The cycling of elements in an ecosystem are called Biogeochemical cycles. They have two components; 1-Biotic and 2-Reservoir. On the basis of location of reservoir, Biogeochemical cycle are of three types-(A) Gaseous cycle e.g., C,H and O cycle, (B) Sedimentary cycles e.g., P and S cycles (C) Hydrological cycle (H₂O cycle).

Correct Option: B

The cycling of elements in an ecosystem are called Biogeochemical cycles. They have two components; 1-Biotic and 2-Reservoir. On the basis of location of reservoir, Biogeochemical cycle are of three types-(A) Gaseous cycle e.g., C,H and O cycle, (B) Sedimentary cycles e.g., P and S cycles (C) Hydrological cycle (H₂O cycle).

The transitional zone between two district communities is known as Ecotone. It has the features of both these communities. It often has higher number of species and organisms than both the communities. The influence of the two bordering communities on each other is known as the Edge Effect. Meeting points of two water bodies like Estuaries and Lagoons are examples of Ecotone.

Correct Option: D

The transitional zone between two district communities is known as Ecotone. It has the features of both these communities. It often has higher number of species and organisms than both the communities. The influence of the two bordering communities on each other is known as the Edge Effect. Meeting points of two water bodies like Estuaries and Lagoons are examples of Ecotone.

Ocean is the most stable ecosystem as it is highly productive.

Correct Option: C

Ocean is the most stable ecosystem as it is highly productive.

The greenhouse effect is mostly caused by carbon dioxide in the atmosphere. As the biggest contributor, carbon di oxide causes about 60% of the greenhouse effect in environment, in which returning isolation of higher wavelength gets trapped by layer of greenhouse gases.

Correct Option: A

The greenhouse effect is mostly caused by carbon dioxide in the atmosphere. As the biggest contributor, carbon di oxide causes about 60% of the greenhouse effect in environment, in which returning isolation of higher wavelength gets trapped by layer of greenhouse gases.

Eucalyptus is considered to be an environmental hazard as it depletes ground water table. Eucalyptus species consume more water than others, less productive species. Growing eucalyptus in low rainfall areas may cause adverse environmental impacts due to competition for water with other species and an increased incidence of allelopathy which means killing of other plants.

Correct Option: D

Eucalyptus is considered to be an environmental hazard as it depletes ground water table. Eucalyptus species consume more water than others, less productive species. Growing eucalyptus in low rainfall areas may cause adverse environmental impacts due to competition for water with other species and an increased incidence of allelopathy which means killing of other plants.