NCERT NEET Biology English Medium Part-1 | Chapter 30 : Organisms and populations

NCERT NEET Biology English Medium Part-1 | Chapter 30 : Organisms and populations

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Question 1: Ecology at the organismic level is essentially which type of ecology that tries to understand how different organisms are adapted to their environments?

1. a) Behavioral ecology.
2. b) Physiological ecology.
3. c) Evolutionary ecology.
4. d) Synecology.

Answer: b.

Question 2: Regional and local variations within each biome lead to the formation of a wide variety of what?

1. a) Ecosystems.
2. b) Habitats.
3. c) Communities.
4. d) Populations.

Answer: b.

Question 3: The key elements that lead to so much variation in the physical and chemical conditions of different habitats are primarily?

1. a) Temperature, water, light and soil.
2. b) Temperature, pressure, soil and wind.
3. c) Water, light, pressure and predators.
4. d) Soil, light, parasites and water.

Answer: a.

Question 4: Which of the following statements regarding the temperature as an abiotic factor is incorrect?

1. a) It ranges from subzero levels in polar areas to >50°C in tropical deserts in summer.
2. b) There are unique habitats like deep-sea hydrothermal vents where average temperatures exceed 100°C.
3. c) Temperature decreases progressively from the equator towards the poles and from plains to the mountain tops.
4. d) Eurythermal organisms can tolerate only a narrow range of temperatures.

Answer: d.

Question 5: Snow leopards are not found in Kerala forests and tuna fish are rarely caught beyond tropical latitudes in the ocean. This is primarily due to the limitations imposed by which factor?

1. a) Availability of specific prey.
2. b) Salinity of water.
3. c) Temperature tolerance levels.
4. d) Intensity of light.

Answer: c.

Question 6: In aquatic environments, the quality of water that becomes most crucial for the organisms is?

1. a) Only the pH of the water.
2. b) The chemical composition and pH.
3. c) The temperature and depth.
4. d) The dissolved oxygen alone.

Answer: b.

Question 7: The salt concentration (measured as salinity in parts per thousand), is less than 5 in inland waters, 30-35 in the sea, and >100 in some hypersaline lagoons. Organisms tolerant of a wide range of salinities are called?

1. a) Stenohaline.
2. b) Euryhaline.
3. c) Eurythermal.
4. d) Stenothermal.

Answer: b.

Question 8: Many freshwater animals cannot live for long in sea water and vice versa mainly because of the?

1. a) Temperature variations they would face.
2. b) Osmotic problems they would face.
3. c) Lack of food resources.
4. d) Extreme light intensities.

Answer: b.

Question 9: For many small plants (herbs and shrubs) growing in forests, light is a limiting factor because they are?

1. a) Unable to absorb nutrients without bright light.
2. b) Adapted to photosynthesize optimally under very low light conditions due to overshadowing by tall canopies.
3. c) Lacking chlorophyll molecules necessary for bright light.
4. d) Found in areas where the soil is highly reflective.

Answer: b.

Question 10: The spectral quality of solar radiation is also important for life. Which component of the spectrum is known to be harmful to many organisms?

1. a) Infrared.
2. b) Visible light.
3. c) Ultraviolet.
4. d) Far-red.

Answer: c.

Question 11: In the deep oceans (>500m), the environment is dark and its inhabitants are not aware of the existence of a celestial source of energy called Sun. What is the source of energy for these ecosystems?

1. a) Photosynthesis by floating algae.
2. b) Geothermal energy and detritus.
3. c) Decomposition of surface materials only.
4. d) Chemosynthesis by archaebacteria.

Answer: d.

Question 12: The nature and properties of soil in different places vary depending on the climate, the weathering process, and whether soil is transported or sedimentary. Which of the following does not directly determine the vegetation of an area?

1. a) Soil composition.
2. b) Grain size.
3. c) Distance from the ocean.
4. d) Water holding capacity.

Answer: c.

Question 13: The process by which organisms maintain a constant internal environment despite varying external environmental conditions is called?

1. a) Acclimatization.
2. b) Homeostasis.
3. c) Adaptation.
4. d) Hibernation.

Answer: b.

