CBSE Class 12 Biology Biodiversity and Conservation Assignment Set B

Read and download free pdf of CBSE Class 12 Biology Biodiversity and Conservation Assignment Set B. Get printable school Assignments for Class 12 Biology. Standard 12 students should practise questions and answers given here for Biology in Grade 12 which will help them to strengthen their understanding of all important topics. Students should also download free pdf of Printable Worksheets for Class 12 Biology prepared as per the latest books and syllabus issued by NCERT, CBSE, KVS and do problems daily to score better marks in tests and examinations

Biodiversity And Conservation Class 12 Biology Assignment Pdf

Class 12 Biology students should refer to the following printable assignment in Pdf for Biodiversity And Conservation in standard 12. This test paper with questions and answers for Grade 12 Biology will be very useful for exams and help you to score good marks

Class 12 Biology Assignment for Biodiversity And Conservation



Biodiversity : Term used to describe diversity at all levels of biological organisation. Term coined by socio-biologist Edward Wilson and was also used by Walter G Rosen for the diversity of life forms. Biodiversity refers to totality of genes in species and ecosytems of a region.

Three inter-related levels of Biodiversity : Genetic diversity, Species diversity, Ecological diversity.

 Genetic diversity : Diversity in the number and types of genes, as well as chromosomes present in different species and the variations in the genes and their alleles in the same species. It helps in speciation.

 Species diversity : Varieties in the number and richness of the species of a region.

 Ecological diversity : Variety in the types of ecosystems. IUCN : International Union for Conservation of Nature and Natural Resources. It is situated in Morges, Switzerland.

India has : More than 50,000 genetically different varieties of rice; 1000 varieties of mango;

 India has 1,42,000 known species of plants and animals (Around 45,000 species of plants and rest of animals);

 India has 8.1% of share of global biodiversity.

 India is one of 12 Mega diversity countries of the world. Latitudinal Gradients

 In general, species diversity decreases as we move away from the equator towards the poles.

 With very few exceptions, tropics (latitudinal range of 23.5¢X N to 23.5¢XS) harbour more species than temperate or polar areas.

 Colombia located near the equator has nearly 1,4000 species of birds while New York at 41°X N has 105 species and Greenland at 71°X N only 56 species.

q India has more than 1,200 species of birds.

q A forest in a tropical region like Equador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest of the USA.

q The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth.

Species-Area relationships

 German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit.

 The relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola. 

 On a logarithmic scale, the relationship is a straight line decribed by the equation

log S = log C + Z log A

Where S = Species richness, A = Area; Z = slope of the line (regression coefficient) C = Y - intercept.

q Value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region.

q The species-area relationships among very large areas like the entire continents has much steeper slope of the line (Z values in the range of 0.6 to 1.2).

Causes of Biodiversity Losses

1. Habitat loss and fragmentation : This is most important cause of plants and animals extinction. For example : Tropical rain forest being destroyed fast. The Amazonian rain forest is called the lungs of the planet. It is being cut for cultivating soyabeans.

2. Over exploitation : Many species extinctions are due to over exploitation by humans. eg :- extinction of steller's cow, passenger pigeon is last 500 years.

3. Alien Species Invasions : When alien species are introduced some of them turn invasive and cause decline or extinction of indigenous species. eg. :- Carrot grass (Parthenium), Lantana and water hyacinth (Eichornia) posed threat to native species.

4. Co-extinctions : When a species becomes extinct, the plant and animal species associated with it in an obligating way also become extinct. eg.:- When a host fish species becomes extinct, its assemblage of parasites also becomes extinct.

Reasons for Conservation of Biodiversity

1. Narrowly utilitarian : Humans derive countless direct economic benefit from nature food (cereals, pulses, fruits), firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and products of medicinal importance.

2. Broadly utilitarian : Biodiversity plays a major role in many ecosystem services that nature provides.

3. Ethical : every species has an intrinsic value, even if it may not be of any current economic value to us. We have a moral duty to care for their well-being and pass on our biological legacy in good order to future generations.


Important Questions for NCERT Class 12 Biology Biodiversity and Conservation


Question. In species area relationship, on a logarithmic scale.
The relationship is -
(a) Rectangular hyperbola
(b) Rectangular parabola
(c) Straight line
(d) Sigmoid

Answer : C

Question. More species in community, tends to more stability than communities with less species'. It was supported by-
(a) David Tilman
(b) Paul Ehrlich
(c) Humboldt
(d) Tansley

Answer : A

Question. "Rivet popper hypothesis" was proposed by -
(a) Tilman
(b) Hombolat
(c) Paul Ehrlich
(d) Mayer

Answer : C

Question. Alien species invasion is one of the cause of Biodiversity loss. Introduction of Nile perch in victoria lake lead to extinction of more than 200 species of -
(a) Cichlid fish
(b) Gambusia
(c) Salmon fish
(d) Cat fish

