Short & Long Question Answers with Solution: Biodiversity and its Conservation | Biology Class 12 - NEET PDF Download

Short Answer Type Questions

Q1: Is more solar energy available in the tropics? Justify your answer.
Ans: Yes, this statement is accurate, and it can be explained by the following factors:

• Sunlight has to pass through a shorter path in the atmosphere, resulting in less energy being lost due to reflection and absorption by the atmosphere.
• Sunlight is more concentrated in tropical regions.
• The presence of dense vegetation in tropical rainforests leads to a higher absorption of solar radiation.

Q2: What is meant by the invasion of an alien species? List two foreign species of plant and animal that are a threat to indigenous Indian species.
Ans: Alien species invasion is the deliberate or unintentional introduction of non-native species by humans to new islands or countries.
For example, the introduction of the Nile perch to Lake Victoria in East Africa led to the extinction of more than 200 species of cichlid fish. In India, our native species face threats from introduced plant species like Lantana camara and introduced animal species like Clarias gariepinus.

Q3: Define sacred groves. What is their role in the conservation of biodiversity?
Ans: These are revered areas of significant importance to local communities. They are dedicated to ancestral spirits and indigenous deities and are protected by local communities through cultural taboos and traditional practices, encompassing ecological and spiritual significance. These regions are biodiversity hotspots, providing a nurturing environment for rare plant and animal species, and can be found in various locations such as the Aravalli hills, Meghalaya, and the Western Ghats.

Q4: Make notes on Paul Ehrlich’s “rivet popper theory”.
Ans: Paul Ehrlich proposed a theory to elucidate the advantages of species diversity. He employed the analogy of comparing each species to a rivet in an airplane's structure. This analogy illustrates how species function as the rivets that provide stability to the ecosystem, much like the components of an aircraft. Initially, the safety of the journey would not be immediately affected if passengers started removing rivets (symbolizing species extinction). However, over time, the airplane would become unstable and eventually crash, symbolizing the increasing threat and eventual extinction of species.

Q5: State two ways through which humans are benefitted from biodiversity.
Ans: Economic advantages are obtained from the variety of organisms, including:

• Food, fiber, and firewood
• Industrial resources and construction materials
• Medicinal substances sourced from plants
• Pure oxygen, flood control, and soil erosion prevention, as well as natural pollinators
• Waste recycling facilitated by microbes
• Nutrient replenishment

Q6: Why does species variety decrease as we move farther from the equator?
Ans: The decline in biodiversity as we move towards the poles is due to worsening environmental conditions with decreasing temperatures. This results in reduced solar radiation, diminished vegetation, and a decrease in available resources to support a wide range of species. The harsh conditions in polar regions make it challenging for species to adapt and thrive, leading to a decrease in biodiversity.

Q7: How do scientists estimate the total number of species on earth?
Ans: Biodiversity can be estimated using two approaches:

• Estimating the rate at which new species are discovered.
• Statistically analyzing the relationship between the richness of tropical and temperate species in well-studied insect communities. This analysis helps deduce a ratio that can be used to predict the total species estimate based on the known species.

Q8: Describe how the entrance of an alien species affects the local species diversity.
Ans: Certain alien species engage in invasion when they intentionally or unintentionally become established in a specific habitat. This can lead to a reduction in the population or even the extinction of native species. For instance, lantana and water hyacinth have become invasive species. Another example is the invasion of Lake Victoria in East Africa by the large predatory fish known as the Nile perch. This invasion led to the extinction of more than 200 species of cichlid fish, which were ecologically distinct. The extinction of these cichlid fish occurred due to a shortage of food caused by both the predatory Nile perch and the cichlid fish themselves.

Q9: In comparison to other animal groups, why are amphibians more vulnerable to extinction?
Ans: This occurs due to the following reasons:

• Fragmentation of Habitats
• Destruction or Alteration of Habitats
• Significant Climate Change on a Large Scale

Q10: There are more than a thousand different mango varieties in India. What type of biodiversity does this represent and what makes it possible?
Ans: In India, the diverse types of mango cultivars reflect the genetic diversity of the nation.
India is situated in a tropical region with a consistent and predictable climate, resulting in a region rich in biodiversity. Furthermore, the abundance of available sunlight contributes to increased productivity.

Long Answer Type Questions

Q1: Where would you anticipate a higher species diversity, in the tropics or in the polar regions? Give justifications for your answer.
Ans: Tropical latitudes exhibit greater biodiversity compared to temperate or polar regions, and this can be attributed to several factors.

• Firstly, the passage of time has had a significant impact on speciation. Tropical regions have remained relatively stable and unchanged for extended periods, allowing more time for the evolution of diverse species compared to temperate areas, which experienced periodic glaciations in the past.
• Secondly, tropical regions receive higher levels of solar radiation, leading to increased productivity. This heightened productivity, both directly and indirectly, contributes to greater species diversity.
• Lastly, the tropical climate is characterized by less cyclical variations, making it more stable and predictable. This climatic stability promotes species diversity and specialization within ecological niches.

