forests our lifeline class 7 pdf

 

NOTES PREPARED BY

ASHAQ HUSSAIN BHAT 

GL TEACHER SCHOOL EDUCATION 
DEPARTMENT JAMMU AND KASHMIR

 Lesson no 17 ;- Forests Our Life line

Point to Remember.

Forests are green lungs and natural water purifying system.

Forest is a place where land is covered by trees and no land is visible from the top

Forests are almost green in colour.

Many different varieties of animals, plants and insects are found in forests.

Animal, plants, forests all are dependent on one another

Trees, herbs, shrubs, climber, creepers etc. all type of plants are found in a forest. 

The forests protect the soil from soil erosion.

Forests help in bringing rain. 

Forests provide food, shelter, medicine and other useful products.

Animals in a forest alert one another by special warning calls.

Many types of food chain are available in forests.

Decomposers feed on dead and decaying leaves to form simple substance (nutrients).

SOME IMPORTANT DEFINITIONS

Humus. The organic material formed by decomposition of dead and decaying plant leaves.

Crown. The branchy upper part of stem in a tree is known as crown.

TEXT BOOK EXERCISES

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

Ans. Animals live in forest. They either feed on it directly (herbivores) 
or indirectly (carnivores). In both cases, they consume plants 
and excrete thrown by their bodies get decomposed by micro-organisms 
to produce simple forms and nutrients. These get dissolved by soil to be used 
by growing plants. Animals also help in scattering seeds to
 different parts of the forest. When seeds get favourable conditions 

they grow and thus forest regenerate.

Q. 2. Explain how forests prevent floods.

Ans. Forests prevent floods because forests act as a natural absorber of 
rain water and allows it to seep. It helps in maintaining the flow of water 
in streams so that a steady supply of water is available normally. The seeped 

water maintains the water level throughout the year. 

Q. 3. What are decomposers ? Name any two of them, 

What do they do in the forest ?

Ans. Decomposers. The micro-organisms which convert the dead 
plants and animals to humus are known as decomposers. Examples are
 bacteria, mushrooms. Decomposers help in maintaining the supply of 

nutrients to  the growing plants in the forests.

Q. 4. Explain the role of forests in maintaining the balance between 

oxygen and carbon dioxide in the atmosphere.

Ans. Forests are large area covered with different varieties of trees. 
Trees are green in colour. Their leaves photosynthesize in the sunlight 

and use atmospheric carbon dioxide and release oxygen.  In this way, 

balance of oxygen and carbon dioxide is maintained in the forests. 

In this way forest help in maintaining a balance between oxygen and 

carbon dioxide  of the atmosphere.

Q. 8. Explain why there is no waste in a forest.

Ans, Forests are habitat of various animals. They excrete and die but
 there is no waste in forests. Because the dead bodies are food of vultures, 
crow, jackal and insects. While other things like excreta and remains of dead
 matter get decomposed by mushrooms and other micro-organisms to nutrients 

required by soil.

Q. 6. List five products we get from forests.

Ans. Products obtained from forests are:

(i) Wood

(ii) Oxygen

(iii) Medicinal plants.

(iv) Rain

(v) Lac, Gum, Resin etc.

Q. 7. Fill in the blanks :

(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........

Ans. 

(a) Pollination

(b) air, water.

(c) Lower

(d) Soil.

Q. 8. Why should we worry about the conditions and issues

 related to forests far from us?

Ans. Forests indirectly or directly influence human life.
They control floods and rainfall. They maintain balance of
oxygen and carbon dioxide in the atmosphere. They are also
provider of many useful items needed by us in our daily life.
They provide food shelter and habitat to many animals. They
form a part of food web. So, we should worry about the conditions 

and issues related to forests far from us.

Q. 9. Explain why there is a need of variety of animals and 

plants in a forest.?

Ans. When there is variety of animals and plants then
opportunity increases for food and habitat for the herbivores.
When herbivores increase, then there is also increase in
number of carnivores of different varieties. Different varieties of 

animals helps the forest to regenerate and grow.

