Worksheet No: 1
Name of the Student: ________________________________________________
Grade: 8 CAM Date: 30-04-24
Subject: Science Topic: Unit 1 Photosynthesis and
carbon cycle
Focus: To assess student's understanding about Photosynthesis.
Task: Answer the following questions in the space provided.
I. Completing sentences about the carbon cycle.
Underline the correct word to complete each sentence.
1. Plants use carbon dioxide when they photosynthesis/photosynthesis/photosynthesizing.
2. Cells that can photosynthesize contain/containing/contains chloroplast.
3. Carbon dioxide moves into a leaf by diffuse/diffuses/diffusion.
4. Photosynthesis is the only process that remove/removes/removing carbon dioxide from
the atmosphere.
5. Decomposers release carbon dioxide into the air when they respiring/respire/respiration.
6. The collision/collide/collides of an asteroid with Earth cased a mass extinction.
7. Combustion of fossil fuels release/releases/releasing carbon dioxide in the atmosphere.
8. The increase in the mean global temperature is causing sea level to rise/rising/rises.
II. Making predictions.
Each of these sentences is a prediction of what will happen if something else happens.
Complete each sentence. There is more than one possible way of completing each one.
1. If a plant does not have enough sunlight, it will
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2. If a plant respires faster than it photosynthesizes,
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3. If a plant is growing in soil that does not have enough magnesium,
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4. If we burn fossil fuels,
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5. If a lot of Earth’s glaciers melt,
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III. Building a carbon cycle.
Use the words given in the boxes to complete the diagram of carbon cycle by placing them
into the correct places.
IV. The beginning of photosynthesis.
Here are some important events that occurred during the very early history of the Earth:
1. How long ago do we think that the Earth was first formed?
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2. For how many years have there been living things on Earth?
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3. How long ago did photosynthesis begin?
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4. There was almost no oxygen in the Earth’s atmosphere until 3000 million years ago. Then
oxygen began to build up in the air.
Suggest why.
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V. State whether the following statements are true or false.
a. plants get all their food from the soil. ………………….
b. plants need chlorophyll to carry out photosynthesis. ………………….
c. Water for photosynthesis is absorbed through the leaves. ………………….
d. leaves that are de-starched give blue-black colour when tested with iodine.
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VI. To find out if photosynthesis has taken place in a leaf, we can carry out a test. Match
each of stages with the correct reason on the light.
Stage in test Reason
• Wash the leaf in cold • To test for starch
water
• Boil the leaf in ethanol • To soften it
• Add drops of iodine • To remove the ethanol
solution to the leaf and rehydrate the leaf
• dip the leaf in boiling • To extract the chlorophyll
water
