Answer: A

Explanation:

The natural habitat of a plant or an animal is the area in which an organism or a population of organisms is adapted to live and develop. Natural habitat is characterized by the biotic and abiotic factors of the area such as climate, vegetation, soil, water, etc. Many species may have natural habitats in one area. Hence, statement 1 is correct.

In this niche, many species live in the same natural habitat without competing with each other and without destroying each other. Predator-prey relationships occur in natural habitats but rarely lead to the complete extinction of a species. Hence, statement 2 is incorrect.

In a stable ecosystem each species finds its own ecological niche and thus acquires the ability to co-exist with other species. The ecological niche of an organism includes all the physical, chemical and biological conditions necessary for it to survive in its natural habitat. The niche also includes the organism's feeding habits, nesting methods and regeneration, etc. Hence, statement 3 is incorrect.

Answer: A

Explanation:

According to the Indian Institute of Marine Science, there are four major coral reef areas in India – Andaman and Nicobar Islands, Lakshadweep, Gulf of Mannar and Gulf of Kutch. Hence, option (a) is the correct answer.

Answer: A

Explanation:

Carbon is essential for cells. Most of the carbon on Earth is stored in rocks. The remaining carbon is stored in the oceans, atmosphere, plants, soil and fossil fuels. Hence, statement 1 is correct.

During photosynthesis, producers take in CO2 and release oxygen into the atmosphere. In the process of respiration, humans and animals take in oxygen and release CO₂ which goes back to the plant. Decomposers break down organic matter and in this process CO₂ is released into the atmosphere. When a volcano erupts or there is a forest fire, more CO₂ enters the atmosphere. Hence, statement 2 is incorrect.

Answer: A

Explanation:

Cells need nitrogen to make their proteins and genes. Most of the nitrogen on Earth is present in the atmosphere as gas. Organisms need nitrogen but cannot absorb it directly. Hence statement 1 is not correct.

The complex nitrogen cycle converts nitrogen into ammonia which can be absorbed by organisms. This process is called nitrogen fixation which is carried out by bacteria. These bacteria are found in the roots of leguminous plants; like they live in beans etc. Hence statement 2 is correct.

Answer: A

Explanation:

Ecosystem diversity refers to the variety of ecosystems found in a region or landscape. India as a whole has immense ecological diversity. Yet if we consider only the Thar Desert region you will find very little ecological diversity. There are three spatial scales for measuring biodiversity – alpha, beta and gamma diversity.

Alpha diversity refers to the diversity within a particular region or ecosystem and is usually expressed by the number of species in that ecosystem. Hence, pair 1 is not correctly matched.

Beta diversity compares diversity across ecosystems. It counts the total number of unique species found in the compared ecosystems. Hence, pair 2 is not correctly matched.

Gamma diversity is a measure of overall diversity for different ecosystems within a region. It counts the total number of unique species found in the entire region. Hence, pair 3 is correctly matched.