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CBSE Questions for Class 7 Biology Forests Our Lifeline Quiz 2 - MCQExams.com
CBSE
Class 7 Biology
Forests Our Lifeline
Quiz 2
The top part of trees in forest is called
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Canopy
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Crown
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Understorey
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Tindall effect
Explanation
The upper or top parts of trees in the forest is called as canopy.
The branchy part of a tree above the stem is known as the crown.
Trees creating different horizontal layers in the forest are called Understoreys.
Hence, Option "A" is correct.
Which of the following is a natural habitat?
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Forest
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Zoo
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Aquarium
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None of the above
Explanation
Zoo and Aquarium are man made habitat, whereas forest is natural habitat which provide food and shelter for wildlife and other small animals in the ecosystem.
Option "A" is correct.
The most rapidly depleting resource in the world is
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Water
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Forest
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Wind
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Sunlight
Explanation
Forest is depleting day by day due to the rapid urbanisation. As urbanising is increasing rapidly thus forest is most rapidly depleting natural resource.
Which of the following will be affected due to the absence of forest?
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Food and shelter of animals
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Percentage of carbon dioxide
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Percentage of oxygen
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All of the above
Explanation
Due to cutting of trees or deforestation-
Many animals loose their source of food and shelter.
Percentage of oxygen and carbon dioxide varies i.e. balance in the atmospheric concentrations is disturbed.
Option D is correct.
Which of the following forest tree is used for medicinal purpose?
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Neem
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Oak
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Turmeric
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Basil
Explanation
Turmeric has some antioxidant and anti-inflammatory properties and basil is used for stomach spasms, loss of appetite, intestinal gas but they come under herbs, not a tree.
Oak is mainly used for furniture purposes as oak wood is exceedingly strong, heavy, and durable.
Neem tree has various medicinal properties such as antioxidant, anti-inflammatory, anti-diabetic, anticancer, antifungal, antiviral.
So, option A is the correct answer.
What are the effects of deforestation?
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Increase in the temperature of the Earth
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Increase in the soil erosion
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Increase in the CO$$_2$$ level of atmosphere
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All of the above
Explanation
Deforestation is the cutting down of trees of the forest. Due to this, the number of trees that can consume CO$$_2$$ and give out oxygen through photosynthesis, decreases.
Thus, there is an increase in atmospheric CO$$_2$$ levels. As the CO$$_2$$ level increases, the greenhouse effect starts.
In this, CO$$_2$$ and other greenhouse gases, trap the heat of the sunlight and do not let it go.
This raises the temperature of the Earth causing global warming.
The roots of the trees hold the soil particles. Therefore, without trees, the topsoil gets washed away by water and wind and causes soil erosion.
Thus, the correct answer is option D.
The image depicts which of the following activity?
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Deforestation
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Aforestation
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Flood
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Both A and B
Explanation
Deforestation is the permanent removal of trees to make room for something besides the forest. This can include clearing the land for agriculture or grazing or using the timber for fuel, construction, or manufacturing.
It effects the wildlife present in that habitat.
So, option A is correct.
What would happen if forest disappears?
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Flood
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Global warming
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Extinction of animals
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All of the above
Explanation
Deforestation (disappearance of the forest) is when humans remove or clear large areas of forest lands and related ecosystems for non-forest use.
Without trees, rain runs off soil into rivers and streams i.e, soil erosion, raising the water level, leading to floods.
When deforestation takes place, it results in an increase in carbon dioxide concentration in the atmosphere, resulting in global warming.
If forests are destroyed, animals and other creatures of the forests will come out to human settlements searching for a place to stay. They will be killed more, thus leading to their extinction.
So, the correct answer is option D.
Which of the following provides nutrients to the seedling to grow in forest ?
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Grubs
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Beetles
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Bacteria
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Decaying animals dung
Explanation
The animals living in the forests excrete the nitrogenous wastes which is acted upon by the microbes. The complex materials in the dung is converted into simpler form of nutrients. These nutrients are taken up by the plants and trees in the forests. The new seedling utilises the nutrients from this decayed dung.
Thus, the correct answer is option D.
Leaves and branches are collectively known as
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Crown
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Trunk
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Root
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None of the above
Explanation
The branchy part of a tree above the stem is the region where leaves grow.
Hence Leaves and branches are collectively known as Crown.
