Ncert Solutions for Class 7 Science Chapter 17 Forest: Our Life Line

The NCERT Solutions Class 7 Science Chapter 17 – Forest: Our LifeLine is crucial for the students of the 7th standard. The solutions are provided here to assist the students in understanding the Forest: Our LifeLine easily and interestingly.

All the NCERT Solutions are prepared and compiled by subject experts as per the latest CBSE syllabus (2020-2021). The students need to practice the solutions regularly for effective preparation for the examination.

FOREST OUR LIFELINE

CHAPTER 17_FOREST: OUR LIFELINE NCERT SOLUTIONS

1. Explain how animals dwelling in the forest help it grow and regenerate.

A. i) Micro-organisms that convert the dead plants and animals to humus are known as decomposers. This humus helps in returning the nutrients to the soil. Plants absorb these.

ii) The animals also help in dispersing the seeds of certain plants.

iii) The decaying animal material and cattle dung provides nutrients for various types of seedlings to grow.

All these activities of animals dwelling in the forest help it grow and regenerate.

2. Explain how forests prevent floods.

A. i) The uppermost layer of the forest canopy intercepts the flow of raindrops, and most of the water comes down through the branches and the stems of the trees.

ii) From the leaves, it drips slowly over branches of the shrubs and herbs.

iii) Thus, forests act as natural absorbers of rainwater and allow it to seep.

iv) In this way, forests help in controlling the floods and maintain a steady supply of

3. What are decomposers? Name any two of them. What do they do in the forest?

A. i) Decomposers are micro-organisms. They decompose the dead plants and animal tissues and convert them into humus (dark-colored substances).

ii) Bacteria and fungi are the two types of decomposers.

iii) They help recycle nutrients by decomposing various dead organisms such as plants and animals to form humus.

4. Explain the role of forests in maintaining the balance between oxygen and carbon dioxide in the atmosphere.

A. i) Forests are called the green lungs. This is because plants in the forest release oxygen through photosynthesis and help provide oxygen to animals for respiration.

ii) Plants consume carbon dioxide released by the animals.

iii) In this way, plants help maintain a balance of oxygen and carbon dioxide in the atmosphere.

5. Explain why there is no waste in a forest.

A. i) The microbes present in the forest act on the wastes and convert them into useful materials like hummus.

ii) The hummus gets mixed with the soil and ensures the enrichment of soil fertility.

iii) Hence, there is no waste in a forest.

6. List five products we get from forests.

A. i) Medicines ii) Wood iii) Paper iv) Oil

v) Gum.

7. Fill in the blank :

a) The insects, butterflies, honeybees, and birds help flowering plants in

b) A forest is a purifier of _______________ and _______________.

c) Herbs form the _______________ layer in the forest.

d) The decaying leaves and animal droppings in a forest enrich the

A. a) pollination b) air and water c) lowest d) soil fertility

8. Why should we worry about the conditions and issues related to forests far from us? (Or) Why should we conserve forests?

A. There are various reasons we should be vigilant about matters related to forests.

i) A decrease in forest area would lead to an increase in carbon dioxide in the air. This will lead to an increase earth’s temperature.

ii) Soil erosion would occur if there were no forests.

iii) Floods would be more frequent in the absence of forests.

iv) When forests are adversely affected, the habitats of wild animals are also adversely affected. Therefore, we need to conserve our forests.

9. Explain why there is a need for various animals and plants in a forest.

A. i) The plants and animals in a forest are interdependent.

ii) The diversity of plants and animal facilitates them to meet their needs.

iii) Having a variety of plants and animals also helps maintain the ecological balance.

10. In the figure, the artist forgot to put the arrows’ labels and directions. 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.

A.

11. Which of the following is not a forest product?

i) Gum ii) Plywood iii) Sealing wax iv) Kerosene

A. 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.

A. 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

A. Humus.

Introduction to NCERT Solutions Class 7 Science Chapter 18 Wastewater Story

This chapter specifically deals with the issue of contaminants in the water. Water is an important resource not just for humans but for all the organisms on earth. Therefore, contaminating this natural resource has dire consequences. The main reasons for water pollution are our commercial and industrial activities. All the waste effluents that reach water bodies result in water pollution. This can cause many diseases and health hazards for us in the long run.

For instance, in Minamata City, Japan, mercury runoff from a factory polluted the waters, and the poisoning went undetected for decades. It came to notice only when the people saw their newborns had unusual congenital disabilities. It was found that mercury runoff had contaminated the marine ecosystem, resulting in fish species ingesting the mercury. Over a period of time, mercury accumulation in fish species got transferred into human bodies that consumed contaminated fish. This adversely affected bodily functions and caused many problems for the people and their descendants. Hence, we need to prevent such issues by preventing industrial effluents, which pollute our most precious resource – water.

Wastewater Story Chapter has eight subtopics which are listed below.

1. Water our lifeline
2. What is sewage
3. Water freshens up-an eventful journey
4. Wastewater treatment plant
5. Better housekeeping practices
6. Sanitation and diseases
7. An alternative arrangement for sewage disposal
8. Sanitation in public places

Water is a resource that we use for almost all of our activities. Consequently, polluting this resource can adversely affect our health. Human activities mainly pollute it as a result of commercial or industrial exploits. The waste by-products contain many poisonous chemicals that disrupt the marine ecosystem. Also, human excreta poses a major threat and could potentially be a bio-hazard due to the many harmful microbes it carries. These microbes or chemicals could leech into the aquatic environment affecting every life form that comes into contact.

NCERT Solutions Class 7 Wastewater Story guides the students to segregate waste to reduce water pollution. This chapter demonstrates the importance of water in balancing the ecosystem. Students will get to study the meaning of sewage, its treatment, and disposal methods. This chapter creates an awareness of sanitation in students, which helps them to become responsible citizens.

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