Question

(A) Plants → Deer → Lion
In the given food chain, what will be the impact of removing all the organisms of second trophic level on the first and third trophic level?
Will the impact be the same for the organisms of the third trophic level in the above food chain if they were present in a food web? Justify.
OR
(B) A gas ‘X’ which is a deadly poison is found at the higher levels of atmosphere and performs an essential function.
Name the gas and write the function performed by this gas in the atmosphere. Which chemical is linked to the decrease in the level of this gas? What measures have been taken by an international organization to check the depletion of the layer containing this gas?

Answer 1

Part (A):
Plants → Deer → Lion
In the given food chain, removing all the organisms of the second trophic level (Deer) will have a significant impact on the first and third trophic levels.

Impact on the First Trophic Level (Plants):
The plants (producers) would be impacted indirectly. The removal of herbivores (Deer) would mean that there would be fewer organisms feeding on the plants, leading to an overgrowth of plant populations. However, this could cause an imbalance in the ecosystem, affecting plant species diversity and overall ecosystem health.

Impact on the Third Trophic Level (Lion):
The removal of deer (secondary consumers) would directly affect the lions (tertiary consumers) because the lions rely on deer for food. Without their primary prey, lions would face starvation, which could result in a decrease in their population or force them to shift their diet to other species, possibly causing further ecological disruption.

Impact in a Food Web:
If the organisms of the third trophic level (Lions) were present in a food web, the impact would not be the same. In a food web, organisms have multiple sources of food, and the lions may have alternative prey species that could fill the gap left by the disappearance of deer. This redundancy in feeding relationships in a food web makes ecosystems more resilient to the loss of one species, unlike in a simple food chain where organisms are more reliant on specific trophic levels.

Part (B):
The gas 'X' referred to in the question is Ozone (O₃).
Function of Ozone:
Ozone performs an essential function by absorbing most of the Sun’s harmful ultraviolet (UV) radiation, protecting living organisms on Earth from these harmful rays.

Chemical Linked to the Decrease of Ozone:
Chlorofluorocarbons (CFCs) are the chemicals linked to the depletion of the ozone layer. These compounds break down ozone molecules in the stratosphere, leading to thinning of the ozone layer.

Measures Taken by International Organizations:
The Montreal Protocol, adopted in 1987, is the international treaty aimed at phasing out the production and use of substances, including CFCs, that deplete the ozone layer. This protocol has led to a significant reduction in the use of ozone-depleting chemicals worldwide.