CELLS AND SIMPLE CELL TRANSPORT

Specialised and Dissolved Cells

Specialised and Dissolved Cells

Specialisation

Cells

Certain cells within an organism are specialised. This means that they have developed to carry out a specific function. See the table below for some examples.

Type Function Adaptations
Sperm cell

Palisade cell

Cilia cell

To fertilise a female egg cell (the ovum)

For photosynthesis

Helps prevent dirt and bacteria entering your lungs

It’s very small and has a tail which allows it to swim and find the ovum.Its head contains enzymes which allow it to digest its way through the membrane of the egg.Its nucleus only contains 23 chromosomesIt has a large surface so that it can absorb as much light as possible

It’s located on the top side of the leaf so that it can easily absorb light and carbon dioxide

It’s full of chloroplasts which are required for photosynthesis

It’s found in all air passages connected to the lungs

It has minute hairs which filter the air as it moves past

Mucus with trapped dirt and bacteria can be swept to the back of the throat where it’s swallowed

——————————————————

Dissolved substances

CellsDissolved substances are able to enter and leave a cell through its cell membrane. One way in which they can achieve this is through a process known as diffusion.

Diffusion can occur in either a liquid or gas. It involves the particles of a substance moving from an area in which there’s a high concentration of it to an area in which there’s a lower concentration. The bigger the difference in concentration, the faster the rate at which diffusion occurs.

There are a number of ways diffusion is used by living organism:

  • lungs: oxygen from the alveoli in the lungs is able to move across into the red blood cells so that carbon dioxide can then diffuse into the alveoli and then be expelled out of the body via the lungs.
  • photosynthesis: similarly, green plants take in carbon dioxide from the air via chloroplasts by diffusion and release oxygen back into the atmosphere also by diffusion.
  • respiration: this process also involves diffusion. In animals, for example, oxygen diffuse from the red blood cells into the tissue cells and then carbon dioxide diffuses in the other direction.