UGC NET — Environmental Sciences (subject code 89) · India · National Testing Agency for the University Grants Commission
Original practice questions written to the published syllabus · not past papersWhat a warmer, more variable climate does to crops, livestock, fisheries, pests, water and food security, and how impacts are studied with experiments and crop models.
In the exams: ICAR AICE subjects 60 and 71 (climate variability, adaptation and mitigation); ICAR AIEEA-PG Agronomy Unit II (climate shift); UGC NET Unit 10
UGC NET Environmental Sciences (Unit 10) and CUET-PG
Climate change and food security, impacts on crops, fisheries and livestock, CO2 fertilisation and nutrition, sea-level rise and salinity, IPCC findings on agriculture, and matching items on mechanisms and methods.
How our questions for UGC NET spread across the units of Climate Change Impacts on Agriculture & Food Systems. Difficulty: 18 easy, 15 medium, 6 hard.
| Fisheries and aquaculture under climate change | 6 | |
| Pathways of climate impact on food systems | 5 | |
| Climate change, food security and nutrition | 5 | |
| Regional vulnerability and climate hotspots | 5 | |
| Drought, floods and changing rainfall patterns | 4 | |
| CO2 fertilisation, C3 and C4 responses and nutritional quality | 3 | |
| Methods: field experiments, FACE, statistical and process models | 3 | |
| Temperature, heat stress and crop phenology | 2 | |
| Climate and pests, diseases and weeds | 2 | |
| Livestock heat stress and feed availability | 2 | |
| Sea-level rise and salinisation of coastal farmland | 1 | |
| Crop simulation models for impact assessment | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A maize crop experiences Tmax = 32 °C and Tmin = 18 °C on one day. Using the simple averaging method with a base of 10 °C and no upper cap, how many growing degree days accumulate?
D. 15
GDD = (32 + 18)/2 − 10 = 25 − 10 = 15. Capping Tmax at 30 °C (the 86/50 method) would give 14; forgetting the base gives 25; halving the range gives 7.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
Which crop group gains most yield directly from rising atmospheric carbon dioxide under well-watered conditions?
B. C3 crops such as wheat, rice and soybean
In C3 crops Rubisco is unsaturated and photorespiration is significant at current CO2, so more CO2 raises photosynthesis. C4 crops concentrate CO2 internally and gain little directly when water is ample.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
Which type of drought is defined by soil moisture too low to meet crop needs?
D. Agricultural drought
Agricultural drought refers to soil-moisture deficit for crops. Meteorological drought is a rainfall deficit; hydrological drought is low streamflow, reservoir or groundwater; socioeconomic drought is when shortage affects supply of goods.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
What is 'peak water' in a glacier-fed river basin?
D. Meltwater flow first rises as glaciers shrink, then falls as the ice runs out
As glaciers melt, runoff first increases, peaks and then declines as ice mass dwindles, a pattern important for the Indus, Ganges, Amu Darya and Andean basins. The other definitions describe floods, water balance or crop transpiration.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
Aflatoxin contamination of maize and groundnut tends to increase under which conditions?
C. Heat and drought during grain filling, and poor drying after harvest
Aspergillus flavus infection and aflatoxin production are favoured by heat and drought stress late in the season and by inadequate drying and storage. Cool conditions and frost do not favour it.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
Using the NRC (1971) formula THI = (1.8T + 32) − (0.55 − 0.0055RH)(1.8T − 26), with T in °C and RH in per cent, compute the THI for a dairy shed at 32 °C and 60 per cent relative humidity.
D. 82.6
1.8 × 32 + 32 = 89.6; 0.55 − 0.0055 × 60 = 0.22; 1.8 × 32 − 26 = 31.6; THI = 89.6 − 0.22 × 31.6 = 82.6. 89.6 is the dry-bulb temperature in °F; 88.3 forgets to convert T in the second bracket; 72.2 drops the humidity term.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
Why is rising carbon dioxide itself a threat to nutrition in populations that depend on rice and wheat?
A. It lowers zinc, iron and protein levels in these C3 grains
Elevated CO2 reduces grain zinc, iron and protein in C3 cereals, worsening deficiencies where these staples supply most intake. Toxic metals, vitamin C (negligible in cereal grains) and starch hardness are not the documented effects.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
What is the 'chamber effect' in open-top chamber experiments?
D. Altered temperature, humidity and wind inside that confound the treatment
Chambers warm the air, change humidity and reduce wind, so responses partly reflect the enclosure rather than the treatment. The other descriptions are not the recognised effect.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
What is the minimum set of daily weather inputs needed by most crop simulation models?
A. Maximum and minimum temperature, rain and solar radiation
Most models require daily Tmax, Tmin, rainfall and solar radiation; humidity and wind are added for Penman–Monteith evapotranspiration. Monthly totals are too coarse, and soil properties are separate inputs.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
Why should index-based vulnerability assessments be read as screening tools rather than precise rankings?
D. Results depend heavily on which indicators are chosen and how each of them is weighted
Composite indices aggregate indicators of exposure, sensitivity and adaptive capacity, and rankings can change with indicator choice, normalisation and weights. They use survey and census data as well, are updated regularly, and include more than hazards.
Further reading: See the manual sources: IPCC AR6 WGII, FAO-29/FAO-33 and the primary studies named in the explanation
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