Science 2 Marks Questions

A greater variety of plants and animals in the forests helps it to regenerate and grow. Greater variety of plants means more food and habitat for the herbivores. An increase in herbivores means more food for carnivores. Decomposers help to maintain the supply of nutrients to the soil and to the growing plants. This wide variety makes forest a dynamic living entity.

There is no waste in a forest because micro-organisms act on the wastes and convert them to humus. This humus ensures that the nutrients are returned back to the soil.

Difference between decomposers and scavengers is:

Decomposer	Scavenger
These are the microbes which break dead organic matter into simple molecules to be used by plants again.	These animals eat the body of dead animals and are called cleaning agent of forests, e.g. jackal, fox, vultures, etc.

A dark-brown or black organic substance made up of decayed plant or animal matter. Humus provides nutrients for plants and increases the ability of soilto retain water. But decomposers are the microorganisms that convert the dead plants and animals to humus.

The forest plays an important role in maintaining the balance between oxygen and carbon dioxide in the atmosphere. As we know plants for their food nutrition requirement make use of process of photosynthesis, in which they consume Carbon Dioxide, released by the living organism from the environment. As a result of photosynthesis, plants release oxygen which is again consumed by living beings for respiration and this cycle goes on.

• Fruits and Vegetable.
• Timber and wood.
• Trupentine, latex (rubber raw product)
• Medicine and herbs.

Grass is eaten by insects, which in turn, is taken by the frog. The frog is consumed by snakes.
This is said to form a food chain:
Grass → insects → frog → snake → eagle. Many food chains can be found in the forest. All food chains are linked. If anyone food chain is disturbed, it affects other food chains. These food chains produce a lot of supplementary products which are vital for the plants growth. The micro-organisms which convert the dead plants and animals to humus are known as decomposers.

No, they would not have seen the same type of plants and animals. This is so because climatic conditions in the two forests would vary leading to variations in the types of plants and animals.

The forest plays an important role in maintaining the balance between oxygen and carbon dioxide in the atmosphere. As we know plants for their food nutrition requirement make use of process of photosynthesis, in which they consume Carbon Dioxide, released by the living organism from the environment. As a result of photosynthesis, plants release oxygen which is again consumed by living beings for respiration and this cycle goes on.

The body of the dead animal is eaten up by scavengers like vultures, jackals, hyanas, etc.
These animals do the functions of cleaning in the forest. This also shows that nothing goes waste in the forests.

The four birds which we expect to see in a forest are jungle crow, hornbill, myna and koel.

Plants are known as the producers of a food chain. It is because green plants (autotrophs) make their own food from carbon dioxide and water in the presence of sunlight and chlorophyll by a process called photosynthesis and provide food to all living organisms which live in the forest.

Paheli observed that there was no noise pollution in a forest even though there were lots of heavy vehicles passing from the nearby highway. It is because trees present in the forest absorb the noise.

As forests are covered with green trees and bushes which maintain the balance of oxygen and carbon dioxide in the atmosphere, they are called ‘green lungs’.

Animals disperse the seeds of certain plants with the help of their droppings. Therefore, pipal seed would have come to the wall by a bird dropping. On coming in contact with water and suitable nutrient medium, it would have grown into pipal sapling.

Four useful products other than wood which we get from forests are gum, spices, fodder for animals and medicinal plants.

The upper layer of the forest canopy intercepts the flow of rain drops and most of the water comes down through the branches and the stems of the tree, from the leaves rain water drips slowly over branches of the shrubs and herbs, thus the ground does not wet at all.

Forest products play vital role in socio-economic development. We get food (cereals, pulses, fruits) fire wood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and products of medicinal importance. It is also the home of diverse wildlife which maintains the ecosystem. Thus, forests are valuable resources.

Forests produce a number of economically important products like timber, bamboo, cane, oils, resins, etc. Forest animals provide honey, ivory, lac, etc.

Energy is lost at each link of the food chain due to,

• Food that cannot be digested and is passed out of the organism.
• Energy that is used up by the organism for carrying out its activities.

The correct food chain is: Grass → Insects → Frog → Snake → Eagle An insect eats green plant or grass a frog eats the insects the frog Is eaten by snake the snake is eaten by an eagle.

The micro-organisms called decomposers play an important role in the forest. The presence of humus ensures that the nutrients of the dead plants and animals are released into the soil. From there, these nutrients are again absorbed by the roots of the living plants. The dead animals become food for vultures, crows, jackals and insects. In this way, the nutrients are cycled. So, nothing goes waste in a forest.

Decomposers break down fallen leaves, branches, etc. into materials that plants can use. This also amends the soil so that it holds more water for longer periods of time. Soil is a living entity, made up of the dirt (inorganic sand, clay, etc.), nutrients, and microbes. The decomposers live in the soil, which is enriched by the dead forest material.

No, in any food chain, producers are always at the beginning. It is the producer which provides food to all living organisms. In a food chain, if producer is absent, then there will be no flow of energy. So, we can say that it is not possible to construct a food chain without a producer.

• Crown: The branchy part of tree above the stem is called crown.
• Understoreys: Trees have crowns of different type and sizes, these creates different horizontal layers in the forest, these are known as understoreys.

Animals and plants in a forest are dependent on the other for food. So there is a need of variety of animals and plants in a forest. Many food chains can be found in the forest like. Grass → insects → frog → snake → eagle.

The four factors which are responsible for the destruction of forests are:

1. Construction of roads.
2. Construction of buildings.
3. Industrial development.
4. Increasing demand of wood.

Every component of forest depend on other. If we remove one, the other will be affected, e.g. if we remove top carnivores (lion/ tiger) in a forest, herbivores will increase and if they increase they will end up eating all plants, so ecosystem will get disturbed.

Through transpiration from the leaf surfaces of trees in forests, the water vapour reaches the atmosphere resulting in rainfall which maintains the water table.