IB Diploma Biology chapter 2: B Form and function MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

90 exam-style questions on B Form and function, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

90 questions · 9 topics · 10 per test

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What chapter 2 covers

Ten B Form and function questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Red blood cells from a person with a mutation that removes aquaporins are placed in distilled water. Compared with normal red blood cells, what is most likely?

  1. A
    they do not swell at all, because aquaporins are the only route by which water can cross the membrane
  2. B
    they burst more quickly, because the cell cannot pump water out without aquaporins
  3. C
    they shrink, because water leaves the cell when it cannot move through channels
  4. D
    they swell and burst more slowly, because water enters by osmosis at a lower rate
Show answer

Answer: D. Aquaporins increase the permeability of the membrane to water, so osmosis is faster. Some water still crosses the bilayer, so cells without aquaporins still swell, but more slowly.

2. Why are the digestive enzymes of lysosomes kept inside a membrane?

  1. A
    so that they can be transported to chloroplasts and used in photosynthesis
  2. B
    so that they can be exported from the cell to digest food outside it
  3. C
    so that they cannot digest the cell's own components in the cytoplasm
  4. D
    because they are too large to exist freely in the cytoplasm of the cell
Show answer

Answer: C. Compartmentalization separates incompatible processes: the hydrolytic enzymes act only inside the lysosome or phagocytic vacuole.

3. Xylem vessels are dead, hollow and have walls thickened with lignin. What is the function of the lignin?

  1. A
    it makes the walls impermeable, so that no water can leave the vessel at any point on its way up the stem
  2. B
    it makes the walls rigid, so they can resist the tension of water being pulled up without collapsing inwards
  3. C
    it keeps the cells alive, so that the cells can pump water actively up the stem against a gradient
  4. D
    it makes the lumen narrower, so that the pressure of the water rises as it moves up the stem
Show answer

Answer: B. Water in xylem is under tension, which would pull the walls inwards; lignin makes them rigid. Pits allow water in and out.

4. Site P has a mean annual temperature of 26 °C and 2 500 mm of rain spread evenly through the year. Site Q has a mean annual temperature of −8 °C and 200 mm of rain. Site R has a mean annual temperature of 25 °C and 100 mm of rain. Which lists the biomes correctly?

  1. A
    P tundra, Q taiga, R tropical rainforest
  2. B
    P tropical rainforest, Q hot desert, R tundra
  3. C
    P hot desert, Q tundra, R tropical rainforest
  4. D
    P tropical rainforest, Q tundra, R hot desert
Show answer

Answer: D. High temperature and high rainfall all year give tropical rainforest; very low temperature and low precipitation give tundra; high temperature and very low rainfall give hot desert.

5. Which property of carbon atoms allows living organisms to make such a diversity of compounds?

  1. A
    each carbon atom can form up to four covalent bonds, so it can build chains, branches and rings
  2. B
    carbon atoms can form only single covalent bonds, so long chains are made with many identical links
  3. C
    carbon atoms form ionic bonds with metals, so they can build the salts found in living tissues
  4. D
    carbon is the most abundant element in the atmosphere, so it is always available in large amounts
Show answer

Answer: A. Four covalent bonds, single or double, let carbon build unbranched or branched chains and rings with other carbons and with other non-metals.

6. An archaeon lives in a dark, hot vent. It obtains energy by oxidizing hydrogen sulfide and makes organic compounds from carbon dioxide. Which statement is correct?

  1. A
    it is photosynthetic, because it makes organic compounds from carbon dioxide and so must have chlorophyll in its cells
  2. B
    it is holozoic, because it obtains its energy from a chemical substance that it takes into its cell as food
  3. C
    it does not depend on light or on other organisms for organic food, because it gets energy by oxidizing an inorganic chemical
  4. D
    it is saprotrophic, because it lives in a dark habitat that contains no light and no other living organisms
Show answer

Answer: C. Archaea are metabolically diverse: different archaea obtain energy from light, from oxidation of inorganic chemicals or from oxidation of carbon compounds.

7. Stem cells in adult bone marrow can produce all types of blood cell but not neurons or muscle cells. How are they described?

  1. A
    totipotent, because they can form every type of cell found in the body and the placenta
  2. B
    pluripotent, because they can form nearly every type of cell in the body except the placenta
  3. C
    multipotent, because they can form only a limited range of related cell types
  4. D
    unipotent, because they can form a single type of cell and no other type in the body
Show answer

Answer: C. A limited range of related cell types is multipotent. Cells of early embryos are totipotent, then soon pluripotent.

8. In digestion, starch is broken down to maltose by an enzyme. Which description of the reaction is correct?

  1. A
    hydrolysis: a molecule of water is used to break a glycosidic bond, and its –H and –OH are added to the two ends produced
  2. B
    condensation: a molecule of water is released as a glycosidic bond is broken between two adjacent glucose units
  3. C
    hydrolysis: energy from ATP is used to join glucose units, and a molecule of water is released for each bond made
  4. D
    oxidation: each glucose unit is converted to carbon dioxide and water, and the energy released breaks the bonds
Show answer

Answer: A. Digestion of a polymer is by hydrolysis, which uses water to split the bond between monomers. Condensation is the reverse reaction and releases water.

9. Researchers wanted to show that mitochondria are the site of aerobic respiration. How would cell fractionation be used?

  1. A
    the mitochondria would be stained in living cells, and the stain would show where in the cell oxygen is being used
  2. B
    mitochondria would be separated by ultracentrifugation, and that fraction tested for oxygen use and ATP production
  3. C
    the number of mitochondria per cell would be counted in electron micrographs of tissues with different energy needs
  4. D
    the mitochondria would be frozen and split along their membranes to see where the enzymes lie in the membranes
Show answer

Answer: B. Spinning broken cells at increasing speeds separates organelles by size and density, so the function of each fraction can be tested on its own.

10. A piece of potato with a mass of 4.0 g is placed in a sucrose solution. After one hour its mass is 3.4 g. What is the percentage change in mass, and what does this show?

  1. A
    −15%; water left the tissue by osmosis, so the solution had a higher water potential than the potato cells
  2. B
    +15%; water entered the tissue by osmosis, so the solution had a lower water potential than the potato cells
  3. C
    −15%; water left the tissue by osmosis, so the solution had a lower water potential than the potato cells
  4. D
    −17.6%; water left the tissue by osmosis, so the solution had a lower water potential than the potato cells
Show answer

Answer: C. Percentage change = (3.4 − 4.0) ÷ 4.0 × 100 = −15% (dividing by the final mass gives the wrong value of −17.6%). Water moves by osmosis from higher to lower water potential, so the loss of mass shows that the solution had the lower water potential.

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B Form and function: questions students ask

How many B Form and function MCQs are there?

90, each with the answer and a short explanation, across 9 topics: B1.1 Carbohydrates and lipids, B1.2 Proteins, B2.1 Membranes and membrane transport, B2.2 Organelles and compartmentalization, B2.3 Cell specialization, B3.1 Gas exchange, B3.2 Transport, B4.1 Adaptation to environment, B4.2 Ecological niches. Every chapter test draws ten of them, so you can take it many times.

Is the IB Diploma Biology chapter 2 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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