NEET Biology Organism And Its Environment Multiple Choice Question And Answers

Biology MCQs with answers for NEET Organism And Its Environment

Question 1. Different organisms are adapted to their environment in terms of not only survival but also reproduction’.

This statement belongs to

1. Physiological ecology
2. Species ecology
3. Population ecology
4. All of the above

Answer: 1. Physiological ecology

Ecology at the organism level is essentially called physiological ecology which tries to understand how different organisms are adapted to their environments.

Question 2. A wide variety of habitats are formed by

1. Different kinds of species inhibiting that area
2. Different kinds of predation
3. Regional and local variations of environmental conditions
4. All of the above

Answer: 3. Regional and local variation of environmental conditions

Regional and local variations of environmental conditions within each biome lead to the formation of a wide variety of habitats.

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Question 3. Major biomes of India include

1. Tropical rainforest
2. Alpine region
3. Deciduous forest
4. Desert
5. Himalayan region
6. Sea Coast

Choose the correct combination for a given question.

1. 1, 3, 4 And 5
2. 1, 2, 3 And 4
3. 2, 3, 4 And 6
4. 1, 3, 4 And 6

Answer: 4. 1, 3, 4 And 6

“organism and population neet pyq “

There are four major biomes in India tropical rainforest, deciduous forest, desert, and sea coast.

According to the climate conditions, there are four major forest types in India.

Forest Types

• Mean Annual Temperature
• Tropical rainforest – 23-27ºC
• Tropical deciduous forest – 22-32ºC
• Temperate broad-leaved forest – 6-20°C
• Temperate needle-leaved forest – 6-15°C

Thus, option (4) is correct.

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Question 4. The formation of major biomes such as deserts, and rainforests takes place by

1. Rotation of earth around the sun
2. Tilting of the earth on its axis
3. Both (1) and (2)
4. None of the above

Answer: 4. Both (1) and (2)

The rotation of our planet around the sun and the tilt of the earth on its axis causes annual variations in the intensity and duration of the temperature, which leads to the formation of major biomes. Thus, option (3) is correct.

Question 5. Which determines the flora and fauna of a place?

1. Weather
2. Climate
3. Both (1) and (2)
4. Habitat

Answer: 2. Climate

Climate

• It is the long-term property of the atmosphere. It is an average weather.
• The climate is the same over larger areas.
• Climate determines the flora and fauna of a place.
• Climate remains the same over a long period of time.

Question 6. Severe winters with few months of summer are found in

1. Tundra
2. Arctic
3. Taiga
4. Antarctica

Answer: 1. Tundra

Light is very poor in Tundra with temperatures as low as –30 to –40°C in winter. Summer is only for about 60 days with l0ºC.

Question 7. Match the following columns.

Answer: 4. A-6, B-5, C-4, D-3, E-2, F-1, G-7

Biology MCQs with answers for NEET

Question 8. Which part of the world has a high density of organisms?

1. Grasslands
2. Savannahs
3. Deciduous forests
4. Tropical rainforests

Answer: 4. Tropical rainforests

• Tropical rainforests occur in equatorial and subequatorial regions. The forests receive all the external inputs for optimum plant growth.
• Due to abundant plant growth, a large number of animals live in tropical rainforests. Thus, tropical rainforests of the world have a high density of organisms.
• Other options are explained as If grassland fire occurs periodically it prevents tree growth. In savannahs, periods of drought are common. In deciduous forests are found
  predominantly broad-leaved hardwood deciduous trees.

Question 9. Select the incorrect statement about the coniferous forest.

1. They are found in cold regions of heavy rainfall and high humidity
2. They have long winters with short summers
3. The soil is basic (alkaline) and mineral-rich
4. Essential nutrients like ca, n, and k are leached down due to the absence of evaporation

Answer: 3. The soil is basic (alkaline) and mineral-rich

The statement in option (3) is incorrect and can be corrected as The soil in the coniferous forests is low in minerals and nutrient content. The soil is light in color and usually acidic in nature. Rest statements are correct about coniferous forests.

Question 10. Dense evergreen vegetation of broad sclerophyllous leaves and shrubs with fire-resistant resinous plants is known as

1. Chaparral vegetation
2. Savannah vegetation
3. Steppe grassland
4. Tundra vegetation

Answer: 1. Chaparral vegetation

Chaparral vegetation is composed of broad-leaved evergreen shrubs, bushes, and small trees usually less than 2.5 m (about 8 feet) tall. It is an evergreen shrub forest that usually contains resin but is resistant to fires. Chaparral is found in regions with a climate similar to that of the Mediterranean area, characterized by hot, dry summers and mild, wet winters.

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Question 11. Plants such as Prosopis, acacia, and Capparis represent examples of tropical

1. Thorn forests
2. Deciduous forests
3. Evergreen forests
4. Grasslands

Answer: 1. Thorn forests

• Prosopis, Acacia, and Capparis are non-succulent, thorny hot desert plants, i.e. examples of thorn forest plants. Other options are explained as Deciduous forests are present in both the Northern and Southern hemispheres and contain broad-leaved, hardwood deciduous trees, for example. oak, maple, chestnut, etc.
• Evergreen forests occur in equatorial and sub-equatorial regions important plants are rosewood ebony, mahogany, fig, etc. Grasslands are large plains covered by grasses.

Question 12. One of the following biomes has evergreen vegetation and animals well-adapted to drought

1. Chaparral
2. Veldts
3. Tundra
4. Pampas

Answer: 1. Chaparral

The extreme conditions found in the chaparral biome are very different just like day and night. As a result, animals and plants that live here have to be highly adaptable.

Question 13. Which one of the following pairs is mismatched?

1. Tundra – permafrost
2. Savannah – acacia trees
3. Prairie – epiphytes
4. Coniferous forest – evergreen trees

Answer: 3. Prairie – epiphytes

(3) Option (3) is a mismatched pair and can be corrected as Prairie is grassland and epiphytes and ephemerals are found in the desert. Rest options are correct matched pairs as

• In Tundra, much of the ground stays frozen around the year, this condition is called permafrost.
• The Acacia trees are common in African savannahs.
• In coniferous forests, all plants do not shed their leaves at the same time hence forests remain evergreen.

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Question 14. The presence of plants arranged into well-defined vertical layers depending on their height can be seen best in

1. Tropical savannah
2. Tropical rainforest
3. Grassland
4. Temperate forest

Answer: 2. Tropical rainforest

Tropical rainforest exhibits five different vertical strata, i.e. ground vegetation, shrubs, short canopy trees, tall canopy trees, and tall emergent trees.

Question 15. The geographical limit within which a population exists is called

1. Niche
2. Ecosystem
3. Habitat
4. Biome

Answer: 3. Habitat

The geographical limit within which a population exists is called habitat. A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant, or other type of organism.

Question 16. According to Odum, …………… Is the address of an organism.

1. Habitat
2. Niche
3. Adaptation
4. Community

Answer: 1. Habitat

According to Odum, habitat is the address of an organism and a niche is its ‘profession’.

Question 17. Environmental factors that characterize the habitat of an ecosystem is/are

1. Abiotic components
2. Biotic components
3. Both (1) and (2)
4. Temperature

Answer: 3. Both (1) and (2)

• The most important elements that lead to so much variation are temperature, water, light, and soil.
• Physiochemical components alone do not characterize the habitat of an organism completely.
• They include biotic factors also. So, for the characterization of habitat, both abiotic and biotic components are needed. Thus, option (3) is correct.

