CBSE Class 12 (Science) Organisms and Populations — practice questions
85 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 12 (Science) Organisms and Populations in the app →Seasonal changes in temperature and precipitation create major biomes such as desert, rain forest and:An organism's tolerance range, resources used and functional role together make up its:Mango trees cannot grow in Canada, and snow leopards are absent from Kerala. The factor behind both is:Temperature matters to organisms because it affects the kinetics of:An animal that thrives across a wide range of temperatures is:Freshwater fish die in sea water mainly because of:Birds and mammals keep a constant body temperature. They are called:About what fraction of animals cannot maintain a constant internal environment?Very small animals are rare in polar regions because they:Thousands of Siberian birds winter every year at Keoladeo National Park in:Bears escape winter by going into:Some snails and fish avoid summer heat and drying by:The kangaroo rat meets all its water needs from:Desert plants sink their stomata in deep pits to reduce:Mammals from cold climates have shorter ears and limbs to:Seals in polar seas stay warm thanks to a thick layer of fat called:All the lotus plants in one pond form a:Natural selection operates at the level of the:A Paramecium doubling daily illustrates which growth when food and space are unlimited?Prickly pear cactus overran Australia until a cactus-feeding ___ was introduced.The Monarch butterfly is distasteful to birds because as a caterpillar it fed on a:On Scottish coasts the larger barnacle Balanus excludes the smaller:Which feature belongs to a population but not to a single organism?A pond had 20 lotus plants and 8 new plants were added by reproduction. What is the birth rate?In a lab, 4 of 40 fruitflies died in a week. What is the death rate per fruitfly per week?What is the graphical representation of the age distribution of a population called?What does the shape of an age pyramid indicate about a population?Why is biomass better than counting for one huge banyan tree?Which is the technical term for population size?The tiger census in reserves is often estimated indirectly from which signs?Which pair of processes increases population density?What does emigration mean in population ecology?A population of 100 has 20 births, 5 immigrants, 10 deaths and 5 emigrants. What is the new density?Which growth pattern occurs when resources are unlimited?Which equation describes exponential population growth?In dN/dt = rN, what does r stand for?What shape of curve does exponential growth give when N is plotted against time?What is the integral form of the exponential growth equation?A population doubles in 3 years while growing exponentially. What is r approximately?Which animal did Darwin use to show how a slow breeder could reach huge numbers unchecked?What is the maximum population size a habitat can support called?Which phase order describes logistic growth?What is the logistic growth curve called, based on its shape?Who are the two scientists after whom logistic growth is named?In the logistic equation, what happens to dN/dt when N equals K?Why is the logistic model considered more realistic than the exponential one?What is the intrinsic rate of natural increase r for the Norway rat?Which organisms breed only once in their lifetime?Which organisms produce many small-sized offspring?Populations evolve to maximise which property in their habitat?Which interaction is +/+ for the two species?Which interaction harms one species while the other is unaffected?Which interaction benefits one species with the other neither helped nor harmed?An orchid growing on a mango branch is an example of which interaction?Which interaction is shown by barnacles growing on the back of a whale?Why do cattle egrets forage close to grazing cattle?In the clown fish and sea anemone association, who gains protection?Which statement about predators is correct?How was the prickly pear cactus controlled in Australia?What ecological principle underlies biological control of pest insects?What happened when the starfish Pisaster was removed from an intertidal area?Why are predators in nature said to be prudent?Why is the Monarch butterfly distasteful to birds?Which is the most common morphological defence of plants against herbivores?What do flamingoes and resident fishes in South American lakes compete for?How is competition best defined in terms of fitness?Which principle states that two closely related species competing for the same resources cannot co-exist indefThe Abingdon tortoise became extinct after which animal was introduced to its island?What is competitive release?In Connell's Scottish coast experiments, which barnacle dominated the intertidal zone?What mechanism lets competing species co-exist by feeding at different times or ways?MacArthur showed that five warbler species on one tree co-existed because of what?Which adaptation is typical of parasites?Which two intermediate hosts does the human liver fluke need?Which is an ectoparasite?What is brood parasitism in birds?Why have eggs of brood parasitic birds evolved to resemble the host's eggs?Lichens are an association of a fungus with which partner?What do mycorrhizae supply to the plant?In fig trees, what does the pollinating wasp receive in return for pollination?What does the orchid Ophrys use to get pollinated by a bee?Which term describes tightly linked evolution of a flower and its pollinator?In a Type I survivorship curve, when does death mainly occur?Which survivorship curve typically characterises r-selected species?An r-selected species such as aphids is marked by what trait?