Please refer to Class 12 Biology Chapter 13 Organisms and Populations MCQ Questions with Answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Biology. Students should refer to MCQ Questions for Class 12 Biology with Answers to score more marks in Grade 12 Biology exams. Students should read the chapter Organisms and Populations and then attempt the following objective questions.

Class 12 Biology Chapter 13 Organisms and Populations MCQ Questions with Answers

Class 12 Biology Chapter 13 Organisms and Populations MCQ provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. Which of the following is the stage of suspended development?
(a) Dormancy
(b) Hibernation
(c) Aestivation
(d) Diapause

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

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. _______________ is the number of individuals of the population who left the habitat and have gone elsewhere during the time period under consideration.
(a) Natality
(b) Mortality
(c) Immigration
(d) Emigration

Question. In growth pattern, (1 – N/K) is
(a) carrying capacity
(b) intrinsic rate of natural increase
(c) environmental resistance
(d) biotic potential

Question. Thorns of Acacia and cactus are the most common morphological means of
(a) reproduction
(b) competition
(c) defence
(d) economical importance

Question. Connell’s elegant field experiments are related to barnacle, in which superior barnacle Balanus dominates the inter tidal area, and excludes the smaller barnacle Chathamalus from that zone. This phenomenon is called
(a) competitive exclusion principle
(b) competitive release
(c) interspecific competition
(d) none of the above

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. The interaction is detrimental to both the species, in
(a) predation
(b) commensalism
(c) amensalism
(d) competition

Question. An interaction where one species is harmed while the other is unaffected is called
(a) commensalism
(b) competition
(c) amensalism
(d) parasitism

Question. Which of the following is the most ecologically relevant environmental factor?
(a) Water
(b) Light
(c) Temperature
(d) Soil

Question. Which of the following might contribute to determining an organism’s habitat?
(a) Amount of sunlight
(b) Temperature of soil
(c) Humidity and other organisms
(d) AII

Question. Which one is correct?
I. In a hot climate.reptiles can maintain a constant body temperature in the day by behavioural regulation.
II. The body temperature of thermoconformers changes with ambient temperature.
III. In aquatic osmoconformers, the osmolarity of. body fluids changes with that of ambient water.
IV. Small animals have a larger surface area relative their volume, they tend to lose body heat very fast when it is cold outside, then they have to expend much energy to generate body heat through metabolism.
(a) All
(b) None
(c) Only IV
(d) I, II, III

Question. Acclimatization (compensatory mechanisms) to altitude sickness includes all except –
(a) Polycythaemia
(b) Hyperveritilation
(c) Asphyxia
(d) Decreasing binding capacity of Mb

Question. Next to temperature, which is the most important factor influencing the life of organisms?
(a) Light
(b) Soil
(c) Water
(d) Wind velocity

Question. Which of the following is not a part of an organism’s physical environment?
(a) Temperature
(b) Water
(c) Shade
(d) Other organisms

Question. Ecology is basically concerned with four levels of biology organizations. These levels are –
(a) Organisms, populations, communities and biomes
(b) Organisms and communities, species and population
(c) Species, populations, biomes and organisms
(d) Organisms, populations, biomes and species

Question. False statement is –
(a) habitat includes both biotic and abiotic factors
(b) Ecology at the organismic level is essential physiological ecology
(c) Abiotic and biotic components interact constantly with each other
(d) None of the above

Question. The location of terrestrial biomes is strongly influenced by –
(a) Which animal species live in the area
(b) Climate
(c) Other nearby biomes
(d) Which plant species live in the area

Question. A few organisms can tolerate and thrive a wide range of temperature. Such animals are called _______.Avast majority of animals are restricted to a narrow range of temperature. Such animals are called ______.
(a) Eurythermal, stenothermal
(b) Stenothermal, eurythermal
(c) Thermoscopic, Unthermoscopic
(d) Thermophobic, thermophilic

Question. Each of the following is an important factor in determining the productivity of fresh water lake except –
(a) Nutrients
(b) Depth
(c) Proximity to marine coast •
(d) Temperature

Question. Human can get homeostasis through-
(a) Only physiological means
(b) Only physical means
(c) Both physiological and physical means
(d) neither physiological nor physical means

Question. Deep (> 500m) in the oceans inhabitants are not aware of existence of a celestial source of energy called
(a) Sun
(b) ATP
(c) Photosynthesis
(d) Chemosynthesis

Question. The nature of soil in a given area is independent of –
(a) Climate
(b) Weathering process
(c) Weather soil is transported or sedimentary and how the soil development occurred
(d) None of the above

Question. The two sides of a given mountain have the same latitude and altitude. Are they likely to have the same climate?
(a) No, because there is likely to be less water on the side of the mountain that faces away from the prevailing wind
(b) No, because there is always on desert on one side of a mountain
(c) Yes, because latitude and altitude are the two most important climate-controlling factors
(d) Yes, because locations at the same latitude all have the same climate