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Question 18. Biotic factors are

1. Chemical factors of soil which affect life
2. Physical factors of soil which affect life
3. Any living component that affects another organism
4. Factors of atmosphere that affect life

Answer: 3. Any living component that affects another organism

Biotic components or biotic factors can be described as any living component that affects another organism or shapes the ecosystem.

Question 19. Which of the following factors cannot be regarded as non-living?

1. Light
2. Temperature
3. Interspecific competition
4. Rainfall

Answer: 3. Interspecific competition

Interspecific competition in ecology is a form of competition in which individuals of different species compete for the same resources in an ecosystem (for example. food or living space). So, it is not regarded as a non-living factor.

Question 20. Which of these is an edaphic factor?

1. Soil
2. Light
3. Rainfall
4. Wind

Answer: 1. Soil

Edaphic factors are environmental conditions that are determined by the physical, chemical, and biological characteristics of the soil.

Question 21. Which of the following is an indirect ecological factor?

1. Temperature
2. Soil structure
3. Light
4. Air

Answer: 2. Soil structure

Temperature, light, and air are direct ecological factors because these factors have a direct influence on the processes and behavior of the organisms. So, soil organism slopes are indirect ecological factors.

Question 22. Abiotic factors affect

1. Structure of organisms.
2. Physiology of organisms.
3. Behaviour of organisms.

Choose the correct option.

1. 1 And 2
2. 2 And 3
3. 1, 2 And 3
4. 1 And 3

Answer: 3. 1, 2 And 3

Abiotic factors are non-living or physical factors that influence the survival, growth, structure, physiology, behavior, interactions, and reproduction of organisms in an ecosystem. Thus, option (3) is correct.

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Question 23. Niche is

1. All the biological factors in the organism’s environment
2. The functional role played by the organism where it lives
3. The range of temperature that the organism needs to live
4. The physical space where an organism lives

Answer: 2. The functional role played by the organism where it lives

Ecological niche was termed by J. Grinnell. It refers to the functional role played by the organism where it lives.

Question 24. Temperature decreases progressively from the

1. The equator towards the poles
2. Poles towards the equator
3. Plain towards mountain
4. Both (1) and (3)

Answer: 4. Both (1) and (3)

Temperature decreases progressively from the equator towards the poles because the sun is less far from the equator and it receives more direct sunlight as we go to the equator it decreases and in poles, it becomes very little or none.

Question 25. Temperature plays a key role in the sustenance of living beings because

1. Kinetics of locomotion depend on temperature
2. The Kinetics of enzymes depend on the temperature
3. High temperature facilitates digestion
4. Low temperature facilitates digestion

Answer: 2. Kinetics of enzymes depend on temperature

Enzymes are very sensitive to variations in temperature. A slight decrease or increase in temperature can cause denaturation or inactivation of enzymes. That way temperature is very significant to living beings.

Question 26. Metabolic reactions in animals take place at very …… temperature ranges as enzymes are sensitive to temperature changes. But for some microorganisms such as those living in deep-sea thermal vents or geysers, metabolism occurs at a temperature beyond … b….

1. A–narrow, b–100°c
2. A–broad, b–100°c
3. A–median, b–100°c
4. A–broad, b–40°c

Answer: 1. A–narrow, b–100°c

Question 27. The temperature gradient over the earth’s surface is

1. 6.4 to 6.5ºc per 1000 m altitude
2. 6.4 to 6.5ºc per 1000 m latitude
3. 7.5 to 9.5°c per 1000 m latitude
4. 7.5 to 9.5°c per 1000 m altitude

Answer: 1. 6.4 to 6.5ºc per 1000 m altitude

• The temperature gradient over the earth’s surface is 6.4-6.5ºC per 1000 m altitude or 10° latitude. Therefore, there is a lowering of mean temperature from the equator to the poles.
• Tropical, subtropical, temperate, and Arctic organisms living in these zones are respectively called megatherms, mesotherms, microtherms, and hekistotherms.

Question 28. The average temperature of thermal springs and deep-sea hydrothermal vents exceeds

1. 50°C
2. 60°C
3. 70°C
4. 100°C

Answer: 4. 100°C

There are unique habitats such as thermal springs and deep-sea hydrothermal vents where average temperature exceeds 100°C.

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Question 29. Organisms that can tolerate a narrow range of temperatures are called

1. Polythermal
2. Stenothermal
3. Oligothermal
4. Eurythermal

Answer: 2. Stenothermal

Stenothermal organisms are those organisms, which can tolerate a narrow range of temperature. They live within a narrow range of temperatures because of their requirement for nearly constant temperature throughout the year, for example. amphibians, reptiles.

Question 30. Eurythermal are

1. Organisms that can tolerate a wide range of temperature
2. Organisms that can tolerate a low range of temperature
3. Organisms that cannot tolerate a low range of temperature
4. Organisms that cannot tolerate a wide range of temperature

Answer: 1. Organisms that can tolerate a wide range of temperature

“population attributes “

Eurythermal organisms are those organisms, that can tolerate a wide range of temperature variations. Most mammals and birds can live in very wide temperature variations.

Question 31. Given below are examples of various organisms. Identify stenothermals from the given examples.

1. Birds
2. Family-Asteraceae
3. Polar bear
4. Human
5. Lizards
6. Amphibians
7. Coconut

Choose the correct option.

1. 3, 5, 6 And 7
2. 2, 3, 4 And 6
3. 1, 2, 3 And 4
4. 7, 6, 5 And 1

Answer: 1. 3, 5, 6 And 7

Stenothermal organisms are those organisms, that live within a narrow range of temperatures because of their requirement of nearly constant temperature throughout the year, e.g. polar bears, lizards, amphibians, and coconut (warm tropical areas). Thus, option (1) is correct.

Question 32. The organisms present in tropical regions are

1. Mesotherms
2. Megatherms
3. Microtherms
4. Hekistotherms

Answer: 2. Megatherms

Organisms, which present in tropical regions are called megatherms. Tropical, subtropical, temperate, and Arctic organisms living in these zones are respectively called megatherms, mesotherms, microtherms, and hekistotherms.

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Question 33. Match the following columns.

Answer:

Question 34. The productivity and distribution of plants mainly depend on

1. Soil
2. Temperature
3. Water
4. Light

Answer: 3. Water

A–3, B–2, C–1

“population attributes “

Question 35. Life on Earth is said to have originated in

1. Air
2. Water
3. Soil
4. All of these

Answer: 3. Soil

Next to temperature water is the most important factor that influences life. Life originated in water. Life is unsustainable without water.

Question 36. Salt concentration (parts per thousand) is less than 5% in

1. Sea water
2. Inland water
3. Hypersaline water
4. Freshwater

Answer: 2. Inland water

• The salinity of water bodies is generally measured in parts per thousand. It determines what kind of organisms can live in it.
• The salinity of the sea is 30-35 parts per thousand, while inland water and some lagoons is less than 5 parts per thousand or more than 100 parts per thousand, respectively.

Question 37. Salt concentration in

1. Sea water is …a…
2. Hypersaline water is …b….

Choose the correct option for a and b.

