ECOLOGY MCQ QUESTIONS

1) In many aquatic bio-systems, the biomass pyramid is 

A) Non-existent 

B) Upright 

C) Inverted 

D) Ever changing in shape

Solution : 

• In many aquatic ecosystems, the biomass pyramid is inverted due to the high turnover rate of primary producers. 

• Phytoplankton, the primary producers in aquatic ecosystems, reproduce rapidly and have a short lifespan, creating a small biomass. 

• Zooplankton and other primary consumers can have a larger biomass than the phytoplankton they consume, resulting in an inverted pyramid. 

• This inversion is typical in aquatic environments where the energy flow is high but the standing biomass of primary producers is low. 

2) The biomass in the upper trophic levels is generally ______ as compared to the lower trophic levels. 

A)Very high 

B) Very low 

C) Similar 

D) Sequenced

Solution :

• The biomass in higher trophic levels (e.g., carnivores) is less than in lower trophic levels (e.g., plants). 

• This phenomenon is due to energy loss at each trophic level as energy is transferred. 

• Only about 10% of the energy is transferred from one trophic level to the next; the rest is lost primarily through metabolic processes. 

• The pyramid of biomass typically shows a decreasing trend from primary producers to apex predators. 

• This decrease in biomass is a direct result of the second law of thermodynamics which states that energy transformations are not 100% efficient.

Trophic Levels: 

• Each step in a food chain or food web is called a trophic level. 

• Primary producers (e.g., plants) occupy the first trophic level.

• Herbivores, which eat plants, occupy the second trophic level. 

• Carnivores that eat herbivores occupy the third trophic level, and so on. 

Energy Transfer Efficiency: Energy transfer between trophic levels is typically around 10%, known as the 10% law. 90% of the energy is lost to the environment as heat, movement, or undigested food. Pyramid of Biomass: It is a graphical representation showing the relative biomass at each trophic level. The pyramid typically narrows at higher trophic levels. The biomass of primary producers is the highest, followed by primary consumers, secondary consumers, and so forth. Second Law of Thermodynamics: This law states that energy transformations are not 100% efficient. In an ecosystem, this inefficiency is observed as energy is lost as heat at each trophic level transfer.