VBQs Biodiversity and Conservation Class 12 Biology with solutions has been provided below for standard students. We have provided chapter wise VBQ for Class 12 Biology with solutions. The following Biodiversity and Conservation Class 12 Biology value based questions with answers will come in your exams. Students should understand the concepts and learn the solved cased based VBQs provided below. This will help you to get better marks in class 12 examinations.
Biodiversity and Conservation VBQs Class 12 Biology
Very Short Answer Type Questions
Question. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major vertebrate taxa.
Answer : (a) Mammals
Question. Name the type of biodiversity represented by the following :
(i) 1000 varieties of mangoes in India.
(ii) Variations in terms of potency and concentration of reserpine in Rauwolfia vomitoria growing in different regions of Himalayas.
Answer : (i) Genetic diversity.
(ii) Genetic diversity.
Question. Eichhornia crassipes is an alien hydrophyte introduced in India. Mention the problems posed by this plant.
Answer : When an alien hydrophyte Eichhornia crassipes were introduced unintentionally, they turned invasive and caused decline or extinction of indigenous species.
Question. Name the unlabelled areas ‘a’ & ‘b’ of the pie chart representing the biodiversity of plants showing their proportionate number of species of major taxa.
Answer : (i) Fungi
Question. Why are mango trees unable to grow in temperate climate?
Answer : Because temperature affects the basal metabolism/ physiological function of the plant not adapted to low temperature of temperate climate. Mango trees are not able to grow in temperate below 30 degree, thus cannot grow in temperate climate.
Question. Give an example of a plant which came into India as a contaminant and is a cause of pollen allergy.
Answer : Parthenium / Carrot grass.
Question. Name the unlabelled area of the pie chart given alongside representing the global biodiversity of invertebrates showing their proportionate number of species of major taxa.
Answer : (i) Insects
Short Answer Type Questions
Question. Identify the areas labelled i, ii, iii and iv in the pie chart given below representing the biodiversity of plants showing their proportionate number of species of major taxa.
Answer : i – Lichen, ii – Algae, iii – Fungi, iv – Mosses
Question. Write what was the percentage of forest cover of India at the beginning and at the end of the twentieth century. How different is it from the one recommended by the National Forest Policy of our country ?
Answer : Beginning of 20th century – 30%
End of 20th century – 19.4%
Recommendations were 33% for the plains and 67% for the hills (thus forest cover shrunk substantially)
Question. Where would you expect more species diversityin tropics or in polar regions? Give reasons in support of your answer.
Answer : Tropics have more species biodiversity than that of the polar regions. The maximum biodiversity in the tropical regions is due to the following reasons :
(i) Prolonged evolutionary time : The tropics have remained undisturbed in the past and therefore evolved more species diversity.
(ii) High productivity : There is more solar energy available in tropics which contributes directly to more productivity, population sizes and indirectly to greater species diversity.
Question. Justify with the help of an example where a deliberate attempt by humans has led to the extinction of a particular species.
Answer : The Nile perch introduced into Lake Victoria in East Africa, eventually led to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake // Abingdon tortoise in Galapagos islands became, extinct, after goats were introduced due to greater browsing efficiency of goats // Connell’s field experiment showed that the competitively superior barnacle Balanus, excludes smaller barnacle Chathamalus // Over exploitation by man, caused extinction of Stellar’s sea cow / Passenger pigeon.
Question. With the help of one example, explain how does alien species invasion cause biodiversity loss.
Answer : When alien species are introduced, some of them become invasive, compete with the native species and cause extinction of indigenous species.
(i) Partheniun, Lantana and Eichhornia are the exotic species of plants that have invaded India and caused environmental damage. They pose threats to the survival of many of our native species.
(ii) Introduction of African catfish (Clarias gariepinus) for aquaculture purposes is posing a threat to our indigenous catfish Clarias batrachus.
Question. How does over-exploitation of beneficial species affect biodiversity ? Explain with the help of one example.
Answer : Humans have always depended on nature for food and shelter, but when need turns to ‘greed’, it leads to over-exploitation of natural resources. Many species extinctions in the last 500 years (Steller’s sea cow, passenger pigeon) were due to overexploitation by humans.
Presently, many marine fish populations around the world are over harvested, endangering the continued existence of some commercially important species.
Question. List the features that make a stable biological community.
Answer : The features of a stable community are as follows :
(i) Communities should have greater biodiversity for greater stability.
(ii) It should be able to prevent invasion by alien species.
(iii) It should be able to restore itself in a short period of time.