1. A–30-35%, b–>100%
2. A–> 100%, b–30-35%
3. A–>100%, b–<10%
4. A–< 10%, b–< 10%

Answer: 1. A–30-35%, b–>100%

Question 38. An animal species was found to have a wide tolerance towards salinity and habitat conditions but narrow towards temperature conditions. Which of the following options expresses the said species correctly?

1. Stenothermal, euryhaline, and precious
2. Eurythermal, stenohaline and stenophagic
3. Eurythermal, trihydric, and tenacious
4. Stenophagic, euryhaline, and eurythermal

Answer: 1. Stenothermal, euryhaline, and precious

Question 39. 1. Eel, 2. Whale, 3. Sting ray which of them is/are stenohaline and euryhaline?

Stenohaline euryhaline

1. 1, 3 2
2. 1, 2 3
3. 2, 3 1
4. 1 2, 3

Answer: 1. 1, 3 2

Stenohaline (whale and string rays) and euryhaline (eel). Thus, option (3) is correct.

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Question 40. The plant of this group is adapted to live partly in the water, partly above the substratum, and free from water.

1. Xerophytes
2. Thalophytes
3. Halophytes
4. Hydrophytes

Answer: 3. Halophytes

“population attributes “

• Halophytes are plants adapted to grow in saline conditions. They adapted to live partly in water, partly above the substratum, and free from water. They grow in mangroves, coastal dunes, and marshes.
• The environmental conditions are high salinity and high levels of water. A number of these plants possess negatively geotropic vertical roots called pneumatophores.

Question 41. Pneumatophores are characteristic of

1. Halophytes
2. Freshwater plants
3. Oxylophytes
4. Psammophytes

Answer: 3. Oxylophytes

• Halophytes are plants adapted to grow in saline conditions. They adapted to live partly in water, partly above the substratum, and free from water. They grow in mangroves, coastal dunes, and marshes.
• The environmental conditions are high salinity and high levels of water. A number of these plants possess negatively geotropic vertical roots called pneumatophores.

Question 42. Which of the following is a xerophytic condition?

1. High temperature and high humidity
2. High temperature and low humidity
3. Low temperature and high humidity
4. Low temperature and low humidity

Answer: 2. High temperature and low humidity

A xerophyte is a species of plant that has adaptations to survive in an environment with low humidity and high temperatures such as a desert or an ice or snow-covered region in the Alps or the Arctic.

Question 43. Xerophytes are mostly

1. Succulents
2. Water-related
3. Mesophytes
4. None of the above

Answer: 1. Succulents

Desert plants (xerophytes) are generally succulent, i.e. the plants conserve water by storing it in fleshy leaves or stems.

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Question 44. Which of the following is an ecological energy source?

1. Air
2. Sunlight
3. Soil
4. Both (2) and (3)

Answer: 2. Sunlight

Sunlight is the primary ecological energy source for all living organisms.

“population attributes “

Question 45. Sunlight is crucial for

1. Photosynthesis
2. Heterotrophic mode of nutrition
3. Chemosynthesis
4. All of the above

Answer: 1. Photosynthesis

Light is essential for photosynthesis. The amount of photosynthesis depends upon the quality, intensity, and duration of light. Photosynthetic yield is maximum in equator and tropical areas.

Question 46. Photosynthetic yield is maximum at the

1. Equator region
2. Polar region
3. Both (1) and (2)
4. Arid region

Answer: 1. Equator region

In tropical areas (equator region), there is more sunlight than the other areas. So, tropical areas have more photosynthetic yield than other areas.

Question 47. Differentiation in certain organisms occurs in light. It is called

1. Morphogenesis
2. Photomorphogenesis
3. Organogenesis
4. Embryogenesis

Answer: 2. Photomorphogenesis

• In plants, growth is favored by increased availability of food, moderate light intensity, and red light. Maximum photosynthesis occurs in red light. Blue light favors moderate but normal growth.
• The differentiation of various tissues and organs in response to light is called photomorphogenesis.

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Question 48. The radiation with a greater wavelength than visible light is

1. Uv
2. Ir
3. Microwaves
4. Radiowaves

Answer: 1. Uv

• Radiation below the visible light (less than 400 nm) is ultraviolet (UV) radiation, while those above (more than 700 nm) the visible light are infrared or heat waves.
• The amount of light and its intensity vary with latitude and season. Light intensity, light duration, and light quality influence a number of life processes of organisms.

Question 49. Plants adapted to grow in shade are

1. Psammophytes
2. Sciophytes
3. Mesophytes
4. Xerophytes

Answer: 2. Sciophytes

Sciophytes are shade plants that grow in 10 areas having moderate to low intensity of light. Optimum growth occurs with light of 10-30% of full sunlight.

Question 50. The sun-loving plants are referred to as

1. Halophytes
2. Heterotrophs
3. Sciophytic
4. Heliophysics

Answer: 4. Heliophytic

Heliophytes are plants which grow under sunlight. Their buds lie in the mud. They are referred to as sun-loving plants. Other options are explained as

• Halophytes are plants that grow in saline soil.
• Sciophytes are those plants that grow in shades.
• Heterotrophic organisms do not make their own food and depend on other plants and animals for their nutritional requirements.

“population attributes “

Question 51. The environment is perpetually dark in oceans at depths of

1. More than 100 m
2. More than 500 m
3. Less than 100 m
4. Less than 500 m

Answer: 2. More than 500 m

Deep (>500 m) in the oceans, the environment is perpetually dark and its inhabitants are not aware of the existence of celestial sources of light.

Question 52. In which area, do diurnal temperatures in the soil surface vary?

1. Sea
2. Lake
3. Tundra
4. Desert

Answer: 4. Desert

Diurnal temperature variations are greatest very near the earth’s surface. High desert regions typically have the greatest diurnal temperature variations, while low-lying humid areas typically have the least.

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Question 53. Edaphology is the relationship between

1. Plant and biosphere
2. Soil and living organisms
3. Animal and ecosystem
4. Soil and biosphere

Answer: 2. Soil and living organisms

• Edaphic factors are environmental conditions that are determined by the physical, chemical, and biological characteristics of the soil.
• The study of edaphic factors is called edaphology. So, edaphology is the relationship between soil and living organisms.

Question 54. Plants that grow in sandy soil are known as

1. Heliophytes
2. Psammophytes
3. Sciophytes
4. Mesophytes

Answer: 2. Psammophytes

Plants growing on sandy soils are known as psammophytes. Psammophytic plants can be grown on sand and gravel. So, these plants can convert desert areas into greenland.

Question 55. What is the best pH of the soil for the cultivation of plants?

1. 3.4-5.4
2. 6.5-7.5
3. 4.5-8.5
4. 5.5-6.5

Answer: 4. 5.5-6.5

• Soil nature is described in pH values. It can be alkaline, acidic, or neutral. Highly acidic and highly saline soil often remains injurious to plant growth, microorganisms, etc.
• Soil pH strongly affects microbial activities. Neutral or slightly acidic soil (5.5-6.5) remains best for the growth of the majority of plants.

Question 56. Soil salinity is measured by

1. Parameter
2. Potometer
3. Calorimeter
4. Conductivity meter

Answer: 4. Conductivity meter

“population attributes “

• The conductivity meter measures soil salinity. A photometer is used for measuring the rate of transpiration. A pedometer is an apparatus for knowing the relative sizes of stomata.
• A calorimeter is an object used for calorimetry for the process of measuring the heat at any chemical reaction.

