Environmental Biology MCQ Quiz - Objective Question with Answer for Environmental Biology - Download Free PDF

The correct answer is: 1, 2, and 4 are true.

Key PointsUnderstanding the statements in relation to metapopulation structures

• Classical Metapopulation Model
  • In a classical metapopulation model, all patches are indeed small and prone to extinction due to their size and isolation.
  • This model assumes that individual patches experience frequent extinctions and are recolonized by dispersers from other patches. Hence, statement 1 is correct.
• Patchy Metapopulations
  • Patchy metapopulations are characterized by high rates of dispersal among patches, causing the population to function as a single subpopulation rather than separate, isolated groups.
  • This means that extinction in one patch is quickly compensated by recolonization from others. Hence, statement 2 is correct.
• Non-equilibrium Model
  • In the non-equilibrium model, local extinctions occur at a higher rate than recolonizations, leading to a decline in the number of occupied patches over time.
  • This model is often used to describe populations in highly fragmented landscapes where recolonization is difficult. Hence, statement 3 is incorrect.
• Mainland-Island Metapopulation Model
  • The mainland-island metapopulation model assumes that the mainland (or large central population) is stable and never goes extinct, serving as a source of colonists for surrounding smaller patches.
  • This ensures the persistence of the metapopulation despite the extinction of smaller patches. Hence, statement 4 is correct.

Additional Information

• Comparison with Other Metapopulation Models
  • Metapopulation models are important in understanding the dynamics of species in fragmented landscapes.
  • Each model (classical, patchy, non-equilibrium, and mainland-island) offers different insights based on the degree of patch isolation, size, and dispersal rates.
• Application in Conservation Biology
  • Metapopulation theory is widely applied in conservation biology to manage species in fragmented habitats, where the understanding of these dynamics can inform habitat restoration and connectivity efforts.

The correct option is '1 and 4 only'

Key Points

• r-selected species typically inhabit unstable environments.
  • This statement is correct.
  • r-selected species thrive in unstable or unpredictable environments where the ability to reproduce quickly is advantageous.
  • These species focus on rapid growth and high reproductive rates to ensure some offspring survive the adverse conditions.
• K-selected species tend to have a shorter lifespan.
  • This statement is incorrect.
  • K-selected species generally have longer lifespans because they invest more in individual offspring, ensuring higher survival rates through parental care and stable environmental conditions.
• r-selected species produce fewer offspring with a longer maturation period.
  • This statement is incorrect.
  • r-selected species typically produce a large number of offspring with a shorter maturation period, which increases the likelihood of at least some surviving in unstable environments.
• K-selected species are typically found in climax communities.
  • This statement is correct.
  • K-selected species are well adapted to stable environments, such as climax communities, where competition for resources is high and populations are near the carrying capacity of the environment.

Hence, Statements 1 and 4 are correct.

Additional Information

• r/K Selection Theory: This ecological theory describes the reproductive strategies of species in relation to their environmental contexts.
• r-selected species:
  • Typically inhabit unstable or unpredictable environments.
  • Produce a large number of offspring with small chances of individual survival.
  • Have short maturation periods and often do not invest in parental care.
• K-selected species:
  • Typically inhabit stable environments with high competition for resources.
  • Produce fewer offspring with higher chances of individual survival.
  • Have long maturation periods and often invest significantly in parental care.

The correct answer is Invasion.

 Key Points

• Primary succession starts from the primitive substratum where there was no previously any sort of living matter.
• The first group of organisms established there are known as the pioneers or primary colonisers.
•  The general process of primary succession includes:
  • Nudation
  • Invasion (migration, ecesis, aggregation)
  • Competition and coaction
  • Reaction, and
  • Stabilisation (Climax)
• Secondary succession starts from a previously built-up substratum with already existing living matter.
• The action of any external force, such as a sudden change in climatic factors, biotic intervention, fire etc., causes the existing community to disappear.
• Thus the area becomes devoid of living matter but its substratum, instead of primitive, is built-up.
• Such successions are comparatively more rapid and species do not need to invade a new habitat for their growth.

Therefore, the correct answer is an invasion.

The correct answer is the Western Ghats.

