Biology,  Ecology,  Q & A

Q & A ON ORGANISM AND POPULATIONS

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Q. 1. Give two examples to biomes.

Ans. (1) Desert

(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.

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 kinetics of the enzymes and through this, it affects the basal metabolism of the individual.

Q.5. If a marine fish is placed in a freshwater aquarium, will the fish be able to survive? Why or why not?

Ans. It will not able to survive because of the 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 a phenotypic adaptation. It is temporary in nature e.g. escaping temperature rises by avoiding it and going to shade.

Q.7. Most living organisms cannot survive at a temperature above 45°C. How are some microbes able to live in habitats with a 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 represent 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. 16. 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. 17. 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. 18. Name important defence mechanisms in plants against herbivores?

Ans. (1) Thorns,

(2) Storage of highly poisonous chemicals.

Q. 19. Define competition.

Ans. When the fitness of one species (in terms or V the intrinsic rate of increase) is significantly lower in the presence of another species is called competition.

Q. 20. What is brood parasitism?

Ans. The laying of eggs by a parasitic bird in the nest of its host and lets it incubate is called brood parasitism.

Q. 21. 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. 22. How are pollinators rewarded by plants/flowers?

Ans. Pollinators get nectar or other kinds of food in reward of the act of pollination.

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 the 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.

Q. 27. Define the terms—eurythermal, stenothermal.

Ans. Organisms that can tolerate a wide range of temperature are called eurythermal.

Organisms that can tolerate a narrow range of temperatures are called stenothermal.

Q. 28. Why are plants and animals dependent on light?

Ans. Plants are dependent on light for:

(1) Photosynthesis.

(2) Photoperiodism—for flowering.

(3) Formation of chlorophyll.

Animals are dependent on light for:

(1) Photoperiodism—foraging, reproductive and migratory activities.

Q. 29. What is an adaptation? Why do animals/plants adapt?

Ans. Any change of the organism that enables the organism to survive and reproduce in its habitat is called adaptation.

It is done for reproduction i.e. to increase its population (r) and survival.

Q. 30. What are behavioural responses or adaptations? Give one example.

Ans. Responses shown in the behaviour of an organism to cope with the changes in its immediate environment is called a behaviour response, e.g.

For example, desert lizards bask in day – sunshine to increase their body temperature.

When their body temperature falls below the comfort zone. When basking in sun raises the temperature they then move to shade.

Q. 31. How have some organisms (animals) evolved to defend themselves from predation? Give examples.

Ans. The organisms have developed/evolved with certain defensive mechanisms such as in animals – insects, frogs are cryptically coloured (camouflaged) in order to escape the site of predator.

They are difficult to be distinguished from the background e.g. melanism in the moths; Monarch butterfly is highly distasteful to it predator (bird) because of a special chemical that it acquires from a poisonous weed during its caterpillar (developmental stage).

Q. 32. An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?

Ans. This is an example of commensalism. This interaction between the orchid and mango tree is beneficial to one species-orchid but the other species-mango tree is neither benefited nor harmed.

Q. 33. Briefly mention of one example to the employment of sexual deceit.

Ans. Ophrys a mediterranean orchid employs sexual deceit i.e. One petal of its flower bears the resemblance of female bee in its colour, size and markings.

The male bee mistakes it for its partner and ‘pseudocopulates’ it and thereby gets brushed with pollens. When it repeats the act with other orchid flowers of same species the flower gets pollinated.

Q. 34. Give an example for:

(a) An endothermic animal

(b) An exothermic animal

(c) An organism of benthic zone.

Ans. (a) Human,

(b) Frog,

(c) Fish.

Q. 35. Define population and community.

Ans. A group of organisms of a particular species, living in an area that shares or compete for similar resources and potentially interbreed is called as population.

A group of various organism populations that exist in an area and interact in various ways is called a community.

Q. 36. Define the following terms and give one example for each:

(a) Commensalism

(b) Parasitism

(c) Camouflage

(d) Mutualism

(e) Interspecific competition.

Ans. (a) Commensalism:

The interaction between two species in which one species is benefited and the other is neither benefited nor harmed is called commensalism e.g. barnacles growing on the back of whale.

(b) Parasitism:

The interaction between two species in which one species survives on the expense of other the host.

The host is harmed by this association. It is called parasitism e.g. malarial parasite causes harm to human host.

(c) Camouflage:

The ability of the prey to escape itself from its predator by its cryptically coloured pattern to make its predator difficult to prey on it is called camouflage e.g. moths are camouflaged to escape its predator (bird).

(d) Mutualism:

The association of two species in which both are benefited is called mutualism e.g. lichens are the association of fungus and algae where both are benefited.

(e) Interspecific competition:

The competition between different individuals of species/ population for limited sources of food, space, is called interspecific competition e.g. flamingoes and resident fishes of South American lake compete for their common food — zooplankton in the lake.

Q.37. Describe the logistic population growth curve.

Ans.

Logistic Growth Model:

No population of any species in nature has its disposal unlimited resources to permit the exponential growth.

It leads to competition between the individual of the limited resources and eventually the fittest individual survives and reproduces. In nature, the given habitat the population cannot grow beyond its carrying capacity (K) for that species in a habitat.

The population growth in a habitat with limited resources first shows lag phase, then acceleration and deceleration and finally asymphote when it reaches (K).

The plot formed is sigmoid curve-S-shaped. It is also called Verhulst-Pearl logistic growth. It is more realistic one.

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