B1b - cell transport exam questions

Question 1

complete the sentences (3 marks)

• Plants absorb substances from the soil.
• Plant cells use osmosis to absorb ___________.
• Active transport is used by plant cells to absorb ____________________.
• Active transport moves substances against the concentration gradient and needs ___________.

Answer 1

IN THIS ORDER ONLY
water
mineral ions
energy

Question 2

what is meant by the term diffusion (2 marks)

Answer 2

• movement of particles
• from an area of highER concentration to an area of lowER concentration

Question 3

explain how the human lungs are adapted for efficient exchange of gases by diffusion (6 marks)

Answer 3

• (many) alveoli
• to provide a large SA:V ratio
• capillaries are thin/one cell thick
• which provides short diffusion path (for oxygen and carbon dioxide)
• breathing moves air in and out
• to bring in oxygen OR remove carbon dioxide OR maintain a concentration gradient
• good blood supply
  to remove oxygenated blood OR to bring carbon dioxide to the lungs quickly OR maintain a concentration gradient

Question 4

name the process by which water molecules enter a root hair cell (1 mark)

Answer 4

osmosis

Question 5

nitrate ions need a different method of transport into a root hair cell. Explain how nitrate ions are transported into the root hair cell (3 marks)

Answer 5

• active transport
• because energy is needed
• (to move nitrate ions) from a lower concentration (in the soil) to a higher concentration (in the root/cell)

Question 6

complete the sentences (2 marks)

• some glucose is absorbed into the bloodstream against the concentration gradient by the process of _________________.
• water moves out of the large intestine and into the bloodstream by the process of ________________.

Answer 6

IN THIS ORDER ONLY
active transport
osmosis

Question 7

complete the sentences (2 marks)

• the process that makes carbon dioxide is ____________.
• during exercise, extra carbon dioxide can be removed from the body by increasing the rate of ________________.

Answer 7

IN THIS ORDER ONLY
respiration
breathing

Question 8

what is the name of the process in which oxygen enters the skin cells (1 mark)

Answer 8

diffusion

Question 9

suggest why a large surface area to volume ratio is an advantage (1 mark)

Answer 9

can absorb more oxygen so increase in gas exchange

Question 10

earthworms have a large surface area to volume ratio. suggest why it is an advantage to the earthworm (1 mark)

Answer 10

absorb more oxygen or increases gas exchange

Question 11

a student used cubes of potato to investigate the effect of surface area to volume on the rate of osmosis. why did the student dry the surface of each potato cube? (1 mark)

Answer 11

so that excess water does not contribute to the mass of the cubes

Question 12

what process do plants use to move mineral ions into root cells (1 mark)

Answer 12

active transport

Question 13

describe how water moves from roots to leaves (2 marks)

Answer 13

by transpiration stream in xylem

Question 14

why is having very few stomata on the upper surface of a leaf an advantage to the plant (2 marks)

Answer 14

less water lost so it does not wilt

Question 15

suggest 2 possible sources of error in the osmosis required practical (2 marks)

Answer 15

any 2 from:
- concentrations of solutions
- drying of chips
- accuracy of balance
- evaporation from tubes

Question 16

describe how water, ions and sugar are obtained and transported through plants (6 marks)

Answer 16

ions
- taken up by diffusion or active transport
- from an area of high to low concentration (diffusion)
- or an area of low to high concentration (active transport)
- travels in the xylem
- to the leaves or from the roots/soil

water
- taken up by osmosis
- from an area of low to high concentration
- travels in the xylem
- to the leaves or from the roots
- transpiration stream - movement replaces water as it evaporates from leaves

sugar
- made during photosynthesis
- travels in the phloem
- to other parts of the plant or to storage organs or travels up and down