7th Grade > Chemistry
FORESTS OUR LIFELINE MCQs
Total Questions : 81
| Page 3 of 9 pages
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Each point: 1 Mark
Any three:
1. Destruction of homeland - due to deforestationthe habitats of innumerable species are destroyed.
2. Lot of different species would become extinct without their habitat, and this in turn affects the food chain.
3. It increases the risk of soil erosion drastically.
4. It results in less amount of rainfall, leading to droughts.
5. It causes an increased amount of carbon dioxide in the air.
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Each part: 1.5 Marks
a)Gum, oils, spices.
b) Owl,Hawk,Humming bird.
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Each point: 1 Mark
1) Forests are the dominant terrestrial ecosystem of Earth, and are distributed across the globe
2) Forests account for 75% of thegross primary productivityof the Earth'sbiosphere, and contain 80% of the Earth's plant biomass.
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Stating yes or no: 1 Mark
Reasoning out: 1 Mark
Yes, there is a need for diversity of animals and plants in a forest.
This is so because each of them contributes uniquely towards the maintenance of the ecosystem of the forest. Plans and animals help forests in their regeneration and growth. For example, Herbivores are needed to eat green plants and they become food for the carnivores. Carnivores are needed to eat herbivores and in turn, check their population. Decomposers are needed to maintain the supply of nutrients to the soil for the growth of plants.
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Each point: 0.5 Mark
Animals dwelling in the forests are instrumental in the forest's growth and regeneration. For example:
(i) Herbivorous animals clear the land by eating grass for the new growth of vegetation.
(ii) Animals help in seed dispersal and pollination.
(iii) Dead and decaying bodies of animals get converted to humus after decomposition, which increases the fertility of the soil of the forest.
(iv) Dung of animals provide nutrients to various types of seedlings to grow.
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Role: 1 Mark
Each Example: 1 Mark
The micro-organisms which convert dead plants and animals to humus are known as decomposers.They play an important role in the decomposition of dead remains of the plants and animals and converting them to humus which adds nutrients to the soil.
Bacteria and fungi are the two examples of decomposers.
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Each correct match: 1 Mark
The correct match would be(a) (iii); (b) (v); (c) (iv); (d) (i); (e) (ii)
a) Decomposers are usually microorganisms that feed on dead and decaying matter.
b) Canopy is usually made of branches of tall trees.
c) Porcupine is a wild animal.
d) Humus consists of dead plants and animal tissues.
e) Forest serves as a habitat for wildlife.
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Each factor : 1 Mark
Factors which areresponsible for the destruction of forests are:
(i) Construction of roads
(ii) Construction of buildings andIndustrial development
(iii) Increasing demand of wood
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Identification: 1 Mark
Correct food chain and explanation: 2 Marks
The food chain is incorrect.
The correct food chain will be:Grains→Rats→Snakes→Eagle.
Rats feed on grains, while ratsare consumed by snakeswhich in turn are eatenby eagles.
Question 30. State whether the following statements are true or false. If false, give the correct statement. [3 MARKS]
(a) Forests influence climate, water cycle and air quality.
(b) In a forest, trees form the uppermost layer, followed by herbs. The shrubs form the lowest layer of vegetation.
(c) The forest keeps on growing and changing and can regenerate.
(a) Forests influence climate, water cycle and air quality.
(b) In a forest, trees form the uppermost layer, followed by herbs. The shrubs form the lowest layer of vegetation.
(c) The forest keeps on growing and changing and can regenerate.
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Each part: 1 Mark
(a) True.Forests influence climate, water cycle and air quality.
(b) False. The sequence is trees, shrubs and lowest one herbs.
(c) True.The forest keeps on growing and changing and can regenerate.