Question

Class 12 Biology MCQ Questions of Organisms and Populations with Answers?

Answer 1

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Practice MCQ Question for Class 12 Biology chapter-wise

1. Habitat together with functions of a species constitute its:

(a) Topography
(b) Trophic level
(c) Boundary
(d) Ecological niche

2. The maximum growth rate occurs in :

(a) Lag phase
(b) Exponential, phase
(c) Stationary phase
(d) Senescent phase

3. In which one of the following habitats, does the diurnal temperature of soil surface view most?

(a) Shrub land
(b) Forest
(c) Desert
(d) Grassland

4. Water holding capacity is maximum in:

(a) Clay
(b) Sand
(c) Silt
(d) Gravel

5. Animals undergo inactive stage during winters. It is called :

(a) Acclimatisation
(b) Hibernation
(c) Aestivation
(d) Adapatation

6. Praying mantis is a good example of:

(a) Camouflage
(b) Mullarian mimicry
(c) Warning colouration
(d) Social insect

7. Ozone protects biosphere from high energetic:

(a) Infra-red rays
(b) Ultraviolet rays
(c) X-rays
(d) gamma rays

8. Mycorrhiza is an example to:

(a) Decomposers
(b) Endoparasitism
(c) Symbiotic relationship
(d) Ectoparasitism

9. Which plants is found in mangroove zone?

(a) Rhizophora
(b) Acacia
(c) Pinus
(d) Tectona grandis

10. The term ‘precipitation’ includes

(a) rain
(b) snow
(c) hails
(d) all forms of water that fall to the ground

11. What are the key elements that lead to so much variations in the physical and chemical conditions of different habitats?

(a) Temperature and water
(b) Light and soil
(c) Only temperature
(d) Temperature, water, light and soil

12. A majority of organisms which are restricted to narrow range of temperature are called as

(a) stenothermal
(b) endothermal
(c) ectothermal
(d) eurythermal

13. Organisms that are restricted to a narrow range of salinity, are called

(a) ectohaline
(b) osmoconformer
(c) euryhaline
(d) stenohaline

14. The process in which the body’s internal environment is kept stable is known as

(a) homeostasis
(b) adaptation
(c) geometry
(d) acclimatization

15. Ecotone is

(a) A zone of transition between two communities
(b) A zone of developing community
(c) The bottom of a lake
(d) A polluted area

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

(a) 30 – 35
(b) 0 – 5
(c) 30 – 70
(d) 10 – 15

17. A group of populations of two or more species occupying the same geographical area during a particular time is called

(a) Community
(b) Interaction
(c) Commensalism
(d) None of these

18. An organism that lives in or on another organism and derives nutrients for itself at the expense of the host organism is called

(a) Parasite
(b) Predator
(c) Both
(d) None of these

19. What parameters are used for tiger census in our country’s national parks and sanctuaries?

(a) Pug marks and faecal pellets
(b) Actual head counts
(c) Faecal pellets only
(d) Pug marks only

20. The rate of individuals born per 1,000 individuals per year is called

(a) Mortality rate
(b) Growth rate
(c) Vital rate
(d) Natality rate

21. In which of the following interactions both partners are adversely affected ?

(a) Predation
(b) Parasitism
(c) Mutualism
(d) Competition

22. Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot summer, thousands of migratory birds from Siberia and other extremely cold northern regions move to:

(a) Western Ghat
(b) Meghalaya
(c) Corbett National Park
(d) Keoladeo National Park

23. Organisms capable of maintaining constant body temperature are

(a) Poikilothermal
(b) Conformers
(c) Stenothermal
(d) Homeothermal

24. The most ecologically relevant environmental factor is:

(a) Temperature
(b) Water
(c) Light
(d) Soil

25. To get pollinated by a bee, the Mediterranean Orchid, Ophrys, employs:

(a) Sexual deceit
(b) Pseudo-copulation
(c) Reward in the form of Nectar
(d) Place for laying eggs

Answer 2

1. Answer : (d) Ecological niche

Explanation: The functional role of an organism in acommunity is ecological niche.

2.Answer : (b) Exponential, phase

Explanation: Maximum growth rate occurs in exponential or acceleration or log phase. The point at which the exponential growth begins to slow down is known as inflexion point.

3. Answer : (c) Desert

Explanation: Deserts are places where the diurnal temperatures very greatly. It is extremely hot during ; the day time and very cold at night. This change in temperature also affects the temperature condition of j the soil.

