Cell Structure and Organisation: Question 7

Worked solution

Part (a): Functions of the two cells

(i) Red blood cell

The main function of a red blood cell is to carry (transport) oxygen around the body. Oxygen binds to the red pigment haemoglobin that fills the cell.

(ii) Neurone

The main function of a neurone is to carry (conduct) electrical impulses rapidly between different parts of the body, for example from a receptor to the brain or spinal cord, or from the brain or spinal cord to a muscle.

Part (b): How the red blood cell’s structure relates to its function

1. A red blood cell has a biconcave disc shape (thinner in the middle than at the edges). This gives it a larger surface area in relation to its volume than a simple sphere would have, which allows oxygen to diffuse into and out of the cell more quickly.
2. A mature red blood cell has no nucleus. This leaves more room inside the cell to be packed with haemoglobin, so the cell can carry a greater amount of oxygen.

Part (c): How the neurone’s structure relates to its function

A neurone has a long, thin fibre called an axon that extends out from the main cell body, sometimes over a considerable distance. This shape allows an electrical impulse to travel rapidly along a single continuous cell from one part of the body to another, rather than having to cross the boundaries of many separate short cells, which would slow the impulse down.

Final answers

• (a)(i) Red blood cell: carries oxygen around the body.
• (a)(ii) Neurone: carries electrical impulses around the body.
• (b) Red blood cell: biconcave shape gives a large surface area for fast oxygen diffusion; no nucleus gives more space for haemoglobin.
• (c) Neurone: a long, thin axon allows an impulse to travel rapidly over a long distance within one cell.