CBSE Class 12 Biology Organisms and Populations MCQs Set G

Question: Behavioural response to cope with variations in the environment can be seen in
a) CAM plants
b) Opuntia plant
c) Desert lizards
d) C4 plants
Answer: c

Question: The tiger counting in our national parks and tiger reserves is often based on
a) Pug marks
b) Manual counting
c) Fecal pellets
d) Both 1 and 3
Answer: d

Question: Majority of plants belong to which of the following category
a) Regulators
b) Conformers
c) Partial regulators
d) Eurytherms
Answer: b

Question: Phytophagous insects show which of the following interaction
a) Predation
b) Competition
c) Mutualism
d) Commensalism
Answer: a

Question: The famous ‘Australian havoc’ is associated with which of the following invasive species
a) Nile perch
b) Prickly pear cactus
c) Red fox
d) Rabbit
Answer: b

Question: Temperature is one of the important abiotic factors. Significance of temperature on living beings can be realised through
a) Kinetics of enzymes
b) Basal metabolism
c) Physiological functions
d) All the above
Answer: d

Question: Which of the following alternative is used by zooplanktons to overcome partial stressful conditions
a) Migration
b) Diapause
c) Hibernation
d) Aestivation
Answer: b

Question: Find out the correct match with reference to their habitat
a) Mango tree – Canada
b) Snow leopards – Kerala forest
c) Tuna fish – Temperate latitudes in oceans
d) Lion – Gujarat
Answer: d

Question: Population ecology is an important area of ecology because it links ecology with
a) Population genetics
b) Evolution
c) Physiognomy
d) Both 1 and 2
Answer: d

Question: In rocky intertidal communities, removal of which of the following predator caused destruction of 10 species of invertebrates
a) Monarch butterfly
b) Starfish Pisaster
c) Paramecium aurelia
d) Abingdon tortoise
Answer: b

Question: Temperature is the most ecologically relevant environmental factor. In which of the following habitats can temperature exceed 100°C
a) Tropical desert
b) Thermal springs
c) Deep sea hydrothermal vents
d) Both 2 and 3
Answer: d

Question: Next to temperature, water is the most important factor influencing the life of organisms. Which among the following water characteristics is not an influencing character
a) pH
b) Turbidity
c) Colour
d) Salinity
Answer: c

Question: Which of the following cannot be used by prey for defence against predator
a) Cardiac glycosides
b) Strychnine
c) Nectar
d) Quinine
Answer: c

Question: Regarding competition, find out the wrong statement
a) Unrelated species could compete for the same resource
b) Fitness of one species is lowered in presence of other species
c) Abingdon tortoise became extinct due to competitor starfish
d) Balanus leads to exclusion of Chthamalus from rock coasts of Scotland
Answer: c

Question: Match the following given population interactions
(a) + / + (i) Predation
(b) – / – (ii) Ammensalism
(c) + / – (iii) Competition
(c) – / 0 (iv) Mutualism
a) a(i), b(ii), c(iii), d(iv)
b) a(i), b(iii), c(ii), d(iv)
c) a(iv), b(iii), c(i), d(ii)
d) a(iv), b(iii), c(ii), d(i)
Answer: c

Statement Type Questions

Question: Consider the following statements (A)-(D) each with one or two blanks.
(A) Bears go into (i) during winter to(ii) cold weather.
(B) A conical age pyramid with a broad base represents(iii) human population.
(C) A wasp pollinating a fig flower is an example of(iv) .
(D) An area with high levels of species richness is known as (v) .Which one of the following options, gives the correct fill ups for the respective blank numbers from (i) to (v) in the statements?
(a) (i) – hibernation, (ii) – attract, (iii) – expanding, (iv) – commensalism, (v) – biodiversity park
(b) (i) – hibernation, (ii) – escape, (iii) – expanding, (iv) – mutualism, (v) – hot spot
(c) (i) – aestivation, (ii) – escape, (iii) – stable, (iv) – commensalism, (v) – marsh
(d) (i) – aestivation, (ii) – escape, (iii) – stable, (iv) – mutualism, (v) – hot spot
Answer: b

Question: Study the following statements and answer the Question :
(i) Mango trees cannot grow in temperate countries like Canada and Germany.
(ii) Tuna fish are rarely caught beyond tropical latitude in the ocean.
(iii) Snow Leopards are not found in Kerala.
Which of the following factor is responsible for the above statements?
(a) Light
(b) Water
(c) Temperature
(d) Soil
Answer: c

Question: Read the following statements and choose the correct option.
(i) Light is essential for life to exist on the earth.
(ii) Many species of small plants under the canopy to tall trees in forest show optimal use of available light due to having large sized antenna and higher number of thylakoids.
(iii) UV rays are not harmful to many organisms.
(iv) Photoperiodic requirement is essential for many plants for flowering.
(v) Red algae can live in deeper water of sea because of having pigment, phycoerythrin.
(a) (i) and (iii)
(b) (i), (iii) and (iv)
(c) only (iii)
(d) (i), (ii), (iv) and (v)
Answer: d

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
Answer: d

Question: Read the following statements regarding adaptation and choose the correct option.
(i) Many xerophytic plants have a thick cuticle on leaf epidermis and sunken stomata to prevent transpiration.
(ii) Some xerophytic plants have special photosynthetic pathway (CAM) that enables their stomata to close during day.
(iii) Opuntias has no leaves, they are reduced to spines.
(iv) All adaptation are genetically fixed in all organisms.
(v) In Opuntia, the pathway of photosynthesis is through C3 cycle.
(a) (i), (ii) and (iii)
(b) Only (ii)
(c) (iv) and (v)
(d) All of these
Answer: a

