Access to the AP 7th Class Science Study Material 12th Lesson Forests Our Lifeline Questions and Answers are aligned with the curriculum standards.
AP 7th Class Science 12th Lesson Forests Our Lifeline Questions and Answers
AP Board Solutions Class 7 Science Chapter 12 Forests Our Lifeline
Exercises
Question 1.
Explain how animals dwelling in the forest help it grow and regenerate.
Answer:
Animals help in the growth and regeneration of the forest in many ways:
- The excreta or droppings of animals are decomposed by bacteria and add the nutrient content to the soil.
- They help in seed dispersal either by eating and dropping the seed at different places along with their excreta.
- They helps to increase soil fertility and helps in the growth of new plants.
Question 2.
Explain how forests prevent floods.
Answer:
The forest acts as a natural absorber of rainwater and allows it to seep. lt helps to maintain the water table throughout the year. Forests not only help in controlling floods but also help to maintain the flow of water in the streams so that we get a steady supply of water. Also, the trees present in the forest prevents the rain directly hitting the ground and bind the soil together which helpș in the absorption of rainwater and thus prevent floods.
Question 3.
What are decomposers? Name any two of them. What do they do in the forest?
Answer:
The organisms which derive their food from the dead and decaying animals or plants are called decomposers. Bacteria and fungi are examples of decomposers. They play a very important role in sustaining the forests. They help to return the nutrients of dead and decaying substances back to the soil, so that they can be used by the living plants.
Question 4.
Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Answer:
Forests are called the green lungs. This is because of plants and forest release oxygen through the process of photosynthesis and help in providing oxygen to animals for respiration. Plants consume carbon dioxide released by the animals. In this way, plants help in maintaining a balance of oxygen and carbon dioxide in atmosphere.
Question 5.
Explain why there is no waste in a forest.
Answer:
Forests are the natural recycling factories. Whatever is produced in the forest use utilised by different components of the forest.The decomposers decompose the dead organisms. The decomposed matter is absorbed by plants as nutrients. Thus, there is no waste in a forest.
Question 6.
List five products we get from forests?
Answer:
Five products obtained from forests include:
- Medicinal plants
- Wax
- Gum
- Wood
- Rubber
Question 7.
Fill in the blanks :
a) The insects, butterflies, honeybees and birds help flowering plants in …………
b) ………… 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 …………
Answer:
a) pollination
b) air, water
c) lowest
d) soil
Question 8.
Why should we worry about the conditions and issues related to forests far from us?
Answer:
We should worry about the conditions and issues related to forests far from us because:
- The amount of carbon dioxide in air will increase if forests will disappear and thus less oxygen will be there in the atmosphere.
- The water cycle would be disturbed.
- With the destruction of forests, many animals and birds species would become extinct as they lose their habitat.
- Soil erosion and flooding would increase.
- There will also be an imbalance in the nature and thus causing climate changes and less rainfall.
Question 9.
Explain why there is a need of variety of animals and plants in a forest.
Answer:
There is a need of variety of animals and plants in the forest and as each of them contribute for maintaining the ecosystem of the forest. They also helps forests in regeneration and growth. Herbivorous are needed to eat green plants and to provide food for the carnivorous and carnivorous are needed to eat herbivorous and check their population. Also, decomposers are need to maintain the supply of nutrition to the soil and the growing plants.
Question 10.
In figure 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.
Answer:
Question 11.
Which of the following is not a forest product ?
i) Gum
ii) Plywood
iii) Sealing wax
iv) Kerosene
Answer:
iv) Kerosene
Question 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.
Question 13.
Micro – organisms act upon the dead plants to produce:
i) sand
ii) mushrooms
iii) humus
iv) wood
Answer:
iii) humus
Questions given in the lesson
Page No. 134
Question 1.
Paheli reminded their friends that they have studied photosynthesis in Chapter 1.
Answer:
The process of preparing food from CO2 and water by the chlorophyll containing leaves of plants in the presence of sunlight is called photosynthesis. Carbohydrate and oxygen is produced in this process.
Page No. 136
Question 2.
Paheli remembered that she saw a Pipal sapling on the sidewall in her school. Can you help her to understand how this would have happened?
Answer:
The pipal see might have reached on the sidewall of school through the dropping of birds. It germinates there due to presence of moisture in the air and grows in sapling.
Page No. 140
Question 3.
What would happen if forests disappear ?
