Science 3 Marks Question

(i) The list of things we see in the forest are as follows
• Wild animals - Boar, bison, jackal, elephant, monkey, etc.
• Birds - Woodpecker, jungle crow, hornbill, etc.
• Plants - Sal, teak, semal, bamboo, mosses, ferns.
• Insects - Beetles, ants, butterflies, moth, bees, etc.
• Fungi - Mushroom
(ii) Various types of trees and layers formed by them include 
1. Canopy It is the uppermost layer of the forest, consisting of the tallest trees that form a dense covering. Mostly trees of sal, teak, semal, etc. form the canopy.
2. Understorey It is located beneath the canopy and consisting of smaller trees, sapling and shrubs. The constituents of understorey are as follows 
• Herb layer It is located on the forest floor and consists of herbaceous plants such as wild flowers, ferns and mosses. 
• Forest floor It is the lowest layer of the forest and is covered with fallen leaves, decaying organic matter and soil.

Different types of food chain are as follows

Refer to text on page no.211.212

Nothing goes waste in a forest because of the following reasons
(i) Dry leaves and remains of dead animals are converted to a dark coloured substance called humus. This provides nutrients to the plants.
(ii) Dead animals become food for vultures, crows, jackals and insects.
(iii) Broken branches of trees are used as fuel by the people living in the vicinity of the forest.

The three activities going on in the forest on the basis of the given figure are
(i) Oxygen is given out by plant leaves.
(ii) Carbon dioxide is consumed by the plants to prepare their food by the process of photosynthesis.
(iii) Nutrients are being added to the soil by the action of decomposers.

The removal of forest to meet the various demands of the increasing population, is called deforestation.
Factors Responsible for Deforestation
The factors which are responsible for the deforestation are as follows
(i) Expansion of agriculture
(ii) Construction of road
(iii) Industrial development
(iv) Increasing demand of wood
(v) Overgrazing by animals

Plants present in the forest fulfill all the needs of animals present there is following ways
(i) Plant provide oxygen to the animals to respire.
(ii) They also provide food to all the animals directly or indirectly. Herbivores obtain food directly from plants, carnivores depend on herbivores for food.
(iii) Trees in forest provide shelter to animals.
(iv) Decomposers help in maintaining the supply of nutrients to the growing plants in the forest.

There are various reasons for which we should be vigilant about matters related to forests
The various things which are obtained from the forests are called forest products. Forests give us a large number of useful products. Many trees in the forests have medicinal value and chemicals extracted from them are used in pharmaceutical or cosmetic industries.
Some of the important products which we get from the forests are wood, honey, gum, sealing wax (or lac), catechu (kattha), fruits, oils, spices, natural rubber, cork, dyes, medicinal plants and fodder for cattle.
Perhaps the most important product obtained from forests is the wood (which is obtained by cutting down the forest trees). The wood obtained from forests is used for a large number of purposes in our day-to-day life.

Forests are called the green lungs. This is because plants in forests release oxygen through the process of photosynthesis and help in providing oxygen to animals for respiration.
They consume carbon dioxide released by the animals. In this way, plants help in maintaining a balance of oxygen and carbon dioxide in atmosphere.

Rainwater does not stagnate in the forest as the upper most layer of the forest canopy intercepts the flows of raindrops. This results in most of the water coming down through the branches and the stems of the tree. The forest acts as a natural absorber of rainwater and allows it to seep.


It 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.
In the absence of plants/trees, the soil will not hold water which will cause flood and soil erosion.

(i) The animals in forests are of various types. These could be herbivores, carnivores, microorganisms, etc. These plays an important role in maintaining the food chains.
(ii) Microorganisms convert the dead plants and animals into humus. This humus helps in returning the nutrients back to the soil. These are then absorbed by plants.
(iii) The animals also help in dispersing the seeds of certain plants.
(iv) The decaying animal dung provides nutrients.
All these activities of animals dwelling in the forest help it to grow and regenerate.

Apart from maintaining the water cycle, forests benefit us in many other ways.
1.Forests help in maintaining the balance of gases in the atmosphere by absorbing carbon dioxide and releasing oxygen, which is essential for all living organisms.
2.Forests prevent soil erosion as the roots of trees hold the soil firmly and protect it from being washed away by wind and rain.
3.Forests provide habitat and shelter to a wide variety of plants and animals, thereby conserving biodiversity and maintaining ecological balance.