Question 57. Abundant plant growth can be observed in

1. Acidic soil
2. Basic soil
3. Neutral soil
4. Slightly acidic soil

Choose the option containing the correct combination.

1. 1 And 2
2. 2 And 3
3. 1 And 3
4. 3 And 4

Answer: 4. 3 And 4

• Most of the plants grow in neutral or slightly acidic soil with pH = 6.5.
• Some plants like chilli grow in acidic soil (pH = 5).
• Basic soils are clay soils with high pH, a poor soil structure, and a low infiltration capacity. Thus, option (4) is correct.

Question 58. A major source of soil moisture is

1. Rainwater
2. Underground water
3. River water
4. Atmospheric humidity

Answer: 1. Rainwater

The major source of soil moisture is mainly rainwater, which is retained by the soil. Sand can retain very less water and clay soil can retain maximum water.

Question 59. Clay soil is obtained

1. In desert
2. On seashore
3. Around ponds
4. On rocks

Answer: 3. Around ponds

Clay particles are rich in nutritive salts and can hold or retain water very firmly. They are mostly found near lakes and ponds.

Question 60. Good soil is

1. Which holds the whole of the water that enters into it
2. Which allows the percolation of the water slowly from it
3. Which allows water to pass very quickly from it
4. Which allows a limited amount of water to be retained in it

Answer: 1. Which holds the whole of the water that enters into it

“population attributes “

A good soil is one that is airy, has water held between its particles, and allows slow percolation of water.

Question 61. Main factors determining the vegetation of any area.

1. Ph of soil.
2. Mineral composition of the soil.
3. Water holding capacity of soil.
4. Precipitation.

Choose the correct option.

1. 1 And 2
2. 2 And 3
3. 1, 2 And 3
4. 1, 2, 3 And 4

Answer: 3. 1, 2 And 3

All given factors (1, 2, and 3) determine the vegetation of any area except 4.

• Weather changes have little impact on the flora and fauna of a place because it is the short-term property of the atmosphere and it changes from place to place. pH, mineral, water water-holding capacity of soil determine the flora and fauna of any area.
• Incorrect factors can be corrected as Precipitation also plays a key role in determining the vegetation of an area. Thus, option (3) is correct.

Question 62. Identify the factors that affect the property and nature of soil in different places.

1. Climate
2. Weathering process
3. Topography
4. All of the above

Answer: 4. All of the above

• Soil nature and properties of soil depend on climate, topography, and the weathering process or weathering of rocks into fine powder can occur due to atmospheric changes, mechanical forces, chemical changes, and biological breakdown.
• The physical and chemical properties of soil determine the type of plants that can grow in a particular habitat and the characteristics of the bottom sediments of the aquatic environment determine the type of benthic animals. Thus, option (4) is correct.

Question 63. Homeostasis is

1. The tendency of biological systems to change with changes in the environment
2. The tendency of biological systems to resist change
3. Disturbance of self-regulatory system and natural controls
4. Biotic materials used in homeopathic medicines

Answer: 2. Tendency of biological systems to resist change

Homeostasis is any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival. It is the tendency of biological systems to resist change.

Question 64. The figure given below is a diagrammatic representation of the response of organisms to abiotic factors. What does a, b, and c represent respectively?

1. Conformer regulator partial regulator
2. Regulator partial regulator conformer
3. Partial regulator conformer
4. Regulator conformer partial regulator

Answer: 4. Regulator conformer partial regulator

• In the graph, line A represents the regulator, line B represents the conformer, and line C represents the partial regulator. Organisms that are able to maintain homeostasis by physiological means that ensure constant body temperature are called regulators. Organisms that are not able to maintain a constant internal temperature are called conformers.
• Partial regulators are organisms that have the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.

Question 65. Plants grow sparsely in arid regions of the world

1. Only because of the high temperature
2. Because no seeds fall on their soil
3. Because of several factors combined together
4. Because the soil is sandy

Answer: 3. Because of several factors combined together

“population attributes “

• The growth of plants in arid regions is sparse. The reason is that the plants have adapted to these regions. They have developed specialized structures which help in the reduction of the transpiration rate.
• These regions have less amount of water in the soil. The temperature is very high so the level of vegetation is low. Thus, plants grow sparsely in arid regions of the world because of several factors combined together.

66. Most mollusks and cry fishes are

1. Thermoconformers
2. Osmoconformers
3. Osmoregulatory
4. All of the above

Answer: 3. Osmoregulatory

Most mollusks and cry fishes are osmoregulatory. Birds and mammals are thermoconformers and osmoconformers, respectively. Thus, option (3) is correct.

Question 67. Organisms capable of maintaining constant body temperature are

1. Stenothermal
2. Homoiothermal
3. Poikilothermal
4. Conformers

Answer: 2. Homoiothermal

• Homoiothermal organisms are those who can maintain their internal body temperature at a relatively constant value by using metabolic processes to counteract fluctuations in the temperature of the environment, e.g. birds and mammals.
• They have relatively high internal temperature which permits fast action of muscles, and nerves and enables them to lead highly active lives.

Question 68. Regulators are also called

1. Endotherms
2. Exotherms
3. Ectotherms
4. Hydrothermal

Answer: 1. Endotherms

Regulators are also called endotherms. Evolutionary biologists believe that the success of mammals is mainly due to their ability to maintain a constant body temperature (endotherms) and live comfortably.

Question 69. Gloger’s rule is related to

1. Color
2. Extremities
3. Narrow wing
4. Size

Answer: 1. Colour

Gloger’s rule is related to color. In warm-blooded animals, including, humans, pigmentation is lesser in colder areas, yellow-brown to red in arid climates, and black in humid hot areas.

Question 70. Regulators are the animals that

1. Cannot maintain their body homeostasis
2. Maintain their body homeostasis
3. Regulate their heartbeat
4. Regulate their blood circulation

Answer: 2. Maintain their body homeostasis

Some organisms are able to maintain a constant body temperature (homeostasis) and constant osmotic concentration despite changes in the external environment. They are called regulators. Only birds, and mammals belong to the category of regulators.

“population attributes “

Question 71. What percentage of animals on this earth are regulators?

1. 2%
2. 3%
3. 4%
4. 1%

Answer: 4. 1%

About 99% of animals and nearly all plants do not have a mechanism to maintain a constant internal body environment. Only 1% of organisms can maintain body temperature changes with the surrounding temperature (ectotherms). Thus, 1% of animals on this earth are regulators.

Question 72. The animals that rely on the heat from the environment rather than metabolism to raise their body temperature are, in the strict sense, called

1. Ectothermic
2. Poikilothermic
3. Homeothermic
4. Endothermic

Answer: 1. Ectothermic

Ectotherms gain most of their heat from the environment to raise their body temperature. This is because they have a low metabolic rate, i.e. the amount of heat to generate, is too small to have much effect on body temperature.

Question 73. Circadian rhythm is a metabolic or behavioral

1. 24 Min cycle
2. 24 Hrs cycle
3. 24 Sec cycle
4. 24 Day Cycle

Answer: 2. 24 Hrs cycle

Circadian rhythm is the 24-hour internal clock in our brain that regulates cycles of alertness and sleepiness by responding to light changes in our environment. Our physiology and behavior are shaped by the earth’s rotation around its axis.

