CBSE Class 12 Biology HOTs Organism And Population

Question. The attributes of population but not of the individual are
(a) birth rate
(b) death rate
(c) sex ratio
(d) All of these
Answer : D

Question. Select the statement which explains best parasitism.
(a) One organism is benefitted
(b) Both the organisms are benefitted
(c) One organism is benefitted, other is not affected
(d) One organism is benefitted, other is harmed
Answer : D

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
Answer : B

Question. Ecotone is
(a) a polluted area
(b) the bottom of a lake
(c) a zone of transition between two communities
(d) a zone of developing community
Answer : C

Question. Biosphere is
(a) a component in the ecosystem
(b) composed of the plants present in the soil
(c) life in the outer space
(d) composed of all living organisms present on earth which interact with the physical environment
Answer : D

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
Answer : C

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
Answer : D

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
Answer : D

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 : A

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
Answer : C

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 microclimate
(d) It grows very well because the plant gets more sunlight
Answer : C

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
Answer : D 

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
Answer : B

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
Answer : C

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
Answer : B

Question. Which of the following would necessarily decreasethe den sity of a population in a given habitat?
(a) Natality > mortality
(b) Immigration > emigration
(c) Mortality and emigration
(d) Natality and immigration
Answer : C

Question. A protozoan reproduces by binary fission. What will be the number of protozoans in its population after six generations?
(a) 128
(b) 24
(c) 64
(d) 32
Answer : C

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) 25 millions
(b) 17 millions
(c) 20 millions
(d) 18 millions
Answer : B

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
Answer : B

Question. Lichens are the associations of
(a) bacteria and fungus
(b) algae and bacterium
(c) fungus and algae
(d) fungus and virus
Answer : C

Question. Which of the following is a partial root parasite?
(a) Sandal wood
(b) Mistletoe
(c) Orobanche
(d) Ganoderma
Answer : A

Question. Which one of the following organisms reproduces sexually only once in its lifetime?
(a) Banana plant
(b) Mango
(c) Tomato
(d) Eucalyptus
Answer : A

Question. The correct sequence of levels of biological organisation is
(a) Macromolecules® Cells® Tissues® Organs® Individual organism® Population® Communities® Ecosystem® Biomes
(b) Macromolecules® Tissues® Cells® Organs® Population® Ecosystem® Communities® Biomes 
(c) Micromolecules® Cells® Tissues® Organs® Individual organism® Communities® Population® Biomes® Ecosystem
(d) Macromolecules® Cells® Tissues® Organs® Individual organism® Biomes® Ecosystem® Population® Communities
Answer : A

Question. The study of interactions among organisms and between the organism and its physical (abiotic) environment is
(a) ecosystem study
(b) environmental study
(c) ecology
(d) population study
Answer : C

Question. Identify the basic levels of ecology.
I. Organisms II. Populations
III. Communities IV. Biomes
V. Human VI. Vertebrates
Choose the correct option.
(a) I, II and III
(b) II, III and VI
(c) I, II, III and IV
(d) I, II, III and V
Answer : C

Question. Highest level of biological hierarchy in the given options is
(a) biome
(b) ecosystem
(c) individual
(d) species
Answer : A

Question. An association of individuals of different species living in the same habitat and having functional interaction CBSE-AIPMT 2015
(a) ecological niche
(b) biotic community
(c) ecosystem
(d) population
Answer : B

Question. Different organisms are adapted to their environment in terms of not only survival but also reproduction. This statement belongs to
(a) physiological ecology
(b) species ecology
(c) population ecology
(d) All of these
Answer : A

Question. Major biomes of India include
I. Tropical rainforest II. Alpine region
III. Deciduous forest IV. Desert
V. Himalayan region VI. Sea coast
Choose the correct combination for given question.
(a) I, III, IV and V
(b) I, II, III and IV
(c) II, III, IV and VI
(d) I, III, IV and VI
Answer : D

Question. Formation of major biomes such as desert, rainforest takes place by
(a) rotation of our planet around the sun
(b) tilting of our planet to its axis
(c) Both (a) and (b)
(d) seasonal periodicity
Answer : C

