Ecosystems

House

Reason — The term ecosystem comes from the Greek word “Oikos”, which means “house” or “home”. It refers to the natural home or environment where living organisms interact with each other and their surroundings.
Body weight is not related to the origin of the word. Food is not the meaning of “Oikos”. Size is unrelated.

Primary consumer

Reason — A rat usually feeds on plants, grains, and seeds, so it acts as a herbivore in most food chains. Rat is the primary consumer in the food chain. Rat is eaten by snake which is a secondary consumer of the food chain or ecosystem.
Producers are plants (make their own food). Primary consumers are herbivores. Secondary/Tertiary consumers are carnivores.

Tropical rain forests

Reason — Evergreen broad-leaved trees are typical of tropical rain forests. These forests grow in regions where year-round rainfall is high and steady and frost is rare. Evergreen trees have broad leaves to permit transpiration of surplus moisture.
Temperate deciduous forests are trees that shed leaves in a particular season. Coniferous forests are trees which have needle-like leaves, not broad leaves.

Five

Reason — At each level, a large amount of energy is lost as heat (only about 10% energy is transferred to the next level). After a few steps, there is not enough energy left to support another level. Therefore, food chains generally do not exceed five steps.

Lichen

Reason — A lichen is a perfect example of a symbiotic relationship (two organisms living together and benefiting each other). Algae makes food by photosynthesis. Fungi provides shelter, protection, and absorbs water.
Algae, Bacteria, Fungi are individual organisms, not necessarily living in a mutually beneficial partnership in this context.

Only P

Reason — Predators are carnivores. Predators eat other animals, so they are carnivores.
Trophic level-2 is for primary consumers (herbivores). Decomposers (like bacteria and fungi) break down dead matter. Predators hunt and kill, so they are not decomposers.

Only 1, 3 and 4

Reason — A food web is a network of interconnected food chains and includes different living components of an ecosystem. Producers form the first trophic level. Herbivores are primary consumers that feed on producers. Secondary consumers feed on herbivores. Sunlight is the primary source of energy for producers, but it is not itself a living component of a food web.

A is false but R is true.

Reason — A is false as all plant-eating animals are called herbivores, not primary producers. Primary producers are plants and algae, which make their own food.
R is true as producers are indeed the first trophic level in a food chain and provide food for all other organisms.

Therefore, A is false but R is true is the correct option.

A is true but R is false.

Reason — A is true as an ecosystem indeed has two components: biotic and abiotic. Both are interdependent, meaning they depend on and affect each other for survival and functioning.
R is false as biotic components depend not only on abiotic factors, but also on other biotic components.

Therefore, A is true but R is false is the correct option.

A is false but R is true.

Reason — A is false as symbiosis, parasitism, and predation are types of interactions (interdependence) between organisms. However, they are not all ways of energy transfer between trophic levels. Energy transfer mainly happens through feeding relationships in food chains, not all forms of symbiosis (e.g., mutualism in lichens is not simply a trophic energy transfer step in a chain).
R is true as energy transfer from one trophic level to another occurs through food chains and interconnected food chains forming a food web.

Therefore, A is false but R is true is the correct option.

Both A and R are true and R is the correct explanation of A.

Reason — A is true as the flora (plants) and fauna (animals) of forests vary in different parts of the world because environmental conditions are not the same everywhere. The climatic conditions significantly affect the type of plants and animals that can survive in a forest. R is true as different regions have different climates (temperature, rainfall, humidity, etc.), and only organisms that are adapted to those conditions can survive there.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

A is true but R is false.

Reason — A is true as scavengers are called “cleaners of the environment” because they feed on dead animals (and sometimes plant remains). Examples include vultures and hyenas.
R is false as scavengers do not consume remains left by detritivores and decomposers. Scavengers eat dead organisms directly. Detritivores (like earthworms) and decomposers (like bacteria, fungi) act on dead matter after scavengers or alongside them.

Therefore, A is true but R is false is the correct option.

1. Lichens are the good example of symbiotic association.
2. Two intermediate hosts of liver fluke are snail and fish .
3. Evergreen trees are common flora of tropical rain forests.
4. Producers will always be trophic level-1 in a food chain.
5. Jaldapara Wildlife sanctuary is found in West Bengal which is famous for rhinoceros.

1. False
   Corrected statement - Snakes are carnivores, usually secondary or tertiary consumers, not primary consumers.

2. True

3. True

(a) Grass → Grasshopper → Frog → Snake

(b) Grass → Deer → Tiger

(c) Wheat → Rat → Snake → Peacock

(d) Grass → Grasshopper → Lizard → Crow

(e) Maize → Goat → Man

(a) Vulture

Reason — Vulture is a scavenger, not a microorganism. Bacteria, fungi and protists are mostly microscopic organisms. Therefore, the category of the remaining terms is microorganisms.