Question 14: Mammals from colder climates generally have shorter ears and limbs to minimize heat loss. This ecological principle is known as?

1. a) Gloger's Rule.
2. b) Bergmann's Rule.
3. c) Allen's Rule.
4. d) Cope's Rule.

Answer: c.

Question 15: Why are very small animals rarely found in polar regions?

1. a) They cannot find small enough prey.
2. b) They have a larger surface area relative to their volume, causing rapid heat loss.
3. c) Their metabolic rate is too slow to generate heat.
4. d) They have a smaller surface area relative to their volume, leading to freezing.

Answer: b.

Question 16: If an organism cannot maintain a constant internal environment and its body temperature changes with the ambient temperature, it is classified as a?

1. a) Regulator.
2. b) Conformer.
3. c) Partial regulator.
4. d) Migrator.

Answer: b.

Question 17: Some organisms are able to maintain homeostasis by physiological (and sometimes behavioral) means which ensures constant body temperature and constant osmotic concentration. They are called?

1. a) Conformers.
2. b) Migrators.
3. c) Regulators.
4. d) Suspenders.

Answer: c.

Question 18: Every winter the famous Keoladeo National Park in Bharatpur hosts thousands of migratory birds coming from?

1. a) Africa and South America.
2. b) Siberia and other extremely cold northern regions.
3. c) Antarctica and New Zealand.
4. d) Australia and Southeast Asia.

Answer: b.

Question 19: Under unfavorable conditions, many zooplankton species in lakes and ponds are known to enter a stage of suspended development called?

1. a) Hibernation.
2. b) Aestivation.
3. c) Diapause.
4. d) Migration.

Answer: c.

Question 20: Bears going into hibernation during winter is an example of escape in?

1. a) Space.
2. b) Time.
3. c) Size.
4. d) Physiology.

Answer: b.

Question 21: To avoid summer-related problems like heat and desiccation, snails and fish go into?

1. a) Hibernation.
2. b) Diapause.
3. c) Aestivation.
4. d) Mutation.

Answer: c.

Question 22: Which of the following is an adaptation of the kangaroo rat in North American deserts to meet its water requirements?

1. a) It drinks large amounts of water when available and stores it in its hump.
2. b) It fulfills water needs through internal fat oxidation where water is a byproduct.
3. c) It has specialized gills to extract moisture from the desert air.
4. d) It absorbs water through its skin from the morning dew.

Answer: b.

Question 23: Many desert plants have a thick cuticle on their leaf surfaces and have their stomata arranged in deep pits (sunken) to?

1. a) Maximize light absorption.
2. b) Minimize water loss through transpiration.
3. c) Prevent herbivores from eating them.
4. d) Increase the rate of gas exchange.

Answer: b.

Question 24: Plants that use the CAM (Crassulacean acid metabolism) photosynthetic pathway are adapted because it enables their stomata to?

1. a) Remain open during the day and closed at night.
2. b) Remain open during the night and closed during the day.
3. c) Remain open constantly.
4. d) Close permanently, relying on root absorption of gases.

Answer: b.

Question 25: The thick layer of fat (blubber) below the skin of aquatic mammals like seals acts as an?

1. a) Insulator reducing loss of body heat.
2. b) Organ for storing water.
3. c) Excretory sink for metabolic wastes.
4. d) Osmotic regulator.

Answer: a.

Question 26: When you visit a high altitude place (>3,500m) like Rohtang Pass, you may experience altitude sickness. This is primarily due to?

1. a) Low atmospheric pressure causing a decrease in available oxygen.
2. b) Extremely low temperatures affecting lung capacity.
3. c) High ultraviolet radiation causing cellular stress.
4. d) High concentrations of carbon dioxide at high altitudes.

Answer: a.

Question 27: How does the human body eventually acclimatize to high altitude?

1. a) By decreasing red blood cell production and increasing hemoglobin affinity for oxygen.
2. b) By increasing red blood cell production, decreasing binding affinity of hemoglobin, and increasing breathing rate.
3. c) By storing extra oxygen in muscle tissues and reducing breathing rate.
4. d) By increasing the size of the lungs permanently.

Answer: b.

Question 28: Desert lizards lack the physiological ability to deal with high temperatures of their habitat. How do they manage their body temperature?