4. Answer : (a) Clay

Explanation: The water holding capacity is highest in sandy soil clay soil loamy soil or mixture of sand and Loom, so it is highest in clay soil.

5. Answer : (b) Hibernation

Explanation: Hibernation is the inactive stage during winter or the dormancy during winter. It is known as winter sleep.

6. Answer : (a) Camouflage

Explanation: Praying mantis is an insect which preys on other insects for its food and thus falls in the category of carnivorous insects. Therefore Praying mantis is a good example of Camouflage.

7. Answer : (b) Ultraviolet rays

Explanation: The stratospheric ozone layer the part of the atmosphere that protects us from the sun's ultraviolet radiation has deteriorated.

8. Answer : (c) Symbiotic relationship

Explanation: Mycorrhiza is the product of a symbiotic association between fungi and green plants. .For example, mycorrhizal plants are more resistant to disease and drought, They also increase resistance to insects by releasing chemicals which attract the insect's predators.

9. Answer : (a) Rhizophora

Explanation: Rhizophora belongs to the genus of tropical mangrove trees, sometimes they're collectively called true mangroves. The most notable species is the red mangrove. In estuarine ecosystems, it is distributed throughout the tropics.

10. Answer : (d) all forms of water that fall to the ground

Explanation: Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. Most precipitation falls as rain.

11. Answer : (d) Temperature, water, light and soil

Explanation: Physico-chemical components, temperature, water, light, soil and abiotic factors are the key elements that lead to so much variation in the physical and chemical condition of different habitats.

12. Answer : (a) stenothermal

Explanation: Stenothermal organisms are those organisms which are capable to live or survive within a limited range of temperature.

13. Answer : (d) stenohaline

Explanation: Some organisms are tolerant of a wide range of salinities, these are called euryhaline. On the other hand, organisms which are restricted to a narrow range of salinity are called stenohaline.

14. Answer : (a) homeostasis

Explanation: The tendency to maintain a stable, relatively constant internal environment is called homeostasis. The body maintains homeostasis for many factors in addition to temperature.

15. Answer : (a) A zone of transition between two communities

Explanation: Ecotone, a transitional area of vegetation between two different plant communities, such as forest and grassland. It has some of the characteristics of each bordering biological community and often contains species not found in the overlapping communities.

16. Answer : (a) 30 – 35

Explanation: Salinity of the sea is 30-35 parts per thousand, while for inland waters and some lagoons is less than 5 and more than 100, respectively.

17. Answer : (a) Community

Explanation: In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time, also known as a biocoenosis, biotic community, biological community, ecological community, or life assemblage. The term community has a variety of uses.

18. Answer : (a) Parasite

Explanation: The organism that benefits and brings harm to its host is called a parasite. The parasitic organism obtains nutrition from its host, which in turn hurts or deprives the host organism. An example of a parasitic relationship is between humans and tapeworms. The host, on the other hand, is deprived of nutrients.

19. Answer : (a) Pug marks and faecal pellets

Explanation: In our country, parameters for tiger census in national parks and sanctuaries include both pug marks and faecal pellets. They can be used to determine the number as well as distribution of tiger population. Newer techniques of excreta DNA analysis and camera trappings are considered more accurate for tiger census.

20. Answer : (d) Natality rate

Explanation: Birth rate or natality rate is defined as a number of births per 1,000 individuals of a population per year.

21. Answer : (d) Competition

Explanation: Competition is the rivalry between two or more organisms for obtaining the same resources such as food, light, water, space, shelter, mate etc. Competitors adversely affect each other.

22. Answer : (d) Keoladeo National Park

Explanation: The birds are called Siberian cranes. More than 230 types of birds are known to be occupant.

23. Answer : (d) Homeothermal

Explanation: Homoiothermal organisms are those who can maintain their internal body temperature at a relatively constant value by using metabolic processes to counteract fluctuations in the temperature of the environment, e.g., birds and mammals.

24. Answer : (a) Temperature

Explanation: Temperature is considered as the most ecologically relevant environmental factor because it affects of organisms.

25. Answer : (a) Sexual deceit

Explanation: A mediterranean orchid Ophrys employs sexual deceit to ensure its pollination by the bees. In this case, one petal of this flower bears an uncanny resemblance to the female bee in size, colour, and markings. The male bee gets attracted to it as it perceives it as a female bee.

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