The VIDYANKER team has thoughtfully prepared the NCERT Solutions for Class 12 Biology Chapter 15, "Biodiversity and Conservation" These solutions are designed to help you tackle the NCERT textbook questions with ease. We recommend going through the chapter's theory before diving into the solutions for a deeper understanding. Feel free to share these NCERT Solutions for Class 12 Biology with others—learning is always better when shared!
QUESTIONS FROM TEXTBOOK SOLVED
1. Name the three important components of biodiversity.
Ans: Three components of biodiversity are:
(a) Genetic diversity
(b) Species diversity
(c) Ecological diversity
2. How do ecologists estimate the total number of species present in the world?
Ans: Ecologists obtain an estimate of the total number of species found in the world by comparing the species richness of some exhaustively studied groups between any two regions, be that the tropics, temperate or polar regions. Species density or the number of species per m² is most commonly used to measure species richness. Species richness is a measure of diversity that has been widely adopted among ecologists. Other alternative approaches to the measurement of diversity are species abundance and species proportional abundance-based indices.
3. Give three hypothesis for explaining why tropics ’”show greatest levels of species richness.
Ans: There are three contrasting hypotheses suggested by scientists to explain species richness in the tropics.
- Species richness is higher in tropical latitudes than in temperate regions because the tropical latitudes receive more solar energy than temperate regions, resulting in high productivity and high species diversity.
- Tropical regions have fewer seasonal variations, and their environment is largely constant. That promotes niche specialization and thus, high species richness.
- Tropical regions were not glaciated during the ice age, whilst the temperate regions were subjected to glaciations, thus resulting in an increase in the species diversity in this region.
4. What is the significance of the slope of regression in a species-area relationship?
Ans: The slope of regression (z) has a great importance so as to find a species-area relationship. It gives an estimate of species richness of area. It is independent of taxonomical category or type of area studied. It has been found that in the areas small in size where the species-area relationship is analysed, the value of slopes of regression is similar irrespective of the taxonomic group or the region. But when the same analysis is performed at greater lengths, then the slope of regression is very steep.
5. What are the major causes of species losses in a geographical region?
Ans: Species are lost in a geographical region due to natural disturbances such as forest fires; famine and drought and also due to human disturbance with over replantation, habitat destruction, habitat displacement, over specialization, intensive agriculture and pollution.
6. How is biodiversity important for ecosystem functioning?
Ans: An ecosystem with high species diversity is much more stable compared to an ecosystem with low species diversity. The biodiversity also makes the ecosystem highly stable in productivity as well as resistant towards disturbances, like alien species invasions and floods.
If an ecosystem is rich in biodiversity, then the ecological balance would not get affected. Because, we all know, different trophic levels are inter-linked through food chains. If a number of one organism or all organisms of any one trophic level is killed, then it will disrupt the whole food chain. For example, in food chain, if all plants are killed, then all deer's will die due to lack of food. If all deer's are dead, soon the tigers will also die. Hence, it can be inferred that if the richness in species of an ecosystem is high, then it would have other food alternatives at each trophic level that would not lead to death of any organism at any given time due to lack of their food resource. So, the importance of biodiversity lies in maintaining the health and ecological balance of an ecosystem.
7. What are sacred groves? What is their role in conservation?
Ans: Sacred groves are tracts of forest that regenerated around places of worship. They have been reported in Rajasthan, Western Ghats of Karnataka and Maharashtra, Meghalaya and Madhya Pradesh.
Sacred groves help protect several rare, threatened, and endemic species of plants and animals that exist in an area. Deforestation is strictly not allowed in this region by tribals. Therefore, the sacred grove biodiversity is a rich area.
8. Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?
Ans: Ecosystem services are products or benefits given by ecosystem processes to the environment for its purification, beauty, biodiversity, protection of natural resources, habitat to wild life and tribals, protection of soils, CO2 – O2 balance, retention of water against floods, drought and pollution. Plants play a vital role in the control of floods and soil erosion. Their roots hold the soil 10. particles firmly and in this way they do not allow the top soil to be drifted away by winds or moving water. Roots of plants also make the soil porous and allow water to go into the soil.
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?
Ans: More than 70 percent species recorded on the Earth are animals and only 22 percent species are plants. There is quiet a large difference in their percentage. This is because animals have adapted themselves to ensure their survival in changing environments in comparison to plants.
For example, insects and other animals have developed an elaborate nervous system in order to control and coordinate their body structure. Also, repeated body segments with paired appendages and external cuticles have made insects versatile and have given them the ability to survive in various habitats as compared to other life forms.
10. Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
Ans: Humans can drive a species to extinction through various means. We are making an attempt to eradicate disease-causing micro-organisms, like poliovirus, from this earth so that this earth may be delivered from such diseases. As such micro-organisms are harmful to the human society, the attempt has its justification. Besides, such micro-organisms are not the essential constituent (producers or decomposers) of any ecosystem and the loss of one or two such organisms will not affect the proper working of the ecosystem.
