the degree to
which an image is
larger than the
1.1.2 RESOLUTION: the
ability to clearly
two objects that are
very close together.
1.1.3 LIGHT MICROSCOPE
188.8.131.52 Uses a number of
lenses to produce
184.108.40.206.1 Light passes from the
bulb under the stage,
through a condenser
lens then through the
220.127.116.11.1.1 This light is focussed
through the objective
lens then through the
18.104.22.168.1.1.1 To view things at different
magnifications different objective
lenses can be rotated into position.
22.214.171.124.126.96.36.199 Usually four lenses are present. X4,
X10, X40 and the X10 lens is an oil
188.8.131.52.184.108.40.206.1 The eye piece them magnifies
the image usually by X10.
220.127.116.11 Max magnification of X1500
18.104.22.168 Max resolution 200nm.
22.214.171.124 Wide range of specimen
126.96.36.199 Resolution of 0.1 nm.
188.8.131.52 Magnification of X100,000
184.108.40.206 SEM gives a 3D image
so cell surface
structures can be seen.
220.127.116.11 Resolution of 0.1nm
18.104.22.168 Magnification of X500,000
22.214.171.124 2D picture but allows details
of organelles to be seen.
126.96.36.199 White blood cells
cant be seen without
188.8.131.52 Creates a higher
contrast within the
1.2.1 Nucleus: largest organelle,
houses genetic information
1.2.2 Nucleolus, dense sphere
inside nucleus. makes ribosomes and RNA
1.2.3 Nuclear envelope: surrounds
nucleus Double membrane with
nuclear pores allowing mRNA
1.2.4 R/S ER: Continuous with
nuclear envelope, ER has
184.108.40.206 SER Involved in
the making of
1.2.5 Golgi apparatus:
stack of flattened
sacs. Used to
and package them
1.2.6 Mitochondria: sausage shaped, double
membrane. Where ATP is made.
1.2.7 Lysosomes:Spherical sacs, single
membrane Contain digestive enzymes
to break down organelles pathogens
1.2.8 Chloroplasts: only in
plants. Two membranes,
contains thylakoids. Site of photosynthesis.
1.2.9 Plasma membrane: phospholipid bilayer.
controls what enters and exits the cell.
1.2.10 Centrioles: small tubes of protein
fibres, pair next to nucleus. Form
spindle fibres during cell divistion
1.2.11 Flagella and cilia, hair like
extensions from the surface of
a cell. Move using ATP.
220.127.116.11.1 provides strength support
the shape of
18.104.22.168.3 moves organelles e.g mitochondria.
22.214.171.124.4 moves vesicles
126.96.36.199.5 micro tubules do not move they
provide an anchor for protein to
188.8.131.52.6 Cilia move out of time with
eachother to produce a wave.
1.2.12 Ribosomes: tiny, some in cytoplasm
some attached to RER, site of protein
184.108.40.206 PROTEIN SYNTHESIS
220.127.116.11.1 1) The gene is copied onto mRNA
18.104.22.168.1.1 2) mRNA leaves the nucleus
through a nuclear pore.
22.214.171.124.1.1.1 3) mRNA attaches to a ribosome.
126.96.36.199.188.8.131.52 4) ribosome reads the instructions on the gene to assemble a
184.108.40.206.220.127.116.11.1 5) Molecules are 'pinched off' in vesicles and travel towards the golgi
18.104.22.168.22.214.171.124.1.1 6)Vesicle fuses with the golgi apparatus
126.96.36.199.188.8.131.52.1.1.1 7) golgi apparatus processes and packages the molecules, ready for
184.108.40.206.220.127.116.11.18.104.22.168 8) The molecules are pinched off in vesicles from the golgi apparatus and
moves towards the cell surface membrane
22.214.171.124.126.96.36.199.188.8.131.52.1 9) vesicles fuse with cell surface membrane.