Key Points

• There are 4 biodiversity hotspots: the Himalayas, the Western Ghats, the Indo-Burma region, and the Sundaland.
• These hotspots have numerous endemic species.
• The Western Ghats are present along the western edge of peninsular India and cover most of the deciduous forests and rain forests.
  • This region consists of 6000 plant species of which 3000 are endemic.
  • The vegetation in this region was spread over 190,000 km2 but has been now reduced to 43,000 km2.
  • The region is also known for 450 species of birds, 140 mammals, 260 reptiles, and 175 amphibians.

Additional Information

• The Sundaland hotspot is located in South-East India (south of West Bengal, Bangladesh).
  • In the year 2013, the Sundaland was declared as a World Biosphere Reserve by the United Nations.
  • This region is famous for its rich terrestrial and marine ecosystem.
  • It is one of the biologically richest hotspots in the world which comprises 25,000 species of vascular plants, of which 15,000 are found only in this region.
• The Himalayas comprises North-East India, Bhutan, Central and Eastern parts of Nepal.
  • This region holds a record of having 163 endangered species which includes the Wild Asian Water Buffalo, One-horned Rhino, and as many as 10,000 plant species, of which 3160 are endemic.
  • This mountain range covers nearly 750,000 km2.
• The Indo-Burma Region is stretched over a distance of 2,373,000 km², this region spans over the North-eastern states, Myanmar, Cambodia, Laos, Thailand, Vietnam, and the southern part of China.
  • In the last 12 years, 6 large mammal species have been discovered in this region: the Large-antlered Muntjac, the Annamite Muntjac, the Grey-shanked Douc, the Annamite Striped Rabbit, the Leaf Deer, and the Saola.
• Endangered Animal Species in India: The Royal Bengal Tiger, The Great Asiatic Lion, The Snow Leopard, The Pig Nosed Frog, The Pink Headed Duck.

The correct answer is a - 4, b - 3, c - 2, d - 1.

Key Points

•  Charles Darwin proposed 'theory of natural selection'. It states that organisms which are better adapted to their environment tend to survive and produce more offspring.
• Gregor Mendel proposed the 'law of inheritance'. It consists of law of dominance, law of segregation and of law of independent asortment.
•  Jean Lamarck proposed the 'theory of inheritance by acquired characters'. It states that, the characters acquired during the lifetime of an organism are always passed on to the next generation.

The correct answer is Norman Myers.

Key PointsBiodiversity Hotspots:

• Biodiversity hotspots are regions with high species richness and a high degree of endemism. 
• The British biologist Norman Myers coined the term “biodiversity hotspot” in 1988 as a biogeographic region characterized both by exceptional levels of plant endemism and by serious levels of habitat loss.
• Conservation International (CI) adopted Myers’ hotspots and in 1996, the organization made the decision to undertake a reassessment of the hotspots concept. 
• In 1999, CI identified 25 biodiversity hotspots in the book “Hotspots: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions”.
• In 2005 CI published an updated titled “Hotspots Revisited: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions”.
• The 35 biodiversity hotspots cover 2.3% of the Earth’s land surface, yet more than 50% of the world’s plant species and 42% of all terrestrial vertebrate species are endemic to these areas.

Biodiversity hotspots in India:

• Himalaya: Includes the entire Indian Himalayan region (and that falls in Pakistan, Tibet, Nepal, Bhutan, China, and Myanmar).
• Indo-Burma: Includes entire North-eastern India, except Assam and Andaman group of Islands (and Myanmar, Thailand, Vietnam, Laos, Cambodia, and southern China).
• Western Ghats and Sri Lanka: Includes the entire Western Ghats (and Sri Lanka).
• Sundalands: Includes the Nicobar group of Islands, Indonesia, Malaysia, Singapore, Brunei, and Philippines.

The correct answer is: Littoral zone, Limnetic zone, Profundal zone, Benthic zone.

Lentic ecosystems are standing water bodies such as lakes and ponds. Stratification in these ecosystems refers to the layering of water into different zones based on certain physical and biological characteristics. Understanding the correct order of these zones is essential for studying the ecological interactions and biodiversity within lentic ecosystems.

