NCERT Solutions for Class 7th Science Chapter 12 Forest Our Lifeline according to the Latest Syllabus Of JKBOSE and CBSE NCERT Books
1. Explain how animals dwelling in the forest help it grow and regenerate.
Animals play a crucial role in the growth and regeneration of forests. They help in seed dispersal by carrying seeds from one place to another, which allows new plants to grow. Animals like earthworms and termites break down dead plants and animals, turning them into humus, which enriches the soil and provides nutrients for new plants. Herbivores feed on plants, keeping their growth in check and promoting biodiversity. Predators help maintain the balance of animal populations, preventing any one species from becoming too dominant.
2. Explain how forests prevent floods.
Forests prevent floods by absorbing and storing large amounts of rainwater. The roots of trees and plants help to hold the soil together, reducing soil erosion and allowing the ground to absorb more water. The canopy of the forest slows down the falling rain, giving it more time to seep into the soil rather than running off quickly into rivers and streams. This gradual absorption of water helps to maintain a steady flow in rivers and streams, preventing sudden surges that can lead to flooding.
3. What are the decomposers? Name any two of them. What do they do in the forest?
Decomposers are organisms that break down dead plant and animal material into simpler substances. Two examples of decomposers are fungi and bacteria. In the forest, decomposers play a critical role by breaking down dead organic matter, turning it into humus. This process recycles nutrients back into the soil, making them available for plants to use and helping to maintain the fertility of the forest ecosystem.
4. Explain the role of the forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Forests play a vital role in maintaining the balance between oxygen and carbon dioxide in the atmosphere through the process of photosynthesis. During photosynthesis, trees and plants absorb carbon dioxide from the air and use sunlight to convert it into oxygen and glucose. The oxygen is then released back into the atmosphere, providing the essential gas for respiration by animals and humans. By absorbing carbon dioxide, forests help to reduce the amount of this greenhouse gas in the atmosphere, mitigating the effects of climate change.
5. Explain why there is no waste in a forest?
There is no waste in a forest because everything is recycled. Dead plants and animals are broken down by decomposers into nutrients that enrich the soil. These nutrients are then taken up by plants to grow. This continuous cycle of growth, death, and decomposition ensures that nothing goes to waste in a forest ecosystem. Additionally, fallen leaves and branches decompose and contribute to the formation of humus, which supports new plant growth.
6. List five products we get from forests.
Five products we get from forests are:
- Timber: Used for construction, furniture, and paper production.
- Medicinal plants: Many plants used in traditional and modern medicine are found in forests.
- Fruits and nuts: Forests provide a variety of edible fruits and nuts.
- Gum and resin: Used in the production of adhesives, varnishes, and other products.
- Latex: Extracted from rubber trees and used to produce rubber products.
7. Fill in the blanks:
(a) The insects, butterflies, honeybees, and birds help flowering plants in pollination.
(b) A forest is a purifier of air and water.
(c) Herbs form the lowest layer in the forest.
(d) The decaying leaves and animal droppings in a forest enrich the soil.
8. Why should we worry about the conditions and issues related to forests far from us?
We should worry about the conditions and issues related to forests far from us because forests play a crucial role in the global ecosystem. They regulate the climate, produce oxygen, absorb carbon dioxide, and provide habitats for countless species. Deforestation and degradation of forests can lead to loss of biodiversity, disruption of water cycles, and increased carbon dioxide levels, contributing to global warming. These changes can have far-reaching effects, impacting weather patterns, food security, and overall environmental health worldwide.
9. Explain why there is a need for a variety of animals and plants in a forest.
There is a need for a variety of animals and plants in a forest to maintain a balanced and resilient ecosystem. Biodiversity ensures that different species can fulfill various ecological roles, such as pollination, seed dispersal, and decomposition. It also helps to stabilize the ecosystem, making it more resilient to disturbances like disease, pests, and climate change. A diverse range of species supports complex food webs, ensuring that energy and nutrients are efficiently cycled through the ecosystem.
10. In Fig 12.15, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels: clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.
11. Which of the following is not a forest product?
(i) Gum
(ii) Plywood
(iii) Sealing wax
(iv) Kerosene
Answer: (iv) Kerosene
12. Which of the following statements is not correct?
(i) Forests protect the soil from erosion.
(ii) Plants and animals in a forest are not dependent on one another.
(iii) Forests influence the climate and water cycle.
(iv) Soil helps forests to grow and regenerate.
Answer: (ii) Plants and animals in a forest are not dependent on one another.
13. Micro-organisms act upon the dead plants to produce?
(i) Sand
(ii) Mushrooms
(iii) Humus
(iv) Wood
Answer: (iii) Humus
14. Tick mark (✓) the correct choice:
- Micro-organisms which convert dead plants, animals into humus are known as:
(a) Decomposers
(b) Omnivores
(c) Herbivores
(d) Carnivores
Answer: (a) Decomposers
- Which of the following is not a forest product?
(a) Plywood
(b) Gum
(c) Teak
(d) Gasoline
Answer: (d) Gasoline
- Deforestation results in:
(a) Soil erosion
(b) Increased rainfall
(c) Increased wildlife
(d) None of these
Answer: (a) Soil erosion
- Forests are not responsible for:
(a) Providing timber
(b) Maintaining the water cycle
(c) Balance of oxygen and carbon dioxide in the atmosphere
(d) Adding pollutants to the air
Answer: (d) Adding pollutants to the air
- Which of the following are decomposers?
(a) Bacteria
(b) Butterflies
(c) Rabbits
(d) Foxes
Answer: (a) Bacteria
