Slides in this set
1.1 Animal and plant cells
These cells have structures in common. They have:
A nucleus which holds genetic information and control cell activity
A cytoplasm where chemical reactions take place
A cell membrane which controls substances entering and leaving the cell
Ribosomes where protein synthesis takes place
Mitochondria which release energy during respiration
However, plant and algal cells also have:
A cell wall made from cellulose which strengthens and supports the cell
Chloroplasts containing chlorophyll (A green substance that uses light energy to make
A permanent vacuole containing cell sap…read more
1.2 Bacteria and yeast
· A bacterium is a single-celled organism and they are very small
· They have a cell membrane, a cell wall and a cytoplasm
· Bacteria do not have a nucleus so the genetic material is in the cytoplasm
· When they multiply they form a bacterial colony which can be seen with the naked eye.
· They are very small
· Yeast cells are similar to bacterial cells in that they have a cytoplasm, cell membrane and cell
· However they have a nucleus which contains the DNA.…read more
1.3 Specialised cells
Cells may be specialised for a particular function. Their structure will allow them to carry
this function out.
Examples of the functions of cells:
Absorbs light energy Packed with chloroplasts. Regular shaped,
Leaf cell closely packed cells form a continuous layer
for efficient absorption of sunlight.
Absorbs water and Long 'finger-like' process with very thin wall,
Root mineral ions from the
soil which gives a large surface area.
Fertilises an egg cell - The head contains genetic information and the
Sperm cell female gamete acrosome contains an enzyme to help penetrate the
egg cell membrane. The middle section is packed
with mitochondria for energy. The tail moves the
sperm to the egg.
Contains haemoglobin Thin outer membrane to let oxygen diffuse through
Red blood cells to carry oxygen to the easily. Shape increases the surface area to allow
more oxygen to be absorbed efficiently. No nucleus,
so the whole cell is full of haemoglobin.…read more
· Diffusion is when particles spread out
· It is the net movement of particles down a concentration gradient from an area
of high concentration to an area of low concentration
· The larger the difference in concentration, the faster the rate of diffusion.
· It only occurs when particles are free to move (gases and particles dissolved in
· It is a passive process which means that it does not need energy
· Molecules diffuse until they are evenly spaced apart and equilibrium is reached.
Examples in the body:
The diffusion of oxygen into the cells from the bloodstream
The diffusion of carbon dioxide out of the cells
The diffusion of simple sugars and amino acids from the gut…read more
1.5 Tissues and organs
A tissue is a group of specialised cells that have a similar structure and function
Animal tissues include:
Plant tissues include:
Organs are made of tissues.
The stomach is an organ made up of:
Muscular tissue to churn the food
Glandular tissue to produce enzymes to break down the food
Epithelial tissue to cover the inside and the outside of the stomach…read more