Question. In regions of hot temperatures and wet climate, you will most likely find _______ biomes, whereas in the regions of hot temperature and dry climate you will find _______.
(a) Desert, tropical
(b) temperature, arid
(c) Tropical, desert t
(d) Tundra, chaparral

Question. I. Thermoregulation, osmoregulation and excretion are mechanisms that moderate change in the body.
II. 99% animals and almost all plants are confomers
III. Heat loss or heat gain is a function of surface area.
IV. Thermoregulation energetically least expensive process for many organisms like shrews and humming birds.
V. 99% animals are thermoregulator
VI. Archaebacteria cannot tolerate high temperature
(a) I and II are wrong
(b) IV, V and VI are wrong
(c) None is wrong
(d) All are wrong

Question. Which of the factors dictates the types of animal in a habitat – .
(a) pH of the soil
(b) Type of benthic animals
(c) Types of forests
(d) Types of vegetation that support them

Question. Which of the following term implies the maintenance of relatively constant physical and chemical conditions within organisms?
(a) Homeostasis
(b) Adaptation
(c) Isometry
(d) Acclimation

Question. Find out the false one –
(a) Texture of soil depends upon of size of mineral particles
(b) Soil aeration is inversely proportional to water holding capacity
(c) Waterlogged soil does not suit plants as it creates anaerobic environment
(d) Availability of minerals in soil is independent of soil pH

Question. Many animals use the diurnal and seasonal variations in light intensity and photoperiod as cues timming of –
(a) For age only
(b) Reproductive activities only
(c) Migration only
(d) AII

Question. Animals having a built-in ther mostal to maintain constant body temperature are –
(a) Pliothermic
(b) Poikilothermic
(c) Oligospermic
(d) Homeothermic

Question. To a large extent, the vegetation of an area is determined by –
(a) Physical + chemical properties of soil only
(b) pHofsoil
(c) Physical + Chemical properties of soil and topography
(d) Type of minerals in soil

Question. Seasons are influenced by-
(a) The tilt of earth on its axis
(b) The amount of solar radiation reaching earth’s surface
(c) Earth’s movement around the sun
(d) All

Question. Percolation and water holding capacity of soil is dependent upon –
(a) Soil composition, grain size and aggregation
(b) pH of soil
(c) Colour of soil
(d) holard

Question. The ultimate source of energy for all ecosystems on earth is –
(a) Photosynthesis
(b) Sun
(c) ATP
(d) Creatine phosphate

Question. Which of the following statements is false?
(a) Earth’s climate has varied in temperature overtime
(b) Natural selection acts on the genetic variability present in the population so that it can adapt _
(c) The physical and biotic environments do not interact
(d) The productivity and distribution of plants is heavily dependent upon on water

Question. Life-
(a) Originated on earth in water
(b) Is sustainable with water only
(c) Is possible without water
(d) Both a and c are correct

Question. Snow leopards are not found in Kerala forests. Which factor is responsible for it?
(a) Temperature
(b) Soil
(c) Water
(d) Light

Question. I. Mango trees cannot grow in temperate countries like Canada and Germany
II. Snow leopards are not found in Kerala.
III. Tuna fish are rarely caught beyond tropical latitude in the ocean.
IV. Average temperature exceeds 100°C in thermal springs and hydrothermal vents.
V. In polar areas and high altitudes temperature goes to 70°C.
VI. Temperature goes to > 50°C in tropical desert in summer.
Which of the above statements are false?
(a) I only
(b) II and III only
(c) Vonly
(d) V and VI only

Question. Which of the following accounts for the formation of major biomes?
(a) Annual variations in intensity of temperature
(b) Annual variations in intensity and duration of temperature
(c) Annual variation in precipitation
(d) bandc

Question. What are the key elements that lead to so much variation in the physical and chemical conditions of different habitats?
(a) Temperature and Sight
(b) Soil and water
(c) Only soil
(d) Temperature, light, soil and water

Question. Basic unit of ecological hierarchy is –
(a) Ecosystem
(b) Community
(c) Population
(d) Individual

Question. A regional ecological unit having a specific climate is –
(a) Biome
(b) Landscape
(c) Ecosystem
(d) Biotic community

Question. Select the false statement –
(a) Average temperature on land varies seasonally
(b) Temperature progressively decreases from pole to equator
(c) Temperature progressively decreases from plains to mountain tops
(d) Our intestine is a unique habitat for hundreds of species of microbes

Question. Find out false one-
(a) Mammals from colder climate generally have shorter ears and limbs to minimise heat loss
(b) Some organisms have behavioural adaptations that allow them to respond quickly to a stressful situation
(c) Some organisms possess adaptations that are physiological which allow them to respond quickly to a stressful situation
(d) A large variety of invertebrates and fish live at great depths in the ocean where the pressure could be > 100 times than the normal atmospheric pressure

Question. Choose the odd one out w.r.t adaptations in the organisms –
(a) biochemical adaptation are seen in organisms living in great depth of the ocean to face crushing pressure
(b) en’s rule is seen in mammals living in colder climates
(c) Altitude sickness is caused because of body not getting enough oxygen due to low atmospheric pressure at high altitude
(d) Desert lizards lack the physiological and behavioural means to manage to their body temperature

Question. Choose the odd out w.r.t structure formed in the different organisms during suspended phase.
(a) Bacteria – Thick walled spores
(b) Higher plants – Seeds, vegetative propagules
(c) Zooplankton – Diapause stage
(d) Ectothermic organisms – Torpid state during favourable season.

