CBSE Class 12 Biology Organisms and Populations MCQs Set D

Question: Initiative concerned with the conservation of wetlands of international importance is
a) Ramsar convention
b) Millennium Goals
c) Montreal protocol
d) Kyoto protocol
Answer: a

Question: The measure of resources enough to support a maximum possible number of species, beyond which no further growth is possible, is known as
a) Population growth
b) Biotic potential
c) Carrying capacity
d) None of these
Answer: c

Question: Of the total incident solar radiation, the proportion of PAR is
a) About 60%
b) Less than 50%
c) More than 80%
d) About 70%
Answer: b

Question: What is common to Lantana, Eichhornia, and African catfish?
a) All are endangered species of India
b) All are keystone species
c) All are mammals found in India
d) All the species are not indigenous species of India
Answer: d

Question: In case of plant succession, when climax is reached, the net productivity of the ecosystem
a) Continues to increase
b) Becomes halved
c) Becomes stable
d) Becomes zero
Answer: c

Question: Which kind of pyramid will be obtained if a small standing crop of higher trophic levels is present?
a) Inverted pyramid of number
b) Upright pyramid of number
c) Inverted pyramid of biomass
d) Upright pyramid of biomass
Answer: d

Question: The entire sequence of communities that successively change in a given area is called
a) Climax community
b) Sere
c) Pioneer community
d) Standing state
Answer: b

Question: Choose the correct statement regarding climate change
a) The temperature of Earth has increased by 0.6°C in the past century.
b) CH₄ contributes about 14% of all greenhouse gases to global warming.
c) Clouds and gases reflect about one-third of the incoming solar radiation, and absorb some of it.
d) El Niño effect is referred to the ice caps of the Himalayan region.
Answer: a

Question: ——– refers to the increase in the concentration of toxicant like mercury at a successive level
a) Productivity
b) Biomagnification
c) Decomposition
d) Eutrophication
Answer: b

Question: The rat in North American desert is capable of meeting all its water requirements through its internal fat oxidation. It is an example of
a) Morphological adaptation
b) Behavioral adaptation
c) Anatomical adaptation
d) Physiological adaptation
Answer: d

Question: Mammals from colder climates generally have shorter ears and limbs to minimize heat loss. This is called
a) Bergman’s rule
b) Gloger’s rule
c) Allen’s rule
d) Jordan’s rule
Answer: c

Question: Select the wrong statement regarding energy flow in an ecosystem
a) Energy flows in one direction only
b) About 1 to 5% of the energy reaching the ground is converted by the green plants into chemical energy
c) Energy requirement for maintenance of body gradually decreases in successive trophic levels
d) Only 10% of the gross productivity of producers is entrapped by herbivores for their body building
Answer: c

Question: Which of the following is a matching pair of certain organism(s) and the kind of association between them?
a) Algae and fungi in lichens – Mutualism
b) Shark and sucker fish – Ammensalism
c) Orchids growing on trees – Parasitism
d) Cuscuta (dodder) growing on other flowering plants – Epiphytism
Answer: a

Question: Select the correct statement regarding biogas
a) Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of anaerobic bacteria
b) Biogas is produced by the activity of anaerobic bacteria on animal waste
c) Methanobacterium is an anaerobic bacterium found in the rumen of cattle
d) Biogas, commonly called gobar gas, is pure methane
Answer: b

Question: According to the 2011 census, the population growth rate in India was
a) Less than 2%
b) 3–4%
c) Negative
d) More than 5%
Answer: a

Question: A high density of a protected animal in a national park can result in
a) Mutualism
b) Intraspecific competition
c) Emigration
d) Predation
Answer: b

Question: What are the adaptations seen in animals that live in water scarcity conditions?
a) Having a thick coat to minimize evaporative desiccation
b) Oxidizing stored fat to produce water as a byproduct
c) Producing very concentrated urine and solid faeces
d) All of these
Answer: d

Question: Carnivorous animals lions and leopards occupy the same niche but lions predate mostly larger animals and leopards take smaller ones. This mechanism of competition is referred to as
a) Character displacement
b) Altruism
c) Resource partitioning
d) Competitive exclusion
Answer: c

