Class 8 General Science Notes: - Unit-1: Ecology: Solved Exercise (MCQs)

(National Book Foundation - New Book/New Syllabus Based on National Curriculum Pakistan 2023-2024 and Onwards)

(Class 8 General Science Notes for 8th Centralized Exam 2023-2024 and onward, FDE, Islamabad)

A. MCQs (Choose the Correct Answers).

1. The process which consumes carbon dioxide and produces oxygen is

a. respiration.
b. combustion.
c. photosynthesis.
d. fossilization.

... Answer is c. photosynthesis.
See the definition of photosynthesis

2. Greenhouse gases

a. burn to add heat.
b. trap heat.
c. help heat to escape.
d. do not allow heat to reach the earth's surface

... Answer is b. trap heat.
Greenhouse gases are molecules that have the ability to trap heat (infrared radiation) in the Earth's atmosphere, which leads to global warming.

3. The interaction in which both members get to benefit from each other is

a. mutualism.
b. predation.
c. commensalism.
d. competition.

... Answer is a. mutualism.
See the definition of Mutualism.

4. The organism that kills the other for food is called

a. prey.
b. parasite.
c. pathogen.
d. predator.

... Answer is d. predator.
Predators are those organisms that hunt and kill other organisms for food. The organisms that are consumed by the predators are called the prey. Predators can be both carnivores or omnivores. Lions, tigers, sharks, snakes, etc. are examples of predators

5. Rhizobium is a group of bacteria that live in the roots of some plants. They fix nitrogen for plants and get food in return. This relationship is

a. parasitism.
b. commensalism.
c. mutualism.
d. competition.

... Answer is c. mutualism.
See the definition and example of Mutualism from the book.

6. In a food chain, which type of organisms utilizes most of the solar (sun) energy coming to earth?

a. Producers.
b. Primary consumers.
c. Secondary consumers.
d. Tertiary consumers.

... Answer is a. Producers.
Producers are mostly plants that use sunlight in photosynthesis to produce food.

7. In an ecosystem, the energy flow is always :

a. bidirectional.
b. random.
c. down in a pyramid.
d. unidirectional.

... Answer is d. unidirectional.
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8. Carnivorous plants feed on insects because these plants grow in marshy places deficient in

a. carbon.
b. nitrogen.
c. calcium.
d. iron.

... Answer is b. nitrogen
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9. Greenhouse traps

a. carbon dioxide.
b. heat.
c. light.
d. water.

... Answer is b. heat.
Greenhouse gases are molecules that have the ability to trap heat (infrared radiation) in the Earth's atmosphere, which leads to global warming.
 

10. The most common non-biodegradable pollutant is

a. wood.
b. leaf litter.
c. bodies of dead animals.
d. plastic bags.

... Answer is d. plastic bags.
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Class 8 General Science Notes

Source: General Science Book (National Book Foundation, Pakistan)

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