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Biodiversity and Conservation Set-1 MCQ Online Practice Test | Class 12 | Quiz Tweek

Biodiversity and Conservation Set-1

Practice Important MCQs for Biodiversity and Conservation — Biology, Class 12.

Biodiversity and conservation is a high-scoring and frequently asked CBSE/JEE/NEET topic because it connects core ecology concepts (species diversity, genetic diversity, extinction risk) with real-world conservation strategies (habitat corridors, protected areas, metapopulations). Board questions often test definitions and formulas, while competitive exams emphasize interpreting ecological relationships and applying models to new situations—so mastering both theory and calculation-based reasoning is crucial.

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Q1. A forest sample contains four species with counts: Species A = 10, B = 15, C = 5, D = 20. Using Simpson's index of diversity
$D = 1 - \displaystyle\sum \frac{n_i(n_i-1)}{N(N-1)}$ , calculate $D$ for this community.

(A)

0.286

(B)

0.860

(C)

0.714

(D)

0.571

Q2. Two habitat patches X and Y follow the species–area relationship $S = cA^z$ with $z = 0.25$ . Patch X has area $100\ \text{km}^2$ and initially supports 40 species; patch Y has area $25\ \text{km}^2$ . If both patches lose 50% of their area due to deforestation, which statement is correct?

(A)

Both patches will lose the same proportion of their species; patch X will lose a greater absolute number of species.

(B)

Both patches will lose the same absolute number of species.

(C)

Patch Y will lose a higher proportion of species because it is smaller.

(D)

Patch X will lose a higher proportion of species because larger areas hold more species.

Q3. For an endangered population with $N_m=8$ males and $N_f=2$ females, effective population size is given by $N_e=\dfrac{4N_mN_f}{N_m+N_f}$ . Which management action will produce the largest increase in $N_e$ ?

(A)

Introduce 4 additional males (new $N_e\approx 6.86$ ).

(B)

Introduce 4 additional females (new $N_e\approx 13.71$ ).

(C)

Introduce 2 males and 2 females (new $N_e\approx 11.43$ ).

(D)

Introduce 2 additional females only (new $N_e\approx 10.67$ ).

Q4. Assertion (A): Creating wildlife corridors between fragmented habitats always increases regional biodiversity.
Reason (R): Corridors promote movement, migration and gene flow, which reduce local extinction risk and support recolonisation.
Choose the correct option:

(A)

A and R are true and R is the correct explanation of A.

(B)

A and R are true but R is not the correct explanation of A.

(C)

A is true but R is false.

(D)

A is false but R is true.

Q5. Two isolated populations have initial heterozygosity $H_0=0.9$ . Heterozygosity after $t$ generations follows $H_t = H_0\left(1-\dfrac{1}{2N_e}\right)^t$ . Compare retention after $t=50$ generations for $N_e=50$ and $N_e=500$ .

(A)

For $N_e=50$ , $H_{50}\approx 0.545$ ; for $N_e=500$ , $H_{50}\approx 0.856$ — the larger $N_e$ retains much more heterozygosity.

(B)

For $N_e=50$ , $H_{50}\approx 0.856$ ; for $N_e=500$ , $H_{50}\approx 0.545$ .

(C)

Both populations retain roughly the same heterozygosity ( $\approx 0.70$ ).

(D)

Heterozygosity retention after 50 generations depends mainly on mutation rate, not $N_e$ .

Q6. A nature reserve of area 1600 km^2 supports 200 species. If its area is reduced to 400 km^2 due to development, use the species–area relationship $S = cA^z$ with $z = 0.25$ to estimate the number of species expected to persist in the smaller reserve (nearest whole number).

(A)

(160)

(B)

(141)

(C)

(120)

(D)

(178)

Q7. Two communities each contain 100 individuals. Community X has four species with abundances 40, 30, 20 and 10. Community Y has four species with abundances 25, 25, 25 and 25. Which community has the higher Shannon diversity index $H' = -\sum p_i \ln p_i$ ?

(A)

(Community X has higher $H'$ )

(B)

(Both communities have equal $H'$ )

(C)

(Community Y has higher $H'$ )

(D)

(Cannot compare without information on spatial distribution)

Q8. A breeding population has $N_m = 30$ males and $N_f = 70$ females. Using $N_e = \dfrac{4N_mN_f}{N_m+N_f}$ , what is the effect on effective population size $N_e$ if two males immigrate (become 32) and two females emigrate (become 68)?

(A)

( $N_e$ increases from 84 to about 87)

(B)

( $N_e$ remains 84)

(C)

( $N_e$ decreases to about 81)

(D)

( $N_e$ increases to about 90)

Q9. In the Levins metapopulation model $\dfrac{dp}{dt} = cp(1-p) - ep$ the equilibrium occupancy is $p^* = 1 - \dfrac{e}{c}$ . If a conservation action halves both colonization rate $c$ and extinction rate $e$ (so $c' = c/2$ , $e' = e/2$ ), what happens to the equilibrium $p^*$ and to the characteristic speed at which occupancy approaches equilibrium?

(A)

( $p^*$ increases; approach to equilibrium is faster)

(B)

( $p^*$ decreases; approach to equilibrium unchanged)

(C)

( $p^*$ unchanged; approach to equilibrium is faster)

(D)

( $p^*$ unchanged; approach to equilibrium is slower)

Q10. Assertion (A): Establishing corridors between habitat fragments will invariably (always) increase long-term persistence of the focal species. Reason (R): Corridors increase migration and recolonization rates and can maintain genetic diversity, reducing local extinction probability.

(A)

(Both A and R are true and R explains A)

(B)

(A is false but R is true)

(C)

(A is true but R is false)

(D)

(Both A and R are false)

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