in the
sex organs of the parents. This introduces the variety as each of
the gametes are different. When the gametes fuse one of each pair
of chromosomes, gene comes from each parent.
Stem cells:
•When an egg and sperm fuse they form a zygote (new, single
cell).This becomes a ball of cells called embryo.
•The inner cells of the ball are the stem cells. The stem cells
differentiate to form the specialised cells of your body that make
up your tissues and organs.
•Bone marrow is a good source of stem cells.
•Embryonic ells come from aborted embryos. Others come from
embryos in fertility treatment. This raises ethical issues.
DNA:
•Chromosomes are made up of large molecules of
chemical known as DNA.
•The genes make up the chromosomes in the nucleus of
the cell. This controls the proteins which make up
different specialised cells that form tissues.
•Long strands of your DNA are made up of a
combination of 4 different chemical bases. These are
grouped into 3 and each code for amino acid.

8. •Some alleles control the development of a characteristics even
when they are only present in one chromosomes. These are
dominant alleles.
•To show dominant alleles you use capital letters for example,
D.
•Some alleles only control the development of a characteristic
if they are present in both chromosomes. These are recessive
alleles.
•To show recessive allele you use lower case letters for
example, d.
Genetic Terms:
•Homozygous- Individual with 2 identical alleles. (DD , dd)
•Heterozygous-Individual with different alleles.(Dd)
•Genotype- Genetic make up of an individual. (Dd, dd)
•Physical appearance of and individual. (dimples, no
dimples).
Genetic/inherited disorders: Diseases that are
result of a problem in a gene and can be passed by a
parent to a child.
Polydactyly:
•This is when babies are born with extra fingers or toes.
•Polydactyly is caused by a dominant allele.
•This is inherited from one parent who has Polydactyly.
Cystic Fibrosis:
•This affects the organs in your body especially the lungs and
the pancreas.
•Organs become clogged up with mucus which stops them
from working properly.
•People with cystic fibrosis are infertile.(Can’t have babies).
•Enzymes are used to replace the pancreas which cannot
produce and to thin the mucus.
•Cystic fibrosis is caused by a recessive allele so it has to be
inherited by both parents.
Genetic Cross:
•When genes from the parents are combined .

9. Fossils:
•These are the remains of organisms from many years ago
that are found in preserved rocks and ice.
•Fossils can be formed by hard parts of animals which do
not decay such as teeth, bones, claws or shells.
•When animal or plant do not decay after it dies this is
because the poisonous gases do not kill of the bacteria that
causes decay.
•Formed by the harder parts of the animal/plant as they
are replaced by other minerals.
•Some are formed by traces that have been left behind by
animals/plants. Such as fossil footprints.
Extinction:
•Permanent loss of all the members of a species.
•New species evolve that are better suited to the new
conditions where as the older species cannot cope with the
change and die out. This is because they cannot compete for
food.
•New predators can wipe out the unsuspecting prey animals
very quickly.
•New diseases can bring a species to the point of extinction.
•One species can cause another to become extinct by
successful competition.
•After a mass extinction there has been a huge number of new
species appear in the fossil record.
•When one population becomes isolated from another the
conditions they live are different. This means that the different
characteristics will be selected for. A new specie is evolved.
•Geographical isolation is when two populations become
physically isolated by geographical features.
•Organisms on islands are geographically isolated from the rest of
the world.
•When species are isolated it will find one place in the world –
endemic to that area.
Speciation:
•Any population will contain genetic variety. This is a
wide range of alleles that controls its characteristics
from sexual reproduction and mutation.
•The selection of these different alleles the
characteristics features of the isolated organisms will
change. They can no longer interbreed with the original
organism and a new species form. (Speciation).