(b) Plants

Reason — Plants are living organisms. Air, water and temperature are non-living physical factors needed for life. Therefore, the category of the remaining terms is abiotic components.

(c) Grasshopper

Reason — Grasshopper is an insect and a consumer that eats plants. Rice, grass and maize are green plants. Therefore, the category of the remaining terms is producers.

(d) Tiger

Reason — Tiger is a carnivore that eats other animals. Deer, rabbits and rats mostly eat plants, so they are herbivores. Therefore, the category of the remaining terms is herbivores/primary consumers.

(e) Tiger

Reason — Tiger is a predator, not a parasite. Plasmodium, liver fluke and tapeworm are parasites. Therefore, the category of the remaining terms is parasites.

Five pairs :

1. Oikos – House

“Oikos” is a Greek word meaning house or home.

2. Food – Troph

“Troph” relates to feeding or nourishment.

3. Grasshopper – Primary consumer

Grasshopper is a consumer (feeds on plants).

4. Producers – Green plants

Green plants are called producers because they make food.

5. Tertiary consumer – Lion

Lion is a top carnivore, so it is a tertiary consumer.

3 categories of organisms that feed on dead materials are :

1. Decomposers
2. Detritivores
3. Scavengers

5 abiotic components of the ecosystem are :

1. Air
2. Water
3. Soil
4. Sunlight
5. Temperature

4 kinds of the ecosystem are :

1. Forest ecosystem
2. Desert ecosystem
3. Aquatic ecosystem
4. Grassland ecosystem

3 categories of interdependence between the organisms are :

1. Predation
2. Parasitism
3. Symbiosis

3 categories of consumers are :

1. Herbivores
2. Carnivores
3. Omnivores

Two examples of producers are :

1. Green plants
2. Algae

Two examples of herbivores are :

1. Cow
2. Deer

Two examples of carnivores are :

1. Lion
2. Tiger

Two examples of predators are :

1. Lion
2. Hawk

Two examples of parasites are :

1. Tapeworm
2. Plasmodium

Two examples of scavengers are :

1. Vulture
2. Hyena

An ecosystem is a self-contained area composed of all the different organisms living in it, interacting with each other, as well as interacting with the physical conditions i.e., sunlight, air, water, soil, climatic factors, etc. prevailing in the area.

Autotrophs are organisms that produce their own food through photosynthesis using simple substances like Carbon dioxide and Water in the presence of Sunlight. They come at the beginning of the food chain.

Heterotrophs are organisms that cannot make their own food and depend on plants and other organisms for food.

Food chain is the linear sequence of organisms in which each organism eats the lower member and is itself eaten by the next higher member.

A food web is a network of interconnected food chains showing feeding relationships in an ecosystem.

The organisms that cannot make their own food but consume either plants or animals are called consumers.

Symbiosis is a relationship or interaction in which both interacting species are benefited.

Three members of flora are :

1. Evergreen trees
2. Bamboo
3. Ferns

Three members of fauna are :

1. Monkey
2. Leopard
3. Flying squirrel

Food web illustrates the complex relationships between different species and how they are interdependent on each other for survival. Food webs show the flow of energy and matter, highlighting the importance of each organism in the ecosystem. They help maintain the natural balance of habitats, which is essential for the sustainability of animal and plant life. The complex food web imparts that in case of sudden change in population of a species, the food chain will not collapse at once and the stability of ecosystem will be maintained.

The existence of plant life is integral to the continuity and development of most ecosystems because plants are the primary producers in an ecosystem. Plants convert solar energy into chemical energy, which is passed to all organisms through food chains. Plants release oxygen during photosynthesis, which is essential for respiration of all living organisms. Plants provide habitat and shelter.

(a) Two abiotic components of the Yamuna river ecosystem are :

1. Water
2. Dissolved oxygen

Two biotic components of the Yamuna river ecosystem are :

1. Fish
2. Microorganisms

(b) Two producers in this river ecosystem are :

1. Algae
2. Aquatic plants

Two consumers in this river ecosystem are :

1. Fish
2. Birds

(c) A simple food chain in this ecosystem is :

Aquatic plants → Insects → Fish → Birds

(d) Small actions to prevent pollution and protect the Yamuna River are :

1. Do not throw garbage, plastics, or chemicals into drains or rivers.
2. Reduce use of plastic and promote recycling.
3. Use water carefully and avoid wastage.
4. Participate in cleanliness drives near water bodies.
5. Create awareness among others about keeping rivers clean.