Students of class 12 Biology should refer to MCQ Questions Class 12 Biology Organisms and Populations with answers provided here which is an important chapter in Class 12 Biology NCERT textbook. These MCQ for Class 12 Biology with Answers have been prepared based on the latest CBSE and NCERT syllabus and examination guidelines for Class 12 Biology. The following MCQs can help you to practice and get better marks in the upcoming class 12 Biology examination

Chapter 13 Organisms and Populations MCQ with Answers Class 12 Biology

MCQ Questions Class 12 Biology Organisms and Populations provided below have been prepared by expert teachers of grade 12. These objective questions with solutions are expected to come in the upcoming Standard 12 examinations. Learn the below provided MCQ questions to get better marks in examinations.

Question. To avoid summer – related problems such as heat and dessication fish undergoes
(a) hibernation
(b) diapause
(c) aestivation
(d) none of these

Question. Seals have a thick layer of fat (blubber) below their skin that acts as an
(a) thermostat
(b) capacitor
(c) resistor
(d) insulator

Question. If the age distribution (per cent individuals of a given age or group) is plotted for the population, the resulting structure is called a/an
(a) population density
(b) ecological pyramid
(c) population growth
(d) age pyramid

Question. Which of the following parameter is not a part of population growth?
(a) Natality
(b) Mortality
(c) Metapopulation
(d) Emigration

Question. Interspecific interaction arise from the interaction of
(a) individuals of a community.
(b) populations and their regulatory factors.
(c) populations of two different species.
(d) none of the above

Question. Which of the following secondary compounds are produced by plants for the purpose of defences against grazers and browsers?
(a) Strychnine
(b) Caffeine
(c) Quinine
(d) All of these

Question. Cuscuta is an example of
(a) ectoparasitism
(b) endoparasitism
(c) predation
(d) brood parasitism

Question. Which of the following is not an example of commensalism?
(a) Sea anemone and clown fish
(b) Epiphyte / Orchid on mango branch
(c) Liver fluke and fleas
(d) Cattle egret and grazing cattle.

Question. A wasp pollinating a fig flower is an example of
(a) commensalism
(b) amensalism
(c) parasitism
(d) mutualism

Question. A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is
(a) commensalism
(b) amensalism
(c) ectoparasitism
(d) symbiosis

Question. Which of the following is the most accurate comment on Earth’s carrying capacity (K)?
(a) K is smaller now than it was a thousand years ago.
(b) The human population is still a long way from K.
(c) Our technology has allowed us to keep increasing K.
(d) When it comes to humans, the concept of K is irrelevant.Organisms and Populations 467

Question. To avoid summer – related problems such as heat and dessication fish undergoes
(a) hibernation
(b) diapause
(c) aestivation
(d) none of these

Question. According to Allen’s Rule, the mammals from colder climates have
(a) shorter ears and longer limbs
(b) longer ears and shorter limbs
(c) longer ears and longer limbs
(d) shorter ears and shorter limbs

Question. Salt concentration (Salinity) of the sea measured in parts per thousand is 
(a) 10 – 15
(b) 30 – 70
(c) 0 – 5
(d) 30 – 35

Question. If a population of 50 Paramecium present in a pool increases to 150 after an hour, what would be the growth rate of population?
(a) 50 per hour
(b) 200 per hour
(c) 5 per hour
(d) 100 per hour

Question. What would be the per cent growth or birth rate per individual per hour for the same population mentioned in the previous question ?
(a) 100
(b) 200
(c) 50
(d) 150

Question. Lichens are association of 
(a) bacteria and fungus
(b) alga and bacterium
(c) fungus and alga
(d) fungus and virus

Question. Which of the following would be true of a species with an opportunistic life history?
(a) Members of the species take a relatively long time to reach reproductive age.
(b) They are regulated mostly by density-dependent factors.
(c) They produce large numbers of offspring.
(d) The population usually stabilizes near carrying capacity.

Question. According to population scientists, one of the factors responsible for limiting population is the
(a) availability of food.
(b) daily variation of environmental temperature.
(c) time required for ecological succession.
(d) life span of members of the population.

Question. Reduction in vascular tissue, mechanical tissue and cuticle are characteristics of
(a) mesophytes
(b) epiphytes
(c) hydrophytes
(d) xerophytes

Question. Which one of the following do not account for the formation of major biomes?
(a) Annual variation in intensity of temperature.
(b) Annual variation in duration of temperature.
(c) Annual variation in precipitation.
(d) Annual variation in texture of soil.

Question. Many freshwater fishes cannot live for long in sea water and vice-versa mainly because of the
(a) variation in light intensity.
(b) change in the levels of thermal tolerance.
(c) osmosis.
(d) spectral quality of solar radiation.

