MCQs / Biology / A Level Biology: Cell membranes and transport

A Level Biology: Cell membranes and transport MCQs — Biology

20 multiple-choice questions on A Level Biology: Cell membranes and transport from Biology, each with the correct answer and, where available, a teacher's explanation. Read through them to revise the chapter, then practise the same questions one by one to test yourself.

1. The membrane is described as "mosaic" because

  1. it never moves
  2. it is made of glucose
  3. proteins are scattered among the phospholipids
  4. it has only one layer

Answer: C) proteins are scattered among the phospholipids

Explanation: Proteins are scattered like tiles. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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2. Which process requires ATP?

  1. Simple diffusion
  2. Osmosis
  3. Active transport
  4. Facilitated diffusion

Answer: C) Active transport

Explanation: Pumps use energy from ATP hydrolysis. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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3. Which molecules cross the bilayer most easily by simple diffusion?

  1. Glucose
  2. Ions such as Na⁺
  3. Proteins
  4. Small non-polar molecules such as oxygen

Answer: D) Small non-polar molecules such as oxygen

Explanation: Non-polar molecules dissolve in the bilayer. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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4. A red blood cell placed in a solution of much lower water potential will

  1. shrink (crenate)
  2. plasmolyse
  3. become turgid
  4. burst

Answer: A) shrink (crenate)

Explanation: Water leaves animal cells without a wall. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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5. Plasmolysis occurs when a plant cell is placed in a solution with

  1. pure water
  2. lower water potential than the cell
  3. the same water potential
  4. higher water potential than the cell

Answer: B) lower water potential than the cell

Explanation: Water leaves and the membrane pulls from the wall. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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6. Water moves by osmosis from

  1. areas of more solute to less solute
  2. lower to higher water potential
  3. higher (less negative) to lower (more negative) water potential
  4. cells to pure water always

Answer: C) higher (less negative) to lower (more negative) water potential

Explanation: Down a water potential gradient. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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7. Pure water has a water potential of

  1. 0 kPa
  2. +100 kPa
  3. 1 kPa
  4. −100 kPa

Answer: A) 0 kPa

Explanation: Pure water has the highest water potential, zero. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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8. Glycolipids are found

  1. inside the nucleus
  2. only in bacterial walls
  3. only on organelle membranes
  4. on the outer surface of the membrane

Answer: D) on the outer surface of the membrane

Explanation: Carbohydrate chains face outwards. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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9. Phagocytosis is a type of

  1. exocytosis
  2. osmosis
  3. endocytosis
  4. facilitated diffusion

Answer: C) endocytosis

Explanation: Cells engulf solid particles. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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10. In the fluid mosaic model, the hydrophobic tails of phospholipids

  1. bind to glycoproteins
  2. face inwards, away from water
  3. face the tissue fluid
  4. face the cytoplasm

Answer: B) face inwards, away from water

Explanation: Tails avoid water. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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11. Glycoproteins in cell surface membranes are important in

  1. making ATP
  2. DNA replication
  3. cell recognition and cell signalling
  4. forming the bilayer

Answer: C) cell recognition and cell signalling

Explanation: Carbohydrate chains act as antigens and receptors. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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12. The surface area to volume ratio of a 2 cm cube is

  1. 1 : 3
  2. 2 : 1
  3. 3 : 1
  4. 6 : 1

Answer: C) 3 : 1

Explanation: 24 ÷ 8 = 3. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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13. Potato cylinders lose no mass in 0.3 mol dm⁻³ sucrose. This means

  1. the potato cells burst
  2. the potato tissue has the same water potential as 0.3 mol dm⁻³ sucrose
  3. sucrose entered the cells
  4. the potato has no water

Answer: B) the potato tissue has the same water potential as 0.3 mol dm⁻³ sucrose

Explanation: No net movement = equal water potential. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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14. As organisms increase in size, their surface area to volume ratio

  1. increases
  2. doubles
  3. stays the same
  4. decreases

Answer: D) decreases

Explanation: Volume rises faster than surface area. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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15. Channel proteins allow

  1. facilitated diffusion of specific ions
  2. movement of lipids only
  3. endocytosis
  4. active transport using ATP

Answer: A) facilitated diffusion of specific ions

Explanation: Channels are water-filled pores. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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16. The role of cholesterol in membranes is to

  1. act as a receptor
  2. regulate fluidity and stability
  3. form the glycocalyx
  4. act as a channel protein

Answer: B) regulate fluidity and stability

Explanation: Cholesterol buffers fluidity. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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17. Exocytosis involves

  1. vesicles fusing with the cell surface membrane to release contents
  2. water moving through channels
  3. ions moving through pumps
  4. the membrane engulfing particles

Answer: A) vesicles fusing with the cell surface membrane to release contents

Explanation: Secretion by exocytosis. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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18. Visking tubing containing starch and glucose is placed in water. After an hour,

  1. neither leaves the tubing
  2. both are found in the water
  3. glucose is found in the water but starch is not
  4. starch leaves but glucose stays

Answer: C) glucose is found in the water but starch is not

Explanation: Glucose is small enough to pass; starch is too large. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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19. In cell signalling, a ligand

  1. is always a lipid
  2. is a carrier protein
  3. enters every cell
  4. binds to a complementary receptor on a target cell

Answer: D) binds to a complementary receptor on a target cell

Explanation: Only cells with matching receptors respond. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.1 Fluid mosaic membranes

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20. Facilitated diffusion differs from active transport because facilitated diffusion

  1. moves substances against a gradient
  2. moves substances down a gradient without ATP
  3. uses vesicles
  4. uses ATP

Answer: B) moves substances down a gradient without ATP

Explanation: Facilitated diffusion is passive. AS & A Level Biology · Topic 4 Cell Membranes and Transport · 4.2 Movement into and out of cells

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