2nd Year NotesBiology class 12th

2nd Year Biology Chapter 25 Ecosystem

2nd Year Biology Chapter 24 Ecosystem Question and Answer

Short and Simple Question And Answer

Q 1. What are the biochemical cycles?

Ans. Biochemical cycles are natural processes where chemicals circulate between the environment and living organisms.

Q 2. Define grazing?

Ans. Grazing is when animals like rabbits, cows, and horses feed on grasses in their environment.

Q 3. What percentage of sun energy reaches plants?

Ans. Only 1% of sun energy reaches plants for photosynthesis.

Q 4. What is autecology?

Ans. Autecology is the study of the relationship between a single population and its environment.

Q 5. Define synecology?

Ans. Synecology, or community ecology, studies the relationships between different communities and their environments.

Q 6. Differentiate between food chain and food web?

Ans. A food chain is a linear sequence of eating and being eaten, while a food web is a complex interaction of multiple food chains.

Q 7. Differentiate between pioneer and climax community?

Ans. Pioneer communities are the first in ecological succession, while climax communities are diverse and stable at the end of succession.

Q 8. What is a seral community?

Ans. Each stage in ecological succession is called a seral community, with pioneers at the beginning and climax communities at the end.

Q 9. Differentiate between primary and secondary succession?

Ans. Primary succession occurs on bare land with no previous community, while secondary succession happens in areas where a previous community was disturbed.

Q 10. How are predators related to their prey?

Ans. Predators and prey populations are interrelated; as prey numbers increase, more predators can be supported, leading to a balance in the ecosystem.

Q 11. How is nitrogen lost to the atmosphere?

Ans. Nitrogen is lost to the atmosphere through denitrification, a process where denitrifying bacteria convert nitrates into gaseous nitrogen in the absence of oxygen.

Q 12. Differentiate between gross primary production and net primary production?

Ans. Gross primary production is the total energy fixed by plants into food, while net primary production is the energy left after meeting plant respiratory needs, available for higher trophic levels.

Q 13. Which type of food chain better supports a community and why?

Ans. Short food chains with 2-3 trophic levels support communities more efficiently than long food chains because less energy is lost, ensuring more individuals in higher trophic levels.

Q 14. Why is assimilation called the reverse of nitrification?

Ans. Assimilation converts nitrites and nitrates back into ammonium ions, essentially reversing the process of nitrification.

Q 15. Define ecology?

Ans. Ecology is the study of the relationship between living organisms and their environments.

Q 16. Define ecosystem and eco-components?

Ans. An ecosystem is where organisms interact with their environment, comprising living (biotic) and non-living (abiotic) components.

Q 17. What is a community?

Ans. A community consists of populations of different species interconnected within an ecosystem.

Q 18. What is a biome, and how many types exist?

Ans. A biome is a major type of ecosystem primarily determined by climate. There are several terrestrial biomes like forests, grasslands, and deserts.

Q 19. What is an ecological niche?

Ans. An ecological niche is the role a species plays in a community, including behavior and influence.

Q 20. Differentiate between autecology and gynecology?

Ans. Autecology studies a single population’s relationship to its environment, while synecology studies different populations or communities.

Q 21. Define succession?

Ans. Succession is the gradual change in the community structure of an ecosystem over time, starting with pioneer species and culminating in a stable climax community.

Q 22. Name subdivisions of biotic and abiotic components?

Ans. Biotic Components:

  • Producers
  • Consumers
  • Decomposers Abiotic Components:
  • Atmosphere
  • Hydrosphere
  • Lithosphere

Q 23. What is a trophic level?

Ans. Each feeding level in a food chain is referred to as a trophic level.

Q 24. Explain the association of organisms in lichen and mycorrhizal?

Ans. Lichen: Lichen is a mutualistic partnership between algae living within a fungus. Mycorrhiza: Mycorrhiza is a symbiotic relationship between plant roots and specific fungi, where the fungus aids in nutrient absorption.

Q 25. What is the nitrogen cycle?

Ans. The nitrogen cycle is the circulation and recycling of nitrogen between living organisms and the environment.

Q 26. What is infestation?

Ans. Infestation refers to diseases in living organisms caused by parasites.

Q 27. What is symbiosis? Discuss its types?

Ans. Symbiosis is a close association between two different species that benefits at least one of them. It can be mutualism (both benefit) or commensalism (one benefits while the other is unaffected).

Q 28. Define biogenic elements. Ans. Biogenic elements are chemical elements necessary for life in living organisms, such as carbon, hydrogen, and oxygen.

Q 29. What are the advantages and disadvantages of grazing?

Ans. Grazing has advantages, as moderate grazing can help maintain grassland ecosystems by reducing competition. However, overgrazing can lead to grasslands turning into deserts, which is a disadvantage.

Q 30. What are the functions of Nitrosomonas and Nitrobacter?

Ans. Nitrosomonas convert ammonia and ammonium ions into nitrites, while Nitrobacter convert nitrites into nitrates.

Q 31. Define denitrification?

Ans. Denitrification is a process where, in the absence of oxygen, bacteria break down nitrates and release nitrogen back into the atmosphere while using oxygen for their own respiration.

Q 32. Define habitat?

Ans. A habitat is the specific location where an organism lives.

Q 33. Differentiate between hydrosere and xerosere?

Ans. Hydrosere is primary succession that occurs in a water-based environment like a pond, while xerosere is primary succession on dry soil or rock.

Q 34. How do grazers affect soil texture?

Ans. Grazing animals, while resilient, can compact soil with their hooves, making it hard and impervious to rainwater. Overgrazing can lead to soil erosion and barren land.

Q 35. Write the significance of root nodules in plants?

Ans. Root nodules are significant because they house symbiotic bacteria in legume plants, which fix nitrogen from the air, convert it into amino acids for the host plant, and receive food and protection in return.

Q 36. What is the nitrogen cycle?

Ans. The nitrogen cycle is the process by which a limited amount of nitrogen is circulated and recycled among living organisms and the environment.

Q 37. How many basic interaction components of an ecosystem are there?

Ans. An ecosystem consists of two basic interacting components: living (biotic) and non-living (abiotic) factors.

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