1. a) Through biochemical adaptations like anti-freeze proteins.
2. b) By continuous sweating and panting.
3. c) By behavioral means, basking in the sun when cold and moving to shade when hot.
4. d) By entering aestivation during the entire day.

Answer: c.

Question 29: In a population, if there are 20 lotus plants last year and through reproduction 8 new plants are added, taking the current population to 28, the birth rate is?

1. a) 0.8 offspring per lotus per year.
2. b) 0.4 offspring per lotus per year.
3. c) 0.2 offspring per lotus per year.
4. d) 0.6 offspring per lotus per year.

Answer: b.

Question 30: If 4 individuals in a laboratory population of 40 fruit flies died during a specified time interval (say a week), the death rate in the population during that period is?

1. a) 0.01 individuals per fruit fly per week.
2. b) 0.1 individuals per fruit fly per week.
3. c) 1.0 individuals per fruit fly per week.
4. d) 10.0 individuals per fruit fly per week.

Answer: b.

Question 31: An age pyramid for human populations with a broad base, tapering rapidly towards the top indicates a?

1. a) Declining population.
2. b) Stable population.
3. c) Expanding population.
4. d) Migrating population.

Answer: c.

Question 32: An urn-shaped age pyramid represents a population that is?

1. a) Rapidly growing.
2. b) Stable.
3. c) Declining.
4. d) Experiencing high infant mortality.

Answer: c.

Question 33: The size of a population for any species is not a static parameter. Which four basic processes fluctuate the population density?

1. a) Natality, Mortality, Immigration, Emigration.
2. b) Birth rate, Death rate, Isolation, Speciation.
3. c) Migration, Hibernation, Aestivation, Diapause.
4. d) Predation, Competition, Parasitism, Mutualism.

Answer: a.

Question 34: If N is the population density at time t, then its density at time t+1 is expressed as?

1. a) Nt+1 = Nt + [(B + I) - (D + E)].
2. b) Nt+1 = Nt + [(B + E) - (D + I)].
3. c) Nt+1 = Nt - [(B + I) + (D + E)].
4. d) Nt+1 = Nt + [(B - I) + (D - E)].

Answer: a.

Question 35: Under normal conditions, which two factors are the most important influencing population density?

1. a) Immigration and Emigration.
2. b) Births and Deaths.
3. c) Emigration and Deaths.
4. d) Immigration and Births.

Answer: b.

Question 36: If a new habitat is just being colonized, which process may contribute more significantly to population growth than birth rates?

1. a) Emigration.
2. b) Mortality.
3. c) Immigration.
4. d) Mutation.

Answer: c.

Question 37: When resources in the habitat are unlimited, each species has the ability to realize fully its innate potential to grow in number. This type of growth is known as?

1. a) Logistic growth.
2. b) Exponential or geometric growth.
3. c) Asymptotic growth.
4. d) Sigmoid growth.

Answer: b.

Question 38: The equation for exponential population growth is given by dN/dt = rN. Here, 'r' is called the?

1. a) Environmental resistance.
2. b) Intrinsic rate of natural increase.
3. c) Carrying capacity.
4. d) Mortality coefficient.

Answer: b.

Question 39: For the Norway rat, the 'r' value is 0.015, and for the flour beetle it is 0.12. In 1981, the r value for human population in India was?

1. a) 0.0205.
2. b) 0.015.
3. c) 0.12.
4. d) 0.005.

Answer: a.

Question 40: The integral form of the exponential growth equation is?

1. a) Nt = N0 e^rt.
2. b) N0 = Nt e^rt.
3. c) Nt = N0 e^-rt.
4. d) Nt = N0 + e^rt.

Answer: a.

Question 41: Nature has a given habitat with enough resources to support a maximum possible number, beyond which no further growth is possible. This limit is called?

1. a) Saturation point.
2. b) Carrying capacity (K).
3. c) Intrinsic capacity (r).
4. d) Environmental threshold.

Answer: b.

Question 42: A population growing in a habitat with limited resources shows initially a lag phase, followed by phases of acceleration and deceleration, and finally an asymptote. This growth curve is?

1. a) J-shaped.
2. b) S-shaped or Sigmoid.
3. c) Bell-shaped.
4. d) U-shaped.