Question. In the given graph, identify Coniferous forest, Arctic and Alpine tundra and Tropical forest, respectively. (Image 9) 
(a) I, VI and III
(b) V, VI and III
(c) IV, III and I
(d) I, II and III
Answer : B

Question. Formation of wide variety of habitats takes place by
(a) types of species inhabiting that area
(b) types of predation
(c) regional and local variation of environment conditions
(d) All of the above
Answer : C

Question. Environmental factor(s) that characterise the habitat of an organism is/are
(a) abiotic components
(b) biotic components
(c) Both (a) and (b)
(d) temperature only
Answer : C

Question. Forest floors, tree canopies and edges of a pond are an example of
(a) microhabitat
(b) microclimate
(c) ecological niche
(d) local biome
Answer : A

Question. The key elements that lead to large variations in the physical and chemical conditions of different habitats are
(a) the physico-chemical (abiotic) components
(b) the biotic components like pathogens, parasites, predators and competitors
(c) Both (a) and (b)
(d) None of the above
Answer : C

Question. A defined range of conditions that an organism can tolerate, diversity in the resources it utilises and a distinct functional role in the ecological system, together comprise
(a) habitat
(b) niche
(c) biome
(d) biosphere
Answer : B

Question. The most ecologically relevant environmental factor is
(a) soil
(b) water
(c) temperature
(d) light
Answer : C

Question. Average temperature of thermal springs and deep seahyd rothermal vents exceeds
(a) 50°C
(b) 60°C
(c) 70°C
(d) 100°C
Answer : D

Question. Temperature is very significant to the living beings because
(a) kinetics of locomotion depend on temperature
(b) kinetics of enzymes depend on temperature
(c) high temperature facilitates digestion
(d) low temperature facilitates digestion
Answer : B

Question. Organisms which are restricted to narrow range of temperature are called
(a) eurythermals
(b) stenothermals
(c) amphithermals
(d) mesothermals
Answer : B

Question. Given below are some animals
I. Reptiles II. Snails
III. Killer whales IV.Green crab
V. Desert pupfish VI. Amphibians
VII. Humans
Identify eurythermals from the given examples.
(a) III, IV, V, and VII
(b) II, III, IV and VI
(c) I, II, III and IV
(d) VII, VI, V and I
Answer : A

Question. The organism which tolerates wide range of salinity called …A… .
The organism which tolerates narrow range of salinity called …B… .
Choose the correct option for A and B.
(a) A–stenohaline, B–euryhaline
(b) A–euryhaline, B–stenohaline
(c) A–isohaline, B–euryhaline
(d) A–heterohaline, B–isohaline
Answer : B

Question. Consider the name of the fishes given below.
I. Salmon II. Shark III. Sting ray Which of them is/are stenohaline and euryhaline?
Stenohaline Euryhaline
(a) I, III II
(b) I, II III
(c) II, III I
(d) I II, III
Answer : C

Question. Many fishes of freshwater cannot live in sea water and vice-versa because of
(a) nutrient
(b) osmotic problems
(c) breathing problems
(d) excretion problems
Answer : B

Question. Sunlight is available as a source of energy and is important in
(a) chemosynthesis
(b) photosynthesis
(c) heterotrophic mode of nutrition
(d) All of the above
Answer : B

Question. In the oceans, the environment is perpetually dark at
(a) more than 100 m
(b) more than 500 m
(c) less than 100 m
(d) less than 500 m
Answer : B

Question. Nature and properties of soil in different places vary due to
(a) climate
(b) weathering process
(c) topography
(d) All of the above
Answer : D

Question. Which characteristics determine the percolation and water holding capacity of soils?
(a) Soil composition
(b) Grain size
(c) Aggregation
(d) All of these
Answer : D

Question. Factor which does not determine the large extent vegetation of any area is
(a) pH of soil
(b) mineral composition of the soil
(c) water holding capacity of soil
(d) weather condition
Answer : D

