Fungus kingdom - Dont contain chlorophyll

- Decomposers
- Multicellular except yeast
- Cell walls arent made of cellulose
- Contains nuclei
- Have hyphae as a body
- Feed by digesting waste organic
material and absorbing it into their
cells

Protoctist kingdom - Multicellular OR unicellular

- May/may not have cell wall and
chloroplasts
- Some are autotrophic (make own
food) and some are heterotroph
(eat other organisms)

Prokaryote kingdom - Unicellular

- No nucleus
- Cell walls arent made of cellulose
- No mitochondria
- Circular loop of dna without
cytoplasm
- Contain plasmids

Fish - Vertebrates with scaly skin

- Gills all throughout their life
- Have fins
- Eggs have no shells and are laid in
water

Amphibians - Vertebraes with skin and no scales

- Eggs have no shells, laid in water
- Tadpoles live in water and adults
live on land
- Tadpoles have gills and adults have
lungs

Reptiles - Vertebrates with scaly skin

- Lay eggs with soft shells

Birds - Feathers
- Beak
- Two limbs are wings
- Lay eggs with hard shells
Mammals - Hair on skin
- Young develops in uterus, attached
to mother by placenta
- Females produce milk to their
young
- Different kinds of teeth
- Have pinna on the outside of the
body
- Sweat glands on skin
- They have a diaphgram

Arthrtopods - Several pairs of jointed legs

- exoskeleton

Insect - Arthropods with three pairs of

jointed legs
- Two pairs of wings
- Breathe through trachea
- Body is divided into head, thorax
and abdomen
- One pair of antannae

Crustaceans - Arthropods with more than four

pairs of jointed legs
- Two pairs of antenna

Arachnids - Arthropods with four pairs of

jointed legs
- Have no antenna
- Body divided into two parts –
cephalothorax and abdomen

Myriapods - Body consists of many similar

segments
- Each of body segments have
jointed legs
- One pair of antenna

Ferns - Plants with roots, stems and

leaves
- Dont produce flowers
- Reproduce by spored produced on
the undersides of their fronds

Dicotyledon - Seeds with two cotyledons

- Usually have main root with side
roots coming out
 - Leaves have network of veins
- Have flower parts in multiples of
four or five
- Have vascular bundles in the stem
arranged in a ring

Monocotyledon - Seeds with one cotyledon

- Roots grow out directly from the
stem
- Leaves have parallel veins
- Flower parts in multiples of three
- Vascular bundles arranged
randomly

Diffusion The net movement of particles from a

region of higher concentration to a region
of lower concentration due to their
random movement

Plants: CO2 diffuses from the air and into

the leaves through the stomata – this is
due the lower concentration of CO2 inside
the leaf as compared to the air.
Therefore they diffuse into the leaf via
stomata as a result of their random
movement

Plants: oxygen ( waste product of

photosynthesis ) also diffuses out the
plant the same way. There’s a higher
concentration of oxygen inside the plant
as it’s made there therefore it diffuses
out to the air where there’s lower
concentration via stomata.

Animals: cytoplasm of all cells contains

many solutes, such as glucose molecules
or sodium ions. These particles are free
to move through the cytoplasm so they
diffuse and spread to all parts of the
cytoplasm.

Osmosis Net movement ( diffusion ) of water

particles from a region of higher
concentration to a region of lower
concentration through a partially
permeable membrane.
 High water potential: are with lots of
water molecules ( dilute solution )
Low water potential: area with less water
molecules ( concentrated solution )

Active transport Movement of molecules or ions through a

cell membrane from a region of lower
concentration to a higher concentration
using energy from respiration.

Root hair: this is due to the special Plants: root hair cells take in nitrate ions
carrier proteins in the root hair cell’s from the soil. The concentration of nitrate
membrane that allows the cell to pick up ions inside the root hair cell is usually
nitrate ions from outside the cell and then higher than their concentration in the
change shape with energy from foil. Therefore the diffusion gradient for
respiration so they can push the nitrate the nitrate ions is out of the root hair
ions through the cell membrane and into however root hair cells are still able to
the cell’s cytoplasm. take nitrate ions in with the help of
active transport.