Answer: b.

Question 43: The logistic growth model is described by the equation dN/dt = rN((K-N)/K). This model is known as?

1. a) Darwin-Wallace logistic growth.
2. b) Verhulst-Pearl logistic growth.
3. c) Malthusian exponential growth.
4. d) Hardy-Weinberg equilibrium.

Answer: b.

Question 44: Which population growth model is considered more realistic for most animal populations?

1. a) Exponential growth model.
2. b) Geometric growth model.
3. c) Logistic growth model.
4. d) Malthusian growth model.

Answer: c.

Question 45: Populations evolve to maximize their reproductive fitness, also called?

1. a) Mendelian fitness.
2. b) Lamarckian fitness.
3. c) Darwinian fitness (high r value).
4. d) Physiological fitness (high K value).

Answer: c.

Question 46: Pacific salmon fish and bamboo breed only once in their lifetime. This life history trait is an example of?

1. a) Iteroparity.
2. b) Semelparity.
3. c) Viviparity.
4. d) Parthenogenesis.

Answer: b.

Question 47: Birds and mammals typically exhibit which type of reproductive strategy?

1. a) Breed only once in their lifetime.
2. b) Produce a large number of small-sized offspring.
3. c) Breed many times during their lifetime.
4. d) Rely entirely on asexual reproduction.

Answer: c.

Question 48: Oysters and pelagic fishes are known to maximize their reproductive fitness by?

1. a) Producing a small number of large-sized offspring.
2. b) Producing a large number of small-sized offspring.
3. c) Breeding only once and dying immediately.
4. d) Providing extensive parental care.

Answer: b.

Question 49: According to ecologists, life history traits of organisms have evolved in relation to the constraints imposed by the?

1. a) Abiotic and biotic components of the habitat in which they live.
2. b) Size of the universe.
3. c) Genetic mutations only.
4. d) Human interferences exclusively.

Answer: a.

Question 50: Interspecific interactions arise from the interaction of populations of two different species. If the interaction is detrimental to both species, it is called?

1. a) Predation.
2. b) Parasitism.
3. c) Competition.
4. d) Amensalism.

Answer: c.

Question 51: If species A benefits and species B is neither benefited nor harmed, the interaction is termed?

1. a) Mutualism.
2. b) Commensalism.
3. c) Amensalism.
4. d) Parasitism.

Answer: b.

Question 52: Which of the following pairs of population interactions both result in a (+, -) outcome for the interacting species?

1. a) Mutualism and Commensalism.
2. b) Predation and Parasitism.
3. c) Competition and Amensalism.
4. d) Commensalism and Amensalism.

Answer: b.

Question 53: Besides acting as 'conduits' for energy transfer across trophic levels, predators play an important role in?

1. a) Increasing the carrying capacity of the ecosystem.
2. b) Keeping prey populations under control.
3. c) Maximizing the competition between prey species.
4. d) Eliminating all herbivores from the ecosystem.

Answer: b.

Question 54: The prickly pear cactus introduced into Australia in the early 1920s caused havoc by spreading rapidly. It was finally brought under control by introducing a?

1. a) Fungal pathogen.
2. b) Cactus-feeding moth (a predator).
3. c) Competitive plant species.
4. d) Herbivorous mammal.

Answer: b.

Question 55: Predators also help in maintaining species diversity in a community by?

1. a) Eliminating the dominant prey species completely.
2. b) Reducing the intensity of competition among competing prey species.
3. c) Causing mutations in prey species.
4. d) Increasing the reproductive rate of all prey.

Answer: b.

Question 56: In the rocky intertidal communities of the American Pacific Coast, the starfish Pisaster is an important predator. When all Pisaster starfish were removed experimentally, what was the result?

1. a) Prey species diversity increased dramatically.
2. b) More than 10 species of invertebrates became extinct within a year due to interspecific competition.
3. c) The remaining species lived in complete harmony.
4. d) Algae completely took over the ecosystem.

Answer: b.

Question 57: If a predator is too efficient and overexploits its prey, the prey might become extinct. What usually happens to the predator next in nature?

