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Photosynthesis and Respiration: Practice Questions with Answers

Curriculum: Photosynthesis and RespirationGrades: 7–9Questions: 12Mode: Practice

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1. What is the primary source of energy for photosynthesis?

  1. Soil nutrients
  2. Body heat
  3. Sunlight
  4. Oxygen gas
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Answer: C. Sunlight
Photosynthesis captures light energy from the sun and converts it into chemical energy stored in glucose.

2. Where in a plant cell does photosynthesis mainly take place?

  1. Nucleus
  2. Ribosome
  3. Chloroplast
  4. Mitochondria
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Answer: C. Chloroplast
Chloroplasts contain chlorophyll and the internal structures needed to capture light and build sugar molecules.

3. Which pigment in chloroplasts absorbs light energy for photosynthesis?

  1. Hemoglobin
  2. Melanin
  3. Keratin
  4. Chlorophyll
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Answer: D. Chlorophyll
Chlorophyll is the green pigment in chloroplasts that absorbs light energy, mainly red and blue light, to power photosynthesis.

4. What two raw materials does a plant use during photosynthesis?

  1. Oxygen and glucose
  2. Carbon dioxide and water
  3. Nitrogen and water
  4. Glucose and water
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Answer: B. Carbon dioxide and water
Plants take in carbon dioxide from the air and water from the soil as the raw materials for building glucose during photosynthesis.

5. What are the two main products of photosynthesis?

  1. Oxygen and nitrogen
  2. Carbon dioxide and water
  3. Glucose and oxygen
  4. Water and ATP
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Answer: C. Glucose and oxygen
Photosynthesis produces glucose, which stores chemical energy, and oxygen, which is released into the air as a byproduct.

6. Small openings on a leaf's surface that let gases in and out are called:

  1. Roots
  2. Chloroplasts
  3. Xylem
  4. Stomata
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Answer: D. Stomata
Stomata are tiny pores, usually on the underside of leaves, that open and close to let carbon dioxide in and oxygen and water vapor out.

7. Which organelle is the site of cellular respiration in most cells?

  1. Mitochondrion
  2. Chloroplast
  3. Nucleus
  4. Vacuole
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Answer: A. Mitochondrion
Mitochondria are often called the powerhouse of the cell because they break down glucose using oxygen to release usable energy as ATP.

8. What gas do living cells take in during cellular respiration?

  1. Oxygen
  2. Carbon dioxide
  3. Nitrogen
  4. Hydrogen
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Answer: A. Oxygen
Cells take in oxygen, which is used to help break down glucose efficiently and release energy as ATP.

9. Cellular respiration breaks down glucose to release what usable form of energy?

  1. Chlorophyll
  2. ATP
  3. Sunlight
  4. Heat only
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Answer: B. ATP
Cellular respiration converts the chemical energy stored in glucose into ATP, a molecule cells use directly to power their activities.

10. What waste gas is released by cells during cellular respiration?

  1. Carbon monoxide
  2. Carbon dioxide
  3. Nitrogen dioxide
  4. Sulfur dioxide
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Answer: B. Carbon dioxide
As cells break down glucose using oxygen, carbon dioxide is produced and released as a waste gas.

11. Which statement correctly compares photosynthesis and respiration?

  1. They are reverse processes of each other in terms of gases used and released
  2. They both occur only in animals
  3. Neither process involves energy
  4. Photosynthesis releases CO2 and respiration absorbs it
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Answer: A. They are reverse processes of each other in terms of gases used and released
Photosynthesis takes in carbon dioxide and releases oxygen, while respiration takes in oxygen and releases carbon dioxide, making them roughly opposite in terms of gas exchange.

12. Which organisms are able to carry out photosynthesis?

  1. All animals and other organisms that eat plants for energy
  2. Plants and some other organisms containing chlorophyll
  3. Humans and other mammals that need sunlight for vitamin D
  4. Mushrooms and other fungi that grow in damp, shady places
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Answer: B. Plants and some other organisms containing chlorophyll
Photosynthesis requires chlorophyll, which is found in plants, algae, and certain bacteria, allowing them to make their own food from light energy.
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