Question: Mark the incorrect statement.
(a) Many fishes thrive in Antarctic water where temperature is always below zero .
(b) Microbes can survive in hot springs where temperature exceeds 100°C.
(c) Fishes can survive even at a depth where pressure exceeds 100 atm.
(d) Desert lizards have marvelous physiological ability to survive scorching heat of desert.
Answer: d

Question: Which of the following are the characteristics of expanding population ?
(i) Pyramid – shaped age structure.
(ii) An urn – shaped age structure.
(iii) Pre-reproductive and reproductive age groups become more or less equal in size.
(iv) Rapidly growing population with high birth rate.
(a) (i) and (iii)
(b) (i) and (iv)
(c) (iii) and (iv)
(d) (ii) and (iii)
Answer: b

Question: Which one of the following is categorised as a parasite in true sense?
(a) Human foetus developing inside the uterus draws nourishment from the mother.
(b) The female Anopheles bites and sucks blood from humans.
(c) Head louse living on the human scalp as well as laying eggs on human hair.
(d) The cuckoo (koel) lays its eggs in crow’s nest.
Answer: c

Question: Select the incorrect statement.
(a) Overwhelming majority of animals and nearly all plants maintain a constant internal temperature.
(b) An orchid growing as an epiphyte on a mango branch is an example of commensalism.
(c) In brood parasitism, the parasitic bird lays its eggs in the nest of its host and lets the host to incubate them.
(d) In amensalism, one species is harmed whereas the other is unaffected.
Answer: a

Critical Thinking Type Questions

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
Answer: b

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
Answer: c

Question: If N is the population density at time t, then its density at time t + 1 is
a) Nt + 1 = Nt + [(B + I) + (D + E)]
b) Nt + 1 = Nt – [(B + I) + (D + E)]
c) Nt + 1 = Nt + [(B + I) – (D + E)]
d) Nt + 1 = Nt – [(B + I) – (D + E)]
Answer: c

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
Answer: b

Question: Regarding temperature and osmotic concentration nearly all plants are
a) regulator
b) conformers
c) partial regulator
d) escaper in time
Answer: b

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
Answer: b

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

Question: When certain exotic species are introduced into a geographical area, they become invasive and start spreading fast because
a) they have high reproductive rate
b) they produce chemicals to inhibit the growth of other organisms
c) there is no competition
d) the invaded land does not have its natural predators
Answer: d

Question: The kangaroo rats of North American deserts do not need to drink water because
a) they meet their water requirement through internal fat oxidation
b) they are able to concentrate urine to minimize water loss
c) they do not have sweat glands
d) all of the above
Answer: d

Question: Population ecology is an important area of ecology because
a) it determines interaction among organisms and environment
b) evolutionary changes occur at population level
c) it links ecology to population genetics and evolution
d) it links different types of communities together
Answer: c

Question: The integral form of the exponential growth equation is
a) Nt = N0e–rt
b) N0 = Ntert
c) Nt = N0ert
d) rN = Ntert
Answer: a

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) cannot be predicted
Answer: a

Question: Gause’s competitive exclusion principle states that
a) humans are the most widespread agents of disturbance
b) both participants are benefitted in competition
c) both participants are excluded
d) two closely related species competing for the same resources cannot co-exist indefinitely
Answer: d

Assertion/Reason Type Questions

In the following questions, a statement of Assertion is followed by a statement of Reason.
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Question: Assertion : In a water body, Daphnia populations showed distinct variations in their morphology at different seasons.
Reason : Variations in temperature of water bodies at different seasons influences cyclomorphosis in some organisms.
Answer: a

Question: Assertion : Species are groups of potentially interbreeding natural populations which are isolated from other such groups.
Reason : Distinctive morphological characters are displayed due to reproductive isolation.
Answer: b

Matching Type Questions

Question: Match Column – I with Column – II and choose the correct option.
Column I                                        Column II
A. Pacific salmon fish                 I. Verhulst – pearl logistic growth
B. Nt = N0ert                           II. Breed only once in life time
C. Oyster                               III. Exponential growth
D. dN/dt = rN[K-N/K]              IV. A large number of small sized offsprings

(a) A – IV; B – III; C – I; D – II
(b) A – III; B – IV; C – I; D – II
(c) A – III; B – I; C – IV; D – II
(d) A – II; B – III; C – IV; D – I
Answer: d

Question: Match the following

(a) Breeding once in life                  (i) Mammals
(b) Breeding several times              (ii) Oysters in life
(c) Large number of small              (iii) Most of birds sized offsprings
(d) Small number of large              (iv) Pacific salmon sized offsprings fish
(a) a(iv), b(ii), c(iii), d(i)
(b) a(iv), b(iii), c(ii), d(i)
(c) a(iii), b(iv), c(ii), d(i)
(d) a(ii), b(iii), c(iv), d(i)
Answer: b

Column-I                                        Column-II
A. Pacific Salmon fish               I. Produces a small number of large sized offspring
B. Mammals                           II. Produces a large number of small sized offspring
C. Oysters                             III. Breed only once in their lifetime
D. Birds                                 IV. Breed many times during their lifetime

(a) A – III, B – IV, C – II, D – I
(b) A – I, B – IV, C – II, D – III
(c) A – IV, B – II, C – I, D – III
(d) A – II, B – IV, C – III, D – I
Answer: a