1. a) It evolves into a herbivore.
2. b) It also becomes extinct because of the lack of food.
3. c) It enters a state of diapause indefinitely.
4. d) It starts photosynthesizing.

Answer: b.

Question 58: Prey species have evolved various defenses to lessen the impact of predation. Some species of insects and frogs are cryptically-coloured. This is known as?

1. a) Mimicry.
2. b) Camouflage.
3. c) Aposematism.
4. d) Mutualism.

Answer: b.

Question 59: The Monarch butterfly is highly distasteful to its predator (bird) because of a special chemical present in its body. How does the butterfly acquire this chemical?

1. a) It synthesizes it from nectar during the adult stage.
2. b) It acquires it during its caterpillar stage by feeding on a poisonous weed.
3. c) It absorbs it through its wings from the atmosphere.
4. d) It inherits it as a fully formed chemical from the mother egg.

Answer: b.

Question 60: For plants, herbivores are the predators. Nearly what percentage of all insects are known to be phytophagous (feeding on plant sap and other parts of plants)?

1. a) 10%.
2. b) 25%.
3. c) 50%.
4. d) 75%.

Answer: b.

Question 61: Calotropis growing in abandoned fields is usually not browsed by cattle or goats because it produces highly poisonous?

1. a) Cardiac glycosides.
2. b) Alkaloids like nicotine.
3. c) Tannins and resins.
4. d) Cyanogenic glycosides.

Answer: a.

Question 62: Nicotine, caffeine, quinine, strychnine, and opium are produced by plants primarily for?

1. a) Aiding in pollination.
2. b) Defenses against grazers and browsers.
3. c) Enhancing photosynthesis.
4. d) Attracting seed dispersers.

Answer: b.

Question 63: According to Darwin, organic evolution is fundamentally driven by interspecific competition. Which condition is generally thought to be necessary for competition to occur?

1. a) Unlimited resources.
2. b) Closely related species competing for the same limiting resources.
3. c) Species belonging to completely different kingdoms.
4. d) Total absence of predators.

Answer: b.

Question 64: In some shallow South American lakes, visiting flamingos and resident fishes compete for their common food, which is?

1. a) Aquatic weeds.
2. b) Zooplankton.
3. c) Small insects.
4. d) Benthic algae.

Answer: b.

Question 65: The Abingdon tortoise in Galapagos Islands became extinct within a decade after which animal was introduced on the island?

1. a) Rats.
2. b) Goats.
3. c) Dogs.
4. d) Pigs.

Answer: b.

Question 66: The phenomenon where a species whose distribution is restricted to a small geographical area expands its distributional range dramatically when the competing species is experimentally removed is called?

1. a) Competitive exclusion.
2. b) Competitive release.
3. c) Character displacement.
4. d) Resource partitioning.

Answer: b.

Question 67: Connell's elegant field experiments on the rocky sea coasts of Scotland showed that the larger and competitively superior barnacle Balanus dominates the intertidal area and excludes the smaller barnacle species named?

1. a) Pisaster.
2. b) Chthamalus.
3. c) Macarthuria.
4. d) Paramecium.

Answer: b.

Question 68: Gause's 'Competitive Exclusion Principle' states that?

1. a) Two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior one will be eliminated eventually.
2. b) Two competing species can co-exist if they breed at the same time.
3. c) Predators will always exclude the strongest prey species.
4. d) Resources will spontaneously regenerate when competition is high.

Answer: a.

Question 69: MacArthur showed that five closely related species of warblers living on the same tree were able to avoid competition and co-exist due to?

1. a) Competitive exclusion.
2. b) Morphological convergence.
3. c) Behavioral differences in their foraging activities.
4. d) Interbreeding to form a single species.

Answer: c.

Question 70: Parasites that feed on the external surface of the host organism are called?

1. a) Endoparasites.
2. b) Ectoparasites.
3. c) Brood parasites.
4. d) Hyperparasites.

Answer: b.

Question 71: Which of the following is an example of an ectoparasite?

1. a) Plasmodium in human blood.
2. b) Tapeworm in the human intestine.
3. c) Cuscuta on hedge plants.
4. d) Liver fluke in snails.

Answer: c.

Question 72: The human liver fluke (a trematode parasite) depends on two intermediate hosts to complete its life cycle. What are they?

