Chapter 1 - Cell Structure And Transport

Question 1

What forms the image in a typical school microscope?

Answer 1

A beam of light.

Question 2

The length of an onion cell in an image is 12mm. The magnification is X570. What is the size of the real cell?

Answer 2

Length of cell = 12mm = 12 000μm
real size = 12 000/570
= 21μm.

Question 3

In which part of the cell is energy transferred during respiration?

Answer 3

Mitochondria.

Question 4

What is the function of chloroplasts?

Answer 4

To absorb light for photosynthesis.

Question 5

Onion cells do not look green. Explain why.

Answer 5

Onion bulb cells do not contain chloroplasts for photosynthesis because they are underground and do not receive light.

Question 6

Where is the DNA found in a prokaryotic cell?

Answer 6

In the cytoplasm as a long circle of DNA, and in plasmids.

Question 7

What is the order of magnitude of 1cm compared with 1mm?

Answer 7

1 order of magnitude (or 10^1).

Question 8

Muscle cells contain a lot of mitochondria. Why?

Answer 8

Mitochondria transfer energy during aerobic respiration; muscle cells need energy to contract.

Question 9

Which organ system contains nerve cells?

Answer 9

The nervous system.

Question 10

What is the main function of the root hair cell?

Answer 10

To take up water and mineral ions from the soil.

Question 11

Name the chemical that makes xylem rigid.

Answer 11

Lignin.

Question 12

What determines the net movement of particles across a cell membrane?

Answer 12

The concentrations of the particles on either side of the membrane.

Question 13

Describe what is meant by gas exchange in the lungs.

Answer 13

The diffusion of oxygen and carbon dioxide in opposite directions.

Question 14

What type of membrane is the cell membrane?

Answer 14

Partially permeable.

Question 15

What term is used to refer to two solutions with identical concentrations?

Answer 15

Isotonic.

Question 16

When does turgor pressure occur in a plant cell?

Answer 16

When water enters the cell by osmosis, causing the vacuole to swell, which presses the cytoplasm against the cell wall.

Question 17

If potato chips are placed in pure water, will they get bigger or smaller? Explain your answer.

Answer 17

Bigger. Because water moves into the potato cells by osmosis.

Question 18

Why does active transport require energy?

Answer 18

The particles are being absorbed against a concentration gradient.

Question 19

Name a substance that is moved by active transport into plants from the soil solution.

Answer 19

Mineral ions (or a named mineral)

Question 20

Why do large organisms need specialised exchange surfaces?

Answer 20

Large organisms have a small surface area to volume ratio; exchange surfaces allows materials to be passed to a transport system, which carries them to all the cells.

Question 21

How are leaves adapted to increase their surface area?

Answer 21

Leaves are flat and thin, and have internal air spaces and stomata.

Question 22

Calculate the surface area : volume ratio of a cube with sides 2cm long

Answer 22

24:8 or 3:1