184.108.40.206.220.127.116.11.18.104.22.168.1.1 10) cell surface membrane opens to release molecule to the
outside, this is exocytosis.
22.214.171.124 No nucleus.
126.96.36.199 One membrane
188.8.131.52 no membrane bound organelles
184.108.40.206 cell wall made of peptidoglycan
220.127.116.11 smaller ribosomes
18.104.22.168 Circular DNA
22.214.171.124 Cell wall
126.96.36.199.1 made of cellulose
188.8.131.52.1.1 Sieve like network of strands.
184.108.40.206.2 kept rigid by pressure inside cell
220.127.116.11.2.1 comes from vacuole.
18.104.22.168.2.2 maintains stability.
2 CELL MEMBRANES
2.1.1 Outside cells
22.214.171.124 Seperate cell contents from outside
126.96.36.199 Cell recognition and signalling
188.8.131.52 regulating transport of
2.1.2 Inside cells
184.108.40.206 form organelles
2.2.1 Plasma membranes are partially permeable.
2.2.2 A bilayer of phospholipid molecules forms the main structure, intrinsic and
extrinsic proteins are studded within the bilayer.
2.2.3 Phospholipids have a fatty acid tail
and hydrophillic head. They are
permeable to small non-polar
2.2.4 Cholesterol provides stability
and makes the structure
2.2.5 Glycolipids are hospholipds with a carbohydrate attached,
used for cell signalling, cell surface antigens and cell
2.2.6 Proteins allow for charged and large
molecules to travel through the cell membrane
220.127.116.11 act as antigens
18.104.22.168 Enable self-recognition.
22.214.171.124 Used in cell signalling
126.96.36.199 act as receptor sites for
188.8.131.52 allow cell adhesion
2.3 EFFECTS OF TEMPERATURE
can move in
and out of the
2.4 CELL SIGNALLING AND RECEPTORS
2.4.1 Cell signalling
184.108.40.206 A process that leads to communication and
coordinated between cells, such as
hormones binding to their receptor sites.
2.4.2 Hormones are
used in cell
target cells have
a receptor which
to the hormone
meaning it can
bind to the
2.4.3 Beta blockers are used to prevent a
muscle from increasing the heart rate to
a dangerous level and some
schizophrenia drugs mimic a natural
neurotransmitter which some individuals
2.5.1 Passive transport
220.127.116.11 Diffusion is the movment of
molecules from an area with a
high concentration to an area
with a low concentration, small
18.104.22.168 Facilitated diffusion requires ATP. channel proteins
move ions, carrier proteins carry lage molecules
2.5.2 Active transport is the movement of
molecules or ions against a concentration
22.214.171.124 Mineral ions moved into root hair cells.
126.96.36.199 Hydrogen ions moved out of companion cells.
188.8.131.52 Miovement of sucrose out os sieve tube at
2.5.3 Endocytosis, active
transport of large
quantities of a matierial
into a cell using ATP.
out of a cell
2.5.5 Osmosis is the movement of water molecules from a region of higher
water potential to a region of lower water potential across a partially
184.108.40.206 Pure water
220.127.116.11.1 animal cell will burst,
18.104.22.168.2 Plant cell
22.214.171.124 Negative water potential,
126.96.36.199.1 Animal cell becomes crenated
188.8.131.52.2 Plant cell is plasmolysed
3 DIVISION DIVERSITY AND ORGANISATION
3.1 THE CELL CYCLE
3.1.1 Mitosis occupies only a small percentage of the cell cycle, the rest includes
copying and checking genetic information, growth of organelles, increasing
number of organelles, synthesis of proteins and ATP productioon.
3.1.2 Stages of mitosis.
184.108.40.206 Interphase: DNA replicates.
220.127.116.11.1 Prophase: Chromosomes supercoil and become visible.
nuclear envelope breaks down. Centriole divides in two and
move to form spindle.
