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(a) Weed Tadpole Water beetle

(b) Three

(A) Grasshopper

Graphic representation of the feeding level of an ecosystem by taking the shape of a pyramid is called an ecological pyramid.

The ecological pyramid was first introduced by Charles Elton in 1927.

(a) Third trophic level

(b) Second trophic level

(c) Third trophic level

(d) Second trophic level

(e) Fourth trophic level

Grass → Insect → Frog → Snake 

Frog is 3^rd trophic level.

The terrestrial ecosystems are being determined largely by the variations in climatic conditions between the poles and equator.

Natural ecosystem-Forest/ lake/ Pond/ River.

In a food web, each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms.

So, a food web is a complex network of many interconnected food chains and feeding relationships

Tree and Grass (Both are producers).

Garden and Pond are man-made ecosystems.

Biological magnification.

Ecosystem is the structural and functional unit of biosphere, comprising of all the interacting organisms in an area together with the non-living constituents of the environment.

Two main components of Ecosystem are :

(i) Biotic component

(ii) Abiotic component

An aquarium is an artificial and incomplete ecosystem compared to pond or lakes which are natural, self-sustaining and complete ecosystem where there is a perfect recycling of materials.

We need to clean of aquarium because of the :

(i) absence of natural decomposer.

(ii) stagnancy of water.

Pond is a complete eco system having decomposer organisms which are the cleansing agents themselves. Aquarium is an incomplete ecosystem and does not have decomposer organisms for cleansing purposes.

Goat and Rat (Both are herbivores).

(D) Consumers

 Grass and plants belong to the 1st trophic level of a food chain.

An aquarium is an artificial ecosystem which is incomplete ecosystem when compared to pond or lake which is natural and complete ecosystem.

Grass ----> Grasshopper -------> Frogs -------> Snakes

(4000 J)        (400 J)                   (40 J)              (4 J)

So, for snakes and frogs, 4 J and 40 J energy will be available by 10% law respectively.

a) Bioaccumulation: The process of entry of pollutants into a food chain is known as bioaccumulation. 

b) Biomagnification: It is the tendency of pollutants to concentrate as they move from one tropic level to the next is known as biomagnification.

C) Disturbs equilibrium

D) Spray of pesticides

The bioaccumulation of various metals in cyprinus carpio cause disorders. Such as hypertensions, sporadic fever, renal damage, nausea, etc.

1. a. autotrophs

2. a. Sun

3. b. Always unidirectional

4. b. By the help of pyramid of biomass

5. d. Detrital food chain

Using pesticides indiscriminately results in the killing of a vast number of other animals apart from pests.

Alternative methods for using pesticides to save the crops from pests: 

1. Rotation of crops 

2. Studying the life histories of pests 

3. Biological Control

4. Sterility 

5. Genetic Strains

The techniques like crop rotation, intercropping and organic pesticides can be used. We can use the microbes fro the destruction of the pests.

1. Neem Tree: Neem leaves contain an alkaloid Nimbin to protect themselves from the animals which eat them. 

2. Cactus: They have thorns to protect themselves. 

3. Datura: Datura leaves gives bad odour.

1. b. Stratosphere

2. d. All of these

3. d. Increased skin cancer

4. d. All of these

5. c. O₃

The answer is (c) T₁

• Maximum energy is available for producers.
• Only 10% of the energy is consumed by an organism at next level. 

Hence T₁ > T₂ > T₃ > T₄

1. a. Pyramid of numbers

2. b. Pyramid of biomass

3. c. Pyramid of energy

4. a. Pyramid of numbers

5. d. All of these

The food chain generally consists of four to five steps only because according to 10% law only 10% of energy is transferred from one trophic level to next trophic level. So, there is not much energy left for more than four or five trophic level.

Correct answer is c. Pollution

1. Do not pour leftover oil, old medicines or waste down the drain or into the toilet. 

2. Reduce the use of chemical pesticides and fertilizers to grow crops. 

3. Reduce the use of detergents and bleach to wash clothes. 

4. Do not litter or dump waste always use a waste bin.

Examples of how we can Avoid waste:-
Avoid buying packaged foods. Refuse to buy ‘use-and-throw’ plastic products.

Examples of how we can Reduce waste:-

1. Write on both sides on paper 

2. Share newspaper and magazines with others.

Importance of food chain

1. Learning food chain help us to understand the feeding relationship and interaction between organisms in any ecosystem.
2. Understanding the food chain also helps us to appreciate the energy flow and nutrient circulation in an ecosystem.
3. This is important because pollution impacts the ecosystem. The food chain can be used to understand the movement of toxic substances and their impacts.

If an organism is removed from the food chain, 

1. The food chain will fall apart.

2. The ecosystem will become imbalance and collapse. 

3. For example, Consider a food chain: 

Plants → grasshoppers → frogs → snakes → hawks.

If frogs were to die off in this chain, (due to disease/pollutants), then, there will be an increase in the number of grasshoppers. This will cause a major problem.

Living things : Plants, Beetle, Mosquito, Larva, Water snake, Water scorpion, Snail, Fish, Duck and Frog etc. 

Non- living things : Sun, Air, Water, Chemicals, Soil, Rocks and Temperature etc.

a. Loud Speaker – Noise Pollution. 

b. Plastic – Land Pollution.

(b) Music from radio

Correct answer is Noise.

After two weeks, the wastes in the first pot, such as banana peel, some vegetable peel and tree leaves are degraded.

The wastes in the second pot such as carry bag, sweet wrapper and metal foil are not degraded.

Because, the first pot has biodegradable wastes. So they are degraded. But the second pot has non-biodegradable wastes. So they are not degraded.

We can draw a food chain by connecting the pictures or names of organisms by putting arrows between them. These arrows should always point from food to the feeder.

In deserts, the rainfall and humidity are very low, so the sun’s rays easily penetrate the atmosphere making ground temperatures very high during the day. But the nights are often cold as the earth loses heat rapidly.

The breakdown of organic matter and their conversion into basic inorganic forms is called mineralization. 

Decomposers are the organisms (e.g., bacteria, fungi, crabs) that breakdown organic constituents (e.g., plant material) to release carbon and other nutrients such as nitrogen (N) and phosphorus (P) as inorganic form. 

When an organism dies, decomposers decay or breakdown his body chemically and extract the last bit of energy from it.

In deserts, there is little water available for plants and other organisms. Because of which desert soils are dry, and tend to have poor vegetation (plants found in a particular area). Hence lack of water/water scarcity due to low rainfall is responsible for poor vegetation in deserts (less growth of plants in the desert).

Ozone is a triatomic molecule of oxygen (O₃). It forms a protective blanket over the earth's atmosphere and its depletion causes harmful effects on human. It absorbs the UV-radiation coming from the sun.

Ozone is a gas made up of three oxygen atoms, occurs naturally in small amounts in the upper atmosphere and protects life on Earth from the Sun's ultraviolet (UV) radiations. The chemical that damage Ozone layer is Chlorofluorocarbon (CFCs).

Carbon monoxide.

1. If we introduce a man into a forest ecosystem, he can fit for any level of consumers of food chain.

2. He may feed on plant parts such as fruits. Then we can place him at primary consumer level. 

Plant → Man 

3. He may feed on some of the herbivorous organisms such as rabbit, then we can place him at secondary consumers level. 

Plant → Rabbit → Man 

4. He may also feed on some of the carnivorous organisms such as insectivorous birds then we can place him at tertiary consumers level. 

Plant → Insect → Bird → Man 

5. This is possible to place him at any level of consumers, as he is an omnivore, who feed on both plant originated and animal originated foods.

Plants and blue-green algae.