Enzymes 1. The enzyme and substrate

molecules have a complementary
shape
2. The substrate binds with the
enzyme
3. The enzyme changes the substrate
into products
4. Enzyme’s free to bind with
another substrate molecule

Digestive system processes Ingestion: food taken into the alimentary

canal

Digestion: large, insoluble molecules of

food are broken down into small molecules

Absorption: the small molecules are

absorbed into the blood

Assimilation: nutrients are absorbed by

individual cells and used for energy to
make new substances

Egestion: food which couldnt be absorbed

is removed from the body
Alimentary canal 1. Mouth: teeth bite and grind food
into smaller pieces to increase its
surface area then lubricated by
saliva
2. Saliva allows food to move down
the oesophagus easily when it’s
swallowed, taking the food down to
the stomach
3. Sphincter muscle: relaxes when it
allows food to pass into the
stomach and contracts when it
closes it’s entrance
4. The stomach’s muscular walls
contract and relax to mix the food
with enzymes and mucus.
5. Hydrochloric acids with a low pH
of 2 kills the harmful
microorganisms in the food
6. Sphincter muscle at the bottom of
the stomach relaxes so the food
can move to the duodenum
7. The duodenum: first part of the
small intestinewhere the
pancreatic duct and bile duct
empty fluids
8. The ileum: second part of the
small intestine where digested
nutrients are absorbed into the
blood
9. Colon: first part of large intestine
where water that remains is
absorbed
10. Rectum: second part of large
intestine where undigested food
and feaces are stores
11. Anus: egestion site

Role of liver in digestion Secretes fluid called bile that helps with
digestion of fat

Physical digestion Large pieces of food beaking broken down

into smaller pieces by the teeth. No
chemical components of the food are
changed

Chemical digestion Large molecules of food broken down into

 smaller molecules. This involves chemical
reactions and they’re catalysed by
enzymes.

Water from soil to xylem vessel 1. Water enters root via osmosis
2. Water passes across the root, from
cell to cell, by osmosis. Seeping
between the cells
3. Water is drawn up by the xylem
vessels due to the water being
removed at the top

Transpiration [water moving from xylem 1. Water moves from the xylem
to the air through the plant leaf] vessels to the mesophyll cells via
osmosis
2. Water evaporates from the surface
of the mesophyll cell walls
3. Water vapour diffuses out the air
spaces through the stomata

How water moves upwards in xylem 1. Pressure at the top of the xylem
is lower than the pressure at the
top
2. This difference in pressure is
called a transpirational pull and is
caused by the loss of water vapour

The water molecules have the

tendency to stick to each other
because they have a force of
attraction between them called
cohesion.
As one of the water molecules move
upwards, the rest stick and move
upwards with it aswell in a
continuous column without breaking
apart

Heart function 1. Deoxygenated enters the heart

through the vena cava and into
2. The right atrium which contracts
as the blood moves through the
tricuspid valve and goes into
3. The right ventricle contracts and
the blood exits the heart through
the semilunar valve and
 4. Into the lungs via pulmonary
artery where it gets oxygenated.
The blood then returns to the
heart through
5. The Pulmonary vein and into the
6. Left atrium which contracts as the
blood moves through the bicuspid
valve and into the
7. Left ventricle which contracts as
the oxygenated blood leaves the
heart and passes through the
semilunar valve as it goes into the
8. Aorta which takes the blood around
the body where it gets
deoxygenated again

Blood vessels 1. Vein – takes away deoxygenated

blood and returns it to heart
2. Artery – supplies oxygenated
blood and carries it away from the
heart
3. Hepatic artery – supplies liver
with oxygen
4. Hepatic portal vein – brings blood
from the digestive into the liver
for processing food that’s been
absorbed
5. Hepatic veins – carries blood
away from the liver
6. Capillaries – supplies cells with
all their requirements and take
away waste products