Key Points

• Littoral Zone:
  • This is the topmost layer near the shore. It is well-lit by sunlight and supports a variety of aquatic plants and animals. The abundance of light allows for photosynthesis, making it one of the most productive zones.
• Limnetic Zone:
  • The open surface water layer away from the shore, extending down to the depth that sunlight can penetrate. It supports plankton, fish, and other aquatic life forms that thrive in well-lit conditions.
• Profundal Zone:
  • This deep-water zone below the limnetic zone lacks sufficient light for photosynthesis. It is inhabited by organisms adapted to cold, dark conditions, and low oxygen levels.
• Benthic Zone:
  • The bottommost layer, including the sediment surface and sub-surface layers. It is rich in organic detritus and nutrients and populated by benthic organisms like decomposers, detritivores, and some bottom-dwelling fish.

Additional Information

• Thermal Stratification:
  • Lentic ecosystems may also undergo thermal stratification, especially in summer, forming layers like the epilimnion, metalimnion (thermocline), and hypolimnion based on temperature gradients.
• Seasonal Changes:
  • Seasonal changes such as turnover events in spring and autumn can mix the water layers, redistributing nutrients and oxygen throughout the ecosystem.
• Importance of Stratification:
  • The stratification affects the distribution and abundance of organisms, nutrient cycling, and overall ecological dynamics within the lentic system.

The correct answer is higher.

Key Points

• Ecotones are points along an environmental gradient where there is a sharp transition between two ecological communities, ecosystems, or ecological zones.
• Ecotones are found in many spatial sizes and can be either natural or created by humans.
• The abundance and richness of species tend to peak in ecotonal zones.
• They include transitions between broad biomes and ecoregions as well as mountain treelines (for example, Mediterranean and arid).
• There is evidence that ecotones may potentially serve as centres for the emergence of new species.
• Populations in ecotones may be more resilient to biotic invasions, invading species, and other environmental changes because they are potentially pre-adapted to changing settings.
• Due to their frequent modest spatial size, relatively higher levels of biodiversity, and populations that can adapt to change, ecotones may be a good candidate for conservation.

Therefore, the correct answer is higher.

The correct answer is low biomass.

 Key Points

•  An oligotrophic lake or water body has relatively low productivity due to the low nutrient content in the lake.
• The waters of these lakes are usually quite clear due to the limited growth of algae in the lake.
• The waters of such lakes are of high-drinking quality.
• Such lakes support aquatic species that require well-oxygenated, cold waters such as lake trout.
• Oligotrophic lakes are usually found in the cold regions of the world where the mixing of nutrients is rare and slow due to the low temperatures of the lake waters. 
• Lake is divided into different zones that divide the water from top to bottom.
• The zones are the littoral zone, limnetic zone, profundal zone, euphotic zone, and benthic zone.
• The profundal zone is a deep zone of an inland body of freestanding water, such as a lake or pond, located below the range of effective light penetration.
• This is typically below the thermocline, the vertical zone in the water through which temperature drops rapidly.
• Since oligotrophic lakes have clear water, low nutrient content and relatively low productivity, the profundal zones present there have low biomass.

Therefore, the correct answer is low biomass.

The correct answer is Both (A) and (B) are true.

Key Points

• The word phytophagous is an adjective that means plant-eating, and it’s typically used to describe arthropods that feed on the tissues of living plants, but not those that consume pollen or nectar.
• Phytophagous insects are generally considered to be those that feed on green plants.
• They include species that attack roots, stems, leaves, flowers, and fruits, either as larvae or as adults or in both stages.
• Examples: Orthoptera, Lepidoptera, Coleoptera, Heteroptera, Hymenoptera, and Diptera 

Thus A is true.

• Sarcophagus organisms are those that live and feed on dead and decaying organisms.
• They are considered extremely important in soil biology.
• They break down the complex organic matter into simpler substances that are taken up by the plants for various metabolic activities.

Thus B is also true.

Therefore, the correct answer is both (A) and (B) are true.

The correct answer is 2) Only (i), (ii), (iii).