Question. In aquatic environment, the types of benthic animals are determined by
(a) type of water
(b) type of sediment characteristics
(c) light availability
(d) nutrient availability
Answer : B

Question. During the course of million of years of their existence most species should have evolved a relatively ...A... internal environment (within the body of organisms). This internal environment would permit all biochemical reactions and physiological functions to proceed with ...B... efficiency and therefore, increase the overall fitness of the species in terms of ...C... .
Choose the correct option for A, B and C.
(a) A–constant, B–minimal, C–thermoregulation
(b) A–constant, B–maximal, C–homeostasis
(c) A–variable, B–minimal, C–osmoregulation
(d) A–constant, B–versatile, C–homeostasis
Answer : B

Question. Homeostasis is
(a) maintaining a constant internal environment
(b) maintaining a constant external environment
(c) Both (a) and (b)
(d) maintaining circulation of blood
Answer : A

Question. Identify the lines present in the given graph A, B and C.
(a) A–Partial regulators, B–Regulators, C–Endotherms
(b) A–Partial regulators, B–Ectotherms, C–Endotherms
(c) A–Partial regulators, B–Regulators, C–Conformers
(d) A–Conformers, B–Ectotherms, C–Partial regulators
Answer : C

Question. Attribute of the organisms (morphological, physiological and behavioural) that enable organisms to survive and reproduce in its habitat are called
(a) phenotypic plasticity
(b) adaptations
(c) mimicry
(d) surviving abilities
Answer : B

Question. In the absence of an external source of water,Kangaroo rat in North American desert is capable of meeting all its water requirements through 
(a) internal fat oxidation
(b) taking liquid food
(c) reducing his activities
(d) hibernation
Answer : A

Question. Which is the characteristic of desert plant adaptation?
(a) Thick cuticle on their leaf surface
(b) Stomata arranged in deep pits
(c) Stomata remain closed during day (CAM)
(d) All of the above
Answer : D

Question. Regulators are the animals which
(a) does not maintain their body homeostasis
(b) can maintain their body homeostasis
(c) can regulate their heartbeat
(d) can regulate their circulation
Answer : B

Question. ...A... regulators are able to maintain homeostasis by means which ensure constant body temperature, constant osmotic concentration, etc. All ...B... and ...C... are a very few lower vertebrates and invertebrate species are indeed capable of such regulation (thermoregulation and osmoregulation). Evolutionary biologists believe that the ‘success’ of mammals is largely due to their ability to maintain a constant body ...D... and thrive whether they live in Antarctica or in the Sahara desert.
Choose the correct option for A, B, C and D.
(a) A–Behavioural, B–vertebrates, C–invertebrates, D–temperature
(b) A–Behavioural, B–bird, C–mammals, D–temperature
(c) A–Physiological, B–bird, C–mammals, D–temperature
(d) A–Behavioural, B–vertebrates, C–invertebrates, D–morphology
Answer : C

Question. Regulators are also called
(a) endotherms
(b) exotherms
(c) ectotherms
(d) Either (b) or (c)
Answer : A

Question. What percentage of animals on this earth are regulators and conformers, respectively?
(a) 2%, 98%
(b) 7%, 93%
(c) 4%, 96%
(d) 1%, 99%
Answer : D

Question. Partial regulators are the organisms which
(a) can regulate body temperature to larger extent of environmental condition
(b) can regulate body temperature to limited extent of environmental condition
(c) can regulate body temperature only over a wide range of environmental condition
(d) None of the above
Answer : B

Question. An overwhelming majority ...A... of animals and nearly all plants cannot maintain a constant internal environment. Their body temperature ...B... with the ambient temperature. In aquatic animals, the osmotic concentration of the body fluids ...C... with that of the ambient water osmotic concentration. These animals and plants are simply conformers.
Choose the correct option for A, B and C.
(a) A–98%, B–changes, C–constant
(b) A–97%, B–constant, C–changes
(c) A–96%, B–changes, C–constant
(d) A–99%, B–changes, C–changes
Answer : D

