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Year 8 Science — Life processes in plants

Say what photosynthesis needs and what it gives back, read the experiment that proves each ingredient, and name the tubes that carry water up and food out.

Name: ________________________

Before you start

The parts of a plant, and what each one does with water and with food.

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  1. 1. Leaf
  2. 2. Stem
  3. 3. Roots

The leaf is where the food is made. Water and minerals go up from the roots through tubes called xylem, inside the stem. Food made in the leaves goes out through a second set of tubes called phloem, to wherever the plant needs it or stores it. Tiny pores in the leaf surface, the stomata, let gases in and out.

  1. 1.A leaf with green and non-green patches is taken from a plant that has been standing in sunlight. Iodine is applied. What happens?

    • a) The non-green patches go blue-black and the green ones do not
    • b) Nothing changes colour, because the leaf is still alive
    • c) The whole leaf goes blue-black, green patches and pale ones alike
    • d) The green patches go blue-black and the non-green ones do not

  2. 2.Sort each substance by the part it plays in photosynthesis.

    Groups: Taken in by photosynthesis · Given out by photosynthesis

    • Oxygen
    • Water
    • Glucose
    • Carbon dioxide

  3. 3.Put the steps of the starch test on a leaf in order, starting from softening the leaf in boiling water.

    • Decolourise it in alcohol standing in a beaker of boiling water
    • Lay the pale leaf out on a plate
    • Soften the leaf in boiling water
    • Put a few drops of dilute iodine solution on it
    • A blue-black colour means starch is present

  4. 4.Three identical saplings are grown for two weeks: A in sunlight with water, B in sunlight without water, C in the dark with water. What do their fates show?

    • a) A plant needs both sunlight and water to grow
    • b) A plant needs water and can manage without sunlight
    • c) Neither sunlight nor water makes much difference over two weeks
    • d) A plant needs sunlight and can manage without water

  5. 5.Which pair of ingredients does a plant draw from its surroundings to make food?

    • a) Starch from the soil and sunlight from the sky
    • b) Carbon dioxide from the air and water from the soil
    • c) Carbon dioxide from the soil and oxygen from the air
    • d) Oxygen from the air and glucose from the soil

  6. 6.The food a plant makes is first produced as a simple carbohydrate, which the plant later turns into starch for storage. What is that simple carbohydrate?

  7. 7.What is the name of the process by which a plant prepares its food in the presence of sunlight and chlorophyll?

  8. 8.Why does the chapter call leaves the food factories of a plant?

    • a) They take in the water and minerals the plant lives on
    • b) They store most of the plant's food until it is needed
    • c) They are the part of the plant that animals eat most often
    • d) They are the primary site of photosynthesis, where the food is made

Answer key — Year 8 Science — Life processes in plants

  1. 1. d) The green patches go blue-black and the non-green ones do not
  2. 2. Carbon dioxide → Taken in by photosynthesis; Water → Taken in by photosynthesis; Glucose → Given out by photosynthesis; Oxygen → Given out by photosynthesis
  3. 3. 1. Soften the leaf in boiling water 2. Decolourise it in alcohol standing in a beaker of boiling water 3. Lay the pale leaf out on a plate 4. Put a few drops of dilute iodine solution on it 5. A blue-black colour means starch is present
  4. 4. a) A plant needs both sunlight and water to grow
  5. 5. b) Carbon dioxide from the air and water from the soil
  6. 6. glucose
  7. 7. photosynthesis
  8. 8. d) They are the primary site of photosynthesis, where the food is made