Question 1

Name the three important components of biodiversity.

Accepted Answer

The three important components of biodiversity are:
1. Genetic Diversity: Variation of genes within species.
2. Species Diversity: Variety of species within a habitat or a region.
3. Ecosystem Diversity: Variety of ecosystems in a geographical location. — Biodiversity is broadly classified into three levels: genetic diversity refers to the genetic variation within species; species diversity refers to the number and variety of species; ecosystem diversity refers to the variety of habitats, biotic communities, and ecological processes.

Question 2

How do ecologists estimate the total number of species present in the world?

Accepted Answer

Ecologists estimate the total number of species present in the world by using sampling methods and extrapolation techniques. They study a particular area, count the number of species, and then use statistical models to estimate species richness for larger areas or globally. Methods include species-area curves, mark-recapture methods, and extrapolations based on known species discovery rates. — Because it is impossible to count every species on Earth, ecologists use representative sampling and mathematical models to estimate total species numbers. Species-area relationships help predict how species richness increases with area, and discovery rates help estimate undiscovered species.

Question 3

Give three hypotheses for explaining why tropics show greatest levels of species richness.

Accepted Answer

Three hypotheses explaining why tropics show greatest species richness are:
1. Historical Stability Hypothesis: Tropics have been climatically stable for long periods, allowing species to diversify.
2. Productivity Hypothesis: Higher solar energy and rainfall in tropics increase primary productivity, supporting more species.
3. Evolutionary Rate Hypothesis: Higher temperatures increase mutation and speciation rates in tropics. — The tropics have remained relatively stable over geological time, allowing species to accumulate. High productivity supports larger populations and more niches. Warm temperatures accelerate evolutionary processes, leading to greater diversification.

Question 4

What is the significance of the slope of regression in a species – area relationship?

Accepted Answer

The slope of regression in a species-area relationship indicates the rate at which species richness increases with area. A steeper slope means species number increases rapidly with area, reflecting habitat heterogeneity and species turnover. It helps ecologists understand how species diversity scales with habitat size. — Species-area relationship is often expressed as S = cA^z, where S is species number, A is area, c is a constant, and z is the slope of the log-log regression. The value of z indicates how sensitive species richness is to area changes.

Question 5

What are the major causes of species losses in a geographical region?

Accepted Answer

Major causes of species losses in a geographical region include:
1. Habitat destruction and fragmentation due to human activities like deforestation and urbanization.
2. Pollution affecting air, water, and soil quality.
3. Overexploitation of species through hunting, fishing, and trade.
4. Introduction of invasive alien species that outcompete native species.
5. Climate change altering habitats and species distributions. — Human-induced changes disrupt ecosystems and reduce species populations, leading to local or global extinctions. Habitat loss is the primary driver, followed by other anthropogenic pressures.

Question 6

How is biodiversity important for ecosystem functioning?

Accepted Answer

Biodiversity is important for ecosystem functioning because it:
1. Enhances productivity and stability of ecosystems.
2. Supports nutrient cycling and energy flow.
3. Provides resilience against environmental changes and disturbances.
4. Maintains ecosystem services such as pollination, water purification, and soil fertility. — Different species perform various ecological roles that collectively maintain ecosystem health. Greater biodiversity ensures functional redundancy and adaptability.

Question 7

What are sacred groves? What is their role in conservation?

Accepted Answer

Sacred groves are patches of forest or natural vegetation protected by local communities due to religious or cultural beliefs. Their role in conservation includes:
1. Preserving biodiversity by protecting native species and habitats.
2. Serving as gene pools and refuges for rare and endangered species.
3. Maintaining ecological balance and protecting water sources.
4. Preventing deforestation and habitat fragmentation in the region. — Sacred groves act as natural sanctuaries where human interference is minimal, thus conserving biodiversity and ecological processes.

Question 8

Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?

Accepted Answer

Control of floods and soil erosion by biotic components is achieved through:
1. Vegetation cover such as trees and grasses that bind soil with roots, preventing erosion.
2. Forests and wetlands that absorb and slow down surface runoff, reducing flood peaks.
3. Microorganisms and soil fauna that improve soil structure and water retention.
4. Plant transpiration that regulates local climate and water cycles. — Plants stabilize soil and reduce surface runoff, while ecosystems like forests and wetlands act as natural sponges, mitigating floods and erosion.

Question 9

The species diversity of plants (22 per cent) is much less than that of animals (72 per cent). What could be the explanations to how animals achieved greater diversification?

Accepted Answer

Explanations for greater diversification of animals compared to plants include:
1. Animals have greater mobility allowing them to exploit diverse habitats.
2. Complex body plans and specialized organs enable adaptation to varied niches.
3. Faster reproductive rates and shorter generation times increase evolutionary rates.
4. Co-evolution with plants and other organisms drives speciation. — Animal diversity is enhanced by their ability to move, adapt morphologically and physiologically, and interact dynamically with other species, promoting speciation.

Question 10

Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?

Accepted Answer

A situation where deliberate extinction might be considered is when an invasive alien species threatens native biodiversity, ecosystem stability, or human health. For example, invasive pests or disease vectors may be targeted for eradication to protect agriculture or native species. Justification lies in preserving native ecosystems, preventing economic losses, and protecting human well-being. However, such actions must be carefully evaluated to avoid unintended ecological consequences. — Deliberate extinction is ethically and ecologically sensitive but may be justified to control harmful invasive species that disrupt ecosystems or threaten survival of native species.

Question 11

Which of the following best defines biodiversity as popularised by Edward Wilson?

Accepted Answer

Combined diversity at all levels of biological organisation — Biodiversity, as defined by Edward Wilson, encompasses the total diversity at genetic, species, and ecosystem levels, combining all levels of biological organisation.

Question 12

Which of the following is an example of genetic diversity?

Accepted Answer

Different strains of rice with varying chemical potency — Genetic diversity refers to variation within a species. Different strains of rice exhibiting genetic variation in traits like chemical potency exemplify genetic diversity.

Question 13

India's ecosystem diversity is higher than that of Norway because India has:

Accepted Answer

Deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows — Ecological diversity refers to variety of ecosystems. India has a wide range of ecosystems including deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows, thus exhibiting greater ecological diversity than Norway.

Question 14

According to the IUCN (2004), approximately how many species of plants and animals have been described so far globally?

Accepted Answer

About 1.5 million — The IUCN (2004) states that slightly more than 1.5 million species have been described and recorded globally, though many more remain undiscovered.

Question 15

Which taxonomic group constitutes about 70% of the total recorded animal species on Earth?

Accepted Answer

Insects — Insects are the most species-rich group among animals, constituting about 70% of all recorded animal species globally.

Biodiversity and Conservation

Biodiversity and Conservation — Study Notes

13.1 Biodiversity

13.1.1 How Many Species are there on Earth and How Many in India?

13.1.2 Patterns of Biodiversity

Practice Questions — Biodiversity and Conservation

All 13 Chapters in Biology