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Flashcards · Biology

Photosynthesis

46 cards from 3 lessons

  1. Why are plants and algae the main producers of food?

    They make glucose from carbon dioxide and water using light energy.

  2. What is biomass?

    The mass of living material.

  3. What is photosynthesis?

    A reaction in which plants use light energy to make glucose from carbon dioxide and water.

  4. Write the word equation for photosynthesis.

    Carbon dioxide + water, in light, makes glucose + oxygen.

  5. Write the symbol equation for photosynthesis.

    6CO₂ + 6H₂O makes C₆H₁₂O₆ + 6O₂ (in light).

  6. What are the reactants in photosynthesis?

    Carbon dioxide and water.

  7. What are the products of photosynthesis?

    Glucose and oxygen.

  8. Why is photosynthesis an endothermic reaction?

    It takes in energy from the environment, transferred by light.

  9. Where in the cell does photosynthesis take place?

    In the chloroplasts.

  10. What does chlorophyll do?

    It absorbs the light energy for photosynthesis.

  11. How does water get to the leaf?

    It is taken up by the roots and carried up in the xylem.

  12. Where is the energy stored after photosynthesis?

    In the glucose that is made.

  13. What is a producer?

    An organism that makes its own food, such as a plant.

  14. How can you test a leaf for starch?

    Kill and decolourise it, then add iodine solution, which turns blue-black.

  15. Why is the leaf boiled in ethanol?

    To remove the chlorophyll, so the colour change can be seen.

  16. Name a gas that is a product of photosynthesis.

    Oxygen.

  17. A leaf diagram with a pointer marked X to the oxygen arrow. Name the substance marked X and say where it goes.

    Oxygen. It is a product of photosynthesis and leaves the leaf through the stomata.

  18. A leaf with arrows and no labels. Label everything that goes into and comes out of the leaf. The same leaf with every arrow labelled and the equation.

    Light energy, carbon dioxide and water go in. Oxygen and glucose come out. Photosynthesis happens in the chloroplast.

  19. What is a limiting factor?

    A factor in short supply that sets the rate of a reaction.

  20. Why does more light increase photosynthesis?

    Light provides the energy for the reaction.

  21. Why does more carbon dioxide increase photosynthesis?

    It is a reactant, so more is available.

  22. Why does the rate fall at high temperatures?

    The enzymes are denatured.

  23. What does a flat part on a rate graph show?

    Another factor is now limiting.

  24. What does a rising part of the graph show?

    The factor on the x axis is limiting.

  25. How do you calculate a rate?

    Amount of product or reactant ÷ time.

  26. What is a plateau?

    A flat part of a graph where the rate stops changing.

  27. (HT) What does it mean if factors interact?

    Any one of them might be the limiting factor.

  28. (HT) Why might adding extra heat be a waste of money?

    If temperature is not the limiting factor, the rate does not increase.

  29. Three graphs with curves and no labels. Describe the shape of each graph and say what is limiting. The same three graphs with their labels and marks.

    Light and carbon dioxide: the rate rises then levels off, and another factor is limiting on the flat part. Temperature: it rises to an optimum, then falls because enzymes are denatured.

  30. What gas do the bubbles from pondweed contain?

    Oxygen.

  31. What is the independent variable in the pondweed practical?

    The distance of the lamp from the pondweed.

  32. What is the dependent variable?

    The number of bubbles per minute, or the volume of gas collected.

  33. Why is sodium hydrogencarbonate added to the water?

    To provide carbon dioxide, so it is not the limiting factor.

  34. Why use a heat shield or water bath?

    To stop the temperature rising and affecting the rate.

  35. Name three control variables.

    Any three of the same pondweed, temperature, carbon dioxide level, time and size of beaker.

  36. Why repeat each distance?

    To check reliability and calculate a mean.

  37. Why is counting bubbles a rough measure?

    The bubbles can differ in size.

  38. What is a better way to measure the gas?

    Collect it in a gas syringe or measuring tube and measure the volume.

  39. What happens to the rate as the lamp is moved further away?

    It decreases.

  40. Why does moving the lamp change the light intensity?

    The further away the lamp is, the dimmer the light that reaches the plant.

  41. (HT) State the inverse square law.

    Light intensity is proportional to 1 ÷ distance².

  42. (HT) What happens to light intensity if the distance doubles?

    It falls to one quarter.

  43. (HT) What happens to light intensity if the distance triples?

    It falls to one ninth.

  44. (HT) What should a graph of rate against 1/d² look like?

    A straight line, while light is the limiting factor.

  45. The apparatus with a pointer marked X to the ruler. Name the part marked X and say why it is there.

    The ruler. It measures the distance between the lamp and the pondweed, which is the independent variable.

  46. A practical set-up with no labels. Label the apparatus. The same apparatus with every part labelled.

    Lamp, ruler, pondweed, bubbles of oxygen, beaker of water with sodium hydrogencarbonate and thermometer.