Question 74. Partial regulators are organisms which

1. Can regulate body temperature to a large extent according to environmental conditions
2. Can regulate body temperature to a limited extent according to environmental conditions
3. Can regulate body temperature only over a limited range of environmental conditions
4. None of the above

Answer: 2. Can regulate body temperature to a limited extent according to environmental conditions

• Some species are partial regulators. They have the ability to regulate their body temperature up to a certain limit extent according to environmental conditions.
• Beyond that limit they become conformers. Further, they are not essential that regulators of one attribute would be a regulator of other attributes as well.

Question 75. An overwhelming majority of …a… 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.

1. A–1%, b–varies, c–constant
2. A–97%, b–constant, c–varies
3. A–9%, b–varies, c–constant
4. A–99%, b–varies, c–changes

Answer: 4. A–99%, b–varies, c–changes

Question 76. Which of the following statements regarding responses of organisms to abiotic factors is false?

1. All birds and mammals are capable of thermoregulation
2. The majority of animals and nearly all plants cannot maintain a constant internal environment
3. Shivering is a kind of exercise that produces heat and raises body temperature
4. Very small animals are commonly found in polar regions as they have to spend less energy to generate body heat
5. Diapause is a stage of suspended development seen in zooplanktons

“population attributes “

Answer: 4. Very small animals are commonly found in polar regions as they have to spend less energy to generate body heat

• The statement in option (4) is incorrect and can be corrected as Heat loss or heat gain is a function of surface area.
• Since small animals have a larger surface area relative to their volume they tend to lose body heat very fast, when it is cold outside and they have to expend much more energy to generate body heat through metabolism.
• Hence, very small animals are rarely found in polar areas. Rest all statements are correct regarding responses of organisms to abiotic factors.

Question 77. The lowest temperature of any land mass in the universe was recorded in

1. North America (1949)
2. Greenland (1950)
3. Antarctica (2010)
4. Siberia (1947)

Answer: 3. Antarctica (2010)

The lowest temperature recorded in Antarctica in 2010 was –94.7ºC.

Question 78. The success of mammals on Earth is largely because

1. They have the ability to maintain a constant body temperature
2. They can conform to the changes in the environment
3. They can take care of their young ones as they have mammary glands to suckle them
4. They can reduce metabolic activity and go into a state of dormancy during unfavorable conditions

Answer: 1. They have the ability to maintain constant body temperature

Mammals are endothermic. Endothermy (maintenance of internal temperature) enables these animals to live at temperatures that other land vertebrates cannot bear. Thus, the success of mammals on earth is largely because they have the ability to maintain constant body temperature.

Question 79. Conformers remain dormant in adverse conditions due to

1. The inability to move
2. The inability to digest properly
3. The inability to maintain homeostasis
4. The ability to maintain homeostasis

Answer: 3. The inability to maintain homeostasis

Conformers remain dormant in adverse conditions due to the inability to maintain homeostasis. In conformers, the body temperature changes with the surrounding temperature they are also called ectotherms. 99% of animals are conformers.

“population attributes “

Question 80. Conformers are also referred to as

1. Endotherms
2. Ectotherms
3. Isotherms
4. Both (2) or (3)

Answer: 2. Ectotherms

The animals and plants in which the osmotic concentration and temperature of the body change according to ambient conditions of water are called conformers (also known as ectotherms).

Question 81. It is much easier for a small animal to run uphill than for a large animal, because

1. It is easier to carry a small body weight
2. Smaller animals have a higher metabolic rate
3. Small animals have a lower O2 requirement
4. The efficiency of muscles in large animals is less than in small animals

Answer: 2. Smaller animals have a higher metabolic rate

It is much easier for a small animal to run uphill than for a large animal because smaller animals have higher Basic Metabolic Rate (BMR) related to sustained energy production and delayed muscle fatigue

Question 82. A terrestrial animal must be able to

1. Conserve water
2. Actively pump salts out through the skin
3. Excrete a large amount of salt in urine
4. Excrete a large amount of water in urine

Answer: 1. Conserve water

Terrestrial animals lose water by evaporation from respiratory and body surfaces, excretion in urine, and elimination in the feces. They replace such losses by water in the food, drinking water when available, and retaining metabolic water formed in cells by oxidation of foods, especially carbohydrates. Thus, a terrestrial animal must be able to conserve water.

Question 83. Ephemerals are xerophytes that are

1. Drought enduring
2. Drought escaping
3. Drought resisting
4. None of the above

Answer: 2. Drought escaping

Ephemerals are plants with a short life cycle (seed germination to seed production) having several generations in one year. Desert ephemerals pass the drought/day season as dormant seeds. Therefore, these are called drought escaping.

Question 84. Animals undergo an inactive stage during winter which is known as

1. Aestivation
2. Hibernation
3. Adaptation
4. Acclimatization

Answer: 2. Hibernation

• Animals undergo an inactive stage during winter which is known as hibernation. Hibernation is a sleep-like state in which some animals pass the winter months as a way of surviving food scarcity and cold weather.
• Various physiological changes occur, such as lowering of the body temperature and slowing of the pulse rate and other vital processes and the animal lives on its reserve of body fat. Animals that hibernate include bats, hedgehogs, many fish, amphibians, and reptiles.

“population attributes “

Question 85. The stage of suspended development shown by zooplanktons is called

1. Desiccation
2. Diapause
3. Hibernation
4. Homeostasis
5. Aestivation

Answer: 2. Diapause

Under unfavorable conditions, many zooplankton species in lakes and ponds are known to enter diapause, a stage of suspended development.

Question 86. Consider the following statements.

1. Cold deserts too exist for example. Tibet, gobi.
2. Desert can be hot, for example. Thar, Sahara.

Choose the correct option.

1. Statement 1 is correct, but 2 is incorrect
2. Statement 1 is incorrect, but 2 is correct
3. Both statements 1 and 2 are correct
4. Both statements 1 and 2 are incorrect

Answer: 3. Both statements 1 and 2 are correct

Both statements I and II are correct. Desert can be cold (e.g. Tibet, Gobi) and hot (For example. Thar, Sahara). In true desert is a place that has a rainfall of less than 12 cm/yr, while an extreme desert is less than 7cm/yr.

Question 87. Just as a person moves from Delhi to Shimla to escape the heat for the duration of a hot summer, thousands of migratory birds from Siberia and other extremely cold northern regions move to

1. Western ghats
2. Meghalaya
3. Corbett national park
4. Keoladeo national park

Answer: 4. Keoladeo National Park

A person moving from Delhi to Shimla to escape the heat for the duration of a hot summer, thousands of migratory birds from Siberia and her extremely cold Northern regions move to Keoladeo National Park. Keoladeo National Park is a vast bird sanctuary in Rajasthan.

Question 88. Microorganisms and some lower plants show the formation of …a… To outlive harsh environments, whereas …b… In higher plants are a means of continuing the generation through harsh environmental conditions.

1. A–spores, B–seeds
2. A–seeds, B–spores
3. A–spines, B–spores
4. A–seeds, B–mucilage

Answer: 1. A–spores, B–seeds

Question 89. Diapause is a stage of suspended development in water bodies such as lakes and ponds. The season in which it occurs in

1. Summer
2. Winter
3. Autumn
4. Spring

Answer: 2. Winter

Diapause occurs during unfavorable conditions mostly in winter when the temperature is too low to survive.

Question 90. Match the following columns.

Answer: 5. A–2, B–4, C–1, D–3

Question 91. Match the following columns.