Q. 10. In Fig. below 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..

Ans:-Clouds, rain, atmosphere, carbon dioxide, oxygen,

plants, animals, soil, roots, water.

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

(i) Gum

(ii) Plywood

(iii) Sealing wax

(iv) Kerosene.

Ans. (iv) Kerosene.

Q. 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 dependant
on one another.
(iii) Forest influence the climate and water cycle.

(iv) Soil helps forests to grow and regenerate.

Ans. (ii) Plants and animals in a forest are not dependant

on one another.

Q. 13. Micro-organisms act upon the dead plants to

produce.

(i) sand 

(ii) mushrooms 

(iii) humus 

(iv) wood.

Ans. (iii) humus.

Q. 14. Tick mark (√) the correct choice.

(i) Micro-organism which converts dead plants,

animals into humus is known as:

(b) Omnivores

(a)Decomposers   (√)

(c) Herbivores

(d) Carnivores.

Ans. (i) (a) Decomposers

(ii) Which of the following is not a forest product?

(a) Plywood

(b) Gum

(c) Teak

(d) Gasoline.(√)

(Ans) (d) Gasoline

(iii) Deforestation results in :

(a) Increase in rainfall

(b)Global warming(v)

(c) Increase in water level

(d) Conservation of soil.

(Ans) (b) Global warming

(iv)A food chain includes:

(a) Producers and herbivores

(b) Producers and carnivores

(e)Producers and decomposers

(d) Producers, herbivores and carnivores.(√)

(Ans) (d) Producers, herbivores and carnivores.

Short answer type questions 

Q .1.Why are forests dark?

Ans. The forests are places where a huge variety of trees along with number 

of shrubs and herbs grow. These trees, herbs, shrubs are again covered with 

creepers and climbers.  Sun light cannot reach inside the forest, so, making it

dark and shady.

2. What are under storeys and how are they formed?

Ans. There are different types of trees in a forest. All trees have different types of 
crown and their sizes also vary. So, they create different horizontal layers 
known as under storeys. Giant and tall trees constitute the top layer,  

Shrubs and tall grasses form the middle layer while lower layer is 

constituted by herbs in this way  under storeys are formed in a forest.

Q. 3. Why do water not stagnate in forests ?

Ans. Forests are natural absorber of rain water and allow it to seep deep down the earth.
 Also, the direct pouring of rain is stopped by canopy of forest and it falls drop by drop 

on the floor. So, water do not stagnate in the forests,

Q. 4. Why is soil of forest rich in nutrients ?

Ans. The soil of forest is rich in nutrients because dead

and decaying leaves are decomposed by decomposers to give a

brown coloured nutrient to enrich the soil.

Q. 5. Name the different animals found in a forest.

Ans. Bear, bison, jackal, porcupines, monkeys, birds.

Q. 6. Name the different types of trees found in a

forest?

Ans. Sal, teak,  she sham, neem, amla, bamboo.

Q. 7. What is classification of different plants found

in a forest ?

Ans. Trees, shrubs, herbs, grasses, climbers, creepers etc.

Q. 8. What is a crown ?

Ans. Branchy part of tree above the stem is called crown.

Q. 9. What is a canopy ?

Ans. Canopy is a sort of roof made by branches of tall

trees over the other plants in the forests.

Q. 10. What is dark coloured layer found on the floor

of forest ?

Ans. Humus.

LONG ANSWER QUESTIONS

Q. Describe the importance of forests and

consequences of depletion of forests ?

Ans. A forest is a natural ecosystem. Forests are essential

for sustenance of life on earth.

Importance of forests:

(i) Habitat for animals and plants.

(ii) Provide food to animals and micro-organisms.

(iii) Maintain water cycle.

(iv) Control earth's temperature nature.

(v) Maintain balance of oxygen and carbon dioxide in

(vi) Prevent soil erosion.

Consequences of depletion of forests are:

(i) Improper rainfall.

(ii) Landslides. 

(iii) Extinction of wild animals.

(iv) Retardation of soil quality.

(v) Due to increase in carbon dioxide, increase in green

house effect and global warming