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Biology 20

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Mixed review · Photosynthesis and respiration

Ten questions of mixed difficulty, covering Cellular respiration, Photosynthesis. Print it, or work through it on screen — the answer key starts on its own page.

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Mixed review · Photosynthesis and respiration

Biology 20 · maddyhelps.com

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Circle the best answer for each question. Show your work in the space provided.

  1. The light-dependent reactions supply the Calvin cycle with

    1. a) glucose and oxygen
    2. b) CO₂ and water
    3. c) ATP and NADPH
    4. d) oxygen and NADP⁺

  2. The electron transport chain is located in the

    1. a) matrix
    2. b) outer mitochondrial membrane
    3. c) inner mitochondrial membrane
    4. d) cytoplasm

  3. ATP is described as the cell's energy currency because it

    1. a) carries oxygen to the cells
    2. b) is the only molecule containing energy
    3. c) stores energy permanently
    4. d) releases usable energy when its terminal phosphate bond is broken

  4. The oxygen released by photosynthesis comes from

    1. a) the atmosphere
    2. b) glucose
    3. c) carbon dioxide
    4. d) water

  5. The overall equation for photosynthesis is

    1. a) 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
    2. b) 6CO₂ + 6O₂ → C₆H₁₂O₆ + 6H₂O
    3. c) C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
    4. d) C₆H₁₂O₆ → 6CO₂ + 6H₂O

  6. Paper chromatography separates leaf pigments because

    1. a) pigments have different colours
    2. b) the solvent dissolves only chlorophyll
    3. c) pigments differ in how strongly they are attracted to the paper versus the solvent
    4. d) heavier pigments always travel further

  7. ATP is made in the thylakoid by chemiosmosis, which means

    1. a) ATP is made directly by an enzyme in the stroma
    2. b) protons pumped into the thylakoid space flow back out through ATP synthase
    3. c) electrons are transferred straight to ADP
    4. d) light energy is converted directly into ATP

  8. The Calvin cycle takes place in the

    1. a) cell wall
    2. b) stroma
    3. c) thylakoid membrane
    4. d) thylakoid space

  9. The enzyme rubisco is responsible for

    1. a) breaking glucose down for energy
    2. b) attaching CO₂ to RuBP at the start of the Calvin cycle
    3. c) splitting water in the thylakoid
    4. d) making ATP in the stroma

  10. Chlorophyll appears green because it

    1. a) reflects green light and absorbs red and blue
    2. b) contains a green metal ion
    3. c) emits green light
    4. d) absorbs green light

Answer key · Mixed review · Photosynthesis and respiration

Biology 20 · maddyhelps.com

  1. c) ATP and NADPH — The first stage converts light into two chemical carriers — energy in ATP and reducing power in NADPH. The Calvin cycle spends both to build sugar, and returns ADP and NADP⁺ to be recharged.
  2. c) inner mitochondrial membrane — The inner membrane is folded into cristae, which multiplies the area available for the chain and for ATP synthase. Membrane location is essential, because the proton gradient needs two sides.
  3. d) releases usable energy when its terminal phosphate bond is broken — ATP is spent and remade constantly — a cell recycles its own body weight in it daily. It is a short-term carrier, not a store; that job belongs to fats and carbohydrates.
  4. d) water — Photolysis splits water to replace the electrons chlorophyll loses, and oxygen is the leftover. Tracing photosynthesis with a heavy isotope of oxygen was how this was settled — labelled water produced labelled oxygen gas.
  5. a) 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ — Carbon dioxide and water go in, glucose and oxygen come out, with light supplying the energy. The second option is cellular respiration, which is the same equation run backwards.
  6. c) pigments differ in how strongly they are attracted to the paper versus the solvent — A pigment that dissolves well and sticks to the paper weakly travels far; one that clings travels little. Colour is how you see the result, but it is solubility and adsorption that do the separating.
  7. b) protons pumped into the thylakoid space flow back out through ATP synthase — The electron transport chain uses energy from excited electrons to pump protons, building a concentration gradient. The gradient is the stored energy, and letting it collapse through ATP synthase is what makes the ATP.
  8. b) stroma — The stroma is the fluid surrounding the thylakoids, and it holds the enzymes of the cycle. The two stages are separated in space, which lets the products of one be handed to the other.
  9. b) attaching CO₂ to RuBP at the start of the Calvin cycle — Carbon fixation — joining inorganic CO₂ to a five-carbon sugar — is the cycle's first and defining step. Rubisco is thought to be the most abundant protein on Earth, and it is also famously slow.
  10. a) reflects green light and absorbs red and blue — The colour you see is the light a pigment does not use. Green is reflected, which is why it is the least useful colour for growing plants under.