organisms and population

Ecology provides a unifying perspective to biology.

Assertion is TRUE. Ecology integrates organisms, populations, communities and ecosystems into a holistic framework.

The ‘how-type’ questions in biology deal with significance of a process.

Assertion is FALSE. How-type questions deal with mechanism

Ecology studies only abiotic components of the environment.

Assertion is FALSE. Ecology studies interactions among organisms and between organisms and both abiotic and biotic components.

Natural selection operates at the individual level.

Assertion is FALSE. Natural selection operates at the population level.

Temperature is the most ecologically relevant environmental factor.

Assertion is TRUE. It affects enzyme kinetics and hence metabolism and physiological functions.

Eurythermal organisms tolerate narrow temperature ranges.

Assertion is FALSE. Eurythermal organisms tolerate a wide range of temperatures.

Stenohaline organisms tolerate a wide range of salinity.

Assertion is FALSE. Stenohaline organisms tolerate only a narrow salinity range.

Homeostasis refers to maintenance of constant internal environment.

Assertion is TRUE. It ensures optimal biochemical and physiological functioning.

All organisms are capable of thermoregulation.

Assertion is FALSE. Only birds, mammals and few lower organisms regulate

Small animals are rarely found in polar regions.

Assertion is TRUE. Due to high surface area to volume ratio, they lose heat rapidly and thermoregulation is energetically expensive.

Migration is an adaptation to avoid stress in space.

Assertion is TRUE. Organisms temporarily move to more favourable habitats.

Hibernation and aestivation are examples of escape in time.

Assertion is TRUE. They involve suspended metabolic activity during unfavourable conditions.

Adaptation includes only morphological changes.

Assertion is FALSE. Adaptations can be morphological, physiological or behavioural.

CAM plants keep stomata open during daytime.

Assertion is FALSE. CAM plants keep stomata closed during day to reduce water loss.

Allen’s rule states that mammals in colder climates have shorter extremities.

Assertion is TRUE. Shorter ears and limbs minimise heat loss.

Blubber in polar mammals acts as insulation.

Assertion is TRUE. Thick fat layer reduces heat loss.

A population is a group of individuals of same species in a defined area sharing resources.

Assertion is TRUE. They potentially interbreed and compete for similar resources.

Birth rate in population refers to total number of births.

Assertion is FALSE. It refers to per capita births.

Sex ratio is a population attribute.

Assertion is TRUE. Individuals have sex

Age pyramid shape indicates growth status of population.

Assertion is TRUE. It shows whether population is growing, stable or declining.

Population density must always be expressed as number of individuals.

Assertion is FALSE. It can be expressed as biomass, percent cover, etc.

Population density increases through natality and immigration.

Assertion is TRUE. Births and incoming individuals raise density.

Intrinsic rate of natural increase (r) equals b + d.

Assertion is FALSE. r = b − d (per capita birth minus death rate).

Exponential growth occurs when resources are unlimited.

Assertion is TRUE. It produces a J-shaped curve.

Logistic growth occurs when resources are limiting.

Assertion is TRUE. It produces a sigmoid (S-shaped) curve.

Carrying capacity (K) is the maximum population size supported by habitat.

Assertion is TRUE. Beyond K, no further growth is sustained.

Logistic growth model is more realistic in nature.

Assertion is TRUE. Because resources are finite.

In competition both species benefit.

Assertion is FALSE. In competition both species suffer.

Gause’s Competitive Exclusion Principle states that two closely related species cannot coexist indefinitely if competing for same limiting resources.

Assertion is TRUE. Inferior competitor is eliminated.

Resource partitioning promotes coexistence.

Assertion is TRUE. Species use different resources or times to reduce competition.

Predation facilitates energy transfer across trophic levels.

Assertion is TRUE. Predators transfer energy from lower to higher trophic levels.

Removal of predators always increases species diversity.

Assertion is FALSE. Removal may cause competitive exclusion and reduce diversity.

Parasitism benefits both host and parasite.

Assertion is FALSE. Parasite benefits

Ectoparasites live inside host body.

Assertion is FALSE. Ectoparasites live on host surface.

Endoparasites show high reproductive potential.

Assertion is TRUE. Due to high risk inside host.

Commensalism benefits one species and harms the other.

Assertion is FALSE. One benefits

Mutualism benefits both interacting species.

Assertion is TRUE. Both derive benefit.

Lichens represent mutualism between fungus and algae/cyanobacteria.

Assertion is TRUE. Both partners benefit.

In brood parasitism, parasitic bird lays eggs in host nest.

Assertion is TRUE. Host incubates and raises young.