Phagocytosis [white blood cell destroying 1. Phagocyte moves towards a group

bacteria] of bacteria and flows around them
2. Phagocytes cell membrane fuses
together, enclosing the bacteria in
a vacuole
3. Enzymes are secreted into the
vacuole and digest bacteria
4. Soluble substances diffuse from
the vacuole into the phagocyte’s
cytoplasm

Sequence of events causing blood clot to

form
Body defences 1. Hairs in the nose help filter out
particles from the air
2. Skin prevents pathogens from
entering the body, when skin is
broken a blod clot forms to seal
the wound
3. Mucus in the airways traps
bacteria which gets swept to the
back of the throat and swallowed
rather than put in the lungs
4. Stomach’s hydrochloric acid kills
dangerous microorganisms

How lymphocytes react to pathogen 1. A lymphocyte comes into contact

with antigens that fit the shape of
the antibodies it can make
2. 2. The lymphocyte divides via
mitosis to form identical cells
3. The lymphocytes secrete antibodies
4. Which binds to the antigens and
destroy the pathogens

How a person becomes immune to a 1. After a lymphocyte clones itself

pathogen not all of the new clones produce
antibodies, instead they remin in
the blood and other parts of the
body living there for a long time.
They’re called memory cells
2. If the same pathogen enters the
body, the memory cells will be
ready and waiting for them
3. With the ability to make enough
antibodies at an efficient time
4. Killing the pathogens before they
have time to do any harm

Inspiration [breathing in] 1. Muscles of diaphragm contracts

2. Pulling the diagram downwards,
increasing the volume in the
thorax
3. At the same time, external
intercoastal muscles contract
4. Pulling the rigbcage outwards also
increasing the volume of the
thorax
5. Due to the increase in the
 thorax’ volume the pressure
inside it falls below atmospheric
pressure
6. Air flows in along the trachea and
bronchi into the lungs

Expiration [breathing out] 1. Muscles of diaphragm relaxes

2. Diaphragm springs back up into its
domed shape due to its elastic
tissue
3. This decreases the volume in the
thorax
4. The external intercoastal muscles
relax
5. The ribcage drops down into its
normal position also decreasing the
volume in the thorax

When coughing 1. Internal intercoastal muscles

contract strongly
2. Making ribcage drop down even
further
3. Muscles of abdomen wall contract
which helps squeeze extra air out
of the thorax

Reflex arc 1. Receptor

2. Sensory neurone
3. Relay neurone
4. Motor neurone
5. effector

Reflex arc 2 1. The sensory receptor detects the

stimuli
2. The receptor then starts off an
electrical impulse
3. This electrical impulse travels
through the spinal cord along the
sensory neurone
4. In the spinal cord, the neurone
passes the electrical impulse to
several relay neurons
5. Relay neurones then pass the
impulse to the brain
6. They also pass this impulse along
a motor neurone to an effector
 (usually muscles)
7. The electrical impulse then travels
to the effector along the axon of a
motor neurone

Synapse 1. Electrical impulse arrives along the

axon of sensory neurone
2. Vesicles move to the cell
membrane of sensory neurone
3. Vesicles fuse with the membrane
and empty their contents – the
neurotransmitter molecules – into
the synaptic gap
4. The neurotransmitter molecules
diffuse across gap
5. Neurotransmitter molecules attach
to receptor proteins in the cell
membrane of the relay neurone
due to the complementary shape if
the neurotransmitter to the
receptor proteins
6. The binding of the receptor
proteins and neurotransmitters
triggers an impulse in the relay
neurone.
7. This impulse sweeps along the
relat neurone until it reaches the
next synapse