Answer: 1. A–5, B–1, C–3, D–4

Question 92. An attribute of some organisms that enables them to survive and reproduce in their habitat is called

1. Phenotypic plasticity
2. Adaptations
3. Mimicry
4. Surviving abilities

Answer: 2. Adaptations

Adaptation develops due to the natural selection of suitable variations appearing in living beings through mutation and recombination. It enables the organism to survive and reproduce in its habitat.

Question 93. The adaptations in an organism are meant for

1. Optimum primary production
2. Optimum lifespan
3. Optimum mobility
4. Optimum survival and reproduction

Answer: 4. Optimum survival and reproduction

Adaptation is an attribute of an organism (morphological, physiological, and behavioral) that enables it to survive and reproduce in its habitat. It enables the organism to survive and reproduce in its habitat.

Question 94. Different types of adaptations existing in animals are

1. Morphological
2. Physiological
3. Behavioural
4. All of these

Answer: 4. All of these

There are three different types of adaptations existing in animals. Behavioral–responses made by an organism that help it to survive/reproduce Physiological – a body process that helps an organism to survive and reproduce Morphological feature of an organism‘s body that helps it to survive/reproduce. Thus, option (4) is correct.

Question 95. Examples of behavioral adaptation.

1. Basking by desert lizards in the sun.
2. Hiding in burrows by some animals.
3. Thermal gaping.

Choose the correct option.

1. 2 And 3
2. 2 And 3
3. 1, 2 And 3
4. None of the examples

Answer: 1. 2 And 3

• All given examples (2 and 3) are of behavioral adaptation except because some organisms show behavioral adaptation to cope with variation in the environment. Desert lizards lack the physiological ability to deal with high temperatures.
• They keep their body temperature fairly constant by behavioral means. They enjoy in sun and absorb heat when their body temperature is low. When their body temperature starts increasing it moves into shades. Thus, option (1) is correct.

Question 96. The development of patagia in animals is a

1. Cave adaptation
2. Aquatic adaptation
3. Volant adaptation
4. Arboreal adaptation

Answer: 3. Volant adaptation

The animals that show the presence of patagia or wings show volant or flight adaptations. The patagia or wings are enclosed with light feathers that allow the body of the bird to become light in weight.

Question 97. The adjustment of a pupil of our eye to light intensity is an example of

1. Entropy
2. Steady-state
3. Adaptation
4. All of these

Answer: 3. Adaptation

The adjustment of a pupil of our eye to light intensity is an example of adaptation.

Question 98. In an ecological sense, desert animals are termed as

1. Arboreal
2. Benthos
3. Cursorial
4. Xeric

Answer: 4. Xeric

The organisms, desert plants, or animals adapted to dry conditions are called xeric. As xeric plants have spinous leaves and animals are uricotelic.

Question 99. Desert plants are generally Manipal 1998, 1999

1. Herbaceous
2. Viviparous
3. Heterophyllus
4. Succulent

Answer: 4. Succulent

• Desert plants are generally succulent, i.e. the plants conserve water by storing it in fleshy leaves or stems.
• Succulents are found either in dry regions or in areas, where there is sufficient water but not easily available (e.g. in salt marshes) such plants are often modified to reduce water loss by transpiration.

Question 100. The succulent stem is found in

1. Pisum
2. Casuarina
3. Oxalis
4. Euphorbia

Answer: 4. Euphorbia

Opuntia is a xerophytic plant, which lives in dry habitat. The plant has fleshy organs where water and mucilage are stored. The stem is modified into a flat green structure, therefore Opuntia is also called phylloclades.

Question 101. Which one of the following is a xerophytic plant in which the stem is modified into a flat green and succulent structure?

1. Opuntia
2. Casuarina
3. Hydrilla
4. Acacia

Answer: 1. Opuntia

Opuntia is a xerophytic plant, which lives in dry habitat. The plant has fleshy organs where water and mucilage are stored. The stem is modified into a flat green structure, therefore Opuntia is also called phylloclades.

Question 102. The most effective defense of plants against herbivores are

1. Morphological
2. Chemical
3. Tem oral
4. Developmental

Answer: 1. Morphological

The first line of defense in plants is an intact and impenetrable barrier composed of bark and a waxy cuticle. Both protect plants against herbivores. Leaf modification into spines, the presence of sharp thorns, and spiny leaf margins are some of the morphological defenses.

Question 103. Acacia arabica is a

1. Mesophyte
2. Hydrophyte
3. Xerophyte
4. Halophyte

Answer: 3. Xerophyte

Acacia arabica is a xerophyte. Xerophytes are plants of dry habitats, where the environment favors a higher rate of transpiration than absorption. In these plants, leaves are small and vestigial to cut transpiration.

Question 104. Casuarina equisetifolia is a

1. Mesophyte
2. Xerophyte
3. Halophyte
4. Forest epiphyte

Answer: 2. Xerophyte

Casuarina equisetifolia is a non-succulent xerophyte. In Casuarina, leaves are vestigial to cut off transpiration and to survive in a dry environment.

Question 105. Cactaceae stores water in leaves, it implies

1. Ephemerals
2. Drought resistant
3. Annuals
4. Non-succulents

Answer: 2. Drought resistant

Cactus are drought-resistant or succulents. The plants have fleshy organs where water and mucilage are stored. The stems and leaves of succulents possess very thick cuticles. Stomata are sunken.

Question 106. A succulent xerophyte is

1. Capparis
2. Calotropis
3. Agave
4. None of these

Answer: 3. Agave

In succulent xerophytes, plants have fleshy organs where water and mucilage are stored. Depending upon the organ where succulence occurs, the succulents show chylocauly, for example. Opuntia, chylophylly, example. Agave and Chylorhizy example. Asparagus.

Question 107. Which of the following plants has a non-succulent, xerophytic, and thick leathery leaf with a white sticky waxy coating?

1. Nerium
2. Bryophyllum
3. Calotropis
4. Ruscus

Answer: 1. Nerium

Non-succulents and xerophytes include all non-succulent herbs, shrubs, and trees that can endure wilting. Nerium is a non- succulent xerophyte. Nerium leaves have densely pubescent surfaces which minimize the rate of transpiration because they keep the air current well-elevated above the stomata.

Question 108. Pick up the xerophytic set.

1. Zizyphus, opuntia, euphorbia
2. Musa, Ceratophyllum, legume
3. Labiateae, zizyphus, opuntia
4. Hydrilla, zizyphus, pisum

Answer: 1. Zizyphus, opuntia, euphorbia

Question 109. Among the plants listed, point out one that does not fit into the ecological group represented by other plants.

1. Acacia
2. Rhizophora/vallisneria
3. Euphorbia
4. Aloe

Answer: 2. Rhizophora/vallisneria

Acacia, Aloe, and Euphorbia are xerophytic plants, while Vallisneria is a hydrophyte and Rhizophora belongs to the halophyte plant group. So, option (2) does not fit into the ecological group represented by another plant.

110. The features of the xerophytic plant leaves are

1. Leathery surface
2. Large surface area
3. Waxy cuticle

Sunken stomata on the upper epidermis

1. 1, 2 And 4
2. 2 And 3
3. 1, 3 And 4
4. 1 And 4

Answer: 3. 1, 3 And 4

All given features are of xerophytic plant leaves except 2. Xerophytes are the plants living in xeric (dry) habitats. Plants growing in such regions develop characteristics to tolerate drought. Xerophytes develop the following characteristic features

• In general, the leaves are highly reduced to decrease the loss of water by transpiration.
• In some plants, leaves are modified into spines, for example. Euphorbia, Opuntia.
• The waxy coating is present on leaves and stems as in Calotropis.
• The presence of sunken stomata covered by hair, for example. Nerium and Ephedra.
• Stomata are generally found on the lower surface of the leaves. Thus, option (c) is correct.

