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42 exam-style questions with model answers, plus 56 quick multi-choice questions — every question on the site for this standard, grouped by the 14 pages of notes they come from.
Write a full answer before you reveal the model one — that comparison is where the marks come from. Every block links back to the notes that teach it.
Name the organelle in which aerobic respiration takes place, and name the organelle in which photosynthesis takes place. State one structure found in a plant cell but not an animal cell, other than the chloroplast.
Explain why a plant cell needs both chloroplasts and mitochondria, when an animal cell needs only mitochondria.
A student examines two cells from the same plant under a microscope. Cell A is from a leaf and is packed with chloroplasts. Cell B is from a root and contains none, but has far more mitochondria than Cell A. Both cells contain identical DNA. Discuss how these differences arise and how they relate to the overall functioning of the plant.
A cube-shaped cell has sides of 10 μm. Calculate its surface area to volume ratio, and state what happens to this ratio as a cell grows larger.
Explain why a cell with a low surface area to volume ratio has difficulty supplying its centre with oxygen.
Cells in a growing tissue divide repeatedly rather than continuing to enlarge. Discuss why division, rather than continued growth, is the more effective strategy, and explain how cell shape offers an alternative solution to the same problem.
Define diffusion and define osmosis. State whether each requires energy from the cell.
Explain why oxygen can diffuse straight through the cell membrane but glucose requires a protein to cross it.
A plant cell and an animal cell are both placed in distilled water. The plant cell becomes firm; the animal cell bursts. Discuss the reasons for this difference, and explain why the difference matters for the organisms concerned.
Define active transport, and state where the energy for it comes from.
Explain why a root hair cell contains a large number of mitochondria.
A cell membrane can move glucose by both facilitated diffusion and active transport. Evaluate the effectiveness of each process for a cell lining the small intestine as digestion proceeds and the glucose concentration in the gut falls.
Define the term enzyme, and describe what is meant by the active site.
Explain why boiling an enzyme stops it from working, but cooling it to 5 °C does not.
A mutation changes one amino acid in an enzyme. The enzyme still folds, but the reaction it catalyses now runs at only 5% of its normal rate. The cell's overall respiration rate falls sharply. Discuss how a single amino acid change can have this effect.
Describe what happens to the rate of an enzyme-controlled reaction as the substrate concentration is increased from zero, and state what the rate depends on once the graph has levelled off.
Explain why the rate of an enzyme-controlled reaction increases between 10 °C and 35 °C, but decreases between 45 °C and 60 °C.
A cell is treated with a substance that binds to the active site of one enzyme in the respiration pathway. Researchers find that adding a very large excess of that enzyme's substrate partly restores the reaction rate. Discuss what this tells us about the inhibitor and about the enzyme, and explain the consequences for the cell.
Write the word equation for photosynthesis, and name the organelle and the pigment involved.
Explain why a plant needs to respire, given that it makes its own glucose by photosynthesis.
A sealed glass container holds a healthy pondweed plant in water. Over 24 hours, the oxygen concentration in the water rises during the day and falls at night. Discuss the processes responsible, and explain what would happen to the plant if the container were kept in complete darkness for a week.
State where in the chloroplast each phase of photosynthesis occurs, and name the products of the light-dependent phase.
Explain why the light-independent phase cannot continue for long in the dark, even though it does not use light directly.
Researchers supplied a plant with water containing a labelled form of oxygen, and separately with carbon dioxide containing a labelled form of oxygen. The labelled oxygen gas released by the plant came only from the water, not from the carbon dioxide. Discuss what this shows about the two phases of photosynthesis, and evaluate what conclusion could and could not be drawn if the experiment had used labelled carbon instead.
Name three factors that can limit the rate of photosynthesis, and define the term limiting factor.
Explain why a plant grown in soil lacking magnesium ions photosynthesises slowly, even in bright sunlight and warm conditions.
A commercial glasshouse grower in Canterbury is deciding whether to invest in artificial lighting, a carbon dioxide enrichment system, or heating, in order to increase tomato yield through the winter. Discuss how the grower should decide, and evaluate the risks of choosing wrongly.
State what ATP stands for, and describe how energy is released from an ATP molecule.
Explain why cells transfer the energy from glucose to ATP rather than using the energy in glucose directly.
Cyanide blocks one of the enzymes of aerobic respiration in the mitochondrion. Discuss the effects this would have on a cell, and explain why some cells and tissues are affected far more severely than others.
Write the word equation for aerobic respiration, and write the word equation for anaerobic respiration in human muscle. State where each takes place in the cell.
Explain why aerobic respiration releases about 36 ATP per glucose molecule while anaerobic respiration releases only about 2.
A farmer notices that pasture grass in a paddock dies after a week of flooding, while nearby rushes growing in the same waterlogged ground remain healthy. Discuss the biological reasons for the grass dying, and what this suggests about the rushes.
Name the three stages of interphase and state what happens in each.
Explain why DNA replication must be completed before mitosis begins.
Cancer treatments often target cells that are dividing rapidly. Discuss why this approach works, why it produces the side effects it does, and what this reveals about the normal control of the cell cycle.
State the complementary base pairing rules for DNA, and write the complementary strand for the sequence G G A T C A.
Explain why DNA replication is described as semi-conservative, and explain why the two resulting molecules are identical.
Explain why the specific pairing of A with T and C with G is essential, discussing what would happen if bases could pair in any combination, and why the antiparallel arrangement of the strands matters.
State the four stages of mitosis in order, and describe what happens during anaphase. State how many daughter cells are produced and how they compare genetically to the parent cell.
Explain why a multicellular organism grows by producing more cells rather than by making its existing cells larger.
A kūmara plant reproduces asexually, producing new plants from tubers by mitosis. Discuss the advantages and disadvantages of this for the population, and explain why the process reliably produces plants identical to the parent.