26 Questions with Answers and Explanations on “Organism and Populations” for Biology Students:
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Q. 1. Give two examples to biomes.
Ans. (1) Desert
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(2) Rain forest
Q. 2. How are the major biomes on earth formed?
Ans. The major biomes are formed due to annual variation in the precipitation in a region.
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Q. 3. How are varieties of habitats formed in a biome?
Ans. The variations at regional and local levels within a biome leads to the formation of habitats.
Q. 4. How does the temperature affect the organisms?
Ans. Temperature affects the enzymes kinetics and through this it affects the basal metabolism of the individual.
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Q.5. If a marine fish is placed in a fresh water aquarium, will the fish be able to survive? Why or why not?
Ans. It will not able to survive because of low salinity of water. It will lead to osmotic problems and keep intaking water inside its body cells.
Q.6. Define phenotypic adaptation. Give one example.
Ans. The adaptation shown by organism that is restricted to its body only is phenotypic adaptation. It is temporary in nature e.g. escaping temperature rises by avoiding it and going to shade.
Q.7. Most living organisms can not survive at temperature above 45°C. How are some microbes able to live in habitats with temperature exceeding 100°C?
Ans. The microbes living in hydrothermal vents (100°C) have adapted themselves metabolically.
Q.8. List the attributes that populations but not individuals possess.
Ans. Population attributes are—
(1) Per capita birth and death rates.
(2) Sex ratio.
Q. 9. Mention the various growth status of the human population as shown by age pyramids.
Ans. (1) Expanding,
(2) Stable,
(3) Declining.
Q. 10. Define Darwin fitness (high r value).
Ans. When the populations evolve to maximise their reproductive fitness in the habitat in which they live is called Darwin fitness (high r value).
Q. 11. Mention the two values needed to calculate the population size/density at a given time.
Ans. Per capita births, per capita deaths.
Q. 12. If the population density (W) is at time t, then its density at, time t +1 will represented by which equation?
Ans. Nt+1=N,+ [(B + 1)-(D + E)]
Q. 13. Mention the equation for representing exponential growth at a given unit time period.
Ans. rN =dN/ dt
Q. 15. When the responses are limiting the growth, the growth is represented by which equation? Mention it.
Ans. dN/ dt= rN K N/ K
Q. 15. When do we get growth curves— J and S shaped, when plotted against population density and unit time?
Ans. J-shaped growth curve is obtained when the responses are not limiting growth. S-shaped growth curve is obtained when the responses are limiting.
Q. 16. Mention when the growth plot is exponential and logistic?
Ans. The growth plot is exponential when responses are not limiting growth and it is logistic when responses are limiting the growth.
Q. 17. Name important defence mechanisms in plants against herbivores?
Ans. (1) Thorns,
(2) Storage of highly poisonous chemicals.
Q. 18. Define competition.
When the fitness of one species (in terms or V the intrensic rate of increase) is significantly lower in the presence of another species is called competition.
Q. 19. What is brood parasitism?
The laying of eggs by a parasitic bird in the nest of its host and lets it to incubate is called brood parasitism.
Q. 10. Define Co-evolution.
Ans. The changes that help one species to evolve against the other is equally balanced by the other species that depends on the first by changes in itself is called co-evolution, i.e. both evolve simultaneously.
Q. 21. How are pollinators rewarded by plants/flowers?
Ans. Pollinators get nector or other kind of food in reward of the act of pollination.
Q. 22. Which type of association is—
Sea anemone with down fish. Ans. Commensalism.
Q. 23. Mention the association type shown by pollinators and plants.
Ans. Mutualism.
Q. 24. What is the ecological principle behind the biological control method of managing the pest insects?
Ans. Predation.
Q. 25. List the various abiotic environmental factors.
Ans. Temperature, Water, Soil, Light. .
Q. 26. Select the statement which explains best parasitism.
(a) One organism is benefited.
(b) Both organisms are benefited.
(c) One organism is benefited, other is not affected.
(d)One organism is benefited , other is affected.
Ans. (d) One organism is benefited, other is affected.