Question. Which of the following is a characteristic of biological community?
(a) Startification
(b) Natality
(c) Morality
(d) Sex-ratio

Question. Cuscuta is an example of
(a) ectoparasitism
(b) brood parasitims
(c) predation
(d) endoparasitims

Question. _____________ in birds is an interesting example of parasitism in which the parasitic bird lays its eggs in the nest of its host and the host incubates them.
(a) Bird parasitism
(b) Breed parasitism
(c) Brood parasitism
(d) Ectoparasites

Question. Which statement explains the concept of Allen’s rule?
(a) Aquatic mammals have blubber as insulator.
(b) Mammals of colder climate have shorter ears and limbs.
(c) Mammals of humid and warmer region have more melanin in their skin.
(d) The bears undergoes hibernation during winter

Question. Which of the following is not an example of commensalism?
(a) Sea anemone and clown fish
(b) Epiphyte / Orchid on mango branch
(c) Liver fluke and fleas
(d) Cattle egret and grazing cattle.

Question. Formation of tropical forests needs mean annual temperature and mean annual precipitation as 
(a) 18–25°C and 150–400 cm
(b) 5–15°C and 50–100 cm
(c) 30–50°C and 100–150 cm
(d) 5–15°C and 100–200 cm

Question. Which of the following forest plants controls the light conditions at the ground? 
(a) Lianas and climbers
(b) Shrubs
(c) Tall trees
(d) Herbs

Question. What will happen to a well growing herbaceous plant in the forest if it is transplanted outside the forest in a park?
(a) It will grow normally
(b) It will grow well because it is planted in the same locality
(c) It may not survive because of change in its micro climate
(d) It grows very well because the plant gets more sunlight

Question. Which of the following statement is incorrect ?
(a) Habitat includes both biotic and abiotic factors.
(b) Abiotic and biotic components interact constantly with each other.
(c) Abiotic components alone can characterize the habitat of an organism.
(d) Major abiotic factors includes temperature, water, light and soil

Question. A population has more young individuals compared to the older individuals. What would be the status of the population after some years?
(a) It will decline
(b) It will stabilise
(c) It will increase
(d) It will first decline and then stabilise

Question. Organisms with very high intrinsic growth rates have
(a) long generation times.
(b) short generation times.
(c) no courtship behaviour.
(d) no carrying capacities.

Question. Seals have a thick layer of fat (blubber) below their skin that acts as an
(a) thermostat
(b) capacitor
(c) resistor
(d) insulator

Question. Microbes present in hydrothermal vents where the temperature far exceed 100°C is
(a) cyanobacteria
(b) archaebacteria
(c) eubacteria
(d) none of these

Question. Mac Arthur observed that five closely related species of Warblers living on the same tree were able to avoid competition and co-exist due to
(a) cooperation in their foraging efforts.
(b) behavioural differences in their foraging activities.
(c) different kinds of insects they eat.
(d) all of the above

Question. The Abingdon tortoise in Galapagos Islands became extinct within a decade after goats were introduced on the island. This is apparently due to
(a) lower intrinsic rate of goat.
(b) the greater browsing efficiency of the goats.
(c) limiting resource.
(d) superiority of the goat.

Question. Which of the following adaptation do not lessen the impact of predation?
(a) Some species of insects and frogs are camouflaged.
(b) Some animals are poisonous.
(c) Monarch butterfly is highly distasteful due to having certain chemical in their bodies.
(d) Different feeding habits of finches.

Question. A few organisms can tolerate and thrive a wide range of temperature. Such animals are called
(a) stenothermal
(b) eurythermal
(c) thermophilic
(d) ectothermal

Question. Amensalism is an association between two species where
(a) one species is harmed and other is benefitted
(b) one species is harmed and other is unaffected
(c) one species is benefitted and other is unaffected
(d) both the species are harmed.

Question. When birth rate equals death rate,
(a) a population grows rapidly.
(b) the size of a population remains constant.
(c) density-dependent limiting factors do not affect the population.
(d) a population is in danger of extinction.

Question. Which of the following is a partial root parasite? 
(a) Sandalwood
(b) Mistletoe
(c) Orobanche
(d) Ganoderma

Question. Factors that are important for aquatic organisms include
(a) chemical composition of water
(b) pH of water
(c) spectral quality of solar radiation
(d) both (a) and (b)

Question. _____ is any attribute of the organism (morphological physiological, behavioural) that enables the organisms to survive and reproduce in its habitat.
(a) Exponential growth
(b) Acclimatization
(c) Adaptation
(d) Mutualism

Question. Gause’s ‘competitive exclusion principle’ states that
(a) humans are the most widespread agents of disturbance.
(b) in a competition for similar resource both the  participants are benefitted.
(c) in a competition, both the participants are excluded.
(d) two closely related species competing for the same resources cannot co-exist indefinitely and competitively inferior one will be eliminated eventually.

