Class 12th Biology 2018 Set1 Delhi Board Paper Solution
What is a trophic level in an ecosystem? What is ‘standing crop’ with reference to it?
In an ecosystem each organism occupy a specific place in the food chain called tropic level.
Standing crop: In each tropic level their is certain mass of living material at a particular time called the standing crop. It is a measureal as the biomass of living organism present in unit area.
The role of first tropic level an ecosystem.
Producer or Plant occupies first tropic level in a food cgain. Plant capture 2-4 percent of photosynthetically active radiation and convert into chemical energy. The energy is transferred in an ecosystem in the form of food when one organism is eaten by another. Each step of food chain transfer only 10% to the next trophic level.
Popular Questions of Class 12th biology
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- Q:- Why is reproduction essential for organisms? Answer
- Q:- Write a short note on
(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals. - Q:- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
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- Q:- What is oogenesis? Give a brief account of oogenesis.
- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- Q:- Explain the Law of Dominance using a monohybrid cross.
Recently Viewed Questions of Class 12th biology
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- Q:- Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because −
(a) bacteria are resistant to the toxin
(b) toxin is immature:
(c) toxin is inactive:
(d) bacteria encloses toxin in a special sac. - Q:- Find out through internet and popular science articles whether animals other than man have self-consciousness.
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- Q:- Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
- Q:- Identify True/False statements. Correct each false statement to make it true.
(a) Androgens are produced by Sertoli cells. (True/False)
(b) Spermatozoa get nutrition from Sertoli cells. (True/False)
(c) Leydig cells are found in ovary. (True/False)
(d) Leydig cells synthesise androgens. (True/False)
(e) Oogenesis takes place in corpus luteum. (True/False)
(f) Menstrual cycle ceases during pregnancy. (True/False)
(g) Presence or absence of hymen is not a reliable indicator of virginity or sexual experience. (True/False) - Q:- Which one of the following has the largest population in a food chain?
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers - Q:- How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?