Movement of particles within cells

Define the term diffusion

This is the movement of particles from a region of higher concentration to a region of lower concentration across a semipermeable membrane until evenly distributed.

Outline examples of diffusion in animal cells.

1. Oxygen, for use in aerobic respiration, moves into organisms through gaseous exchange surfaces and cells by diffusion.

2. Carbon dioxide, produced in aerobic respiration moves out of cells and organisms through gaseous exchange surfaces by diffusion.

Outline examples of diffusion in plant cells.

1. Carbon dioxide, for use in photosynthesis, moves into leaves and plant cells by diffusion

2. Oxygen, produced in photosynthesis, moves out of plant cells and leaves by diffusion.

Define the term osmosis

This is the process by which water molecules move from a region of higher concentration to a region of lower concentration through a semipermeable membrane until evenly distributed.

Outline examples of osmosis in living organisms

1. All cells are kept hydrated by water moving into them by osmosis

2. Plant cells are kept turgid by water moving into them by osmosis.

3. Water is reabsorbed into the blood from the filtration in the kidney tubeless by osmosis

Define the term active transport

This is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, requiring the expenditure of energy.

What is the importance of active transport?

It allows cells to accumulate a high concentration of important substances. E.g. glucose, amino acids, and ions.

Describe two examples of active transport in plant cells.

1. Mineral ions move from the soil to plant roots by active transport.

2. Sugars produced in photosynthesize move into the phloem by active transport

Describe two examples of active transport in animal cells.

1. Some of the glucose and amino acids produced in digestion are absorbed from the ileum into the blood by active transport.

2. Useful substances are reabsorbed from the filtrate in the kidney tubeless into the bloody active body

Explain the term hypotonic in regard to concentration in solutions