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# Organisms and Populations

#### Multiple Choice Questions

1.

Interbreeding population of animals is called :

• sub-species

• species

• community

• genus

B.

species

Interbreeding individuals of natural population which are reproductively isolated by other groups is known as species. It was given by Mayr.

2.

Annual migration does not occur in the case of

• salmon

• siberian crane

• salamander

• salamander

C.

salamander

Salamonder is semiterrestrial lizard-like tailed amphibian lives under stones, logs and inside crevices. They show hibernation.
Salmon anadromous i.e., they spend their adult lives at sea but return to fresh water to spawn.  The pacific species is legendary after migrating downstream as a smolt a sockeye salmon ranges many hundreds of miles over the pacific for nearly four year and than returns to spawn in the head waters of its parent stream.
Migration tern travels about 1100 miles during winter and return back during summer.

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3.

Photochemical smog formed in congested metropolitan cities mainly consists of:

• ozone, peroxyacetyl nitrate and NOx

• smoke, peroxyacetyl nitrate and SO2

• hydrocarbons, SO2 and CO2

• hydrocarbons, ozone and SOx

A.

ozone, peroxyacetyl nitrate and NOx

Photochemical smog mainly consists of ozone, pcroxyacetyl nitrate and different oxide of
nitrogen and hydrocarbons released from different engines.

Nitric oxide or NO is formed by reaction between oxygen and nitrogen. This reacts with air forming nitrogen dioxide (NO2). This gas absorbs light due to which nitric oxide (NO) and a molecule of nascent oxygen [O] are formed.

NO2 $\to$NO + [O]

This atomic oxygen reacts with unburnt hydrocarbons to give rise to peroxy radicals which after reaction with oxygen form ozone or reacting with NO2 give rise to peroxyacetyl nitrate (PAN).

4.

Assertion : Inhabitants close to very busy airports are likely to experience health hazards.

Reason : Sound level of jet aeroplanes usually exceeds 160 dB.

• If both Assertion and Reason are true and the reason is the correct explanation of the assertion

• If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

• If Assertion is true statement but Reason is false

• If both Assertion and Reason are false statements

B.

If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

Inhabitants staying close to a very busy airport are likely to experience health hazards because maximum acceptable range of sound is 80-90 dB. But in the places like airports this level is always exceeds, thus it creates sound pollution and related health hazards like auditory fatigue, deafness etc.

Jet planes generally produce sound above 160 dB which is much more than normal level, thus they also produce sound pollution. But as jet aeroplanes are used for some special purposes, they normally do not land in common or very busy airports (without emergency). Thus, it has no direct relation in causing sound pollution and related hazards in areas nearby very busy airports.

5.

Mutualism is found in

• hermit crab and sea anemone

• ox pecker and rhinoceros

• zoochlorellae and Hydra

• E.coli and man

C.

zoochlorellae and Hydra

Mutualism is the ecological interaction between two or more species where each species benefits.

The unicellular photosynthetic algae, called Zoochlorella live symbiotically in the outer tissues of coelenterates. Algae are photosynthetic and produce oxygen and food beneficial to hosts and in exchange, they obtain materials like carbon- dioxide and nitrogenous wastes released by metabolism of host animals.

6.

Which one of the following is a matching pair of certain organism(s) and the kind of association?

• Shark and sucker fish - commensalism

• Algae and fungi in lichens - mutualism

• Orchids growing on trees - parasitism

• Cuscuta (dodder) growing in other flowering plants - epiphytism.

B.

Algae and fungi in lichens - mutualism

The association between fungi and algae in lichen is regarded as the true mutual relationship, in which both the partners are bcncfittcd. In lichen, fungus lives on the algae which manufactures food by virtue of the hlorophyll present in its cells, while the algae enjoys the protection afforded by the fungal envelope, to live in very dry conditions.

7.

On high mountains, difficulty in breathing is due to :

• decrease in partial pressure of O2

• decrease in amount of O2

• increase in CO2 conc

• all of the above

A.

decrease in partial pressure of O2

On high mountains, difficulty in breathing is due to decrease in partial pressure of O2.

8.

Assertion : Lateral line system is found in fishes and aquatic larval amphibians.

Reason : Lateral line system has receptors which are the clusters of sensory cells derived from ectoderm.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both the assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both the assertion and reason are false.

B.

If both the assertion and reason are true but reason is not the correct explanation of assertion

Lateral line system is a sensory system of fishes and aquatic and larval amphibians whose receptors are clusters of sensory cells derived from ectoderm. These clusters of sensory cells are called neuromast organs.

9.

Mr.X is eating curd/yoghurt. For this food intake in a food chain he should be considered as occupying

• first trophic leve

• second trophic level

• third trophic level

• fourth trophic level

C.

third trophic level

Mr. X eating curd / yoghurt should be considered as occupying third trophic level. Producers or greeen plants (first trophic level) are consumed by herbivore (second trophic level). And from them curd, yoghurt (made from dairy breed) is consumed by third trophic level like man.

10.

Assertion : The age-sex structure of human population in countries like France and Germany gives a steep pyramid.

Reason : In countries like Sudan and India the population is increasing at a rapid rate.

• If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion

• If both Assertion and Reason are true but the Reason is not the correct explanation of the assertion

• If Assertion is true but Reason is false

• If both Assertion and Reason are false

B.

If both Assertion and Reason are true but the Reason is not the correct explanation of the assertion

The most important demographic characteristic of a population is its age sex structure which is also known as population pyramids. Age sex pyramids display the percentage or actual amount of a population broken down by gender and age. Developed countries with stable population gives a steep pyramid.

Population of Sudan and India are increasing at a rapid rate. Population growth rate for Sudan is 2.60% and for India is 1.40%.