18.104.22.168.1.1 Metaphase: chromosomes line up along the middle of the cell. They
attach to a spindle thread by centromere.
22.214.171.124.1.1.1 Anaphase: Sister chromatids are separate. The spindle fibres shorten
pulling them apart.
126.96.36.199.188.8.131.52 Telophase: sister chromatids reach the poles of the cell
and a new nuclear envelope forms around each set. The
spindle breaks down. The chromosomes uncoil and are
no longer visible under a light microscope.
184.108.40.206.220.127.116.11.1 Cytokinesis: the whole cell splits
into two new cells. Each one
genetically identical to one
another. These are clones. In plant
cells cytokinesis starts at the
3.1.3 Mitosis only occurs in the meristem cells in plants
and there are no centrioles involved.
3.2 A homologous pair of
chromosomes that have
the same genes at the
same loci. Members of
homologous pairs pair up
during meiosis. Diploid
organisms produced by
sexual reproduction have
homologous pairs of
member from the
mother and one from the
3.3.1 Growth: multicellular
organisms produce extra
cells to grow. each new cell
is geneticall identical to the
parent cells so cam perform
the same fumction.
Damaged cells need
to be replaced by
new ones that
perform the same
functions and so
need the genetically
cells that are
from parts of
3.3.4 Maintains chromosome number in cells.
3.4 Budding: the nucleus
divides by mitosis, the cell
swells on one side and
bulges, the nuceus,
cytoplasm and organelles
move into the bud and it
pinches off as the cell wall
forms so the bud becomes a
3.5 Meiosis produces cells that aren't
3.5.1 They are
produce 4 cells
not 2, they are
3.6 Stem cells.
3.6.1 A cell that is
but is capable
of mitosis and
is able to
18.104.22.168 Differentiation is the changes occuring in cells in
multicellular organisms so that each type of cell
becomes specialised to form a specific function.
22.214.171.124.1 Erythrocytes lose their
nuclus, golgi apparatus
and rough endoplasmic
reticulum. they are filled
with haemoglobin and
their shape changes to a
bi-concave disc giving it a
large surface area to
and lots of
golgi and many
on the surface
126.96.36.199.3 Xylem and phloem
188.8.131.52.3.1 In xylem
the walls are
by deposits of
kills the cell
ends of the cell
tubes with large
184.108.40.206.3.2 In phloem
most of their
their ends to
next to each
phloem cell is
keeps it alive.
220.127.116.11.4 Sperm cells contain many mitochondria , specialised
lysosomes to break down egg wall, nucleus contains
diploid number of cells. they are very small long and
thin to allow movement.
cells are long
and thin to
18.104.22.168.6 Root hair cells increase the surface
area available to absorb water and
minerals from the soil.
22.214.171.124.7 Guard cells contain
spiral thickenings of
cellulose making the
outer wall thinner
than the inner wall. In
light water moves
into them making
them turgid opening
the stoma. They
containa vacuole to
take up water and
become turgid. They
generate ATP for use
in active transport.
3.6.2 Found in meristem cells in plants which are in th e
cambium, in buds, just behind the tip of the root, just
behind the tip of the shoot.
3.7 Tissues organs and organ systems.
3.7.1 A tissue is a
group of cells
3.7.2 An organ is a
group of tissues
to perform a
3.7.3 An organ
system is a
3.7.4 Animal tissues.
126.96.36.199 Epithelium: layers and linings
tha form a thin
Used in blood
alveoli held in
188.8.131.52 Muscle tissue:
specialised to relax
184.108.40.206.1 the muscular and skeletal systems must work together for
movement to take place, thiscan only hapen if the nervous system
'instructs' the muscles to coordinate their actions. This requires
220.127.116.11 Nervous tissue
3.8 Plant specialisations
3.8.1 Xylem are
4 EXCHANGE SURFACES AND BREATHING
4.1 Exchange surfaces
they have a
for oxygen and
they have a
area to volume
ration aswell as
this their sirface
area is too small
alone to to
provide all the
takes too kolg.