Answer : A

Question. The recent illegal introduction of which African fish becomes severe cause of threatening of indigenous cat fishes -
(a) Gambusia
(b) Labeo
(c) Clarias gariepinus
(d) Dog fish

Answer : C

Question. Find out the following w.r.t. economic importance of biodiversity -
(a) Production of oxygen
(b) Pollination
(c) Medicinal utility
(d) All

Answer : C

Question. Match the following-
(a) Ants (i) 20,000 species
(b) Beetles (ii) >28,000 species
(c) Fishes (iii) >3,00,000 species
(d) Orchids (iv) >20,000 species
(a) a (iv), b (ii), c (iii), d (i)
(b) a (ii), b (iii), c (iv), d (i)
(c) a (iv), b (iii), c (ii), d (i)
(d) a (iii), b (ii), c (i), d (iv)

Answer : C

Question. In biosphere, diversity (heterogeneity) exist at -
(a) Species level
(b) Genetic level
(c) Ecosystem level
(d) All the above

Answer : D

Question. Find out the odd one with respect to 'Biodiversity hot spots' -
(a) Western Ghats & Srilanka
(b) Indo - Burma
(c) Himalaya
(d) Gangatic plains

Answer : D

Ques. Which of the following regions of the globe exhibits highest species diversity?
(a) Western Ghats of India
(b) Madagascar
(c) Himalayas
(d) Amazon forests 

Answer: D

Ques. According to Robert May, the global species diversity is about
(a) 1.5 million
(b) 20 million
(c) 50 million
(d) 7 million.

Answer: D

Ques. Which of the following is the most important for animals and plants being driven to extinction?
(a) Alien species invasion
(b) Habitat loss and fragmentation
(c) Drought and floods
(d) Economic exploitation 

Answer: B

Ques. Decline in the population of indian native fishes due to introduction of Clarias gariepinus in river Yamuna can be categoriesd as
(a) co-extinction
(b) habitat fragmentation
(c) over-exploitation
(d) alien species invasion.

Answer: D

Ques. Alexander von Humboldt described for the first time
(a) laws of limiting factor
(b) species area relationships
(c) population growth equation
(d) ecological biodiversity. 

Answer: B

Ques. Which of the following is correctly matched?
(a) Aerenchyma – Opuntia
(b) Age pyramid – Biome
(c) Parthenium – Threat to hysterophorus biodiversity
(d) Stratification – Population 

Answer: C

Ques. Red list contains data or information on
(a) all economically important plants
(b) plants whose products are in international trade
(c) threatened species
(d) marine vertebrates only. 

Answer: C

Ques. Which is the national aquatic animal of India?
(a) Blue whale
(b) Sea-horse
(c) Gangetic shark
(d) River dolphin

Answer: D

Ques. Which of the following is the most important cause of animals and plants being driven to extinction?
(a) Habitat loss and fragmentation
(b) Co-extinctions
(c) Over-exploitation
(d) Alien species invasion 

Answer: A

Ques. A species facing extremely high risk of extinction in the immediate future is called
(a) vulnerable
(b) endemic
(c) critically endangered
(d) extinct. 

Answer: C

Ques. The organization which publishes the Red list of species is
(b) IUCN
(c) UNEP
(d) WWF.

Answer: B

Ques. Which of the following represent maximum number of species among global biodiversity?
(a) Fungi
(b) Mosses and Ferns
(c) Algae
(d) Lichens

Answer: A

Ques. Which of the following has maximum genetic diversity in India?
(a) Mango
(b) Wheat
(c) Groundnut
(d) Rice

Answer: D

Ques. Which organization publishes the ‘Red Data Book’?
(a) IUCN
(b) UNEP
(c) WWF
(d) GEF

Answer: A

Ques. Which one of the following have the highest number of species in nature?
(a) Fungi
(b) Insects
(c) Birds
(d) Angiosperms

Answer: B

Ques. Biodiversity of a geographical region represents
(a) endangered species found in the region
(b) the diversity in the organisms living in the region
(c) genetic diversity in the dominant species of the region
(d) species endemic to the region. 

Answer: B

Ques. Study the four statements (i–iv) given below and select the two correct ones out of them.
(i) A lion eating a deer and a sparrow feeding on grains are ecologically similar in being consumers.
(ii) Predator star fish Pisaster helps in maintaining species diversity of some invertebrates.
(iii) Predators ultimately lead to the extinction of prey species.
(iv) Production of chemicals such as nicotine, strychnine by the plants are metabolic disorders.
The two correct statements are
(a) (ii) and (iii) (b) (iii) and (iv)
(c) (i) and (iv) (d) (i) and (ii).

Answer: D


Please refer to the link below for CBSE Class 12 Biology Biodiversity and Conservation Assignment Set B

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