Question. 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

Question. Identify the correct statement.
(a) The smaller animals have larger surface area relative to their volume.
(b) Smaller animals are rarely found in polar region.
(c) Bear cannot migrate hence hibernate during winter.
(d) All of the above

Question. In an age pyramid, the number of individuals of reproductive age is lesser than pre-reproductive but higher than post reproductive ones. The population is
(a) growing
(b) declining
(c) stable
(d) can not be predicted

Question. Assume that you have been studying a population of cattails at the edge of a pond. After 10 years of observations, you notice that the population has remained steady. What is the most likely explanation?
(a) The birth rate and death rate are both increasing at the same rate.
(b) The pond is drying up.
(c) The carrying capacity of pond has been reached.
(d) Nutrients levels in pond are fluctuating.

Question. The salinity in sea water in parts per thousand (ppt) ranges between
(a) 5-15%
(b) 30-35%
(c) 50-75%
(d) more than 100%

Question. Organisms that are restricted to a narrow range of salinity, are called
(a) ectohaline
(b) osmoconformer
(c) euryhaline
(d) stenohaline

Question. A majority of organisms which are restricted to narrow range of temperature are called as
(a) stenothermal
(b) endothermal
(c) ectothermal
(d) eurythermal

Question. Many animals use the diurnal and seasonal variations in light intensity and photoperiod as cues timing of
(a) for age only
(b) reproductive activities only
(c) migration only
(d) all of these

Question. Natural selection operates to evolve the desired tracts at
(a) cellular level
(b) species level
(c) community level
(d) population level

Question. If in a pond, there were 20 lotus last year and through reproduction 8 new plants are added, taking current population to 28, the birth rate per year is
(a) 0.2
(b) 0.4
(c) 0.6
(d) 0.8

Question. A particular species of tropical fish has only a few offspring and takes care of them for an extended period. We might also expect the fish population to
(a) be controlled mostly by density independent factors.
(b) show exponential growth.
(c) live in a harsh environment.
(d) be relatively stable near carrying capacity.

Question. Ecological niche is 
(a) the surface area of the ocean
(b) an ecologically adapted zone
(c) the physical position and functional role of a species within the community
(d) formed of all plants and animals living at the bottom of a lake

Question. If 4 individuals in a laboratory population of 40 fruitflies died during a specified time interval (i.e., a week), the death rate in the population during that period is
(a) 1
(b) 0.1
(c) 0.01
(d) 0.4

Question. If the age distribution (per cent individuals of a given age or group) is plotted for the population, the resulting structure is called a/an
(a) population density
(b) ecological pyramid
(c) population growth
(d) age pyramid

Question. The age of pyramid with narrow base indicates
(a) high number of young individuals.
(b) low number of young individuals.
(c) high number of old individuals.
(d) low number of old individuals.

Question. Autecology is the
(A) relation of a population to its environment.
(B) relation of an individual to its environment.
(C) relation of a community to its environment.
(D) relation of a biome to its environment.

Question. A population has more young individuals compared to the older individuals. What would be the status of the population after some years?
(A) It will decline
(B) It will stabilize
(C) It will increase
(D) It will first decline and then stabilize

Question. If a population of 50 Paramecium present in a pool increases to 150 after an hour, what would be the growth rate of population?
(A) 50 per hour
(B) 200 per hour
(C) 5 per hour
(D) 100 per hour

Question. Which one of the following organisms reproduces sexually only once in its life time?
(A) Banana plant
(B) Mango
(C) Tomato
(D) Eucalyptus

Question. Which of the following would necessarily decrease the density of a population in a given habitat?
(A) Natality> mortality
(B) Immigration > emigration
(C) Mortality and emigration
(D) Natality and immigration

Question. Snails escape from stressful time in summers by
(A) Hibernation
(B) Aestivation
(C) Diapause
(D) Homeostasis

Question. What parameters are used for tiger census in our country’s National parks and sanctuaries?
(A) Pug marks only
(B) Pug marks and faecal pellets
(C) Faecal pellets only
(D) Actual head counts

Question. Select the statement which explains best parasitism.
(A) One organism is benefited
(B) Both the organisms are benefited
(C) One organism is benefited, other is not affected
(D) One organism is benefited, other is affected.

Question. Lichens are the associations of
(A) bacteria and fungus
(B) algae and bacterium
(C) fungus and algae
(D) fungus and virus

Question. Which of the following is a partial root parasite?
(A) Sandal wood
(B) Mistletoe
(C) Orobanche
(D) Ganoderma

We hope the above multiple choice questions for Class 12 Biology for Chapter 13 Organisms and Populations provided above with answers based on the latest syllabus and examination guidelines issued by CBSE, NCERT and KVS are really useful for you. Organisms and Populations is an important chapter in Class 12 as it provides very strong understanding about this topic. Students should go through the answers provided for the MCQs after they have themselves solved the questions. All MCQs have been provided with four options for the students to solve. These questions are really useful for benefit of class 12 students. Please go through these and let us know if you have any feedback in the comments section.