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Exam questions · Biology · Transport in Cells

Active Transport

  • 10 exam questions
  • 28 marks
  • 10 quick checks
  1. 1 State [1 mark]

    State what is needed for active transport.

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    Model answer

    Energy (from respiration).

    Mark scheme

    • Energy from respiration — 1 mark
  2. 2 Describe [2 marks]

    Describe what is meant by active transport.

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    Model answer

    The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient), using energy from respiration.

    Mark scheme

    • Movement from dilute to concentrated / against a concentration gradient — 1 mark
    • Needs energy from respiration — 1 mark
  3. 3 Name [4 marks]

    Figure 1 shows ions being taken into a cell. A is a carrier protein. Name the structure B, name the process shown, and explain how you know it is that process.

    Ions moving through a carrier protein from a low concentration to a high concentration, with energy supplied by a mitochondrion.
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    Model answer

    B is a mitochondrion. The process is active transport. The ions move from a lower to a higher concentration, which is against the concentration gradient, and the mitochondrion supplies energy from respiration, which diffusion would not need.

    Mark scheme

    • B: mitochondrion — 1 mark
    • Active transport — 1 mark
    • Ions move from lower to higher concentration / against the gradient — 1 mark
    • Needs energy from respiration — 1 mark
  4. 4 Give [1 mark]

    Give one example of active transport in a plant.

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    Model answer

    Mineral ions being taken into root hair cells from the soil.

    Mark scheme

    • Mineral ions into root hair cells — 1 mark
  5. 5 Explain [3 marks]

    Explain why root hair cells take up mineral ions by active transport and not by diffusion.

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    Model answer

    The concentration of mineral ions in the soil solution is lower than in the root hair cell. Diffusion only moves substances from a higher to a lower concentration. Active transport can move ions against the concentration gradient, using energy.

    Mark scheme

    • Lower concentration of ions in the soil than in the cell — 1 mark
    • Diffusion would not move ions into the cell / only goes down the gradient — 1 mark
    • Active transport moves them against the gradient using energy — 1 mark
  6. 6 Explain [2 marks]

    Sugar is absorbed from the gut into the blood by active transport. Explain why the sugar must be absorbed.

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    Model answer

    Sugar molecules are used for cell respiration, so the body needs to absorb them.

    Mark scheme

    • Sugar is used for respiration — 1 mark
    • To release energy for the body's cells — 1 mark
  7. 7 Explain [3 marks]

    Root hair cells contain large numbers of mitochondria. Explain why.

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    Model answer

    Mitochondria release energy by respiration. Root hair cells take up mineral ions by active transport, which needs energy. So they need many mitochondria to supply it.

    Mark scheme

    • Mitochondria release energy / respiration — 1 mark
    • Active transport needs energy — 1 mark
    • Root hair cells take in ions by active transport — 1 mark
  8. 8 Explain [3 marks]

    A farmer notices that plants in waterlogged soil take up fewer mineral ions, although the soil contains plenty. Use ideas about active transport to explain why.

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    Model answer

    Waterlogged soil contains little oxygen, so the root cells respire less. They release less energy, and active transport of mineral ions needs energy. So fewer ions are taken up.

    Mark scheme

    • Little oxygen in the waterlogged soil, so less respiration — 1 mark
    • Less energy released — 1 mark
    • Active transport of ions needs energy, so less uptake — 1 mark
  9. 9 Compare [3 marks]

    Give three differences between diffusion and active transport.

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    Model answer

    Diffusion moves substances from a higher to a lower concentration, but active transport moves them from a lower to a higher concentration. Diffusion does not need energy, but active transport needs energy from respiration. Diffusion goes down the concentration gradient, but active transport goes against it.

    Mark scheme

    • Direction: high to low (diffusion) compared with low to high (active transport) — 1 mark
    • Diffusion needs no energy, active transport does — 1 mark
    • Down the gradient compared with against the gradient — 1 mark
  10. 10 Compare [6 marks]

    Compare diffusion, osmosis and active transport.

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    Model answer

    Diffusion is the net movement of particles from a higher to a lower concentration, down the concentration gradient, and needs no energy. Osmosis is the diffusion of water only, from a dilute solution to a concentrated solution through a partially permeable membrane, and needs no energy. Active transport moves substances from a more dilute to a more concentrated solution, against a concentration gradient, and needs energy from respiration.

    Mark scheme

    • Diffusion: particles from high to low concentration — 1 mark
    • Diffusion needs no energy — 1 mark
    • Osmosis: water only — 1 mark
    • Osmosis: dilute to concentrated through a partially permeable membrane — 1 mark
    • Active transport: dilute to concentrated (against the gradient) — 1 mark
    • Active transport needs energy from respiration — 1 mark

Quick check

  1. 1

    What does active transport need?

    1. AA partially permeable membrane only
    2. BLight
    3. CEnergy from respiration
    4. DNothing at all
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    C: Energy from respiration

    Active transport needs energy from respiration, because it moves substances against a concentration gradient.

  2. 2

    In which direction does active transport move substances?

    1. AFrom low concentration to high concentration
    2. BFrom high concentration to low concentration
    3. COnly out of cells
    4. DOnly into plants
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    A: From low concentration to high concentration

    Active transport moves substances from a more dilute to a more concentrated solution, against the concentration gradient.

  3. 3

    Which structures supply the energy for active transport?

    1. ARibosomes
    2. BThe nucleus
    3. CThe cell wall
    4. DMitochondria
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    D: Mitochondria

    Mitochondria release energy from respiration, so cells that do a lot of active transport have many of them.

  4. 4

    Which of these is an example of active transport?

    1. AOxygen moving into a respiring cell
    2. BMineral ions moving into root hair cells
    3. CWater moving into a potato cell
    4. DCarbon dioxide moving out of a cell
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    B: Mineral ions moving into root hair cells

    Root hair cells take in mineral ions from the very dilute soil solution by active transport.

  5. 5

    Why do plants need mineral ions?

    1. AFor healthy growth
    2. BTo make energy by respiration
    3. CTo absorb water by osmosis
    4. DTo make sugar from the soil
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    A: For healthy growth

    Plants need ions for healthy growth, for example nitrate to make proteins and magnesium to make chlorophyll.

  6. 6

    Sugar concentration is lower in the gut than in the blood. How does sugar move into the blood?

    1. ABy diffusion
    2. BBy osmosis
    3. CBy active transport
    4. DIt does not move
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    C: By active transport

    It has to move against the concentration gradient, so it is absorbed by active transport.

  7. 7

    Which process needs no energy from the cell?

    1. AActive transport only
    2. BNeither diffusion nor osmosis
    3. CPumping ions
    4. DDiffusion and osmosis
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    D: Diffusion and osmosis

    Diffusion and osmosis are passive processes, which move things down a gradient without energy from the cell.

  8. 8

    What happens to active transport if respiration in a cell stops?

    1. AIt speeds up
    2. BIt stops or slows down
    3. CIt does not change
    4. DIt turns into diffusion
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    B: It stops or slows down

    Active transport needs energy from respiration, so it stops or slows down.

  9. 9

    Which statement about osmosis is correct?

    1. AIt needs no energy and moves only water
    2. BIt needs energy from respiration
    3. CIt moves any substance
    4. DIt moves water from concentrated to dilute
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    A: It needs no energy and moves only water

    Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane. It needs no energy.

  10. 10

    A cell takes in a substance from a place where it is at a lower concentration. Which is the most likely process?

    1. ADiffusion
    2. BOsmosis
    3. CActive transport
    4. DCell division
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    C: Active transport

    Moving a substance from a lower to a higher concentration is against the gradient, so it must be active transport.