Question. I. Conformers are the organisms that cannot maintain a constant internal environment.
II. 99% animals and nearly all plants cannot maintain their constant internal environments
III. During the course of evolution, the cost and benefits of maintaining a constant internal environment are discarded.
IV. Conformity is a condition in which an external challenge induces parallel internal changes.
V. Regulation is a condition in which external challenge elicits compensatory action to maintain the internal milien.
(a) All are correct
(b) All are wrong
(c) Only III is wrong
(d) Only IV and V are wrong

Question. Whales, the world’s largest living mammals, live in the ocean, but there are no very smallaquatic mammals why?
(a) They get eaten by larger animals
(b) They cannot regulate body temperature effectively in water
(c) Their kidneys cannot handle life in the marine environment
(d) They lose too much heat from evaporation

Question. Elephants use their ears to dump heat to the environment. What mechanisms might they employ to increase heat loss from ears?
(a) Increased convection due to flapping of the ears
(b) Moving into the sun
(c) Increased blood flow to the ears
(d) a and c

Question. I. Basking by desert lizards in sun
II. Hiding in burrows by some animals
III. Wearing of woolen clothes
IV. Thermal gaping
The above are examples of –
(a) Scansorial adaptation
(b) Behavioral adaptation
(c) Fossorial adaptation
(d) Cursorial adaptation

Question. The Kangaroo rat in North American desert do not drink water. How does it survive in such xeric condition.
(a) Capable of meeting all its water requirements through its internal fat oxidation
(b) Its skin is moist
(c) Hypertonic urine excretion
(d) a and c

Question. Size of population can be decreased by –
(a) A higher birth rate
(b) Immigration
(c) Emigration
(d) Increase in food available

Question. If 4 individuals in a laboratory population of 40 fruitflies died during a specific time (a week) interval, the death rate in the population per week is –
(a) 1
(b) 0.1
(c) 10
(d) 400

Question. I. Organisms living in oceans, lakes and rivers face water-related problems.
II. Euryh ne can tolerate a wide range of s nities
III. Stenoh ne are restricted to a narrow range of s nities
IV. No fresh water animals cannot live for long in sea water but sea animals can live in fresh water for long tim because of osmotic balance
V. The salt concentration is less than 5% in inland water, 30-35% in sea and >100% in some hypers ne lagoonj
(a) All are correct
(b) All are false
(c) Only IV is wrong
(d) Only I, III, V are correct

Question. Major biomes of India include –
(a) Tropical rain forest
(b) Deciduous forest
(c) Desert and sea coast
(d) Ail

Question. Which of the following statement is false w.r.t adaptations?
(a) Many xerophytic plants have thick cuticle on leaf epidermis, sunken stomata
(b) Some xerophytic plants have special photosynthetic pathway (CAM) that enables their stomata close during day
(c) Opuntia has spines (modified leaves), photosynthetic phylloclade (stem)
(d) All adaptations are genetically fixed in all organisms

Question. Organisms have evolved various mechanisms to maintain homeostasis to perform its physiological and biochemical functions. This can be obtained through –
(a) Regulation
(b) Conformation
(c) Migration or suspension
(d) AII

Question. Kangaroo rats –
(a) Have a gener zed diet
(b) Avoid eating fats
(c) Do not need to drink water
(d) Are insensitive to heat

Case Based MCQs

Read the following passage and answer the questions from 41 to 45 given below.
Organism P has thick lips and tongue so that it can easily feed on the commonly available spiny plants. Organism Q has thick layer of insulating fat under the skin. It was strong
hooves to walk steadily on steep surfaces and lives in burrows during winters. Organism R has bright colours and sticky pads on its fingers and toes. It lives on trees.

Question. Which of the following is correct match regarding organism Q and its habitat?
(a) Tundra – Polar bear
(b) Tropical rain forest – Deer
(c) Grassland – Bighorn sheep
(d) Desert – Camel
Answer : A

Question. The dominant plants in habitat where P lives could be
(a) Opuntia
(b) Nymphaea
(c) Deodar
(d) both (a) and (c).
Answer : A

Question. Which of the following is incorrect regarding organisms R’s habitat?
(a) The vegetation shows stratification
(b) Epiphytic growth is rich
(c) Standing crop is highest
(d) Deep rooted shrubs are common due to abundant sunlight
Answer : D

Question. Which of the following is correct habitat fororganisms P regarding its adaptation?
(a) Grassland biome
(b) Desert biome
(c) Tropical rainforest
(d) Tropical deciduous forest
Answer : B

Question. Organisms P, Q and R respectively most likely occur in  (Image 95)
(a) F, B and A
(b) C, A, E
(c) A, F and C
(d) B, D and A.
Answer : C

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