DP Bio (2.5, 2.8, 2.9, 8.1, 8.2, 8.3, 9.1, 9.2)

Plants produce carbon dioxide in respiration and use carbon dioxide in photosynthesis. The graph shows the volume of carbon dioxide exchanged in a plant at different light intensities. What is shown by the graph?

• There is no photosynthesis between W and X.

• There is no photosynthesis between Y and Z.

• There is more respiration than photosynthesis between Y and Z.

• There is more respiration than photosynthesis between W and X.

The diagram shows a section through a thylakoid. Electrons move from X to Y. What do the letters X, Y, and Z represent?

• X: photosystem I

  Y: photosystem II

  Z: thylakoid space

• X: photosystem II

  Y: photosystem I

  Z: thylakoid space

• X: ATP synthase

  Y: photosystem II

  Z: stroma

• X: photosystem II

  Y: ATP synthase

  Z: stroma

Two reactions of the Krebs cycle are shown. What type of reactions are isocitrate and oxalosuccinate undergoing?

• Isocitrate: oxidation

  Oxalosuccinate: reduction

• Isocitrate: reduction

  Oxalosuccinate: decarboxylation

• Isocitrate: reduction

  Oxalosuccinate: oxidation

• Isocitrate: oxidation

  Oxalosuccinate: decarboxylation

The graph shows the percentage of stomata that are open in two different species of plants over a 24-hour period. What does this graph show about plants X and Y?

• Plant X absorbs most carbon dioxide at night.

• Plant Y is adapted to desert conditions.

• Plant X photosynthesis most at midday.

• Plant Y only respires during the day.

What effect do changes in pH have on enzymes?

• All enzymes increase in activity as pH increases.

• The activity of all enzymes is reduced by a pH below or above 7.

• Low pH causes reversible denaturation in all enzymes.

• Extreme pH can alter the active site of all enzymes.

Which compound is a waste product of anaerobic respiration in humans?

• carbon dioxide

• ethanol

• lactate

• pyruvate

The grey line in each of the graphs below represents the rate of reaction catalysed by an uninhibited enzyme as substrate concentration is increased.

Which graph shows expected results if a competitive inhibitor was added to the reaction?

• A

• B

• C

• D

The diagram shows the link reaction between glycolysis and the Krebs cycle.

Which type of reaction is occurring?

• Pyruvate is carboxylated.

• CO₂ is oxidized.

• NAD⁺ is reduced.

• Pyruvate is phosphorylated.

Which structure in the chloroplast diagram is adapted to carry out chemiosmosis?

• A

• B

• C

• D

Which process is most responsible for the movement of water from roots to leaves of plants on a hot summer day?

• Active translocation of mineral ions in roots

• Active transport of organic compounds into sieve tubes

• Raised hydrostatic pressure gradients

• Evaporation of waster from mesophyll cell walls