Which of the following limits the number of trophic levels in a food chain?
Decrease in energy at higher trophic levels
Deficient food supply
Polluted air
Water
(1)
A considerable amount of energy is used to keep organisms alive at each trophic level. As an organism progresses through the trophic levels, it receives less and less energy. The number of trophic levels is restricted to 3–4 since the energy available for the next level is insufficient to keep the organisms alive after that.
Hydrogen is labelled ‘brown’ if the manufacturing process releases both carbon dioxide and carbon monoxide to the air.
In what way is the manufacturing process of brown hydrogen WORSE than that of grey hydrogen for the environment?
It releases into the atmosphere a gas that directly causes a greenhouse effect.
It releases into the atmosphere carbon which was stored for millions of years.
It releases into the atmosphere a gas that is toxic to human beings.
It releases into the atmosphere gases that cause acid rain.
(1)
Brown hydrogen is produced by gasification, where carbonous materials are heated into a gas. This extraction process involves turning coal into gas and produces large quantities of carbon emissions that are released into the atmosphere leading to the formation of greenhouse gases responsible for ozone depletion.
If a grasshopper is eaten by a frog, then the energy transfer will be from:
producer to decomposer
producer to primary consumer
primary consumer to secondary consumer
secondary consumer to primary consumer
(3)
If a frog eats a grasshopper, energy is transferred from primary consumer to secondary consumer in a food chain. Grasshoppers eat producers, such as grass and plants. So, it is classified as a primary consumer. As a result, frogs, which eat grasshoppers, become the secondary consumer.
Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the:
food web
ecological pyramid
ecosystem
food chain
(1)
A food web is a network of interrelated food chains. In a food chain, a creature can occupy more than one trophic level. It eats a variety of organisms of lower trophic level and may be devoured by organisms of higher trophic level.
In the given food chain, suppose the amount of energy at fourth trophic level is 5 kJ, what will be the energy available at the producer level?
5 kJ
50 kJ
500 kJ
5000 kJ
(4)
According to the 10 per cent law, only 10% of the energy available in a trophic level is passed on to the next trophic level. As a result, if the energy available at the fourth trophic level is 5 kJ, then the energy available at the producer level is 5000 kJ:
At which trophic level is maximum energy available in the figure given below for the various trophic levels in a food chain?
(3)
All ecosystems are characterised by a unidirectional flow of energy. At each trophic level, most of the energy available is utilised for respiration and excretion and only ten percent of the available energy is passed on to the next level because only ten percent of the available energy can be passed on to the next trophic level. Higher trophic levels have substantially less energy content and the number of trophic levels in a food chain is limited. The lower the trophic level, the higher will be energy content. Hence, the greatest amount of energy is expected to be in trophic level .
In the food web, which two organisms are competing for food?
A and B
A and C
D and F
B and D
(4)
When members of various species compete for the same resource in an environment, competition develops. Here, B and D are competing for the same resources or food in this food web.
In an area, the frog population decreased due to the spread of some diseases. Frogs are prey for snakes, but no major effect was seen in the population of snakes. Instead, there was a decline in the pesticide sale. What could be the possible reason?
Frogs stopped eating grains due to their infection.
There is no relation between the decrease in frog population and pesticide sales.
Both frog and snake migrated to some other area
Snakes now depended on other organisms that must be the pests for the crops grown.
(4)
Given scenario is an example of a food web. Infection in frogs could have possibly made snakes shift towards another prey such as rats. Rats destroy the stocked grains. When snakes started eating rats, the sale of pesticides against rats decreased.
Supriya listed some important points for energy transfer in a food chain. She made an error. Point out that error.
(i) Primary consumers transfer 10% of energy to the next trophic level in the food chain.
(ii) The population at a lower trophic level is greater than the population at a higher trophic level.
(iii) Producers depend entirely on sunlight to make food.
(iv) Decomposers work at a double pace to convert complex molecules into simpler forms in case of an epidemic.
Only (ii)
Only (iv)
(i) and (iii)
All of these
(2)
The populations at a lower trophic are greater in number than the populations at higher trophic level to fulfil the energy demand of the latter. The population of decomposers might vary but not the pace.
Which of the statements given below is correct?
Omnivores are in the middle of the food chain.
Omnivores are either in the middle or at the top of the food chain.
Omnivores are at the top of the food chain.
Omnivores are capable of modifying the natural food chain.
(2)
Omnivores can consume plants (producers) as well as animals (consumers). They can be at the middle just after plants or at the top of the food chain.