(iv) Variations should be minimal in the community.
Question. Why certain regions have been declared as biodiversity ‘hot spots’ by environmentalists of the world ? Name any two (hotspot) regions of India.
Answer : Faced with the conflict between development and conservation, many nations find it unrealistic and economically not feasible to conserve all their biological wealth. Invariably, the number of species waiting to be saved from extinction far exceeds the conservation resources available.
Hence, conservationists have declared certain regions as “hot spots” for maximum protection of these regions which have high levels of species richness and high degree of endemism.
Example, Western Ghats, Sri Lanka and Himalaya.
Question. Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with any three examples.
Answer : (i) Nile perch introduced into Lake Victoria in East Africa led to the extinction of Cichlids fish.
(ii) Parthenium/Lantana/Eichhornia are invasive plants and pose a threat to indigenous species.
(iii) Introduction of African catfish (Clarias gariepinus) to aquaculture is a threat to Indian catfishes.
Detailed Answer :
(i) The Nile perch introduced into Lake Victoria in east Africa led eventually to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake.
Since, cichlid fish became extinct and so the Nile perch, not finding any food for itself, died too.
(ii) The environmental damage caused a threat to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eichhornia).
(ii) The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.
Question. The following graph shows the species-area relationship. Answer the following question as directed.
(i) Name the naturalist who studied the kind of relationship shown in the graph. Write the observation made by him.
(ii) Write the situations as discovered by the ecologists when the value of ‘Z’ (slope of the line) lies
(a) 0.1 and 0.2
(b) 0.6 and 1.2
What does ‘Z’ stand for ?
(iii) When would the slope of the line ‘b’ become steeper ?
Answer : (i) Alexander Von Humboldt. Within a region species richness increased with increasing explored area but only up to a limit.
(ii) (a) The slopes of regression lines are similar / unaffected distribution in an area / normal range.
(b) The slope of regression is steeper when we analyse the species area relationship among very large areas like entire continent. Z (slope of the line) regression co-efficient.
(iii) If species richness is more / 0.62 – 1.2. 3
Question. Co-extinction and introduction of alien species too are responsible for the loss of biodiversity. Explain, how.
Answer : Co-extinction : When a species becomes extinct, the plant and animal species associated with it in the obligatory way, also becomes extinct Introduction of alien species : When alien species are introduced, some of them turn invasive (because of not having their predator there), and hence cause decline / extinction of indigenous species.
Question. (a) “India has greater ecosystem diversity than Norway.” Do you agree with the statement ?
Give reasons in support of your answer.
(b) Write the difference between genetic biodiversity and species biodiversity that exists at all levels of biological organization.
Answer : (a) Yes
India / tropical region : (i) are less seasonal / more constant / more predictable.
(ii) promote niche specialisation leading to greater bio-diversity.
(iii) Species diversity increases as we move towards equator.
(iv) More number of species exist.
Norway / temperate region : (i) more seasonal / less constant / less predictable.
(ii) do not promote niche specialisation leading to low bio-diversity.
(iii) Species diversity decreases as we move away from equator.
(iv) Less number of species exist.
(b) (i) Genetic diversity : Diversity / variation within a species over its distributional range/ (same explanation with the help of a correct examples)
(ii) Species diversity : Diversity / variation at a species level (same explained with the help of a correct example).
Detailed Answer :
(a) Yes, India has greater ecosystem diversity than Norway. It is because India lies primarily in the tropical and sub-tropical zone while Norway lies near the Arctic region. This exposes the India to greater amounts of sunlight and thus greater level of ecosystem diversity.
(b) Difference between genetic diversity and species diversity :
|Genetic diversity||Species diversity|
|It refers to the number of genes and their alleles found in organisms.||It refers to the numbers of species per unit area.|
|It increases as we move up the biological organization.||It may or may not increase to a greater extent as we move up the biological organization.|
Long Answer Type Questions
Question. (i) Taking one example each of habitat loss and fragmentation, explain how are two responsible for biodiversity loss.
(ii) Explain two different ways of biodiversity conservation.
Answer : (i) Habitat loss—Amazon rain forest destroyed for soya beans cultivation for growing grass land, for grazing cattle / colonisation of Pacific islandsextinction of 2000 species of native birds.
Fragmentation—By human activity— migratory birds and animals are affected.
(ii) Ex situ, Threatened organism are taken out from the natural habitat and placed in special setting with care and protection. e.g., Zoological park / botanical garden / wild safari.
In situ, Threatened organisms are conserved in their natural habitat e.g. National park / Biosphere reserves.