Selina Concise Solutions for ICSE Class 8 Biology Chapter 4 Ecosystems

Multiple Choice Questions:

1. Put a tick mark (✓) against the correct alternative in the following statements:

Question a: The term “ecosystem” is derived from the Greek word “Oikos” meaning.
1. Body weight
2. Food
3. House
4. Size

Answer: 3. House
The word 'Oikos' literally translates to a dwelling place or a home where organisms reside. This term forms the foundation of ecology, emphasizing the study of living beings in their natural homes.

Teacher's Tip: Think of an ecosystem as the "House" of nature where everyone lives together.
Exam Tip: Always read the origin of scientific terms as they often describe the core concept of the chapter.

Question b: Rat in any food chain would occupy the position of
1. Tertiary consumer
2. Secondary consumer
3. Primary consumer
4. Producer

Answer: 3. Primary consumer
Rats are considered primary consumers because they feed directly on producers like seeds, grains, and fruits. In a food chain, the first level of animals that eat plants are always categorized as primary consumers.

Teacher's Tip: Primary means 'first,' so the first animal to eat the plant is the primary consumer.
Exam Tip: Draw a simple arrow from a plant to a rat to visualize why it is at the second level of the chain.

Question 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: 1. Tropical rain forests
These forests are found in regions with high rainfall and consistent warmth, allowing trees to keep their leaves all year. The broad leaves are an adaptation to capture maximum sunlight in the dense jungle canopy.

Teacher's Tip: 'Evergreen' means 'Always Green,' which is only possible in places with plenty of water and sun.
Exam Tip: Associate 'broad-leaved' with 'Tropical' and 'needle-like leaves' with 'Coniferous' forests.

Short Answer Type:

Question 1: Mention if the following statements are true (T) or false (F).

Question (a): Snakes are primary consumers (T/F)

Answer: (F)
No the snakes are not primary consumers as snakes eat rats and frogs as these are primary consumers which eat plant products. As snakes eat the primary consumers so the snakes are secondary consumers.
Snakes are carnivores that hunt other animals for food rather than eating plants directly. This puts them further up the food chain, usually as secondary or tertiary consumers.

Teacher's Tip: If it eats meat, it cannot be a 'Primary' consumer.
Exam Tip: If a statement is False, providing a brief reason why helps ensure full marks.

Question (b): Some humans are strictly primary consumers & some others are of other types of consumers also (T/F)

Answer: (T)
It is true that humans are vegetarians and eat plants or plant products. So these humans are vegetariBut there are certain humans which eat the flesh or eggs of other animals. These are carnivores and humans living plants are called Herbivores.
Humans are omnivores by nature, meaning we can eat both plant and animal matter. Depending on their diet, some people function as primary consumers (vegetarians) while others function as secondary consumers.

Teacher's Tip: Think of your own dinner; if you eat salad, you are a primary consumer!
Exam Tip: Use the term 'Omnivore' to explain human dietary habits in your answers.

Question (c): No ecosystem can survive without light (T/F)

Answer: (T)
The plants and animals and micro-organisms present at a place and interacting with the atmosphere like sun light, air, water, soil and warmth and dwelling at a place like, pond, desert, forest, rock form the ecosystem as pond ecosystem, desert ecosystem forest ecosystem. So ecosystem cannot survive without the presence of light. As the flora (plants) living in that ecosystem can only make food in the presence of light and the animals (Fauna) living in that ecosystem get the food from the plants of that ecosystem. So flora in that area cannot survive in that area without light and animals living in that area will not get the food and the plants and animals will perish and the ecosystem cannot survive.
Light is the primary energy source that fuels photosynthesis in plants, which are the base of every food chain. Without this energy input, there would be no food production to support any other life forms in the system.

Teacher's Tip: Light is like the 'battery' that keeps the entire ecosystem running.
Exam Tip: Mention the process of 'Photosynthesis' as the reason why light is essential for ecosystems.

Question (d): Cattle go to ponds for drinking water, so they are a constituent of pond ecosystem (T/F)

Answer: (F)
Cattles likes tigers, lions, cows, deers, buffaloes, go to take water from the pond and return to their dwellings as tigers, deers etc. come to the forest so they form a forest ecosystem. But plants like hydrilla, vallineria, lotus etc. and animals like frogs, beetles, fish live in the pond and form the pond ecosystem. But animals like buffalo which come only to take~water cannot form a part of the pond ecosystem.
An organism is a constituent of an ecosystem only if it lives, feeds, and interacts within that specific environment. Simply visiting a pond for water does not make a land animal part of the aquatic community.

Teacher's Tip: To be part of an ecosystem, you must 'belong' there, not just 'visit' there.
Exam Tip: Distinguish between 'abiotic' interactions (like drinking water) and 'biotic' roles when defining ecosystem membership.