Question: A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is
a) 5
b) 0
c) 10
d) 15
Answer: b

Question: Select the correct option w.r.t. age pyramids
a) A – Expanding, B – Stable, C – Declining
b) A – Stable, B – Expanding, C – Declining
c) A – Stable, B – Declining, C – Expanding
d) A – Declining, B – Stable, C – Expanding
Answer: a

Question: Which of the following is false?
a) In a population birth rate and death rate refer to per capita births and deaths respectively
b) The size of a population for any species is a static parameter
c) In nature, we rarely find isolated, single individuals of any species
d) Ecological effects of any factors on a population are generally reflected in its size/population density
Answer: b

Question: Biotic potential refers to
a) Increase of population under optimum condition
b) Increase of population under given condition
c) Increase of population under natural condition
d) Increase of population under climate condition
Answer: a

Question: Exponential growth in human population is represented in
a) Lag phase
b) Log phase
c) Plateau stage
d) First stage
Answer: b

Question: Organisms that are restricted to a narrow range of salinity are called
a) Ectohaline
b) Osmoconformer
c) Euryhaline
d) Stenohaline
Answer: d

Question: Limit of the environment to support a population is called its
a) Biotic potential
b) Purifying capacity
c) Carrying capacity
d) Environmental resistance
Answer: c

Question: Which of these is used as vector in gene therapy for SCID?
a) Arbovirus
b) Rotavirus
c) Retrovirus
d) Parvovirus
Answer: c

Question: Photochemical smog does not contain
a) Nitrogen dioxide
b) Carbon dioxide
c) PAN (Peroxy acylnitrate)
d) Ozone
Answer: b

Question: The age structure of a population is its
a) Relative number of individuals at each age
b) Number of newborns each year
c) Number of young reaching puberty each year
d) Relative number of deaths at each age
Answer: a

Question: Which one of the following population interactions is widely used in medical science for the production of antibiotics?
a) Commensalism
b) Mutualism
c) Parasitism
d) Amensalism
Answer: d

Question: Population density of aquatic animals in some waterbody is measured in terms of per
a) m²
b) m⁴
c) m
d) m³
Answer: d

Question: Identify the correctly matched pair
a) Montreal protocol – Ozone depletion
b) Kyoto protocol – Ozone depletion
c) Ramsar convention – Groundwater pollution
d) Basel convention – Biodiversity conservation
Answer: a

Question: Which of the following is correct?
a) Population change = (Birth + immigration) – (death + emigration)
b) Population change = (Birth + immigration) + (death + emigration)
c) Population change = (Birth + emigration) + (death – immigration)
d) Population change = (Birth – immigration) – (death + emigration)
Answer: a

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
Answer: b

Question: Which one of the following causes population explosion?
a) Decrease in infant mortality rate and increase in death rate
b) Decrease in death rate, maternal mortality rate, and infant mortality rate
c) Decrease in infant mortality rate and decrease in the number of people in reproductive age
d) Decrease in death rate and increase in maternal mortality rate
Answer: b

Question: The process in which the body’s internal environment is kept stable is known as
a) Homeostasis
b) Adaptation
c) Geometry
d) Acclimatization
Answer: a

Question: Percolation and water holding capacity of soil is dependent upon
a) Soil composition
b) Grain size
c) Aggregation
d) All of these
Answer: d

Question: What are the key elements that lead to so much variation 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
Answer: d

Question: Which of the following related to integrated wastewater treatment processes within a natural system?
a) The system created by Ramesh Chandra Dagar
b) Jhum cultivation
c) Formation of polyblend
d) Friends of Arcata Marsh (FOAM)
Answer: d

Question: In the forest ecosystem, yeast, molds, and mushrooms are grouped as
a) Producer
b) Consumer
c) Secondary consumer
d) Decomposer
Answer: d

Question: Ecological succession is
a) Directional unpredictable
b) Nondirectional predictable
c) Gradual and predictable
d) Directionless and unpredictable
Answer: c