Chapter 1 - Summary Questions

Question 1

1mm contains 1000μm. What is the order of magnitude of the mm?

Answer 1

An order of magnitude of 3 (or 10^3)

Question 2

Why do some cells have a large number ribosomes?

Answer 2

To produce large quantities of proteins (such as enzymes)

Question 3

What is the difference between diffusion and osmosis?

Answer 3

Diffusion is the movement of all types of particle from a region of higher to lower concentration; osmosis is the movement of water from a dilute solute solution to a more concentrated solute solution across a partially permeable membrane.

Question 4

Name the features that increase the surface area of the lungs.

Answer 4

Alveoli

Question 5

What are the features of an efficient exchange surface?

Answer 5

Large surface area; thin walls or short diffusion path; good transport system.

Question 6

Give two differences between active transport and diffusion.

Answer 6

Active transport requires energy; in active the movement of particles is against the concentration gradient; or diffusion does not require energy; in diffusion, particles move down the concentration gradient.

Question 7

What is meant by the term hypotonic?

Answer 7

A solution with a lower concentration of solute molecules with another solution.

Question 8

Give an example of active transport in:

a) plants b) a human

Answer 8

a) Absorption of mineral ions by roots

b) Absorption of glucose out of the gut or from kidney tubules into the blood.

Question 9

What is meant by turgor pressure and why is it important?

Answer 9

Water enters the vacuole in a plant cell, pushing the cytoplasm against the cell wall, creating a pressure called turgor pressure; the cell becomes rigid and this helps to support the plant.

Question 10

Explain why animals that normally live in fresh water may die if placed in seawater.

Answer 10

Seawater contains salt, so the solution around the animal is hypertonic to its cells (higher solute concentration) water leaves the cells, so chemical reactions in the cytoplasm stop.

Question 11

Explain in detail what happens to plant cells when placed in hypertonic solution.

Answer 11

Water moves out of the cells from a more dilute to the more concentrated solute solution; the vacuole and cytoplasm shrink, so the cell membrane draws away from the wall / the cell becomes plasmolysed.

Question 12

How could you increase the surface area without changing the volume of a clay block?

Answer 12

Roll out the clay so that it is very thin.