← Back to the activity

Grade 7 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.

123
  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.Sort each substance by the part it plays in photosynthesis.

    Groups: Taken in by photosynthesis · Given out by photosynthesis

    • Oxygen
    • Carbon dioxide
    • Water
    • Glucose

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

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

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

  4. 4.Why is a leaf boiled in alcohol until it loses its color before the iodine test?

    • a) So that the chlorophyll starts making starch again
    • b) So that any color change from the iodine is easy to see
    • c) So that the iodine can soak through the waxy surface
    • d) So that the starch dissolves out of it into the alcohol

  5. 5.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?

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

  7. 7.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
    • Put a few drops of dilute iodine solution on it
    • Soften the leaf in boiling water
    • A blue-black color means starch is present
    • Lay the pale leaf out on a plate

  8. 8.What does a plant do in respiration?

    • a) Break down glucose using oxygen, releasing carbon dioxide, water and energy
    • b) Break down oxygen using glucose, releasing sunlight
    • c) Store energy from sunlight without using any gas
    • d) Take in carbon dioxide and give out glucose

Answer key — Grade 7 Science — Life processes in plants

  1. 1. Carbon dioxide → Taken in by photosynthesis; Water → Taken in by photosynthesis; Glucose → Given out by photosynthesis; Oxygen → Given out by photosynthesis
  2. 2. c) They are the primary site of photosynthesis, where the food is made
  3. 3. photosynthesis
  4. 4. b) So that any color change from the iodine is easy to see
  5. 5. glucose
  6. 6. a) The green patches go blue-black and the non-green ones do not
  7. 7. 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 color means starch is present
  8. 8. a) Break down glucose using oxygen, releasing carbon dioxide, water and energy