NCERT Class 12 - Organisms and Populations flashcards Exam Questions with Correct
Answers Latest Update 2025/2026
what is ecology - Answers 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 - Answers organisms,
populaitons, communitites and biomes
Ecology at the organismic level is essentially - Answers 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 - Answers 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 - Answers of a wide
variety of habitats
major biomes of India are - Answers 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? - Answers 1. temperature
2. water
3. light
4. soil
physico-chemical (abiotic) components alone do not characterise the habitat of an organism
completely. What else contributes? - Answers the habitat includes biotic components also -
pathogens, parasites, predators and competitors - of the organism with which they interact
constantly.
define niche - Answers 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 - Answers temperature
temperature of poles and deserts - Answers subzero; >50
temperature exceeds 100 degrees where - Answers 1. thermal springs
2. deep sea hydrothermal vents
significance of temperature to living organisms - Answers it affects the kinetics of enzymes and
through it the metabolic activity and other physiological functions of the organism
eurythermal organisms - Answers organisms can tolerate and thrive in a wide range of
temperatures
stenothermal organisms - Answers restricted to a narrow range of temperatures
salt concentration is measured in - Answers measured as salinity in parts per thousand
different salt concentrations of places - Answers 1. inland waters - 5
2. sea - 30-35
3. >100 hypersaline lagoons
Many freshwater animals cannot live for long in sea water and vice versa because - Answers
osmotic problems
flowering depends on light true or false - Answers true
light is important for animals as - Answers they use the diurnal and seasonal variations in light
intensity and duration (photoperiod) as cues for timing their foraging, reproductive and
migratory activities
where is there no light in oceans - Answers >500m
factors determining the percolation and water holding capacity of the soils - Answers 1. soil
composition
2. grain size
3. aggregation
factors affecting vegetation of an area - Answers 1. ph
2. mineral composition
Answers Latest Update 2025/2026
what is ecology - Answers 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 - Answers organisms,
populaitons, communitites and biomes
Ecology at the organismic level is essentially - Answers 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 - Answers 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 - Answers of a wide
variety of habitats
major biomes of India are - Answers 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? - Answers 1. temperature
2. water
3. light
4. soil
physico-chemical (abiotic) components alone do not characterise the habitat of an organism
completely. What else contributes? - Answers the habitat includes biotic components also -
pathogens, parasites, predators and competitors - of the organism with which they interact
constantly.
define niche - Answers 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 - Answers temperature
temperature of poles and deserts - Answers subzero; >50
temperature exceeds 100 degrees where - Answers 1. thermal springs
2. deep sea hydrothermal vents
significance of temperature to living organisms - Answers it affects the kinetics of enzymes and
through it the metabolic activity and other physiological functions of the organism
eurythermal organisms - Answers organisms can tolerate and thrive in a wide range of
temperatures
stenothermal organisms - Answers restricted to a narrow range of temperatures
salt concentration is measured in - Answers measured as salinity in parts per thousand
different salt concentrations of places - Answers 1. inland waters - 5
2. sea - 30-35
3. >100 hypersaline lagoons
Many freshwater animals cannot live for long in sea water and vice versa because - Answers
osmotic problems
flowering depends on light true or false - Answers true
light is important for animals as - Answers they use the diurnal and seasonal variations in light
intensity and duration (photoperiod) as cues for timing their foraging, reproductive and
migratory activities
where is there no light in oceans - Answers >500m
factors determining the percolation and water holding capacity of the soils - Answers 1. soil
composition
2. grain size
3. aggregation
factors affecting vegetation of an area - Answers 1. ph
2. mineral composition
