Class 12 biology MCQs with answers. organism is a continuous biological system that exists in a given environment and can adapt and maintain a specific structure and behavior. Fungi, bacteria, plants, animals, and humans are all included in this group. A population is formed when a group of organisms band together. The population forms a community that is responsible for the operation of the ecosystem. A population is defined as a collection of individuals or organisms of any species that are found in a well–defined geographical area at a certain moment and can interbreed with other individuals or organisms of that species. For example, the deer population in a woodland.

Class 12 Biology Organisms and Populations MCQs with Answers

Q1. Salt concentration (Salinity) of the sea measured in parts per thousand is:

1. 10–15.
2. 30–70.
3. 0–5.
4. 30–35.

Q2. Select the statement which explains best parasitism.

1. One organism is benefited.
2. Both the organisms are benefited.
3. One organism is benefited, other is not affected.
4. One organism is benefited, other is affected.

Q3. Mycorrhiza is an example of:

1. Ectoparasitism.
2. Mutualism.
3. Endoparasitism.
4. Predation.

Q4. Individuals of one kind, i.e., one species occupying a particular geographie area, at a given time form a/ an:

1. Community.
2. Biome.
3. Population.
4. Deme.

Q5. Ecological niche is:

1. The surface area of the ocean.
2. An ecologically adapted zone.
3. The physical position and functional role of a species within the community.
4. Formed of all plants and animals living at the bottom of a lake.

Q6. If a population of 50 Paramoecium present in a pool increases to 150 after an hour, what would be the growth
rate of population?

1. 50 per hour.
2. 200 per hour.
3. 5 per hour.
4. 100 per hour.

Q7. The interspecific interaction in which one partner is benefitted and the other is unaffected (neutral), is called:

1. Amensalism.
2. Mutualism.
3. Competition.
4. Commensalism.

Q8. Autecology is the:

1. Relation of a population to its environment.
2. Relation of an individual to its environment.
3. Relation of a community to its environment.
4. Relation of a biome to its environment.

Q9. Lichens are the associations of:

1. Bacteria and fungus.
2. Algae and bacterium.
3. Fungus and algae.
4. Fungus and virus.

Q10.In 2005, for each of the 14 million people present in a country, 0.028 were born and 0.008 died during the year.
Using exponential equation, the number of people present in 2015 is predicted as:

1. 25 millions.
2. 17 millions.
3. 20 millions.
4. 18 millions.

Q11. In case of exponential growth pottern of a population, the shope of curve obtained by plotting N in relation to t is:

1. L-shaped.
2. S-shaped.
3. Hyperbola.
4. J-shaped.

Q12. What would be the per cent growth or birth rate per individual per hour for the same population mentioned in
the previous question (Question 10)?

1. 100.
2. 200.
3. 50.
4. 150.

Q13. “Two closely related species competing for the same resources can not co-exist indefinitely and the competitively
inferior one will be eliminated”. This is explained

1. Allen’s rule.
2. Gloger’s rule.
3. Bergman’s law.
4. Gause’s principle.

Q14. Ecotone is:

1. A polluted area.
2. The bottom of a lake
3. A zone of transition between two communities.
4. A zone of developing community.

Q15. It natality is balanced by mortality in a population at a given time, there will be a/ an:

1. Decrease in the population size.
2. Increase in the population size.
3. Zero population growth.
4. Population explosion.

Q16. According to Allen’s Rule, the mammals from colder climates have:

1. Shorter ears and longer limbs.
2. Longer ears and shorter limbs.
3. Longer ears and longer limbs.
4. Shorter ears and shorter limbs.

Q17. A population has more young individuals compared to the older individuals. What would be the status of the 1 Mark
population after some years?

1. It will decline.
2. It will stabilise.
3. It will increase.
4. It will first decline and then stabilise.

Q18. Niche overlap indicates:

1. Mutualism between two species.
2. Active cooperation between two species.
3. Sharing of one or more resources between the two species.
4. Two different parasites on the same host

Q19. When species area relationship is considered for a larger area, slope of the line Become:

1. More steeper.
2. Less steeper.
3. Remain unchanged.
4. Form a straight line.

Q20. What will happen to a well growing herbaceous plant in the forest if it is transplanted outside the forest in a
park?

1. It will grow normally.
2. It will grow well because it is planted in the same locality.
3. It may not survive because of change in its micro climate.
4. It grows very well because the plant gets more sunlight.