Grade 6 Science Worksheet (Age 12) — Food Chain & Food Web | Cambridge Syllabus — 40 MCQs, 20 Short Answers, 10 Problem Solving

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Instructions

Read each section carefully and answer the questions to the best of your ability. The worksheet is divided into three parts: Objective Questions, Short Answer Questions, and Problem Solving. Take your time to think through your answers.

Part 1: Objective Questions

A. Multiple Choice (Questions 1-15)
Circle the letter of the best answer for each question.

1. What is the primary source of energy for almost all ecosystems on Earth?
  • A) Plants
  • B) Water
  • C) The Sun
  • D) Decomposers
2. An organism that makes its own food is called a:
  • A) Consumer
  • B) Producer
  • C) Decomposer
  • D) Scavenger
3. Which of the following is an example of a primary consumer?
  • A) Lion
  • B) Rabbit
  • C) Mushroom
  • D) Hawk
4. In the food chain: Grass → Grasshopper → Frog → Snake, what is the frog?
  • A) Producer
  • B) Primary consumer
  • C) Secondary consumer
  • D) Tertiary consumer
5. An organism that eats both plants and animals is known as a(n):
  • A) Herbivore
  • B) Carnivore
  • C) Omnivore
  • D) Producer
6. What do the arrows in a food chain or food web represent?
  • A) The direction of animal movement
  • B) The flow of energy
  • C) The passage of time
  • D) Who eats whom (in reverse)
7. Bacteria and fungi are important in an ecosystem because they are:
  • A) Producers
  • B) Top predators
  • C) Primary consumers
  • D) Decomposers
8. A complex network of many interconnected food chains is called a:
  • A) Food link
  • B) Food web
  • C) Energy pyramid
  • D) Life cycle
9. A carnivore is an animal that eats:
  • A) Only plants
  • B) Only other animals
  • C) Plants and animals
  • D) Dead organisms
10. Which organism would have the most available energy in a typical food chain?
  • A) The producer
  • B) The primary consumer
  • C) The secondary consumer
  • D) The tertiary consumer
11. A hawk that eats a snake that ate a mouse that ate a seed is a:
  • A) Producer
  • B) Primary consumer
  • C) Secondary consumer
  • D) Tertiary consumer
12. Which of these is a producer?
  • A) A deer
  • B) A wolf
  • C) An oak tree
  • D) A worm
13. An animal that is hunted and eaten by another animal is called:
  • A) A predator
  • B) A prey
  • C) A consumer
  • D) A scavenger
14. If all the producers in an ecosystem were removed, which of the following would be the most likely result?
  • A) The number of consumers would increase.
  • B) The ecosystem would collapse.
  • C) The decomposers would become producers.
  • D) Nothing would change.
15. Which of the following is a herbivore?
  • A) Tiger
  • B) Eagle
  • C) Bear
  • D) Cow

B. True or False (Questions 16-25)
Write 'T' for True or 'F' for False in the space provided.

16. _____ All food chains start with a consumer.
17. _____ Energy is lost at each level of a food chain.
18. _____ A food web is a more realistic model of an ecosystem than a food chain.
19. _____ Humans are carnivores.
20. _____ A snake is a producer.
21. _____ Decomposers return nutrients to the soil.
22. _____ An omnivore only eats meat.
23. _____ In a predator-prey relationship, the predator is the hunter.
24. _____ There are more tertiary consumers than producers in a healthy ecosystem.
25. _____ Photosynthesis is the process plants use to capture energy from the sun.

C. Fill in the Blanks (Questions 26-35)
Choose the best word from the word bank to complete each sentence.

Word Bank: energy, herbivore, food web, carnivore, producer, consumer, decomposer, Sun, prey, omnivore
26. An organism that cannot make its own food is called a __________________.
27. The main source of energy for life on Earth is the __________________.
28. A __________________ is an animal that eats only plants.
29. An animal that is hunted by a predator is known as __________________.
30. A diagram showing multiple, interconnected food chains is a __________________.
31. A plant is an example of a __________________.
32. A lion is an example of a __________________.
33. A bear that eats berries and fish is an example of an __________________.
34. A mushroom is an example of a __________________ that breaks down dead organisms.
35. The arrows in a food chain show the flow of __________________.

