Photosynthesis: how plants make food from light, water and air

Grade 7 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Ari’s friend says plants get their food from the soil, so soil is plant food. Which response is best?

   • Disagree: leaves make their sugar from carbon dioxide and water
   • Agree: the roots pull the plant’s food out of the soil for it
   • Agree: fertilizer is the food that plants live on
   • Disagree: plants live on water and nothing else
2. 2.

   Bo’s friend says plants take in oxygen and give out carbon dioxide when they make sugar. Which response is best?

   • Agree: plants trade gases the very same way people do when breathing
   • Agree: that is why plants need fresh air
   • Disagree: plants trade no gases with the air
   • Disagree: making sugar takes in carbon dioxide and gives off oxygen
3. 3.

   Esme’s friend says sunlight is a plant’s food. Which response is best?

   • Agree: leaves soak up light and store it inside as plant matter
   • Agree: plants grow by turning light into wood
   • Disagree: soil is the plant’s real food
   • Disagree: light gives energy; the food is sugar the leaf makes

4. Read this first

   Investigation card

   Plant 1 sat in a sunny window and was watered every day. Plant 2 sat in a dark closet and was watered once a week. After two weeks Plant 1 was taller.

5. 4.

   Kira tested whether light helps a plant grow. What is the flaw in this test?

   • Two things changed, light and water, so the cause is unclear
   • Plant height is not a thing a class can measure
   • Both plants should have been kept in the dark the whole time
   • There is no flaw, because light caused the growth

6. Investigation card (model data)

   Two matching water plants in sealed jars of water, the same size and temperature. Bubbles counted in 10 minutes: under an LED lamp, 40; in the dark, 0.

7. 5.

   Luz’s class compared two water plants in sealed jars, one under a lamp and one in the dark. Which conclusion is strongest?

   • The lamp plant took in oxygen from the jar
   • Light is needed for the plant to give off oxygen
   • Light turned into the gas in the bubbles
   • The dark plant kept its bubbles for later

8. Use this

   Leaf arrow diagram, not to scale. Boxes: Sun, leaf (green cells with chloroplasts), air, roots and stem, rest of the plant. Arrows: Sun to leaf; roots and stem to leaf; air to leaf; leaf to air; leaf to rest of the plant. Every arrow is labeled. Table (model data), carbon dioxide level in a sealed clear box holding a potted plant, in units: start, 400; after 6 hours in bright light, 300; after 6 more hours in the dark, 350.

9. 6.

   Milo reads two figures. Why did the carbon dioxide level fall during the 6 hours of light?

   • The plant took in carbon dioxide to make sugar
   • The light turned the carbon dioxide into energy
   • The roots pushed the carbon dioxide into the soil
   • The plant gave off carbon dioxide while making sugar
10. 7.

    Pia’s teacher coats the underside of some leaves with petroleum jelly. Use both figures to predict the result for those leaves.

    • Less sugar, because carbon dioxide cannot enter the leaf
    • More sugar, because the oxygen cannot leave the leaf
    • No change, because the roots supply the carbon
    • Less sugar, because light cannot pass the jelly underneath
11. 8.

    Ren grows a bean seedling in a dark box. It grows tall and pale for a week. How can it grow with no light?

    • It uses up the light it took in before it was planted
    • Its roots take in sugar from the water
    • It uses food stored in the seed by the parent plant
    • It makes sugar from the soil in the dark

12. Use this

    Drawing of a leaf with green patches and white patches, not to scale. Test result (read about; an adult did a starch test): starch, the stored form of sugar, found in the green parts, none in the white parts.

13. 9.

    Tala reads about a leaf with green and white patches kept in light. A starch test found stored sugar in the green parts but not the white parts. Why?

    • The white parts take sugar from the soil instead
    • The white parts lack the green chloroplasts that make sugar
    • The white parts give off carbon dioxide instead of oxygen
    • The white parts got less light than the green parts
14. 10.

    Bubbles in 10 minutes under the same lamp: tap water, 40; boiled and cooled water, 8. Zee reads that a water plant gave off fewer bubbles in water an adult had boiled and cooled first. Which explains it?

    • Boiling removed carbon dioxide, an input the plant needs
    • Boiling took out the oxygen that the plant needs to take in
    • Boiling took the plant food out of the water
    • The cooled water blocked the lamp’s light