Biology unit 2 Cells and simple cell transport
Cells and simple cell transport
Cells: All living things are made up of cells. The structures of different types of cells are related to their functions. Cells may be specialised to carry out a particular job for instance root hair cell, egg cell, sperm cell and palisade cell.
Cell structure: Most human, plant and animal cells have the following parts:
- Nucleus - controls the activities of the cell
- Cytoplasm - most chemical reactions take place here
- A cell membrane - controls passage of substances in and out of the cell
- Mitochondria - where most energy is released in repiration
- Ribosomes - where protein synthesis occurs
Plant cells also have a cell wall, chloroplasts and a permanent vacuole.
Diffusion: Diffusion is the spreading of particles of a gas or a substance in solution. It results in net movement from a region where the particles are of a higher concentration to a region of lower concentraction