2. Organisation of the organism

function of nucleus

-contains genetic material in chromosomes which control how cells grow and work
-controls cell division

function of cytoplasm

-supports cell structures
-site of chemical reactions
-contains water and solutes

function of cell membrane

-holds the cell together
-controls substances entering and leaving the cell

function of cell wall

-gives the cell extra support and defines its shape

function of chloroplasts

-site of photosynthesis
-the chlorophyll pigments absorb light energy needed for the reaction to occur

function of vacuole

-contains cell sap
-used for storage
-helps support shape of cell

function of mitochondria

-site of aerobic respiration
-cells with high rates of metabolism will have significantly higher numbers of mitochondria than cells with low rates of metabolism

function of ribosomes

-site of protein production in protein synthesis

How are new cells produced?

By division of existing cells

function and adaptation of ciliated cell

function: movement of mucus in the trachea and bronchi

adaptation:
-extensions of the cytoplasm at the surface of the cell form hair like structures called cilia which beat to move mucus and trapped particles up to the throat

function and adaptation of nerve cell

function: conduction of impulses

adaptation:
-long so nerves can run to and from different parts of the body to the CNS
-has extensions and branches to communicate with other nerve cells, muscles and glands
-the axon is covered with a fatty sheath which insulates the nerve cell and speeds up the nerve impulse

function and adaptation of red blood cell

function: transport of oxygen

adaptation:
-bioconcave disc shape increases surface area for more efficient diffusion of oxygen
-contains haemoglobin which binds to oxygen to transport it
-contains no nucleus to have more space for haemoglobin/to carry oxygen

function and adaptation of sperm cell

function: reproduction

adaptation:
-the head contains the genetic material for fertilisation in a haploid nucleus
-the acrosome in the head contains digestive enzymes to penetrate the egg
-the tails enables the sperm to swim

function and adaptation of egg cell (ovum)

function: reproduction

adaptation:
-contains a lot of cytoplasm which has nutrients for the growth of the early embryo
-haploid nucleus contains the genetic material for fertilisation
-cell membrane changes after fertilisation by a single sperm so that no more sperm can enter

function and adaptation of root hair cell

function: absorption of water and mineral ions from soil

adaptation:
-root hair increases surface area to ensure maximum absorption
-walls are thin to ensure water moves through quickly
-no chloroplasts present

function and adaptation of palisade mesophyll cell

function: photosynthesis

adaptation:
-column-shaped to maximise absorption of sunlight and fit as many as possible in a layer under the upper epidermis of the leaf
-contains many chloroplasts for maximum photosynthesis

cell meaning

basic functional and structural unit in a living organism

tissue meaning

a group of cells of similar structure working together to perform the same function

organ meaning

a group of tissues working together to perform specific functions

organ system meaning

groups of organs with related functions working together to perform bodily functions

magnification formula

magnification = image size ÷ actual size
or
magnification = drawing size ÷ actual size

1 μm in mm

0.001 mm (÷ 1000)

1 mm in μm

1000 μm (x 1000)