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Chapter 4

Ecosystems

Class 8 - Concise Biology Selina



Objective Type Questions

Question 1(a)

The term "ecosystem" is derived from the Greek word "Oikos" meaning.

  1. Body weight
  2. Food
  3. House
  4. Size

Answer

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.

Question 1(b)

Rat in any food chain would occupy the position of

  1. Tertiary consumer
  2. Secondary consumer
  3. Primary consumer
  4. Producer

Answer

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.

Question 1(c)

Evergreen broad-leaved trees are characteristic of

  1. Tropical rain forests
  2. Temperate deciduous forests
  3. Coniferous forests
  4. All of the above types of forests.

Answer

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.

Question 1(d)

The number of steps in a food chain can never be more than

  1. Four
  2. Five
  3. Six
  4. Seven

Answer

Six

Reason — The number of steps in different food chains may vary from 2 to 5 and very rarely these can be 6 but never 7.

Question 2

Fill in the blanks :

(a) Lichens are the good example of ............... association.

(b) Two intermediate hosts of liver fluke are ............... and ............... .

(c) Evergreen trees are common flora of ............... forests.

(d) ............... will always be trophic level-1 in a food chain.

(e) ............... sanctuary is found in West Bengal which is famous for rhinoceros.

Answer

(a) Lichens are the good example of symbiotic association.

(b) Two intermediate hosts of liver fluke are snail and fish .

(c) Evergreen trees are common flora of tropical forests.

(d) Plants will always be trophic level-1 in a food chain.

(e) Jaladpara sanctuary is found in West Bengal which is famous for rhinoceros.

Question 3

Mention if the following statements are true (T) or false (F):

(a) Snakes are primary consumers.

(b) Some humans are strictly primary consumers while others are secondary or tertiary consumers as well.

(c) No ecosystem can survive without light.

Answer

(a) False
Reason — Snakes are tertiary consumers.

(b) True

(c) True

Question 4

Match the following:

Column IColumn II.
GrassCarnivore
DeerDecomposers
CobraPrimary consumer
VultureAutotroph
MicrobesScavenger

Answer

Column IColumn II.
GrassAutotroph
DeerPrimary consumer
CobraCarnivore
VultureScavenger
MicrobesDecomposers

Question 5

Rewrite the following in their correct sequence in a food chain:

(a) Snake → Grasshopper → Grass → Frog

(b) Grass → Tiger → Deer

(c) Snake → Peacock → Rat → Wheat

(d) Lizard → Grass → Crow →Grasshopper

(e) Goat → Man → Maize

Answer

(a) Grass → Grasshopper → Frog → Snake

(b) Grass → Deer → Tiger

(c) Wheat → Rat → Snake → Peacock

(d) Grass → Grasshopper → Lizard → Crow

(e) Maize → Goat → Man

Question 6

Choose the odd one out and write the category of the remaining terms :

(a) Bacteria, Fungi, Vulture, Protists

(b) Air, Water, Plants, Temperature

(c) Rice, Grass, Grasshopper, Maize

(d) Deer, Rabbits, Tigers, Rats

(e) Plasmodium, Tiger, Liver fluke, Tapeworm

Answer

(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

Short Answer Questions

Question 1

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

Answer

  1. Oikos - House
  2. Green plants - Producers
  3. Troph - Food
  4. Tertiary consumer - Lion
  5. Gir forests - Ecosystem

Question 2(a)

Name the 3 categories of organisms that feed on dead materials

Answer

3 categories of organisms that feed on dead materials —

  1. Scavengers
  2. Detrivores
  3. Decomposers

Question 2(b)

Name the 5 abiotic components of the ecosystem

Answer

5 abiotic components of the ecosystem —

  1. Temperature
  2. Water
  3. Sunlight
  4. Atmosphere (air)
  5. Soil

Question 2(c)

Name the 4 kinds of the ecosystem

Answer

4 kinds of the ecosystem —

  1. Forest Ecosystem
  2. Desert Ecosystem
  3. Pond Ecosystem
  4. River Ecosystem

Question 2(d)

Name the 3 categories of interdependence between the organisms

Answer

3 categories of interdependence between the organisms —

  1. Symbiosis
  2. Parasitism
  3. Predation

Question 2(e)

Name the 3 categories of consumers

Answer

3 categories of consumers —

  1. Herbivores
  2. Carnivores
  3. Omnivores

Question 3

Give two examples of each :

(a) Producers

(b) Herbivores

(c) Carnivores

(d) Predators

(e) Parasites

(f) Scavengers

Answer

(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

Question 4(a)

Define Ecosystem.

Answer

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.

Question 4(b)

Define Autotrophs.

Answer

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.

Question 4(c)

Define Heterotrophs.

Answer

The organisms which cannot synthesize their own food and depend on plants and other animals for their food are known as Heterotrophs.

Question 4(d)

Define Food chain.

Answer

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.

Question 4(e)

Define Food web.

Answer

A network of various interconnected food chains which show complex feeding relationships is called food web.

Question 4(f)

Define Consumers.

Answer

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

Question 4(g)

Define Symbiosis.

Answer

Symbiosis is defined as a relationship or interaction in which both the interacting species are benefitted.

Long Answer Questions

Question 1(a)

Differentiate between Flora and fauna.

Answer

Differences between Flora and fauna:

FloraFauna
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.

Question 1(b)

Differentiate between primary and secondary consumers.

Answer

Differences between Primary and secondary consumers:

Primary consumersSecondary 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.

Question 1(c)

Differentiate between parasitism and predation

Answer

Differences between Parasitism and predation:

ParasitismPredation
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 humansExample: Tiger preying on deer.

Question 1(d)

Differentiate between biotic and abiotic components

Answer

Differences between Biotic and abiotic components:

Biotic componentAbiotic 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, AnimalsExample: Temperature, Humidity.

Question 1(e)

Differentiate between scavengers and detritivore.

Answer

ScavengersDetritivore
Scavengers feed on dead animal and plant material.Detritivore 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.

Question 2

Differentiate among primary, secondary and tertiary consumers. Give one example each in a food chain.

Answer

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.
HerbivoresEither carnivores or omnivoresCarnivores
Obtain energy from primary producersObtain energy from primary consumersObtain energy either from primary or secondary consumers
Examples — Grasshopper eating grassExamples — Frog eating GrasshopperExamples — Snake eating Frog.

Question 3

List any three members each of the flora and fauna of tropical rain forests.

Answer

Three members of flora and fauna of tropical rain forests includes —

Flora — Evergreen trees, bamboos, ferns.

Fauna — Jungle cats, Leopards, monkeys.

Question 4(a)

Give reason/explain — Food web is important to maintain an ecosystem.

Answer

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.

Question 4(b)

Give reason/explain — The existence of plant life is integral to the continuity and development of most ecosystems.

Answer

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.

Question 5

Draw the following with a suitable example :

(a) Pyramid of numbers

(b) Pyramid of biomass

Answer

(a) Diagram showing the pyramid of numbers with example is shown below:

Draw the following with a suitable example : (a) Pyramid of numbers (b) Pyramid of biomass Ecosystems, Concise Biology Solutions ICSE Class 8.

(b) Diagram showing the pyramid of biomass with example is shown below:

Draw the following with a suitable example : (a) Pyramid of numbers (b) Pyramid of biomass Ecosystems, Concise Biology Solutions ICSE Class 8.
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