Option "A" is correct.
Which of the following can act as decomposers?
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Lion
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Tiger
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Monkey
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Fungi
Explanation
$$\textbf{Correct option:D}$$
$$\textbf{Solution:}$$
$$\textbf{Explanation for correct option:}$$
$$\bullet$$Microorganisms are those which we can see only under a microscope such as bacteria, protozoa, and fungi act as decomposers.
Microorganisms break down organic matter that is present in the bodies of dead and decaying matter and convert it into a simple substances and mixed in the soil.
$$\textbf{Explanation for incorrect options:}$$
$$\bullet$$Lion, tiger,s and monkeys are carnivorous animals.
$$\bullet$$Carnivores are flesh-eating animals.
Hence, the correct answer is option D
Which part of the tree has leaf?
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Crown
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Trunk
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Root
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None of the above
Explanation
$$\textbf{Correct option:}$$ $$\textbf{(A)}$$
$$\textbf{Solution:}$$
$$\textbf{Option (A)}$$
$$\bullet$$ The crown of the tree is the topmost section of the tree, from which branches extend above the stem.
$$\bullet$$
On the basis of shape, there are eight different types of crowns.
$$\bullet$$
This is where the tree's leaves grow.
$$\bullet$$
Because the trees in this tier are so tall, they are constantly in the sun.
$$\textbf{Option (B)}$$
$$\bullet$$ The tree's bark is made up of all the tissues that aren't part of the vascular cambium.
$$\bullet$$
The bark is made up of a variety of cell layers.
$$\bullet$$
All of these tissues can be found outside of the vascular cambium.
$$\textbf{Option (C)}$$
$$\bullet$$ The root of the plant is frequently found underground.
$$\bullet$$
It is largely responsible for water absorption and fixation.
$$\bullet$$
The root system is made up of the root and its branches.
$$\textbf{Thus the Correct option is (A)}$$
The dead and decaying material present on the forest floor helps
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To increase fertility of the soil
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To increase the carbon dioxide concentration
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To increase the oxygen concentration
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All of the above
Which of the following can be traced at the forest floor?
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Humus
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Herbs
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Birds
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Both A and B
Explanation
Herbs and shrubs obtain nutrients from humus and dead decay from the ground in the forest floors, thus can easily be traced together in the forest.
Option D is correct.
Humus can increase the
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Soil fertility
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Water supply
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Minerals
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None of the above
Explanation
Humus retains moisture from the atmosphere and helps soil aeration, which increases soil fertility.
Hence, Option A is correct.
Which of the following helps in the formation of humus?
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Plants
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Animals
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Decomposers
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None of the above
Explanation
The micro-organisms which convert the dead plants and animals to humus are known as decomposers.
Option "C" is correct.
The decomposers in the forest perform
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Production of the plants
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Decomposition of the dead plants and animals
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Breakdown of the forests
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All of the above
Explanation
Decomposers are saprotrophs, which decompose the organic remains of plants and animals by secreting extracellular digestive enzymes.
Due to the degradation of organic remains, decomposers are also called reducers.
Heterotrophic bacteria and saprophytic fungi are the important organisms that usually act as decomposers.
Thus, the correct answer is option B.
Which of the following plant helps to prepare medicine?
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Amla
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Neem
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Tulsi
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All of the above
Explanation
Amla, Neem and tulsi have healing properties used to prepare medicines.
Amla is rich in vitamin c and other nutrients which are helpful in boosting immunity.
Neem have antibacterial properties which fights infections on the skin.
Tulsi, an herb is used to treat cough, asthma and other respiratory problems.
Hence, Option "D" is correct.
Which of the forest layer shown in the diagram receives the maximum sunlight?
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Emergent layer
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Canopy layer
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Understorey layer
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All of the above
Explanation
The top layer of tall plants receives maximum sunlight. This layer is mentioned as an emergent layer in the diagram.
The below plants in the canopy and understory region receive less amount of sunlight as compared to the emergent layer.
The forest floor receives a minimum amount of sunlight.
Hence, Option "A" is correct.
The microorganisms which convert dead and decay matter into humus are called
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Carnivores
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Omnivores
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Decomposers
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None of the above
Explanation
The micro-organisms which convert the dead plants and animals to humus are known as decomposers.
Option C is corrrect.
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