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Solutions for Biology, Class 8, ICSE
Assertion (A): All plant eating animals are considered as primary producers.
Reason (R): Producers are the first step of the food chain which can supply food to the next trophic level.
A is false and R is true.
Explanation — All plant eating animals are considered as primary consumers. Producers supply food to the next trophic level, i.e. plant eating animals or herbivores.
Assertion (A): An ecosystem consists of two categories of components Biotic and Abiotic which are interdependent on each other.
Reason (R): Biotic components are dependent on abiotic components but never on other biotic components.
A is true and R is false.
Explanation — Biotic components are dependent on both abiotic components and on other biotic components as well.
Assertion (A): Symbiosis, parasitism and predation are the categories of interdependence between organisms, which are the ways of transferring energy.
Reason (R): The transfer of energy from one trophic level to the other always occurs through the food chain.
A is true and R is false.
Explanation — Many organisms get their energy through complex food webs, which include multiple interconnected food chains. Hence, the transfer of energy from one trophic level to the other does not always occur through the food chain, but food web.
Assertion (A): Flora and fauna of a forest are always the same throughout the world.
Reason (R): Usually, forest contains very big trees and animals. So, whatever climatic conditions are present, plants and animals remain the same.
Both A and R are false.
Explanation — Flora and fauna of a forest can never be the same throughout the world. Also, the climatic conditions significantly affect the type of plants and animals that can survive in a forest. They do not remain the same everywhere.
Assertion (A): Scavengers are considered as cleaners of the earth as they feed on dead animal and plant materials remains.
Reason (R): Scavengers consume the remains left by detritivores and decomposers.
A is true and R is false.
Explanation — Detritivores and decomposers consume the remains left behind by the scavengers.
(a) Odd term: Vulture
Category: Microorganisms
(b) Odd term: Plants
Category: Abiotic factors
(c) Odd term: Grasshopper
Category: Autotrophs
(d) Odd term: Tigers
Category: Herbivores
(e) Odd term: Tiger
Category: Parasites
Fill in the blanks :
Lichens are the good example of ............... association.
Two intermediate hosts of liver fluke are ............... and ............... .
Evergreen trees are common flora of ............... forests.
............... will always be trophic level-1 in a food chain.
............... sanctuary is found in West Bengal which is famous for rhinoceros.
Lichens are the good example of symbiotic association.
Two intermediate hosts of liver fluke are snail and fish .
Evergreen trees are common flora of tropical forests.
Plants will always be trophic level-1 in a food chain.
Jaladpara sanctuary is found in West Bengal which is famous for rhinoceros.
Differences between Flora and fauna:
| Flora | Fauna |
|---|---|
| Flora means the plants naturally occurring in a particular area. | Fauna means the animals naturally living in a particular area. |
| Flora is the naturally grown greenery of a region. | Fauna includes all types of organisms from tiny bacteria to giant animals. |
| Flora can make their own food with the help of photosynthesis. | Fauna can't make their own food, they depend on plants for their food. |
| Some examples of flora: mosses, herbs, shrubs and trees etc. | Some examples of fauna: birds, animals, fish, insects, etc. |
Differences between Primary and secondary consumers:
| Primary consumers | Secondary consumers |
|---|---|
| Primary consumers obtain their food from producers (plants). | Secondary consumers obtain energy by eating primary consumers (herbivores). |
| Example - krill eats grass. | Example - Small fish eats krill. |
Differences between Parasitism and predation:
| Parasitism | Predation |
|---|---|
| Parasitism is a relationship between two living organism of different species in which one organism called parasite obtains its food directly from another living organism called host. | Predation is an interaction between members of two species in which members of one species capture, kill and eat up members of other species. |
| Example: Tape worm or liver fluke on humans | Example: Tiger preying on deer. |
Differences between Biotic and abiotic components:
| Biotic component | Abiotic components |
|---|---|
| Living components of environment are known as biotic components. | Non-living components of the environment are known as Abiotic component. |
| Biotic components depend upon abiotic components in various ways. | Abiotic components are independent of biotic components. |
| Examples: Plants, Animals | Example: Temperature, Humidity. |
| Scavengers | Detritivores |
|---|---|
| Scavengers feed on dead animal and plant material. | Detritivores feed on detritus or decomposing plant and animal parts as well as faeces. |
| They are larger animals. | They are smaller animals. |
| Examples: Vulture, Hyena. | Examples: Earthworms, millipedes. |
| Primary Consumers | Secondary Consumers | Tertiary Consumers |
|---|---|---|
| The organisms that feed on primary producers. | The organisms that feed on primary consumers. | The animals that obtain their nutrition by eating primary consumers and secondary consumers. |
| Herbivores | Either carnivores or omnivores | Carnivores |
| Obtain energy from primary producers | Obtain energy from primary consumers | Obtain energy either from primary or secondary consumers |
| Examples — Grasshopper eating grass | Examples — Frog eating Grasshopper | Examples — Snake eating Frog. |
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.
Plants are primary producers. Every food chain starts with plants. They supply food to nearly all terrestrial organisms, including humans. They also provide oxygen on which all organisms depend for respiration. Therefore, the existence of plant life is integral to the continuity and development of most ecosystems.
House
Reason — The term "ecosystem" is derived from the Greek word "Oikos" which means a "house", a dwelling place with the inhabitants living together and interacting with each other and also with their physical environment in some definite ways.
Primary Consumer
Reason — 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.
Tropical rain forests
Reason — 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.
Lichen
Reason — Lichens provide a good example of symbiosis in which a fungus and a photosynthetic alga live in a symbiotic relationship.
Predators are the animals who chase other animals, kill them and feed on their flesh. Which of the following statements supports this given explanation?
P. They are carnivores.
Q. They belong to trophic level-2 of the food chain.
R. They are also considered as decomposers.
Only P
Reason — Predators are carnivores (flesh-eating animals). They belong tp Trophic level-3 of the food chain.
Only 1, 3 and 4
Reason — Producers, Herbivores, and Secondary consumers are components that are part of a food web.
(a) Grass → Grasshopper → Frog → Snake
(b) Grass → Deer → Tiger
(c) Wheat → Rat → Snake → Peacock
(d) Grass → Grasshopper → Lizard → Crow
(e) Maize → Goat → Man
Given below is a box containing some words/phrases. Out of these, ten can be used to make five suitable pairs. Choose and make 5 such pairs.
| Oikos, Food, Grasshopper, Troph, Tertiary consumer, Producers, House, Green plants, Evergreen trees, Gir forests, Ecosystem, Man, Lion |
|---|
(a) Producers - Green Plants, Algae
(b) Herbivores - Goat, Grasshopper
(c) Carnivores - Snakes, Lizards
(d) Predators - Lion, Tiger
(e) Parasites - Mosquito, Tapeworm
(f) Scavengers - Vultures, Crows
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.
False
Reason — Snakes are tertiary consumers.
True
True
