GCSE AQA B2 revision cards

Cells - all organisms are made up of cells. 

Animal cell contains :

Nucleus - controlls cells activities, contains instructions for makink new cells or organisms. 

Cytoplasm - a liquid gel in which the chemical reactions needed for life take place, e.g respiration. 

Cell membran - controlls passage of substances in and out of the cell. 

Mitochondria - structures in the cytoplasm where most of the energy made in respiration is released. 

Ribosomes - where protein synthesis takes place.

Plant cell contains :

All of the above features AND

Cellulose Cell wall - strengthens the cell and gives it support.

Chloroplasts - found in the green part of the plant, contain chlorophyll, absorb light energy to make their food by photosynthesis. 

Permanent vacuole - space in the cytoplasm filled with cell sap, keeps the cells rigid to support the plant. 

In your cells all the time hundreds of different reactions are going on constantly.

Each of these is controlled by a spesific enzyme - this makes sure the reaction takes place correctly. With out getting mixed up in anouther reaction. 

Enzymes are found through out the structure of a cell, but partularly in the mitochondria and chloroplasts. 

Enzyme - a protien - controlls reacactions - e.g 

• respiration (enzymes found in mitochondria)
• photosynthesis (enzymes found in chloroplasts)
• protein synthesis ( enzymes found on the surface of the ribosomes) 

Some cells become specilised so that they can carry out spesific jobs. E.g 

Fat cell

• Little normal cytoplasm - large area for fat storage
• Few mitochondria - as they use very little energy
• They can expand up to 1000x - so it's able to store a lot of fat.

 Root hair cell

• Root hairs - increase surface area so water can move into the cell
• Large permanent vacuole - affects water movement from the soil across the cell
• Always positioned next to the xylem tissue - so it can reach the tissue that carries water up to the rest of the plant fast