D. Matching (Questions 36-40)
Match the term on the left with its correct definition on the right. Write the letter of the definition in the space provided.

36. _____ Producer                A. An organism that breaks down dead organic matter.
37. _____ Herbivore               B. An organism that eats only other animals.
38. _____ Carnivore               C. An organism that makes its own food.
39. _____ Omnivore               D. An organism that eats only plants.
40. _____ Decomposer          E. An organism that eats both plants and animals.
Part 2: Short Answer Questions

Write your answers in the space provided.

1. Define the term 'ecosystem'.
____________________________________________________________________
____________________________________________________________________

2. What is the difference between a food chain and a food web?
____________________________________________________________________
____________________________________________________________________

3. Why are producers essential to an ecosystem?
____________________________________________________________________
____________________________________________________________________

4. Give an example of a food chain with at least three organisms.
____________________________________________________________________

5. What is the role of a decomposer, like a fungus?
____________________________________________________________________
____________________________________________________________________

6. Explain what a tertiary consumer is and give an example.
____________________________________________________________________
____________________________________________________________________

7. Name the three types of consumers based on their diet.
____________________________________________________________________

8. What would happen to the predators of an animal if that animal's population decreased significantly?
____________________________________________________________________
____________________________________________________________________

9. Why are there fewer organisms at the top of a food pyramid than at the bottom?
____________________________________________________________________
____________________________________________________________________

10. Define 'predator' and 'prey' and provide an example of a predator-prey relationship.
____________________________________________________________________
____________________________________________________________________

11. Where does a primary consumer get its energy from?
____________________________________________________________________

12. Is it possible for an animal to be both a secondary and a tertiary consumer? Explain with an example.
____________________________________________________________________
____________________________________________________________________

13. What process do plants use to create their own food?
____________________________________________________________________

14. Why is a food web considered a more stable system than a single food chain?
____________________________________________________________________
____________________________________________________________________

15. Describe a situation where an animal could be considered prey to one animal but a predator to another.
____________________________________________________________________
____________________________________________________________________

16. How do humans fit into food webs? Are we herbivores, carnivores, or omnivores?
____________________________________________________________________
____________________________________________________________________

17. What is the ultimate source of energy for a carnivore like a lion?
____________________________________________________________________

18. Name two examples of decomposers.
____________________________________________________________________

19. If a toxin is introduced at the producer level, which organism in the food chain will have the highest concentration of that toxin?
____________________________________________________________________
____________________________________________________________________

20. Can an ecosystem survive without decomposers? Explain why or why not.
____________________________________________________________________
____________________________________________________________________

Part 3: Problem Solving

Use the simple forest food web diagram below to answer the following questions.

                      +-----------+
                      |   Hawk    |
                      +-----+-----+
                            |
           +----------------+----------------+
           |                |                |
           v                v                v
      +----+----+      +----+----+      +----+----+
      |   Fox   |      |  Snake  |      |   Owl   |
      +----+----+      +----+----+      +----+----+
           |                |                |
   +-------+-------+  +-----+          +-----+
   |               |  |                |
   v               v  v                v
+--+---+        +--+---+          +--+---+
|Rabbit|        |Mouse |          |Lizard|
+--+---+        +--+---+          +--+---+
   |               |                |
   |   +-----------+----------------+
   |   |           |
   v   v           v
+--+---+        +--+---+
| Grass|        | Seeds|
+------+        +------+
1. Identify the two producers in this food web.
____________________________________________________________________

2. List all the primary consumers (herbivores).
____________________________________________________________________

3. Name one secondary consumer.
____________________________________________________________________

4. Name one tertiary consumer.
____________________________________________________________________

5. Construct one food chain from this web that has four levels (four organisms).
____________________________________________________________________

6. Which animals does the fox eat?
____________________________________________________________________

7. If a disease were to eliminate the rabbit population, which predator would be most directly affected?
____________________________________________________________________

8. What would likely happen to the population of grass and seeds if all the mice were removed?
____________________________________________________________________

