The jellyfish in Table 4 take oxygen into their cells by diffusion.
Name one other substance that enters cells by diffusion.
Do not refer to oxygen in your answer.
How to approach this question
Think about the substances that cells need to survive and function. These substances need to move from outside the cell to inside. Recall which of these substances move by diffusion.
Full Answer
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. Cells need various substances to enter them to carry out life processes.
- **Glucose:** Needed for respiration. It diffuses from the blood (high concentration) into cells (low concentration).
- **Amino acids:** Needed for protein synthesis. They also diffuse from the blood into cells.
- **Water:** Moves by a special type of diffusion called osmosis, but water itself is an acceptable answer as it moves down a water potential gradient.
Common mistakes
✗ Naming a substance that is typically removed from cells, like carbon dioxide or urea.\n✗ Naming oxygen, as the question specifically forbids it.
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