4.1.2 Single celled
have a large
have a low
4.1.3 Alveoli produce a large surface area to volume ratio The squamous epithelium
provides a short diffusion pathway. They have capillaries running over their
surfaces delivering CO2 and remoxing oxygen
4.2 Efficient gaseous exchange
4.2.1 Alveoli have a squamous
epithelium and the
surrounding arteries have a
thin endothelium providing a
short diffusion pathway.
18.104.22.168 epithelial cells of the alveoli
produce a surfactant which
reduces the surface tension and
prevents the alveoli collapsing
when the pressure changes.
4.2.3 The diaphragm and
intercostal muscles work
together to maintain a
4.2.4 the ciliated epithelial cells and goblet cells
work together to remove
4.2.6 Smooth muscle can constrict to close the airways, lastic fibres
recoil adding ventilation and returning the size of the umen to
4.2.7 Macrophages and neutrophills engulf and destroy pathogens.
4.2.8 Ventillation increases the concentration of oxygen in the alveoli so
the concentration of is higher than in the blood. IT decreases the
concentration of carbon dioxide so it is smaller thanin the blood,
maintaining a a good diffusion gradient.
4.3 mammalian exchange system.
4.3.1 Trachea and bronchi
22.214.171.124 Thick walls
126.96.36.199 Regular c rings of cartilage to keep
the lumen open and to allow the
oesophogous to expand during
188.8.131.52 Layers of glandular tissue,
connective tissue, smooth
muscle elastic fibres smooth
muscle and blood vessels.
184.108.40.206 Inner layer has a
ciliated epithelium with
220.127.116.11 Much narrower
18.104.22.168 Some have cartilage some dont
22.214.171.124 The wall is made mostly
of smooth muscle and
126.96.36.199 Wall is one cell thick
188.8.131.52 100-300um diameter
184.108.40.206 Good blood supply
4.4.1 Cartilage holds the trachea
open. Prevents collapse
4.4.2 Cilia move in a synchronised pattern to waft
mucus that the goblet cells have secreted in order
to catch bacteria and dust.
4.4.3 smooth muscle contracts to
prevent harmful substances from
entering the lungs.
4.4.4 Elastic fibres recoil returning the lumen to its original
size, also they prevent alveoli from bursting.
220.127.116.11.1.1.1 4) pressure in thorax drops below
18.104.22.168.22.214.171.124 5) air moves into lungs
126.96.36.199 1) diaphragm relaxes and is
pushed up by displaced
188.8.131.52.1 2) Intercostal muscle relax and ribs fall
184.108.40.206.1.1 3) volume of thorax decreases
220.127.116.11.1.1.1 4)pressure in thorax rises above atmospheric
18.104.22.168.22.214.171.124 5) air is pushed out of the lungs.
126.96.36.199 A chamber filled with oxygen or fresh air floating on a tank of water. A healthy person breathes into a disinfected mouthpiece attached to a tube connected to
the oxygen tank. breathing in causes the chamber to sink, breathing out causes it to rise, Lime water is used to absorb carbon dioxide. The movements of the
chamber are recorded using a data logger
188.8.131.52.1 The maximum amount of air that can be
breathed in and out of the lungs in any one
184.108.40.206.2 Breathe in as much as possible then out as much as possible
220.127.116.11 Tidal volume
18.104.22.168.1 The volume of air moved in and out of the lungs during breathing at rest.
22.214.171.124.2 breathe in and out normally whilst sitting dwn at rest
126.96.36.199 Breathing rate is calculated by dividing the number
of breaths by the time in minutes
dm3 by the
5 Transport in animals
5.1 Need for transport systems.
5.1.1 Several layers of cells
means that nutrients and
oxygen will be used up by
the outer layers of the
5.1.2 If an animal
is very active
it will need a