Answer is Option B. -> 1, 2 and 3
: B

Explanation:

An alien species is a species introduced outside its natural past or present distribution; if this species becomes problematic, it is termed an invasive alien species (IAS).

Option 1, 2 and 3 are correct:
When alien species are accidentally or purposely introduced for whatever reason, some of them become invasive, causing the decline or extinction of indigenous species. The Nile perch introduced into Lake Victoria in eastern Africa eventually contributed to the extinction of an ecologically specific assembly of more than 200 species of cichlid fish in the lake. Carrot grass(Parthenium), Lantana and water hyacinth (Eicchornia) are some other invasive species.

Answer is Option A. -> 1 only
: A

Explanation:

Statement 1 is correct: Anaerobiosis inhibits the process of decomposition. It occurs when the rate of absorption of oxygen by microorganisms is greater than the rate of diffusion of oxygen by either air or water. Warm and humid conditions promote decomposition, while low temperature and anaerobiosis prevent decomposition resulting in organic materials being built up.

Statement 2 is incorrect: Decomposition is in large part a mechanism that involves oxygen. The rate of decomposition is regulated by the detritus chemical composition and climatic factors. The rate of decomposition in a particular climatic condition is slower if detritus is rich in lignin and chitin and faster if detritus is rich in nitrogen and water-soluble substances such as sugars.

Answer is Option A. -> 1 and 2 only
: A

Explanation:

Statement 1 is correct: Stenothermal animals are those who can tolerate a narrow range of temperature levels. Stenothermal animals include a penguin, python, crocodile, etc.

Statement 2 is correct: Eurythermal animals are able to tolerate a wide range of temperature levels. Eurythermal animals include cat, dog, man, goat, tiger, etc.

Statement 3 is incorrect: Tigers can tolerate a wide range of temperatures thus they fall under Eurythermal organisms category.

Answer is Option B. -> 1 and 3 only
: B

Explanation:

Global warming is the phenomenon of gradual increase in temperature near the Earth’s surface. Due to anthropogenic causes the rate of warming has increased.

Statement 1 is incorrect: The Cryosphere is the portion of the surface of the earth, where water is found in solid form which includes Antarctica and Greenland. Some of the main impacts of global warming would be the increase in sea and ocean levels due to cryosphere melting. The melting of glaciers and polar ice caps would lead to the worldwide increase in water levels.

Statement 2 is correct: Albedo is the portion of solar energy reflected from the surface of the Earth back into space. Snow and ice have high albedo. They reflect much of the insolation, which helps in cooling of the earth. Thus, the presence or absence of snow and ice affects the heating and cooling of Earth’s surface which influences the entire planet’s energy balance.

Statement 3 is incorrect: The greenhouse gases such as ozone, methane, carbon dioxide, water vapor, and chlorofluorocarbons absorb heat thus limiting the heat to escape our atmosphere. These gases add to the heating of the atmosphere and result in global warming. Thus It is the other way round, Greenhouse effect aggravated global warming.

Answer is Option A. -> 2 only
: A

Explanation:

Statement 1 is correct: Conformers are also known as ectotherms as they cannot regulate their own internal temperature. It adapts its behaviour to the surroundings or migrates to environments with optimal temperatures.

Statement 2 is incorrect: Conformers are referred to as cold-blooded animals as they cannot regulate their own internal temperature. Warm-blooded animals can regulate their own internal temperature.

Statement 3 is correct: Examples of this class – amphibians, reptiles, insects etc. Lizards and fishes come under the Class of Conformers.