1. a) A mosquito and a pig.
2. b) A snail and a fish.
3. c) A cow and a tick.
4. d) A dog and a flea.

Answer: b.

Question 73: Endoparasites are those that live inside the host body at different sites. Which of their anatomical features is often highly simplified compared to free-living organisms?

1. a) Reproductive organs.
2. b) Digestive and morphological features.
3. c) Suckers and hooks.
4. d) Egg production capacity.

Answer: b.

Question 74: Brood parasitism in birds is a fascinating example of parasitism in which the parasitic bird?

1. a) Sucks the blood of the host bird's nestlings.
2. b) Lays its eggs in the nest of its host and lets the host incubate them.
3. c) Kills the host bird and takes over the nest.
4. d) Steals food from the host bird's beak.

Answer: b.

Question 75: During the course of evolution, the eggs of the parasitic bird in brood parasitism have evolved to resemble the host's egg in?

1. a) Yolk composition only.
2. b) Size and colour.
3. c) Incubation period strictly.
4. d) Taste to predators.

Answer: b.

Question 76: An orchid growing as an epiphyte on a mango branch is an example of?

1. a) Mutualism.
2. b) Commensalism.
3. c) Parasitism.
4. d) Amensalism.

Answer: b.

Question 77: Barnacles growing on the back of a whale benefit by getting to move to different feeding grounds. This interaction is?

1. a) Commensalism.
2. b) Mutualism.
3. c) Parasitism.
4. d) Competition.

Answer: a.

Question 78: The cattle egret and grazing cattle in close association represent a classic example of commensalism. How does the egret benefit?

1. a) It feeds on the ticks attached to the cattle's skin.
2. b) It gets milk from the cattle.
3. c) The cattle stir up and flush out insects from the vegetation for the egret to eat.
4. d) The cattle provide warmth to the egret during cold days.

Answer: c.

Question 79: The interaction between sea anemone that has stinging tentacles and the clown fish that lives among them is an example of?

1. a) Mutualism.
2. b) Commensalism.
3. c) Amensalism.
4. d) Parasitism.

Answer: b.

Question 80: Lichens represent an intimate mutualistic relationship between?

1. a) A fungus and a root of a higher plant.
2. b) A fungus and a photosynthetic algae or cyanobacteria.
3. c) An algae and a bacterium.
4. d) Two different species of fungi.

Answer: b.

Question 81: Mycorrhizae are associations between fungi and the roots of higher plants. What does the fungus provide to the plant?

1. a) Energy-yielding carbohydrates.
2. b) Protection from all insect pests.
3. c) Absorption of essential nutrients from the soil.
4. d) Photosynthetic products.

Answer: c.

Question 82: Plant-animal mutualism is commonly seen in pollination and seed dispersion. Why do plants offer rewards like nectar and pollen to animals?

1. a) To poison the animals.
2. b) To ensure the animals visit repeatedly and guarantee pollination.
3. c) To slow down the animal's metabolism.
4. d) Because they produce them in excess as waste products.

Answer: b.

Question 83: In many species of fig trees, there is a tight one-to-one relationship with the pollinator species of?

1. a) Bee.
2. b) Wasp.
3. c) Butterfly.
4. d) Ant.

Answer: b.

Question 84: In the fig-wasp mutualism, the female wasp uses the fig fruit not only as an oviposition (egg-laying) site but also?

1. a) Uses the developing seeds within the fruit for nourishing its larvae.
2. b) Eats the entire fruit from the outside.
3. c) Uses the fruit sap to build its nest elsewhere.
4. d) Sucks nectar from the open flowers on the branch.

Answer: a.

Question 85: The Mediterranean orchid Ophrys employs which specialized mechanism to get pollinated by a species of bee?

1. a) It produces a highly nutritious nectar.
2. b) It offers a safe place for the bee to lay eggs.
3. c) It employs 'sexual deceit' by mimicking the female bee in size, colour and markings.
4. d) It traps the bee inside the flower until pollen is shed.

Answer: c.

Question 86: If the female bee's colour patterns change even slightly during evolution, the pollination success of the Ophrys orchid will be reduced unless?