Question 111. Consider the following statements.

1. Many xerophytic plants have thick cuticles on the leaf epidermis and sunken stomata.
2. Some xerophytic plants have special photosynthetic pathway (cam) that enables their stomata to close during the day.
3. Opuntia has spines (modified leaves), and photosynthetic phylloclade (stem).
4. An animal can adapt to a totally new environment by acclimatizing itself to its surroundings.
5. All adaptations are genetically not fixed.

Choose the option containing

Correct statements.

1. 1, 2, 3 And 4
2. 2, 3, 4 And 5
3. 3, 4, 5 And 1
4. 1, 2, 3, 4 And 5

Answer: 4. 1, 2, 3, 4 And 5

All given statements are correct. Thus, option (4) is correct.

Question 112. Which one of the following is the specific xerophytic adaptation?

1. Presence of spines
2. Absence of stomata
3. Absence of long tap root system
4. Presence of stipular leaves

Answer: 1. Presence of spines

• Xerophytes are the plants living in xeric (dry) habitats. The roots of these plants may be deep tap roots penetrating the soil to great depths so as to absorb water to the maximum.
• Roots can also be shallow but extensive and spread so as to collect and hold rainwater. In many xerophytes, leaves are reduced to form spines to reduce the transpiration losses as in cacti.

Question 113. Match the following columns.

Answer: 1. A–2, B–3, C–1

Question 114. Match the following columns.

Answer: 1. A–2, B–3, C–1

Question 115. Which one of the following hydrophytes has both hydrophytic and xerophytic adaptation?

1. Nerium
2. Agave
3. Vallisneria
4. None of these

Answer: 4. None of these

• Hydrophytes are plants like water lilies that have adapted to living in watery conditions.
• They have little to no root systems and have leaves that often help in flotation.
• Xerophytes are the opposite of hydrophytes and are plants adapted for living in extremely dry conditions with little access to water.
• All given options are not hydrophytes having both hydrophytic and xerophytic adaptations.

Thus, option (4) is correct.

Question 116. Which of the following does not have stomata?

1. Mesophytes
2. Serophytes
3. Submerged hydrophytes
4. Hydrophytes

Answer: 3. Submerged hydrophytes

Stomata are meant for gaseous exchange and are present on the epidermis of the leaf. In submerged hydrophytes, leaves are found submerged in the water and stomata are absent.

Question 117. The waxy surface of the floating leaves of the hydrophytes prevents

1. Respiration
2. Photosynthesis
3. Transpiration
4. Clogging of stomata

Answer: 4. Clogging of stomata

The wax coating protects the leaves from chemical and physical injuries and also prevents the water clogging of stomata.

Question 118. Hydrophytes are characterized by

1. Leaf reduced to spines
2. Well-developed vascular tissue
3. Well-developed mechanical tissue
4. Delicate and mucilaginous stem

Answer: 4. Delicate and mucilaginous stem

• Hydrophytes are water-loving plants. The plant body is covered with mucilage. Mucilage protects the plants from epiphytes, pathogens, and animals.
• It also functions as a lubricant and reduces friction against water current. The stem is delicate because the xylem is poorly developed. So, hydrophytes are characterized by delicate and mucilaginous stems.

Question 119. Which of the following characteristics are exhibited by heliophytes?

1. Well-developed conductive and mechanical tissues
2. Longer branched roots
3. High osmotic pressure
4. All of the above

Answer: 4. All of the above

All given characters are exhibited by heliophytes. Thus, option (4) is correct.

Question 120. Plants that behave as mesophytes in the rainy season and as xerophytes in summer are called

1. Xerophytes
2. Mesophytes
3. Tropophytes
4. Phreatophytes

Answer: 3. Tropophytes

Tropophytes are plants that behave as xerophytes at one period of the year, i.e. in the summer season, and behave as mesophytes or hydrophytes at another part, i.e. during the rainy season. Phreatophytes are plants that depend for their water supply upon groundwater that lies within reach of their roots.

Question 121. Match the following columns.

Answer: 4. A–2, B–1, C–3

Question 122. Positively photo-blastic seeds germinate only in the presence of

1. Soil
2. Air
3. Light
4. None of the above

Answer: 3. Light

A number of seeds are sensitive to light hence they are called photoblastic seeds. Positively photoblastic seeds germinate only in the presence of light, e.g. Viscum, Lactuca, Rumex. Negatively photoblastic seeds do not germinate in the presence of light, for example. onion, tomato.

Question 123. Which one of the following refers to Allen’s rule?

1. An organism can move from a stressful habitat to a more hospitable area and return when the stressful period is over
2. If the stressful conditions are localized or remain only for a short duration, an organism either migrates or suspends itself
3. Low atmospheric pressure in higher altitudes results in altitude sickness
4. Mammals from colder climates have shorter ears and limbs to minimize heat loss

Answer: 4. Mammals from colder climates have shorter ears and limbs to minimize heat loss

• The principle of Allen’s rule describes that organisms undergo changes and adaptations depending on the environment and geographical conditions.
• The organisms When introduced to a stressful climate, organisms develop certain features that will allow them to survive.
• They have small ears and limbs to prevent loss of heat. This property of warm-blooded organisms was observed and stated in Allen’s rule.

Question 124. Match the following columns.

Answer: 3. A–4, B–3, C–2, D–1

Question 125. At high altitudes, we do not feel in good health. The reason for sickness may be due to

1. Low atmospheric pressure
2. High atmospheric pressure
3. High temperature
4. Both (2) and (3)

Answer: 1. Low atmospheric pressure

At high altitudes, there is low atmospheric pressure and due to that body does not get enough oxygen, which leads to altitude sickness.

Question 126. Altitude sickness occurs while in the high mountains or in people not acclimatized to the mountainous environment. Symptoms of this sickness include

1. Nausea
2. Fatigue
3. Heart palpitations
4. All of the above

Answer: 4. All of the above

Nausea, fatigue, and heart palpitations are due to the unavailability of proper oxygen in the body. At high altitudes, the atmospheric pressure is low. So, O2 is not easily available for respiration. So to improve the efficiency of respiration, RBC increases in the blood thus increasing the binding efficiency of haemoglobin. So, all given symptoms include high altitude sickness. Thus, option (4) is correct.

Question 127. The body compensates for low oxygen availability at high altitudes by

1. Increasing rbc.
2. Decreasing binding affinity of hemoglobin.
3. Increasing binding affinity of haemoglobin.
4. Increasing breathing rate.
5. Increasing heartbeat.

Choose the correct option for the given statement.

1. 1, 2 And 3
2. 2, 3 And 4
3. 1, 3 And 4
4. 1, 2 And 4

Answer: 3. 1, 3 And 4

The body compensates for low oxygen availability at high altitudes by increasing RBC production, increasing the binding capacity of hemoglobin (through increasing 2, 3-bisphosphoglyceric acid), and increasing breathing rate. Thus, option (3) is correct.

