CBSE Class 12 Biology Organisms and Populations MCQs Set A

Question :  Autecology is the

a) Relation of an individual to its environment

b) Relation of a community to its environment

c) Relation of a biome to its environment

d) Relation of a population to its environment

Answer :  Relation of an individual to its environment

Question :  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

Answer :  A zone of transition between two communities

Question :  Biosphere is

a) composed of all living organisms present on earth which interact with the physical environment

b) life in the outer space

c) composed of the plants present in the soil

d) a component in the ecosystem

Answer :  composed of all living organisms present on earth which interact with the physical environment

Question :  Ecological niche is

a) the physical position and functional role of a species within the community

b) formed of all plants and animals living at the bottom of a lake

c) an ecologically adapted zone

d) the surface area of the ocean

Answer :  the physical position and functional role of a species within the community

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

a) longer ears and longer limbs

b) shorter ears and shorter limbs

c) longer ears and shorter limbs

d) shorter ears and longer limbs

Answer :  longer ears and longer limbs

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

a) 30 – 35

b) 0 – 5

c) 30 – 70

d) 10 – 15

Answer :  30 – 35

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

Answer :  18 – 25°C and 150 – 400 cm

Question :  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

Answer :  Community

Question :  Biotic factors include

a) Plants and animals

b) Water temperature, fish

c) Plants, animals and physical environment

d) All of these

Answer :  Plants and animals

Question :  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

Answer :  Parasite

Question :  Which of the following forest plants controls the light conditions at the ground?

a) Tall trees

b) Herbs

c) Shrubs

d) Lianas and climbers

Answer :  Tall trees

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 may not survive because of change in its micro climate

b) It grows very well because the plant gets more sunlight

c) It will grow well because it is planted in the same locality

d) It will grow normally

Answer :  It may not survive because of change in its micro climate

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

a) 100 per hour

b) 5 per hour

c) 200 per hour

d) 50 per hour

Answer :  100 per hour

Question :  If a population of 50 Paramoecium present in a pool increases to 150 after an hour, What would be the per cent growth or birth rate per individual per hour of population?

a) 200

b) 100

c) 50

d) 150

Answer :  200

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 increase

b) It will first decline and then stabilise

c) It will stabilise

d) It will decline

Answer :  It will increase

Question :  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

Answer :  Pug marks and faecal pellets

Question :  Asymptote in a logistic growth curve is obtained when

a) K = N

b) K > N

c) K < N

d) None of these

Answer :  K = N

Question :  Plants which produce characteristic pneumatophores and show vivipary belong to

a) Halophytes

b) Mesophytes

c) Psammophytes

d) All of these

Answer :  Halophytes

Question :  Competition is most fierce between

a) Two or more closely related species in the same environment

b) Two or more closely related species in a different environment

c) Unrelated species in the same environment

d) None of these

Answer :  Two or more closely related species in the same environment

Question :  Mimicry is

a) An evolved resemblance between an organism and an object

b) An adaptation made for finding mates

c) An adaptation for surviving temperature fluctuations

d) None of these

Answer :  An evolved resemblance between an organism and an object

Question :  Which of the following would necessarily decrease the density of a population in a given habitat?

a) Mortality and emigration

b) Natality and immigration

c) Immigration > emigration

d) Natality > mortality

Answer :  Mortality and emigration

Question :  A protozoan reproduces by binary fission. What will be the number of protozoans in its population after six generations?

a) 64

b) 32

c) 24

d) 128

Answer :  64

Question :  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

a) 17 millions

b) 20 millions

c) 18 millions

d) 25 millions

Answer :  17 millions

Question :  Amensalism is an association between two species where:

a) one species is benefitted and other is unaffected

b) both the species are harmed

c) one species is harmed and other is benefitted

d) one species is harmed and other is unaffected

Answer :  one species is benefitted and other is unaffected

Question :  Lichens are the associations of

a) fungus and algae

b) fungus and virus

c) bacteria and fungus

d) algae and bacterium

Answer :  fungus and algae

Question :  Which of the following is a partial root parasite?

a) Sandal wood

b) Mistletoe

c) Orobanche

d) Ganoderma

Answer :  Sandal wood

Question :  Which one of the following organisms reproduces sexually only once in its life time?

a) Eucalyptus

b) Tomato

c) Banana plant

d) Mango

Answer :  Eucalyptus

Question :  Xerocoles are

a) Animals adapted to live in deserts

b) Animals adapted to live in the deep sea

c) Animals adapted to a nocturnal lifestyle

d) All of these

Answer :  Animals adapted to live in deserts

Question :  Fossorial refers to

a) Animals that are adapted to burrowing

b) Animals that are adapted to climbing

c) Animals that turned into fossils

d) None of these

Answer :  Animals that are adapted to burrowing

Question :  Most animals are tree dwellers in a

a) tropical rain forest

b) coniferous forest

c) thorn woodland

d) temperate deciduous forest

Answer :  tropical rain forest