9. Which organism in this food web competes with the snake for food?
____________________________________________________________________

10. The hawk is a top predator in this food web. What would happen to the populations of foxes, snakes, and owls if the hawks were hunted to extinction?
____________________________________________________________________
____________________________________________________________________

Answer Key

Part 1: Objective Questions

A. Multiple Choice

  1. C) The Sun
  2. B) Producer
  3. B) Rabbit
  4. C) Secondary consumer
  5. C) Omnivore
  6. B) The flow of energy
  7. D) Decomposers
  8. B) Food web
  9. B) Only other animals
  10. A) The producer
  11. D) Tertiary consumer
  12. C) An oak tree
  13. B) A prey
  14. B) The ecosystem would collapse.
  15. D) Cow

B. True or False

  1. F
  2. T
  3. T
  4. F (Humans are generally omnivores)
  5. F
  6. T
  7. F
  8. T
  9. F
  10. T

C. Fill in the Blanks

  1. consumer
  2. Sun
  3. herbivore
  4. prey
  5. food web
  6. producer
  7. carnivore
  8. omnivore
  9. decomposer
  10. energy

D. Matching

  1. C
  2. D
  3. B
  4. E
  5. A

Part 2: Short Answer Questions

  1. An ecosystem is a community of living organisms (biotic factors) interacting with their non-living (abiotic) environment.
  2. A food chain is a single, linear pathway of energy flow, while a food web consists of many interconnected food chains, showing more complex feeding relationships.
  3. Producers are essential because they form the base of the food web. They convert energy from the sun into food that all other organisms depend on.
  4. (Example) Grass → Zebra → Lion
  5. A decomposer breaks down dead plants and animals, returning essential nutrients to the soil for producers to use.
  6. A tertiary consumer is an animal that eats a secondary consumer. Example: A hawk eating a snake.
  7. Herbivores, carnivores, and omnivores.
  8. The predators would have less food, so their population would likely decrease due to starvation or moving to a new area.
  9. A large amount of energy is lost at each level of the food pyramid (as heat, for movement, etc.), so there is less energy available to support organisms at higher levels.
  10. A predator is an animal that hunts and eats other animals. Prey is the animal that is hunted. Example: A lion (predator) and a zebra (prey).
  11. A primary consumer gets its energy by eating producers (plants).
  12. Yes. For example, a bear can be a secondary consumer when it eats a deer (a primary consumer), and a tertiary consumer when it eats a salmon that ate smaller fish. (Student's own valid example is acceptable).
  13. Photosynthesis.
  14. In a food web, organisms have multiple food sources. If one food source becomes scarce, the consumer can switch to another, making the system more resilient to change.
  15. A frog is a predator to insects (it eats them), but it is prey to a snake (it is eaten by it).
  16. Humans are part of many food webs. Since most humans eat both plants and animals, we are classified as omnivores.
  17. The Sun. The energy flows from the Sun to the grass, to the herbivore the lion eats.
  18. Bacteria and fungi.
  19. The organism at the top of the food chain (the top predator/tertiary or quaternary consumer) will have the highest concentration.
  20. No. Without decomposers, dead organic matter would pile up, and the nutrients within it would not be recycled back into the soil for plants to use, causing the ecosystem to eventually collapse.

Part 3: Problem Solving

  1. Grass and Seeds.
  2. Rabbit, Mouse, Lizard.
  3. Fox, Snake, or Owl. (Any one is correct).
  4. Hawk.
  5. (Example) Grass → Rabbit → Fox → Hawk OR Seeds → Mouse → Snake → Hawk. (Any valid 4-level chain is correct).
  6. The fox eats the rabbit and the mouse.
  7. The fox.
  8. The population of grass and seeds would likely increase because a major consumer has been removed.
  9. The owl competes with the snake for mice, and the fox competes with the snake for mice. (Either answer is acceptable, Owl is a more direct competitor based on the diagram's arrows).
  10. The populations of foxes, snakes, and owls would likely increase because their main predator has been removed. This could lead to a decrease in the populations of rabbits, mice, and lizards.
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