Question 2: Match the items in Column I with as many items as possible in Column II.
Column I:
1. Deer
2. Frog
3. Cobra
4. Pine tree
5. Grasshopper
Column II:
(i) Autotroph
(ii) Mangroves
(iii) Pond
(iv) Deciduous forests
(v) Parasite
(vi) Omnivore
(vii) Herbivore
(viii) Carnivore

Answer:
1. Deer - (vii) Herbivore
2. Frog - (iii) Pond
3. Cobra - (viii) Carnivore
4. Pine tree - (i) Autotroph, (iv) Deciduous forests, Producer
5. Grasshopper - (vii) Herbivore
Matching helps us identify the specific roles and habitats of different organisms within their environments. It shows how every living thing fits into a biological category based on its needs and behaviors.

Teacher's Tip: Start with the easiest matches, like 'Pine tree' being a 'Producer/Autotroph.'
Exam Tip: In matching questions, double-check if one item from Column I can match with multiple items in Column II.

Question 3: 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

Answer:
(a) Grass → Grasshopper → Frog → Snake
(b) Grass → Deer → Tiger
(c) Wheat → Rat → Snake → Peacock
A food chain represents the transfer of energy from one organism to another, always starting with a producer. The direction of the arrow indicates 'is eaten by,' showing the flow of energy upward through trophic levels.

Teacher's Tip: Always put the green plant at the very beginning of your chain.
Exam Tip: Ensure your arrows are pointing in the right direction (from food to feeder).

Long Answer Type:

Question 1: Differentiate among primary, secondary and tertiary consumers. Give one example of each in a food chain.

Answer:
All plants produce food through photosynthesis and are categorised as self food producers i.e. these are autotrophs. There are plant eating animals called herbivores as Rabbits, deers, pigeons, cows, buffaloes etc. and insects like grasshoppers, bees, butterflies and crickets also eat plants or plant products as fruits, flowers, pollen grains and plant juices. Such animals are called primary consumers.
Animals like tigers, lions, wolves, lizards, frogs eat the primary consumers. Birds vultures, kites, eagles eat the primary consumer, (i.e. These birds are well eat the flesh of many birds like pigeons, sparrows.) These animals or birds are called secondary consumers.
Animals like snakes are eaten by the peacocks, they eat the secondary consumers and are called tertiary consumers.
Owls, eagle are top carnivore. So it is quaternary consumer.
Consumers are classified based on what they eat and where they sit in the energy pyramid. This hierarchy ensures that energy is distributed from the sun through plants to all levels of animal life.

Teacher's Tip: Remember: 1st eats plants, 2nd eats 1st, 3rd eats 2nd.
Exam Tip: Providing a clear, labeled example for each category will help you get maximum marks.

Question 2: Define the term (a) flora and (b) fauna.

Answer:
Flora: Plants occurring in a particular is called flora of that area i.e. vegetative growth forms flora. Flora deals with plants. Fauna: The animals occurring in a area form the fauna of that area.
Fauna deals with animals.
Flora and fauna of an area is the plants and animals found in that area.
Flora refers to the entire plant life of a specific region or time, while fauna refers to the animal life. Together, they represent the total biodiversity of a particular ecosystem.

Teacher's Tip: Flora sounds like 'Flower' (plants), and Fauna sounds like 'Fawn' (baby deer/animals).
Exam Tip: Use these terms when describing any specific habitat to show a good scientific vocabulary.

Question 3: List any three members each of the flora and fauna of tropical rain forests.

Answer:
Tropical rain forest are on western coast of India and in the north, east.
Flora: bamboos, ferns, shrubs (Evergreen trees).
Fauna: leopards, jungle cats, monkeys, snakes, flying squirrels, insects, snails, centipedes, millipedes.
Tropical rain forests are incredibly diverse ecosystems that provide home to thousands of unique species. They are characterized by high humidity and thick vegetation that supports a vast variety of wildlife.

Teacher's Tip: Think of a very thick, wet jungle to remember these plants and animals.
Exam Tip: Mentioning the geographical location (like Western Ghats) adds extra value to your answer.

Question 4: Define the following terms and give two examples in each case.
(a) Symbiosis
(b) Parasitism
(c) Predation

Answer:
(a) Symbiosis: It refers to relationships between organisms of different species that show on intimate association with each other. Symbiotic relationships provide atleast one of the participating species with a nutritional advantage. Examples of Symbiosis Relationships are of Fungus and photosynthestic alga and Microbes and cattle.
(b) Parasitism: Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Examples of Parasitism are 4 tapeworms, flukes, the plasmodium species and mosquitoes.
(c) Predation: A predator is any consumer that kills and eats another living organism in order to obtain energy. The organism being eaten is called the prey. Examples are Lions, Deer, Wolves, Eagles.
These biological interactions define how species cooperate or compete for survival within an ecosystem. They maintain the balance of nature by controlling population sizes and ensuring resource sharing.

Teacher's Tip: Symbiosis is often 'Help-Help', Parasitism is 'Benefit-Harm', and Predation is 'Eat-Eaten'.
Exam Tip: Always underline the 'Benefit' and 'Harm' aspects to clearly define these terms.