1. a) The orchid stops relying on insects for pollination.
2. b) The orchid co-evolves to maintain the resemblance of its petal to the female bee.
3. c) The orchid changes its scent to attract wasps instead.
4. d) The orchid starts producing copious amounts of nectar.

Answer: b.

Question 87: Statement I: Predators help in maintaining species diversity in a community. Statement II: Predators reduce the intensity of competition among competing prey species. Which is true?

1. a) Both Statements I and II are correct, and Statement II explains Statement I.
2. b) Both Statements I and II are correct, but Statement II does not explain Statement I.
3. c) Statement I is correct, Statement II is incorrect.
4. d) Statement I is incorrect, Statement II is correct.

Answer: a.

Question 88: In the equation for logistic growth dN/dt = rN(K-N/K), if N approaches K, what happens to the growth rate (dN/dt)?

1. a) It approaches infinity.
2. b) It approaches zero.
3. c) It equals r.
4. d) It becomes negative.

Answer: b.

Question 89: Which of the following best defines the 'Niche' of an organism?

1. a) The physical space where an organism lives.
2. b) The functional role played by the organism in its ecosystem and the range of conditions it can tolerate.
3. c) The geographical distribution of the organism globally.
4. d) The exact time of the day an organism is active.

Answer: b.

Question 90: An organism that tolerates a wide range of temperatures but a narrow range of salinities is termed?

1. a) Eurythermal and Euryhaline.
2. b) Eurythermal and Stenohaline.
3. c) Stenothermal and Euryhaline.
4. d) Stenothermal and Stenohaline.

Answer: b.

Question 91: The population interaction where one species harms the other without getting any benefit or harm itself is known as?

1. a) Parasitism.
2. b) Amensalism.
3. c) Commensalism.
4. d) Predation.

Answer: b.

Question 92: A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20, and emigration 30. The net increase in population is?

10. a) 10.
11. b) 15.
12. c) 0.
13. d) 5.

Answer: c.

Question 93: What does the 'benthic' zone of a lake or ocean primarily refer to?

1. a) The sunlit open water.
2. b) The shoreline vegetation.
3. c) The bottom zone where sediment and soil organisms reside.
4. d) The zone of rapid temperature change (thermocline).

Answer: c.

Question 94: Which adaptation is NOT typically found in desert plants (xerophytes)?

1. a) Thick cuticle on leaf surfaces.
2. b) Leaves reduced to spines.
3. c) Presence of large air spaces (aerenchyma) in stems.
4. d) Sunken stomata.

Answer: c.

Question 95: Assertion: Small animals are rarely found in polar regions. Reason: Small animals have a larger surface area relative to their volume, so they tend to lose body heat very fast when it is cold outside.

1. a) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
2. b) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
3. c) Assertion is correct but Reason is incorrect.
4. d) Assertion is incorrect but Reason is correct.

Answer: a.

Question 96: In a population showing exponential growth, the plot of the logarithm of population density (N) against time (t) results in a?

1. a) J-shaped curve.
2. b) S-shaped curve.
3. c) Straight line.
4. d) Parabola.

Answer: c.

 

Question 97: During the life cycle of the malaria parasite (Plasmodium), the human acts as the?

1. a) Only host.
2. b) Intermediate host.
3. c) Definitive (primary) host.
4. d) Commensal partner.

Answer: b.

 

Question 98: Some bacteria thrive in hot springs and deep sea hydrothermal vents where temperatures far exceed 100°C. Their survival is largely attributed to?

1. a) Thick blubber layers.
2. b) Branched chain lipids in their cell membranes and heat-resistant enzymes.
3. c) Sweating mechanisms to cool the cell.
4. d) CAM pathway of photosynthesis.

Answer: b.

Question 99: If a population is experiencing a logistic growth, the maximum sustainable yield is typically achieved when the population size is?

1. a) At the carrying capacity (K).
2. b) Very close to zero.
3. c) Exactly half of the carrying capacity (K/2).
4. d) Fluctuating widely above and below K.

Answer: c.

Question 100: Resource partitioning is a mechanism to avoid?

1. a) Predation.
2. b) Parasitism.
3. c) Competition.
4. d) Mutualism.

Answer: c.

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