NCERT Solution for Class 10 Science Chapter 15
Our Environment
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Intext Questions
Page No-260
Questions No-1
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
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The various links or steps in a food chain at which the transfer of food and energy takes place are called trophic levels.
The producers form the first trophic level as they manufacture food. The primary consumers form the second trophic level, the secondary consumers form the third, and the tertiary consumers form the fourth trophic level.
Grass is the producer which is eaten by the grasshopper known as primary consumer. Then the grasshopper is eaten by shrew, secondary consumer and lastly shrew eaten up by owl, tertiary consumer.
The various steps in a food chain at which the transfer of food/energy takes place are called trophic levels.In a food chain, each step representing an organism forms a trophic level.
For example,
Grass–> Grasshopper–> Frog–> Snake
In the above food chain Grasshopper eats grass, frog eats the grasshopper and snake eats the frog. Thus, Plants are the producers, and represents the first trophic level. Grasshoppers are the primary consumers, and represent the second trophic level. Frogs are the secondary consumers, and represent the third trophic level. Snakes are the tertiary consumers and represent the fourth trophic level.
The trophic level is the step or level included in a food chain. It denotes the number of steps the organism is from the start of the chain. An organism may not always occupy the same trophic level it can differ accordingly based on the food chain.
For example,
Grass–> Grasshopper–> Frog–> Snake
Plants are the producers, and represents the first trophic level. Grasshoppers are the primary consumers, and represent the second trophic level. Frogs are the secondary consumers, and represent the third trophic level. Snakes are the tertiary consumers and represent the fourth trophic level.
Trophic Levels : The various steps in a food chain at which the transfer of food
(or energy) takes place are called trophic levels. Example A food chain operating in a
grassland is given below :
Grass -> Insects -> Frog-> Birds
In this food chain
1. Grass represents first trophic level.
2 Grasshopper represents second trophic level.
3. Frog represents third trophic level.
4 Eagle represents fourth tropic level.
Those organisms which join the food chain are termed as trophic levels
There are four trophic levels:
(i) First trophic level – Producers (Plants)
(ii) Second trophic level – Primary consumers.
(iii) Third trophic level – Secondary consumers.
(iv) Fourth trophic level – Top consumers.
Plants–> Rabbit–> Wolf–> Tiger
In the above food chain plants are producers and represents the first trophic level.
Rabbit is the primary consumer i.e. herbivorous animal and represent the second Trophic level.
Wolf is the secondary consumer and represents the third trophic level.
Tiger is the top consumer and represents the fourth trophic level.
Trophic levels represent the hierarchical levels in an ecosystem through which energy and nutrients flow. They categorize organisms based on their position in a food chain and their primary source of nutrition. There are typically three main trophic levels:
1. Producers (Autotrophs): Organisms at the first trophic level, also known as producers, are capable of photosynthesis or chemosynthesis. They convert sunlight or inorganic compounds into energy-rich organic molecules. Examples include plants, algae, and certain bacteria.
2. Consumers (Heterotrophs): Organisms at higher trophic levels are consumers that obtain their energy by consuming other organisms. There are several levels of consumers:
a. Primary Consumers (Herbivores): These organisms feed directly on producers. Examples include herbivores like rabbits, deer, or grasshoppers.
b. Secondary Consumers (Carnivores): These organisms feed on primary consumers. Examples include carnivores like foxes, snakes, or birds of prey.
c. Tertiary Consumers (Top Predators): These are predators at the highest trophic level that feed on both primary and secondary consumers. Examples include top predators like lions, eagles, or killer whales.
3. Decomposers (Detritivores): Organisms at the final trophic level break down and decompose the remains of dead plants and animals, returning nutrients to the soil or water. Examples include fungi and bacteria.