Iris/pupil reflex 1. Circular muscles contract – pupil

gets smaller
2. Radial muscles contract – pupils
dilate

How an image is focused onto the retina 1. Light enters through the
cornea which is a clear
outer layer around the eye
and refracts the light rays
2. The light passes through
the pupil – pupil controls
how much light enters the
eye
3. The light rays make its way
onto the lens which is
located behind the pupil
and refracts the light rays
 4. The lens then focuses the
light rays onto the retina
5. The focused imagine
stimulate the
photoreceptors on the retina
which converts it as an
electrical signal
6. These electrical signals are
then sent through the optic
nerve and into the brain
7. The brain then interprets
and processes these images

Focusing on a near object 1. Ciliary muscles contract

2. Suspensory ligaments loosen
3. Allowing lens to become fat

Focusing on a distant object 1. Ciliary muscles relax

2. Pulling the suspensory ligaments
3. Allowing lens o become thinner

Adrenaline 1. When you are frightened or

excited, the brain sends impulses
along a nerve to your adrenal
glands
2. The adrenal glands then secrete
adrenaline into the blood

Adrenaline effects 1. Adrenaline causes the liver to

release glucose onto the blood
allowing the muscles to carry out
aerobic respiration faster
2. It also provides increased
breathing and heart rate to give
you extra oxygen to allow more
oxygen to enter the blood in the
lungs causing the muscles to
increase metabolic activity
3. Adrenaline also causes the pupils
in the eye to widen allowing more
light inside the eye helping you
see more clearly

How auxin controls phototropism in a shoot – auxin is made all the time by the
cells in the tip of the shoot and it
diffuses downwards from the tip, into the
 rest of the shoot
1. Auxins make the cells just behind
the tip elongate (the more auxin
there is, the faster they elongate)
2. When light shines onto the shoot
from all around, the auxin gets
distributed evenly around the tip
of the shoot therefore the cells all
elongate at the same rate
when light shines onto the shoot from one
side,
a. The auxins at the tip concentrates
on the shady side
b. Causing the tip on the shady side
to elongate faster than the ones
on the bright
c. causing the shoot to bend towards
the light

How an auxin helps in gravitropism If a shoot is placed on it’s side..

1. The auxin concentrates on the
lower side of the shoot
2. The cells on that side therefore
elongate at a faster rate than the
ones on the upper surface
3. This causes the shoot to bend
upwards as it grows

Urea production in the liver – when you eat proteins

1. Digestive enzymes in the stomach,
duodenum and the ileum break the
proteins down into amino acids
2. The amino acids are then absorbed
into the blood capillaries in the
villi located in your ileum
3. These blood capillaries all join up
to form the hepatic portal vein
which takes the amino acids to the
liver
4. The liver allows some of the amino
acids to carry on, in the blood or
other parts of your body however
if they’re unneeded then they
get removed from your body
Deamination!
5. extra amino acids are split up by
 enzymes in the liver and the parts
that contain energy are turned
into carbohydrate and stored
6. However the part that contains
nitrogen is turned into urea
7. The urea dissolves in the blood
plasma and is taken to the kidneys
to be excreted

Kidneys – urine formation in the – blood flows into the kidney from the
nephrons renal artery. This divides to form many
coiled capillaries called the glomeruli

1. The blood gets filtered as it flows

through the glomerulus
— small molecules can pass
through (water, urea, glucose,
ions) and large molecules cannot
2. The filtrates then move onto the
nephron
3. IF NOT WASTE: [glucose, water
and ions] are taken back into the
blood as the fluid flows through
the nephron, this is known as
reabsorption.
4. IF WASTE: the final liquid that
flows out of the nephron is a
solution or urea and salts in water
which is called urine
5. This then flows out the kidneys,
goes along the uterus and into the
bladder
6. It stays in the bladder then
eventually gets released through
the urethra

Controlling blood glucose concentration LESS GLUCOSE SUPPLY – cells cannot

– normal concentration: 0.8 to 1.1 mg release the energy they require and die
per cm of blood = 4g of glucose if they’re deprived of this
TOO MUCH GLUCOSE – can cause water
to move out of the cells and into the
blood by osmosis, leaving the cell with
too little water for them to carry out
metabolic processes

