CBSE Class 7 Science Forests Our Lifeline Assignment

L-17
Forests : Our Lifeline

Q.1 Choose the correct option in the following questions.

i) Which of the following in not a forest product?
(a) Gum
(b) Ply wood
(c) Sealing wax
(d) Kerosene
Answer: (d) Kerosene
Kerosene is a petroleum product obtained from crude oil, whereas gum, plywood, and sealing wax are derived from forest resources.
In simple words: Kerosene comes from underground petroleum, not from trees.

Exam Tip: Remember that fossil fuels like petroleum and coal are mined from the earth, while organic products like wood and gum come from plants.

ii) Micro organisms act upon the dead plants to produce.
(a) Sand
(b) Mushrooms
(c) Humus
(d) Wood
Answer: (c) Humus
Decomposers and microorganisms break down dead plant and animal matter to form a dark, nutrient-rich organic layer known as humus.
In simple words: Microorganisms turn dead leaves and plants into rich soil called humus.

Exam Tip: Humus increases soil fertility and provides essential nutrients for plant growth.

iii) If forests disappear
(a) The amount of carbondioxide in air will decrease.
(b) The amount of oxygen in air will increase.
(c) The amount of carbondioxide in air will in crease.
(d) The amount of nitrogen in air will in crease.
Answer: (c) The amount of carbondioxide in air will in crease.
Trees absorb carbon dioxide during photosynthesis and release oxygen. Without forests, carbon dioxide levels will rise, leading to global warming.
In simple words: Trees absorb carbon dioxide, so if they disappear, carbon dioxide in the air will go up.

Exam Tip: Connect deforestation directly with increased greenhouse gases and global warming.

iv) The micro-organism which convert the dead plants and animals to humus are known as
(a) Herbivores
(b) Carnivores
(c) Decomposers
(d) Parasites
Answer: (c) Decomposers
Organisms such as fungi and bacteria that break down complex organic matter into simple inorganic substances are called decomposers.
In simple words: Decomposers like bacteria and fungi break down dead matter into humus.

v) Which of the following animals is not a wild animal.
(i) Jackals
(ii) Elephant
(iii) Goat
(iv) Tiger
Answer: (iii) Goat
Goats are domesticated livestock raised by humans, whereas jackals, elephants, and tigers live naturally in the wild.
In simple words: Goats are farm animals, not wild animals.

Exam Tip: Distinguish carefully between domesticated animals (farm/pets) and wild animals (forest dwellers).

Q.2 List any five products we get from forests.
Answer:
i) Timber / Wood
ii) Medicinal plants and herbs
iii) Gum and resins
iv) Honey and wax
v) Paper pulp / Bamboo
In simple words: Forests provide us with wood, medicine, paper, gum, and honey.

Exam Tip: Mention diverse categories of products like wood, medicines, and food items to score full marks.

Q.3 Make a beautiful collage of forest in the given space and label it using the following labels.
Clouds, rain, plants, animals, soil, routs, water table, carbondioxide, oxygen.
Answer:
(Drawing/Collage activity description): Create a visual representation or collage showing a lush forest ecosystem containing tall trees with visible roots going into the soil, animals (like deer or birds), clouds overhead releasing rain, and indicate arrows for carbon dioxide being absorbed by plants and oxygen being released into the atmosphere.
In simple words: Draw a forest scene and label the clouds, rain, trees, roots, animals, soil, and gases.

Exam Tip: Ensure all required labels from the list are clearly pointed to their respective parts in your diagram.

Q.4 Fill in the blanks
Answer:
- Provide oxygen: Provide us with oxygen
- Provide habitat: Provide habitat at to a large number of animals
- Medicinal plants: A source of medicinal plants
- Prevents floods: Prevents floods
- Brings good rainfall: Brings good rainfall
In simple words: Forests give us oxygen and medicine, provide homes for animals, stop floods, and bring rain.

Exam Tip: Memorize the key ecological roles of forests to quickly answer conceptual flowcharts and fill-in-the-blank questions.

Q.5 After observing these pictures a & b some thoughts must be tickling in your mind, just write them in the given spaces.
A)
Answer:
The picture shows deforestation and rapid industrialization, where trees are being cut down to set up factories emitting smoke. This leads to habitat destruction for wildlife, increase in carbon dioxide, global warming, and severe air pollution.
In simple words: Cutting down forests for factories pollutes the air and destroys animal homes.

Exam Tip: Observe visual contrasts carefully in picture-based questions to identify environmental issues like deforestation and pollution.

b)
Answer:
The picture depicts severe flooding where heavy rains have inundated houses due to the lack of sufficient vegetation and trees that normally bind the soil and absorb excess rainwater. Deforestation removes natural barriers against floods.
In simple words: Without trees to absorb water and hold soil, heavy rains cause devastating floods that damage homes.

Exam Tip: Always link natural disasters like floods and soil erosion directly to the removal of forest cover.

Q. 6. Write a slogan
Topic - Wild life conservation
Answer:
"Save wildlife, save nature; protect animals for a better future!"
In simple words: Protect animals and wildlife to keep our planet balanced and beautiful.

Exam Tip: Keep slogans catchy, short, and directly relevant to the given conservation theme.