BIOLOGY REVISION

There are many different organelles in animal and plant cells:
the is where respiration takes place.
the nucleus contains and controls what the cell does.
the ribosomes occur in great numbers in the cell cytoplasm either freely, in small clusters, and function as the site of manufacture.
the cytoplasm is a jelly like substance that contains and is where the take place.
the cell wall supports, and strengthens the cell and contains cellulose
the vacuole contains and has what the cell needs to survive.
chloroplasts contain which is what makes them this is where the process of takes place.

light microscopes use and to form an image of an object and it
electron microscopes use - they pass through the object and magnify it.
electron microscopes have a higher
is the ability to distinguish between two points.
a higher = a image

the sperm cell has a streamlined which helps it move faster, and it contains many It has lots of mitochondria, and a long tail to help it

*for this question, YOU MUST write the exact definition for the word otherwise you're wrong according to this quiz*
define diffusion
diffusion is the of particles from an area of to an area of

most happens when an organism . in most cells, when they have specialised, they the ability to differentiate.

an eye cell can differentiate into a skin cell.
the statement above is

you need to know these examples of specialised cells.

sperm cells are specialised for
cells are specialised for rapid signalling
muscle cells are specialised for
are specialised for absorbing water and
and cells are specialised for transporting substances

and are too big to pass through a partially membrane.

is the movement of water from a water concentration to a water concentration through a membrane. Osmosis takes place in all living cells.

inside the nucleus, there are
pairs of chromosomes from the mother, and from the , adding up to a total of
the tells us how we make new cells.
when the parent cell splits, it makes two cells.
the cycle has two stages, being stage two.
the cell cycle makes new cells for and
the molecule that chromosomes are made of is called

a person with the disease "" may experience lower while doing physical exercise. This disease affects the , damaging the walls. the reason for this symptom is since the walls of the alveoli, there will be a surface area. a surface area leads to a lower rate of of oxygen. the lower the rate of the less . respiration is what gives us therefore the person will experience lower .

here are some adaptations to make gas exchange easier.
1) : this allows only a short distance to be needed for diffusion to take place.
2) : so a lot can diffuse at once.
3) : good blood supply can get in and out quickly
4) : for dissolving gasses
5) : tiny holes in the leaf. they have cells around them called guard cells which control the size of the stomata and prevent wilting.

the is covered in small which increase to that digested food is absorbed efficiently into the . they have a layer of surface cells and a very good supply to assist quick absorbtion

LEAVES: carbon dioxide diffuses into the in the leaf, then to the cells where happens.
the leaf's structure is adapted so that this can happen easily:
1) the of the leaf is the gas exchange surface and is covered in
2) the size of stomata are controlled by
3) the increases surface area
the walls of the cells inside the leaf form another of which air spaces to increase

REMEMBER! PLANT CELLS need and take out