Question 128. Many freshwater animals cannot live for long in seawater and vice-versa mainly because of the

1. Change in n levels
2. Change in the levels of thermal tolerance
3. Variations in light intensity
4. Osmotic problems
5. Spectral quality of solar radiation

Answer: 4. Spectral quality of solar radiation

• Organisms found in freshwater have a problem of excess internal water because of endosmosis. Organisms found in the ocean or salt water have a problem with low internal water content due to exosmosis.
• For aquatic organisms, the quality (chemical composition, pH) of water becomes important. Many freshwater animals cannot live for long in seawater and vice-versa because of the osmotic problems they would face.

Question 129. Which of the following pairs is correctly matched?

1. Uricotelism – aquatic habitat
2. Parasitism – intraspecific relationship
3. Excessive perspiration – xeric adaptation
4. Streamlined body – aquatic adaptation

Answer: 4. Stream-lined body – aquatic adaptation

• (4) Option (4) is a correctly matched pair. Streamlined body–aquatic adaptation. Rest options are not correctly matched pairs and can be corrected as Parasitism–interspecific relationship in which one species (parasite) benefits for growth and reproduction and other species (host) is harmed.
• Parasites live on or inside the body of the host. Uricotelism is the removal or excretion of uric acid. Excessive perspiration is a warning sign of thyroid problems, diabetes, or infection.

Question 130. What adaptation do seals living in below-freezing temperatures show that enables them to survive?

1. The body surface is covered with long hair
2. The presence of a thick layer of fat beneath the skin
3. Both (1) and (2)
4. They have genetic regulations for avoiding cold climate

Answer: 2. Presence of a thick layer of fat beneath the skin

Seals have a thick layer of fat called blubber that helps, them to trap warmth in their bodies. Younger seal skin is kept warm by a layer of water-repellent fur, which remains until the seals grow the fat layer. Thus, option (2) is correct.

Question 131. Which of the following adaptations is observed in xerocole?

1. Nocturnal habit
2. Concentrated urine
3. Large ears to regulate the body temperature
4. All of the above

Answer: 4. All of the above

A xerocole, commonly referred to as a desert animal, is an animal adapted to live in the desert. The main challenges they must overcome are lack of water and excessive heat. The main adaptation features include concentrated urines the nocturnal habit and large ears to regulate the body temperature. Thus, option (d) is correct.

Question 132. The body temperature of many animals corresponds to the environmental temperature. They are known as

1. Heterothermic
2. Homeothermic
3. Endothermic
4. Poikilothermic

Answer: 4. Poikilothermic

• Poikilothermic or cold-blooded organisms are animals that have no internal metabolic mechanism for regulating their body temperatures.
• Some (usually smaller) animals have unregulated temperatures, but most have sophisticated physiological and behavioral techniques for obtaining their desired core body temperature from the environment. Cold-blooded animals are often referred to as ectotherms.

Question 133. Animals that rely on the heat from the environment, rather than on metabolism, to raise their body temperature is, in the strict sense, called

1. Ectothermic
2. Poikilothermic
3. Homeothermic
4. Endothermic

Answer: 1. Ectothermic

Ectothermic, refers to organisms that control body temperature through external means. As a result, organisms are dependent on environmental heat sources and have relatively low metabolic rates.

Question 134. Ectothermic animals are also called

1. Poikilotherms
2. Cold-blooded
3. Both (1) and (4)
4. Endotherms

Answer: 3. Both (1) and (4)

Poikilothermic or cold-blooded or ectotherms are those animals (e.g. reptiles, fish, amphibians) in which the body temperature fluctuates with changes in environmental temperature.

Question 135. Which of the following is an adaptation for osmoregulation shown by desert animals?

1. Shorter ears
2. Spiny and highly cornified skin
3. Presence of antifreeze proteins
4. Shorter limbs

Answer: 2. Spiny and highly cornified skin

Spiny and highly cornified skin is an adaptation for osmoregulation shown by desert animals. Other options are explained as Shorter ears and limbs are adaptations shown by animals that live in extremely cold conditions. Some of them also accumulate antifreeze proteins which lowers the freezing point of their body fluids.

Question 136. The kangaroo rat found in deserts of North America meets its water needs even without an external source of water by

1. Internal fat oxidation
2. Taking liquid food
3. Aestivation
4. Hibernation

Answer: 1. Internal fat oxidation

Many adaptations have evolved over a long evolutionary time in kangaroo rats. In the absence, of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through internal fat oxidation. It also has the ability to concentrate its urine.

Question 137. Which of the following is dominant in the desert?

1. Lizard
2. Tiger
3. Leopard
4. Hyla

Answer: 1. Lizard

• Desert lizards lack the physiological ability that mammals have to deal with the high temperatures of their habitat, but manage to keep their body temperature fairly constant by behavioral means.
• They bask in the sun and absorb heat when their body temperature drops below the comfort zone, but move into shade when the ambient temperature starts increasing. So, the lizard is dominant in the desert.

Question 138. Which one of the following organs helps in physiological adaptation in desert rodents?

1. Spleen
2. Liver
3. Kidney
4. Lungs

Answer: 3. Kidney

• Kidneys play a major role in reducing the amount of water lost from the body by producing highly concentrated urine.
• The loop of Henle in kangaroo rats is longer than most other animals. The longer the loop of Henle is more surface area, the more fluid traveling through it is exposed.
• This enables efficient reabsorption of water and the production of concentrated urine. Thus, the kidney helps in physiological adaptation in desert rodents.

Question 139. Consider the following four statements (i-iv) about certain desert animals such as kangaroo rats.

1. They have a dark color and high rate of reproduction and excrete solid urine.
2. They do not drink water, breathe at a slow rate to conserve water, and have their body covered with thick hairs.
3. They feed on dry seeds and do not require drinking water.
4. They excrete very concentrated urine and do not use water to regulate body temperature.

Which two of the above statements for such animals are true?

1. 1 And 3
2. 1 And 2
3. 3 And 4
4. 2 And 3

Answer: 3. 3 And 4

• Statements 3 and 4 are true for kangaroo rats as Kangaroo rat (Dipodomys merriami) feeds on dry seeds. It seldom drinks water. The requirement of water is met by food (10%) and metabolic water (90%).
• Water loss is prevented by living in burrows during the day, the concentration of urine, and solidification of feces. It has a thick coat to minimize evaporative desiccation. Other statements are not true about certain desert animals such as kangaroo rats.

Question 140. Consider the following statements.

1. Mammals of warmer climates generally have shorter ears and limbs to minimize heat loss.
2. All organisms have behavioral adaptations that allow them to respond quickly to stressful situations.
3. Some organisms possess behavioral adaptations which allow them to migrate temporarily to a less stressful situation.
4. Invertebrates and fishes live at great depths in the ocean and have biochemical adaptations to cope with high pressure.

Choose the option containing

Correct statements.

1. 1 And 2
2. 3 And 4
3. 1, 3 And 4
4. 1, 2 And 4

Answer: 2. All organisms have behavioral adaptations that allow them to respond quickly to a stressful situation.

• Statements 3 and 4 are correct. Some organisms show behavioral adaptation to cope with variation in the environment.
• Desert lizards lack the physiological ability to deal with high temperatures. Organisms that live in great depths of the oceans are commonly known as deep sea creatures.
• Many deep sea creatures have organic molecules known as piezolytes that prevent the collapse of macromolecules present in their bodies thereby helping them survive under great pressure. Other statements are not correct.