GATE — Environmental Science and Engineering (ES) · India · IITs and IISc on rotation (2026: IIT Guwahati)
Original practice questions written to the published syllabus · not past papersWhat biodiversity is, how it is measured, why it is being lost and how it is conserved, from IUCN Red List categories and protected areas to the Kunming-Montreal Global Biodiversity Framework.
In the exams: ICAR AICE subject 71 Unit 2 (whole unit); GATE ES Section 8 (biodiversity); UGC NET Unit 3; UPSC CSE Prelims environment (heavily asked)
GATE — Environmental Science and Engineering (Section 8) and Ecology and Evolution (EY)
Diversity indices (Shannon, Simpson, evenness, Jaccard), alpha/beta/gamma, species-area and island biogeography, effective population size and inbreeding, population growth, Red List criteria; numerical items common.
How our questions for GATE spread across the units of Biodiversity Science & Conservation. Difficulty: 5 easy, 9 medium, 3 hard.
| Measuring biodiversity: alpha, beta, gamma diversity and indices | 6 | |
| Island biogeography and species-area relationships | 5 | |
| Population viability and minimum viable population | 4 | |
| Biogeographic realms and biodiversity hotspots | 1 | |
| Drivers of biodiversity loss: land-use change, overexploitation, climate, pollution, invasive species | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
For the same proportions (0.5, 0.3, 0.2), what is Simpson's diversity expressed as 1 − Σp²?
B. 0.62
Σp² = 0.25 + 0.09 + 0.04 = 0.38; 1 − D = 0.62. 0.38 is the dominance index itself; 2.63 is the inverse Simpson form; 1.00 ignores the formula.
With H' = 1.030 for three species, what is Pielou's evenness J' = H'/ln S?
D. 0.94
J' = 1.030/ln 3 = 1.030/1.099 = 0.94. 0.34 divides by 3 instead of ln 3; 3.09 multiplies by 3; 1.03 is H' itself.
According to IPBES (2019), which is the largest direct driver of biodiversity loss on land globally?
B. Changes in land use
IPBES ranked land- and sea-use change first, then direct exploitation, climate change, pollution and invasive species. On land, agricultural expansion dominates.
Further reading: IPBES Global Assessment 2019
With z ≈ 0.3 in the species-area relationship, a tenfold reduction in area reduces species to roughly what fraction?
D. One half
10^−0.3 ≈ 0.50, giving the rule of thumb that a tenfold area loss halves species. One tenth would assume z = 1.
Further reading: Species-area literature
A population with Ne = 50 starts with heterozygosity 0.60. Using Ht = H0(1 − 1/(2Ne))^t, what is heterozygosity after 20 generations?
B. 0.491
Ht = 0.60 × 0.99^20 = 0.60 × 0.818 = 0.491. 0.480 subtracts 20 % linearly; 0.600 ignores drift; 0.401 uses 1/Ne instead of 1/(2Ne).
A population of 200 has a finite rate of increase λ = 0.95 per year. What is its expected size after 10 years?
D. 120
N10 = 200 × 0.95^10 = 200 × 0.599 = 120. 190 applies only one year's decline; 100 subtracts 5 % of 200 ten times; 210 treats λ as growth.
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