Biodiversity and Conservation is a core CBSE and competitive-exam chapter because it connects how species diversity is measured (index-based ideas), why habitats shrink and populations decline, and how conservation strategies (in-situ/ex-situ, protected areas, fragmentation effects) help maintain ecosystem stability and evolutionary potential.
20
Minutes
15
Questions
1 / -0
Marking
Q1. In a community with four species having abundances 10, 20, 30 and 40 individuals respectively, calculate Simpson's diversity index using where is the proportion of species . (Take proportions to two decimal places if needed.)
(A)
(B)
(C)
(D)
Q2. Two communities each have five species. Community A has abundances (40, 30, 10, 10, 10) and Community B has abundances (96, 1, 1, 1, 1). Using Simpson's index , which statement is correct about their diversities?
(A) Community B has higher Simpson's diversity than Community A.
(B) Both communities have approximately equal Simpson's diversity.
(C) Simpson's index cannot distinguish because species richness is the same in both.
(D) Community A has much higher Simpson's diversity than Community B because Community A is far more even in species abundances.
Q3. For a population with breeding males and breeding females, effective population size is given by and the approximate per-generation increase in inbreeding coefficient is . Calculate (rounded to four decimal places).
(A)
(B)
(C)
(D)
Q4. Using the species–area relationship , consider a fixed total area . Compare species richness of (i) one reserve of area and (ii) two separate reserves each of area (assume species counts in the two small reserves are additive, i.e., no overlap). For which values of the exponent will the single large reserve support strictly more species than the two small reserves?
(A)
(B)
(C)
(D) For all values of
Q5. Under Wright's island model, , where is effective population size and is the migration rate per generation. For a metapopulation with , what minimum migration rate (as a fraction of the population per generation) is required to keep ?
(A)
(B)
(C)
(D)
Q6. In a small isolated population there are 10 breeding males and 30 breeding females. Using the formula , calculate the effective population size .
40
20
30
15
Q7. A population has effective size . Expected heterozygosity after generations is given by . Approximately after how many generations will heterozygosity decline to half its initial value ()?
69 generations
50 generations
100 generations
35 generations
Q8. A continuous forest of area is reduced to due to habitat loss. Using the species–area relationship with (and unchanged), what percentage of the original species richness is expected to remain?
Q9. Assertion (A): Fragmenting a population into several small isolated reserves of equal total area increases the overall effective population size compared to a single contiguous reserve of the same total area.
Reason (R): Isolation of subpopulations increases genetic drift and inbreeding, which generally reduces and genetic variability.
Both A and R are true and R explains A.
Both A and R are true but R does not explain A.
A is true but R is false.
A is false but R is true.
Q10. Two reserves, each of area , are designed: one circular and one square. Edge effects penetrate into the periphery. Using for the circle and for the square, which shape retains a larger proportion of core habitat and what are the approximate core-area percentages for each (use )?
The circular reserve retains more core habitat — approximately (circle) vs (square).
The square reserve retains more core habitat — approximately (square) vs (circle).
Both retain the same core proportion — approximately each.
Neither retains any core habitat (edge penetrates entire reserve).
Q11. A habitat follows the species–area relation with . If the habitat area is reduced to one-sixteenth of its original value () due to fragmentation, approximately what percentage of the original species richness is expected to persist?
25%
16%
50%
75%
Q12. In a small mammal population there are breeding males and breeding females. Using the effective population size formula , compute and compare the expected rate of genetic drift to an ideal population whose census size equals the total number of breeders (). Which statement is correct?
; the rate of genetic drift (proportional to ) is about times faster than in an ideal population of size 60.
; genetic drift will be similar to that in an ideal population of size 60.
; genetic drift will be roughly times faster.
; effective size equals census size so drift rate is unchanged.
Q13. In a metapopulation model the equilibrium fraction of occupied patches is , where is patch extinction rate and the colonization rate. Initially and . Habitat fragmentation causes to increase by 50% and to decrease by 25%. What fraction of the original equilibrium occupancy remains after fragmentation?
0.25 times the original
0.75 times the original
unchanged (1.0 times the original)
0.5 times the original
Q14. Two reserves have equal total area . Reserve I is circular; Reserve II is square. Edge effects penetrate inward to a width and make the edge zone unsuitable; the remaining area is the ‘core’. Using for the circle and for the square, which reserve retains the larger core area and what are the approximate core areas?
Square retains larger core: square core , circle core .
Circle retains larger core: circle core , square core .
Both retain equal core area .
Square retains larger core: square core , circle core .
Q15. Consider a community with species abundances S1=50, S2=30, S3=15, S4=5 (total ). Shannon diversity is where are relative abundances. Two events occur separately: (i) species S4 (5 individuals) is extirpated; (ii) twenty individuals of the dominant species S1 are removed, yielding new abundances S1=30, S2=30, S3=15, S4=5 (total ). Which scenario causes a larger decrease in relative to the initial community?
Scenario (i) (loss of the rare species) causes the larger decrease; scenario (ii) actually increases because evenness improves.
Scenario (ii) causes the larger decrease; removing individuals from the dominant species always reduces diversity more.
Both scenarios cause the same decrease in .
Both scenarios lead to an increase in .