Biology GCSE (Unit 2) Part 1 : Cells

Purple - In both Plant and Animal Cells Blue - Only in Plant Cells

Nucleus: Contains genetic material, which controls the activities of the cell.

Cytoplasm: Most chemical processes take place here, controlled by enzymes.

Cell Membrane: Controls the movement of substance into and out of the cell.

Mitochondria: Most energy is released by respiration.

Ribosomes: Protein synthesis happens here.

Cell Wall: Strengthens the Cell.

Chloroplasts: Contain chlorophyll, which absorbs light energy for photosynthesis.

Permanent Vacuole : Filled the cell sap to help the cell turaid.

Cell  Function  Adapation

Leaf Cell - Absorbs light energy for Photosynthesis. Filled with chloroplasts, closely packed cells form a continuous layer to absorb sunlight. 

Root Hair Cell - Absorbs water and mineral Irons from soil.Long 'finger-like' process with very thin wall, which gives a large surface area.

Sperm Cell - Fertilises an egg cell - Female Gamete. The head contains DNA and an enzyme which helps penetrate the egg cell membrane. The middle section is full of mitochondria for energy. The tail moves the sperm to the egg.

Red Blood Cells - Contain haemoglobin to carry oxygen to the cells. This outer membrane to let oxygen diffuse through easily.Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of haemoglobin.

Diffusion - The movement of Particles from an area of High Concentration to an area of Lower concentration.

Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions. Particles diffuse down a concentration gradient, from an area of high concentration to an area of low concentration. This is how the smell of cooking travels around the house from the kitchen, for example.

Examples of Diffusion

Location      Particles  Move         From                      To

Gut          Digested food products Gut Cavity  Blood capillary of villus

 Lungs      Oxygen                          Alveolar air Blood Circulating around the                                                                   Space         lungs

Osmosis - The movement of water from a less concentrated solution to a more concentrated solution through a partially permeable membrane.

Eventually the level on the more concentrated side of the membrane rises, while the one on the less concentrated side falls. When the concentration is the same on both sides of the membrane, the movement of water molecules will be the same in both directions. At this point, the net exchange of water is zero and there is no further change in the liquid levels. Plants gain water through osmosis.