Pancreas [hormones] Insulin – lowering blood glucose

 concentration
Glucagon – increases blood glucose
concentration by allowing liver cells to
break down glycogen to glucose and
release it into the blood

How blood glucose concentration is — low levels of blood glucose

regulated 1. Glucagon gets secreted
2. Causing the liver to break down its
glycogen into glucose
3. Glucose is released from the liver
into the blood which causes the
blood glucose concentration to
increase leading to a normal level
of blood glucose concentration
– high levels of blood glucose
1. Insulin gets secreted
2. Liver cells use some glucose in
respiration and store some glucose
as glycogen
3. This is used to decrease the blood
glucose concentration

Hypothalamus Part of the brain that is involved in

control of body temperature

Diabetes Result from the body’s own immune

system attacking and destroying the cells
in the pancrease that secretes insulin
EATING TOO MUCH CARBOHYDRATES: the
concentration of blood glucose increases
however the secretion of insulin wasn’t
triggered therefore the blood glucose
concentration stays up causing dry mouth,
blurry vision, thirst, and increased
breathing and heart rate.
EATING TOO LESS CARBOHYDRATES: the
blood glucose concentration is very low
and due to the lack of insulin secreted
the liver doesn’t have stores of glycogen
to be broken down to produce glucose
therefore the cells dont have a supply of
glucose for respiration causing tiredness,
confusion and irrational behaviour

Temperature regulation: skin [37] WHEN BODY IS TOO COLD:

 1. Muscles contract using the energy
from respiration. Some of the
energy gets released as heat
which warms the muscles as blood
flows through them. The blood
then distributes the heat all over
the body
2. Speed of chemical reaction
increases in muscles and tissues
like the liver which respires faster
in order to release more heat
3. The erector muscles in the skin
contracts which pulls the hairs up
which traps a layer of warm air
next to the skin to insulate it
4. Vasoconstriction is when
thearterioles that supply the blood
capillaries near to the surface of
the skin become narrow causing
the blood to not lose so much heat
to the air
5. Sweat glands reduce the quantity
of sweat that’s produced
WHEN BODY IS TOO HOT:
1. The erector muscles on the skin
relax causing the hairs to lie flat
allowing the heat to leave the skin
through radiation into the air
2. Vasolidation is the process of the
arterioles near the surface of the
skin to be widened allowing the
blood to lose hear from the blood
into the air
3. Sweat production increases which
evaporates on the skin helping it
cool the body

Chromosome numbers in sexual production – the cells in a human body each

contain 46 chromosomes
1. In sexual reproduction, cells in
testes and ovaries producse
gametes that have half the
number of chromosomes [23]
2. When the male and female
gametes join together, a zygote is
 formed with the full number of
chromosomes [46] – fertilisation
3.

Mitosis Division of a cell nucleus resulting in two

– occurs in repair of damaged tissues, genetically identical nuclei [with the
replacement of cells, asexual reproduction same number and kind of chromosomes as
the parent nucleus]

Meiosis Division of haploid nucleus resulting in

– occurs when gametes are being made four genetically different haploid nuclei
[eggs and sperm] [reduction division]

Pollen formation – the anther has four spaces inside it

called pollen sacs
1. The cells around the edge of the
pollen sacs divide to make pollen
grains
2. When the flower bud opens, the
anthers split open
3. Causing the polen to go on the
outside of the anther

Pollination – often carried out by insects

1. The insects get attracted by the
flower’s color and sweet scent
2. The bee follows the guide lines to
the nectaries, brushing past the
anthers
3. Some of the pollen sticks to its
body
4. The bee foes to another flower, in
search for more nectar
5. Some of the pollen picked up from
the first flower sticks onto the
stigma of the second flower when
the bee brushes past it
– pollination has only taken place
if the second flower and the first
flower are the same species of
plant