Question. Conformers are inactive in adverse conditions due to
(a) inability to move
(b) inability to digest properly
(c) inability to maintain homeostasis
(d) ability to maintain homeostasis
Answer : C

Question. It can be said that some animals in their evolutionary development preferred to be conformers than regulators. Which of the following can be the best suited reason for it?
(a) The metabolic reactions of these organisms can occur at a very wide range of temperature
(b) Maintaining homeostasis is an energetically expensive process
(c) The enzymes of these organisms are functional at high temperatures
(d) Both (b) and (c)
Answer : C

Question. Conformers are also called
(a) endotherms
(b) ectotherms
(c) Both (a) and (b)
(d) isotherms
Answer : B

Question. Very small animals are rarely found in polar region because
(a) small animals have a larger surface area relative to their volume, so they lose body heat very fast when it is cold outside
(b) small animals have a smaller surface area relative to their volume, so they lose body heat very fast when it is cold outside
(c) small body volume makes internal heat production very difficult
(d) None of the above
Answer : A

Question. Every winter the famous ...A... (Bharatpur) in Rajasthan host thousands of migratory birds coming from ...B... and other extremely cold ...C... regions.
Fill in the blanks A, B and C.
(a) A–Keolado National Park, B–America, C–West
(b) A–Keolado National Park, B–Mexico, C–Eastern
(c) A–Keolado National Park, B–Siberia, C–Northern
(d) A–Keolado National Park, B–Siberia, C–Southern
Answer : C

Question. In bacteria, fungi and lower plants, various of thick-walled ...A... are formed, which help them to survive ...B... conditions-these germinate on availability of suitable environment. In higher plants, ...C... and some other vegetative reproductive structures serve as means to tide over periods of stress besides helping in dispersal-they germinate to form new plants under favourable moisture and temperature conditions.
Choose the correct option for A, B and C.
(a) A–spores, B–unfavourable, C–seeds
(b) A–seeds, B–unfavourable, C–spores
(c) A–seeds, B–favourable, C–spores
(d) A–spores, B–favourable, C–seeds
Answer : A

Question. Animals like snail and fish go into …… to avoid summer related problem and animal like bear go into …… to avoid winter related stress.
(a) aestivation, migration
(b) migration, hibernation
(c) aestivation, hibernation
(d) hibernation, aestivation
Answer : C

Question. Diapause is a
(a) stage of development
(b) stage of suspended development
(c) stage of delayed morphology
(d) rapid developmental stage
Answer : B

Question. Which of the following is an incorrect match?
(a) Bacteria — Thick-walled resting spores
(b) Bear — Hibernation
(c) Lizard — Diapause
(d) Fish — Aestivation
Answer : C

Case-based MCQs

I. Read the following text and answer the following questions on the basis of the same :
All biomes of the earth constitute the earth’s ecosystem. All flora and fauna occur in the lithosphere, atmosphere and hydrosphere along with their environments. Air, water, soil, biota,
temperature and light are the major environmental factors that directly affect the flora and fauna in different geological areas of the earth.

Question. Hydrological cycle is concerned with :
(a) Lithosphere
(b) Hydrosphere
(c) Atmosphere
(d) All of these.
Answer : D

Question. Climate of an area depends upon :
(a) Altitude of the area
(b) Latitude of the area
(c) Topography
(d) Both (a) and (b).
Answer : D

Question. Edaphology is concerned with study of :
(a) Soil
(b) Climate
(c) Biota
(d) Topography
Answer : A

Question. Soil aeration is inversely proportional to :
(a) Soil pore spaces
(b) Diameter of soil particles
(c) Water holding capacity of soil
(d) None of the above.
Answer : C

Directions : In the following questions a statement of Assertion (a) is followed by a statement of reason (R). Mark the correct choice as :
(a) Both Assertion (a) and reason (R) are true and reason (R) is the correct explanation of Assertion (a).
(b) Both Assertion (a) and reason (R) are true but reason (R) is not the correct explanation of Assertion (a).
(c) Assertion (a) is true but reason (R) is false.
(d) Assertion (a) is false but reason (R) is true.