Q2: Write notes on the ‘rivet popper hypothesis’ by Paul Ehrlich.
Ans: He proposed a hypothesis to elucidate the importance of species richness, using an analogy where each species is likened to a rivet in an airplane's structure. This analogy illustrates that the ecosystem can be likened to an airplane, and the individual species within it act as rivets, essentially holding all the components together. In this analogy, if passengers were to remove rivets (symbolizing species extinction), it might not have an immediate impact on the flight's safety (representing the stable functioning of the ecosystem). However, over time, the plane would become increasingly fragile and eventually crash, symbolizing the endangerment and eventual extinction of species within the ecosystem.

Q3: How can we prevent the loss of biodiversity?
Ans: Biodiversity refers to the presence of diverse habitat types, species, ecosystems, gene pools, and genes within a specific area. It can be conserved through effective conservation strategies and the management of biotic and abiotic resources.
The following are some conservation strategies:

• Conservation of native plant and animal species in their natural habitats.
• Protection of critical habitats, including breeding and feeding sites, and the promotion of the growth and reproduction of endangered species.
• Regulation or complete prohibition of hunting.
• Protection of the habitats of migratory species through bilateral and international agreements.
• Raising awareness among people about the importance of conserving biodiversity.
• Prevention of the excessive use of natural resources.

Q4: Explain the ecosystem service. Write any four ecosystem services rendered by the natural ecosystem. Are you in support of or against imposing a charge on the service given by the ecosystem?
Ans: Ecosystem services are the outcomes of ecosystem processes, and one of the primary providers of these services is forests.
Some of the vital services provided by ecosystems like forests include:

• Purifying water and air.
• Mitigating droughts and floods.
• Recycling nutrients.
• Generating fertile soil.
• Offering habitat for wildlife.
• Supporting biodiversity.
• Pollinating crops.
• Serving as carbon storage sites.
• Contributing to cultural, aesthetic, and spiritual values.

I am not in favor of imposing a fee for these services. However, it's essential to recognize the value of what nature provides for free, and irresponsible or excessive resource use can come with a significant cost.

Q5: Describe the importance of biodiversity to human beings.
Ans: Biodiversity holds significant importance for humans in various aspects:

• Diverse Resources: Biodiversity serves as a direct or indirect source of food, shelter, and clothing for human populations.
• Resins: Humans utilize plant resins in various ways.
• Oils: Different types of oils are extracted from various plant sources.
• Medicinal Benefits: Biodiversity is crucial in the development of medicines and drugs, as living organisms contain valuable therapeutic compounds.
• Ecosystem Stability: Biodiversity contributes to the stability of ecosystems, ensuring the smooth flow of food webs, food chains, and biochemical cycles.
• Cultural and Recreational Values: Many people in India hold plants sacred and engage in recreational activities related to nature.

Q6: Besides the relationship used by Paul Ehrlich, can you arrive at a scientific explanation to explain the direct association between stability and diversity of an ecosystem?
Ans: Imagine a situation where a wide range of species is thriving. Various plants support a multitude of species, including a variety of insects that rely on these plants for their food. The survival of these dependent insect species becomes highly precarious when a specific plant species dies off, leading to a scarcity of food. Furthermore, if this particular plant had the ability to fix nitrogen, its demise would result in the soil losing its capacity to replenish essential nitrogen nutrients, affecting the growth of other plants. If this pattern of events were to repeat and become a regular occurrence, it could have detrimental consequences for the entire ecosystem.

Q7: Describe IPR. Mention the disadvantages of IPR.
Ans: IPR, which stands for Intellectual Property Rights, is sometimes employed to patent genetically modified plants, animals, and microorganisms, effectively turning them into exclusive private property.
There are several drawbacks associated with Intellectual Property Rights:

• Seed costs rise as a result of IPR.
• Indigenous varieties are substituted with foreign varieties.
• The spread of new varieties is sluggish.
• Multinational corporations have significant dominance in agriculture.

Q8: How can the loss of biodiversity be prevented?
Ans: Biodiversity refers to the presence of various habitat types, species, ecosystems, gene pools, and genes in a specific location. It can be preserved through various conservation methods and the management of biotic and abiotic resources.
Here are some conservation strategies:

• Protection of valuable plants and animals in their natural environments through natural conservation.
• Preservation of critical habitats such as breeding and feeding grounds, and promoting the growth and propagation of endangered species.
• Regulation or prohibition of hunting activities.
• Conservation of the habitats of migratory species through bilateral or multilateral agreements.
• Raising awareness about the importance of biodiversity conservation.
• Avoiding the overexploitation of natural resources.

Q9: Why do the tropics account for greater biological diversity? Give reasons.
Ans: The higher biodiversity observed in tropical regions can be attributed to the following factors:

• Tropical regions receive more solar energy, resulting in increased productivity and, consequently, greater biological diversity.
• The tropical environment experiences less seasonality, making it more predictable and stable.
• Tropical latitudes have remained relatively undisturbed for millions of years, contributing to their higher levels of biological diversity.

Q10: Explain how species diversity of an area is reduced by the invasion of an alien species.
Ans: When alien species are introduced to a specific habitat, whether intentionally or accidentally, some of these species can become invasive, leading to the decline or extinction of native species. For example, plants like lantana and water hyacinth have become invasive in certain areas. In another instance, the introduction of the Nile perch, a large predator fish, to Lake Victoria in East Africa resulted in the extinction of over 200 species of cichlid fish, which were ecologically unique to the lake. As the cichlid fish disappeared due to a shortage of food, the predatory Nile perch also perished.