Key PointsUnderstanding the statements in relation to Lacustrine Zone

• Broad Deep Lake-like Basin
  • The lacustrine zone in a reservoir typically describes the part that resembles a deep lake, characterized by a broad and deep basin.
  • This area is generally found near the dam where water is the deepest. Hence statement (i) is correct.
• Autochthonous Nature
  • Autochthonous refers to materials such as organic matter that originate within the lake itself rather than being transported from outside.
  • The lacustrine zone, being deep and inactive, often supports autochthonous production due to the presence of internally generated nutrients. Hence statement (ii) is correct.
• P > R (Production greater than Respiration)
  • P > R indicates that the primary production (P) of organic material via photosynthesis exceeds respiration (R).
  • This condition can occur in the lacustrine zone where nutrient inputs can lead to high productivity. Hence statement (iii) is correct.
• Turbid Water
  • Turbid water usually contains high levels of suspended particles, making it less clear.
  • The lacustrine zone in a reservoir typically has clearer, less turbid water compared to other zones such as the riverine zone. Hence statement (iv) is incorrect.

Additional Information

• Characteristics of Lacustrine Zones
  • Lacustrine zones are key areas in large artificial reservoirs where water resides for long periods, allowing sedimentation to occur.
  • The water in these zones is generally more stable and clearer due to reduced sediment inflow and higher settling rates of suspended particles.
• Comparison with Riverine and Transitional Zones
  • Unlike the riverine (inflow) and transitional (middle) zones of a reservoir, the lacustrine zone is characterized by its depth and clearer water.
  • The riverine zone is more turbulent with high levels of suspended sediments and nutrients, leading to turbid conditions.

The correct answer is Chaparral forest.

 Key PointsChaparral forest:

• Chaparral is a type of woodland characterized by a combination of dry soil, warm weather, and short, hardy shrubs.
• The chaparral biome is dominated by short woody plants, rather than grasses (as in the grassland biome) or tall trees (as in forest biomes). 
• Chaparral occurs in the Mediterranean area.
• The climate over there is hot with dry summers and wet winters.
• The rainfall in this area is about 60 to 80 cm.
• It has evergreen vegetation.
• It has summer-drought-tolerant plants and drought-adapted animals.

Therefore, the correct answer is chaparral forest.

 Additional InformationTropical forest:

• Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforests.

Temperate forest:

• A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone.
• It is the second largest biome on our planet, covering 25% of the world's forest area, only behind the boreal forest, which covers about 33%.

Deciduous forest:

• Deciduous forest is vegetation composed primarily of broad-leaved trees that shed all their leaves during one season. 

The correct answer is Restriction endonucleases purified from bacteria can be used in vitro. 

 Key Points

• Recombinant DNA is used to make changes to the original genome of a plant or animal to add desired traits that are not present in them naturally and to delete genes that are harmful to plants and animals.
• This process is known as genetic engineering.
• The presence of restriction endonuclease, which enables us to alter the original DNA sequence, makes genetic engineering conceivable.
• As restriction enzymes, restriction endonucleases can recognise and cut DNA only at specific locations known as restriction sites.

Therefore, the correct answer is restriction endonucleases purified from bacteria can be used in vitro. 

The correct answer is MacArthur and Wilson (1967).

 Key Points

• The r and k classification was originally proposed by the biologists Robert MacArthur and E.O. Wilson (1967).
• The r-selected species live in highly variable populations.
• The fittest individuals in these environments have many offsprings and reproduce early.
• Examples: Oysters, insects, daphnia, goldenrod etc.
• K-selected species live in populations that are at or near equilibrium conditions for long periods.
• Competition for limited resources is very important in these environments.
• Examples: Lemurs, bats, elephants, giraffes etc.

Therefore, the correct answer is MacArthur and Wilson (1967).

The correct answer is Invasion.

 Key Points

• Primary succession starts from the primitive substratum where there was no previously any sort of living matter.
• The first group of organisms established there are known as the pioneers or primary colonisers.
•  The general process of primary succession includes:
  • Nudation
  • Invasion (migration, ecesis, aggregation)
  • Competition and coaction
  • Reaction, and
  • Stabilisation (Climax)
• Secondary succession starts from a previously built-up substratum with already existing living matter.
• The action of any external force, such as a sudden change in climatic factors, biotic intervention, fire etc., causes the existing community to disappear.
• Thus the area becomes devoid of living matter but its substratum, instead of primitive, is built-up.
• Such successions are comparatively more rapid and species do not need to invade a new habitat for their growth.

Therefore, the correct answer is an invasion.