Wind pollination adaptive features – wind pollinated flowers usually produce

much more pollen than insect pollinated
flowers and usually dont have petals as
 they don’t need to attract insects
– their anthers and stigmas dangle
outside the flower helping them catch the
wind
– the filaments of the anthers are very
flexible allowing them to sway in the
wind and release their pollen
– the feathery stigmas have a large
surface area which increases the chances
of catching pollen

Self pollination Transfer of pollen grains from the anther

of a flower to the stigma of the same
flower, or a different flower on the same
plant

Cross pollination The transfer of pollen grains from the

anther of a flower to the stigma on a
different plant of the same species

Fertilisation – for fertilisation to occur, the male

gamete (nucleus inside pollen grain) must
fuse with the female gamete inside the
ovule
1. If the pollen has landed on the
correct stigma, it grows a tube
2. The pollen tube grows down
through the style and the ovary,
going towards the ovule
3. It then secretes an enzyme to
digest a pathway through the style
4. The pollen tube grows through the
micropyle (hole in the protective
layers of cell around the ovule)
and goes into the ovule
5. The male gamete travels along the
pollen tube and goes into the ovule
6. It then fuses with the female
gamete
– one pollen grain can only fertilise one
ovule, if there are many ovules in the
ovary then many pollens are required to
fertilise them all

Seeds After the ovules have been fertilizes,

many of the parts of the flower arent
 needed anymore therefore the sepals,
petals and stamens all wither and fall off
1. Inside the ovary the ovules start
to grow
2. Each ovule now contains a zygote
which has been formed with
fertilisation
3. The zygot divides via mitosis to
form an embryo plant converting it
into a seed

Conditions for seed germination — seeds are dehydrated in the formation

process therefore they require water,
oxygen and warm temperature in order to
germinate

Sperm’s route to an egg 1. Sperm is left in the top of the

– sperms can only swim at a rate of vagina
4mm per minute 2. Sperm swims through the uterus
and goes into the oviduct
3. If there’s an egg in the oviduct,
it’ll get fertilised

Implantation – when the sperm and egg have fused,

they form a zygote. After several hours
it forms a ball of cells called the embryo
1. Ovulation: A mature follicle bursts
and releases an egg into the
oviduct
2. Fertilisation: a sperm and egg
nucleus fuses to form a zygote
3. The zygote then divides
4. Embryo is formed and moves down
the oviduct
5. Implantation: the embryo sinks into
the soft lining of the uterus

Placenta adaptive features – the placenta contains capillaries filled

with the fetus’ blood, the lining of the
uterus contains large spaces filled with
the mother’s blood.
– the mother and fetus’ blood are
separated by the placenta wall
1. Oxygen and dissolved nutrients in
the mother’s blood diffuse across
the placenta and into the fetus’
 blood
2. It is then carried along the
umbilical cord to the fetus
3. Carbon dioxide and other excretory
products diffuse in the other
direction being carried away in the
mother’s blood

Testosterone Secreted by testes

- Causes secondary sexual
characteristics to develop
- Growth of facial and pubic hair
- Broadening of shoulders
- Deepening voice
- General muscular development

Oestrogen Secreted by ovaries

– during menstrual cycle, produced by - Causes breasts to grow larger
developing ovarian follicles - Pubic hair growth
- Wider hips

FSH - Stimulates follicle production and

– produced in pituitary gland development of the egg cell
- Stimulates oestrogen production

LH - Stimulates egg being released

– produced in pituitary gland from the ovary – ovulation
- Stimulates production of
progesterone

Progesterone - Maintains thick uterus lining

– corpus luteum allowing an embryo to implant on
it
- High levels of progesterone during
pregnancy inhibits the secretion of
FSH leading to no more follicles
being developed in the ovary

Menstrual cycle 1. Follicle turns into a corpus luteum,

lining of uterus becomes more
vascular, ready to recieve the
embryo
2. Menstruation: when the egg
hasn’t been fertilised, the thick
uterus lining breaks down and is
lost through the vagina
3. Inside the ovary, a follicle
 containing an egg cell develops
and the uterus lining gets repaired
4. Ovulation: the follicle bursts,
releasing an egg cell from an
overy – this is when fertilisation
is possible