Answer:
If forests disappear, the amount of carbon dioxide in the air will increase which in turn increase the Earth’s temperature. In the absence of trees and plants, the animals will not get food and shelter. In the absence of trees, the soil will not hold water, which will cause floods. We will not be able to avail many things such as food, furniture, paper, wood fuel, gum, rubber etc. Deforestation will endanger our life and environment. Hence, disappearing of forest will make our survival difficult.
Extended Learning – Activities and Projects
Question 1.
The Department of Environment is to decide whether some portion of a forest in your area could be cleared for a housing complex. Write a letter to the department explaining your point of view as a concerned citizen.
Answer:
To
The Director,
Department of Environment,
New Delhi.
Subject : Deforestation in ………. area.
Sir,
I have come to know that your department has granted permission to clear the forest adjoining to my residential area. In this regard, I want to draw your kind attention towards the following points, i.e., after-effects of your decision:
- Due to the destruction of forests, wild animals will move to residential areas for food and shelter.
- There will be climatic change due to an imbalance in oxygen and carbon dioxide.
- Deforestation will cause an increase in CO2 concentration in the atmosphere resulting in the greenhouse effect and an increase in temperature.
- Loss of trees and other vegetation may cause soil erosion.
- In absence of trees, the soil will not hold water which will cause a flood.
Aforesaid are some of the points which may cause danger to our lives and environment due to deforestation. As a concerned citizen, I request to reconsider your decision in the public interest.
Thanking You,
Yours faithfully,
A concerned citizen.
Question 2.
Visit a forest. Here is a list of points that would make your visit more fruitful.
a) Make sure that you have permission to go into the forest.
b) Make sure that you can find your way around. Get a map and go along with some one who is familiar with the area.
c) Keep a record of the things you see and do. Observations make the visit interesting. Sketches and photographs are useful.
d) You may record bird calls.
e) Collect different kinds of seeds or hard fruits like nuts.
f) Try to recognise various types of trees, shrubs, herbs, etc. Make lists of plants from different places in the forest and of different layers. You may not be able to name all the plants, but it is worth recording and seeing where they grow. Make a record of approximate heights of plants, crown shape, bark texture, leaf size, and flower colour.
g) Learn to recognise the animal’s droppings.
h) Interview the forest officials and the people of surrounding vil lages and other visitors.
Answer:
Student activity.
Activities
Activity 12.1 Page No : 126
Question 1.
Observe the various things in your home and make a list of those which are made from material which may have been obtained from the forest. You might have many wooden items on your list like plywood, fuel wood, boxes, paper, matchsticks, and furniture. Do you know that gum, oils, spices, fodder for animals and medicinal plants are also some of the products which we get from the forest. Based on the products that we get from plants, try to fill Table. One example of each plant is already given. Fill the table by adding more examples.
Plants and their products
| Gum | Timber | Medicinal | Oil |
| Babool | Sheesham | Neem | Sandalwood |
Answer:
Plants and their products
| Gum | Timber | Medicinal | Oil |
| Babool | Sheesham | Neem | Sandalwood |
| Guggul | Mahogany | Amla | Coconut |
| Neem | Pine | Tulsi | Soybean |
| Karaya | Oak | Bael | Palm tree |
| Ghatti | Teak | Drumstick tree | Sunflower |
Activity – 12.2 Page No : 128
Visit a forest or a park in your neighbourhood. Observe the tree and try to identify them. You can take the help of some elders or books on trees. List the characteristics of the trees that you observe, such as the height, shape of leaves, crown, flowers, and fruits. Also draw the crowns of some trees.
Answer:
Crown is the top part of the tree from which branches grow above the stem. There are 8 types of crown on the basis of shape such as
- Pyramidal crown : E.g : Deodar cedar
- Full crowned : E.g : Sugar maple
- Vase crown : E.g: Hawthorn
- Fountain : E.g: Palm tree
- Spreading crown: E.g : Oak tree
- Layered crown : E.g: Banyan tree
- Columnar crown : E.g : Poplar
- Weeping crown : E.g : Willow
Activity 12.3 Page No: 128
Question 3.
Dig a small pit: Put vegetable waste and leaves in it. Cover them with soil. Add some water. After three days, remove the upper layer of the soil. Does the pit feel warm inside?
Answer:
Aim : To verify the fact that the decaying organic matter is always moist and warm. Materials required: Khurpi, leaves, water etc.
Procedure:
- Dig a small pit.
- Fill the vegetable wastes and dry leaves in this pit.
- Cover them with soil.
- Add some water.
- After three days, remove the upper layer of the soil.
- Observe the decaying matter.
Observation : We observe that the decaying matter is moist and warm.
Conclusion: From the above activity, we can conclude that the decaying organic matter is always moist and warm.