Question. Assertion (a) : Some organisms like Salmon are known as Euryhaline.
Reason (R) : Euryhalines can tolerate a wide range of salinities.
Answer : A

Questions And Answer

Question. Flowers have different adaptations for pollination (essential for reproduction), one of them being colour. But night blooming flowers are generally white in colour. Why? 
Answer. Such flowers depend mainly on fragrance; also the white colour has reflective effect so it becomes visible during night.

(a) What is the terminology for B& E.?

(b) If B + I is more then D + E then what will happen to population density?

(c) What are the most important factors which influence a population density of an area under normal condition ?

(d) If a habitat is being colonised recently then which factor contribute more to the population growth ?

Answer. (a) B- Natality ( births), E- Emigration

      (b) Population density will increase

      (c) Births and deaths

      (d) Immigration.

 

Question. Abingdon tortoise in Galapagos Island became extinct with in a decade after goatswere introduced on the island. Why? What could be principle behind this situation? 

Answer. Greater browsing efficiency of goat’s. Gause’s Competitive Exclusion Principle

 

Question. An orchid plant is growing on the branch of a mango tree. How do we describe this interaction b/w orchid and mango tree? 

Answer. Commensalism.

 

Question. Mutualism often involves co-evolution of the mutualist . Explain this statement taking example of plant animal relationship? 

Answer. Evolution of the flowers & its pollinator species.

Ex. Fig species can be pollinated only by its partner wasp species and no other species. In turn female fly uses the fruit for laying its egg as well as nourishment of its larvae from the developing speed.

 

Question . Name the type of population interaction in each of the following 1,2,3,4

Ans.14 a) Commensalisms

          b) Competition

          c) Amensalism

          d) Mutualism

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ANSWERS:

1) Microbes posses physiological and biochemical adaptations which allow them to live in habitats with temperature exceeding. 100°c. There are branched chain lipids in the cell membrane and special resistant enzymes which deal with high temperatures.

2) Commensalisms, In this interaction the orchid is benefitted on attaining the support where as ,mango tree is neither benefitted nor harmed.

3) Due to low atmospheric pressure at higher attitudes body compensates low oxygen availability by increasing red blood cell production, decreasing the binding affinity of hemoglobin and by increasing breathing rate.

4) The plant produces highly poisonous cardiac glycosides.

5) Gause's competitive exclusion principle

6) Declining population.

7) Goats have greater browsing efficiency and hence the tortoises died of lack of food. 

2 marks

1) Curve 'a' represents exponential growth where the resources are not limiting the growth.
b) Curve 'b' represents logistic growth where the resources are limiting the growth

2)a) Logistic growth curve
b) N= population density at-time 't'
r=Intrinsic rate of increase
K= carrying capacity

3) Kangaroo rat is capable of meeting all its water requirement through its internal fat oxidation in which water is a by -product. It has the ability to concentrate urine.

4) Smaller animals tend to lose more body heat due to large surface area relative to their volume. Therefore, they have to spend more energy to generate body heat.

5) No, it will not survive in fresh water aquarium because of osmotic problem it would face.

6) Change in temperature from their established habitats affects the kinetics of the enzymes and through it the basal metabolism, activity and other physiological functions of the organism.

3 marks

1) Atmospheric pressure in Rohtang pass, which is at high altitude, is low and hence the body does not get enough oxygen. Ram is suffering from altitude sickness.
If he stays for long the following change will occur in the body and he will become acclimatised to the conditions.
a)RBC production increases
b) Breathing rate increases
c) Binding capacity of hemoglobin decreases.

2) a) Relation between sea anemones and hermit crab is mutualism since sea anemones protects the hermit crab and crab provides bits of food to sea anemone, thus both benefitted.
b) Relation between shark and suckerfish is commensalisms because only sucker fish gets food and is benefitted while shark is neither harmed nor benefitted.
c) Relation between sea anemone and clown fish is also commensalism since only the fish gets protection from predators.