Sexually transmitted infection (STI) Infection that’s transmitted tthrough

sexual contact

Human immunodeficiency virus (HIV) - Infects white blood cells leading to

the inability to fight against
pathogens effectively
After 10 years of initial infection with
HIV, host is likely to start developing
symptoms of AIDS and become vulnerable
to other infections like pneumonia
- This virus could also pass down
from a mother to her child during
childbirth when the mother’s
blood comes into contact with the
baby
- Sharing needles could transfer this
virus. Especially when unsterilised
- HIV could be transmitted sexually
- If a woman has HIV she could also
pass it down to her baby through
breastfeeding

How to avoid HIV - Have less sexual partners

- Use contraceptives
- Getting tested regularly

Chromosomes Length of DNA found in the nucleus of a

cell containing genetic information in the
form of many different genes

Gene Length of DNA that codes for one protein

– allele is an alternative form of DNA

Sex inheritance The inheritance of sex in humans is

determined by the combination of X and Y
chromosomes.
- Females have XX
- Males have XY
The sex is determined depending on
 wether they recieve X or Y chromosome
from their father

Sequence of bases in a gene Determines the sequence of amino acids

used to make a specific protein

Sequences of amino acids Different sequences of amino acids can

give different shapes to protein molecules

DNA Controls cell function by controlling the

production of proteins including enzymes,
membrane carriers and receptors for
neurotransmitters

Protein synthesis 1. Gene is copied into mRNA

2. The mRNA leaves the nucleus and
goes into the cytoplasm
3. mRNA passes through the
ribosomes
4. Ribosomes assemble the amino
acids into protein molecules
5. The sequence of bases in DNA
determine the sequence of amino
acids that code for a specific
protein

Specific proteins Most body cells in an organism contain

the same genes, but many genes in a
particular cell arent expressed because
the cell only makes proteins that are
needed

Haploid nucleus Nucleus containing a single set of

chromosomes

Diploid nucleus Nucleus containing two sets of

chromosomes
- There is a pair of each type of
chromosome in a diploid cell, in a
human diploid cell there are 23
pairs [46 in total]

Mitosis Cell division that leads to the production

of two genetically identical cells

Role of mitosis 1. Growth: produces new cells to

make the body grow larger or
 replace damaged cells
2. Asexual reproduction: produces two
genetically identical daughter cells

Replication of chromosomes Before mitosis occurs, each of the

chromosomes in the parent cell are copied
and remains attached to it’s original.
- However when mitosis occurs, the
copies separate which maintains
the chromosome number in each
daughter cell

Stem cells Unspecialised cells that divide by mitosis

to produce daughter cells that are
genetically identical that can become
specialised cells to perform specific
functions

Meiosis Human gametes are formed by the

division of cells in the ovaries and testes
via meiosis
- Meiosis is a reduction division in
which the chromosome number is
halved from diploid to haploid
resulting in genetically different
cells

Inheritance Transmission of genetic information from

generation to generation

Genotype Genetic make up of an organism

Advantage of asexual reproduction Disadvantages of asexual reproduction

- More efficient as compared to - Limited genetic variation

asexual reproduction - Vulnerability to environmental
- Desirable traits are preserved changes
- Guaranteed production even in - Harmful mutations due to the lack
isolation of shuffle in genetics
- Less energy consumption due to - Competitive disadvantage
the lack of need for pollens,
flowers, seeds

Advantage of sexual reproduction Disadvantages of sexual reproduction

- Genetic variation - Dependent of pollinators
- Adaptability - Time and resource consumption
- Evolutionary potential - Costs a lot of energy
- Enhanced fitness – lessening - Inbreeding depression may cause
chances of accumulating harmful decrease in genetic variation
mutations