NCERT CLASS 12 - ORGANISMS AND POPULATIONS
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What is ecology - Answer: Ecology is a subject which studies the interactions among
organisms and between the organism and its physical (abiotic) environment.
Ecology is concerned with 4 levels of biological organisation namely - Answer:
organisms, populaitons, communitites and biomes
Ecology at the organismic level is essentially - Answer: physiological ecology which
tries to understand how different organisms are adapted to their environments in terms
of not only survival but also reproduction.
Factors accounting for the formation of major biomes such as deserts, rainforests and
tundra are - Answer: 1. Rotation of Earth around Sun
2. Tilt of axis
3. Variation in temperature
4. Variation in precipitation
Regional and local variations within each biome lead to the formation - Answer: of a
wide variety of habitats
Major biomes of India are - Answer: 1. Tropical rain forest
2. Deciduous forest
3. Desert
4. Sea coast
What are the key elements that lead to so much variation in the physical and chemical
conditions of different habitats? - Answer: 1. Temperature
1
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, 2. Water
3. Light
4. Soil
Physico-chemical (abiotic) components alone do not characterise the habitat of an
organism completely. What else contributes? - Answer: the habitat includes biotic
components also - pathogens, parasites, predators and competitors - of the organism
with which they interact constantly.
Define niche - Answer: Each organism has an invariably defined range of conditions
that it can tolerate, diversity in the resources it utilises and a distinct functional role in
the ecological system, all these together comprise its niche
Most important ecologically relevant environmental factor - Answer: temperature
Temperature of poles and deserts - Answer: subzero; >50
Temperature exceeds 100 degrees where - Answer: 1. Thermal springs
2. Deep sea hydrothermal vents
Significance of temperature to living organisms - Answer: it affects the kinetics of
enzymes and through it the metabolic activity and other physiological functions of the
organism
Eurythermal organisms - Answer: organisms can tolerate and thrive in a wide range of
temperatures
Stenothermal organisms - Answer: restricted to a narrow range of temperatures
Salt concentration is measured in - Answer: measured as salinity in parts per thousand
2
APPHIA - Crafted with Care and Precision for Academic Excellence.
FLASHCARDS | QUIZ SMART | SCORE HIGH |
GUARANTEED ACCURACY!
What is ecology - Answer: Ecology is a subject which studies the interactions among
organisms and between the organism and its physical (abiotic) environment.
Ecology is concerned with 4 levels of biological organisation namely - Answer:
organisms, populaitons, communitites and biomes
Ecology at the organismic level is essentially - Answer: physiological ecology which
tries to understand how different organisms are adapted to their environments in terms
of not only survival but also reproduction.
Factors accounting for the formation of major biomes such as deserts, rainforests and
tundra are - Answer: 1. Rotation of Earth around Sun
2. Tilt of axis
3. Variation in temperature
4. Variation in precipitation
Regional and local variations within each biome lead to the formation - Answer: of a
wide variety of habitats
Major biomes of India are - Answer: 1. Tropical rain forest
2. Deciduous forest
3. Desert
4. Sea coast
What are the key elements that lead to so much variation in the physical and chemical
conditions of different habitats? - Answer: 1. Temperature
1
APPHIA - Crafted with Care and Precision for Academic Excellence.
, 2. Water
3. Light
4. Soil
Physico-chemical (abiotic) components alone do not characterise the habitat of an
organism completely. What else contributes? - Answer: the habitat includes biotic
components also - pathogens, parasites, predators and competitors - of the organism
with which they interact constantly.
Define niche - Answer: Each organism has an invariably defined range of conditions
that it can tolerate, diversity in the resources it utilises and a distinct functional role in
the ecological system, all these together comprise its niche
Most important ecologically relevant environmental factor - Answer: temperature
Temperature of poles and deserts - Answer: subzero; >50
Temperature exceeds 100 degrees where - Answer: 1. Thermal springs
2. Deep sea hydrothermal vents
Significance of temperature to living organisms - Answer: it affects the kinetics of
enzymes and through it the metabolic activity and other physiological functions of the
organism
Eurythermal organisms - Answer: organisms can tolerate and thrive in a wide range of
temperatures
Stenothermal organisms - Answer: restricted to a narrow range of temperatures
Salt concentration is measured in - Answer: measured as salinity in parts per thousand
2
APPHIA - Crafted with Care and Precision for Academic Excellence.
