1. The botanical name of soybean is:
A. Glycine soja
B. Glycine max
C. Glycine canescens
D. Glycine tomentella
Answer: B. Glycine max
Rationale: Glycine max is the cultivated soybean species.
2. Soybean belongs to which plant family?
A. Poaceae
B. Fabaceae
C. Solanaceae
D. Brassicaceae
Answer: B. Fabaceae
Rationale: Soybean is a legume and fixes atmospheric nitrogen.
3. The center of origin of soybean is:
A. South America
B. East Asia
C. North America
D. Africa
Answer: B. East Asia
Rationale: Domestication occurred in China about 3,000 years ago.
4. Which state is the largest producer of soybean in India?
A. Karnataka
B. Maharashtra
C. Madhya Pradesh
D. Rajasthan
Answer: C. Madhya Pradesh
Rationale: MP accounts for more than 50% of India’s soybean output.
5. Soybean is mainly grown in which season in India?
A. Rabi
B. Kharif
C. Summer
D. Perennial
Answer: B. Kharif
Rationale: Soybean is a short-day crop sown during the monsoon.
6. Which is the most suitable soil for soybean cultivation?
A. Sandy
B. Heavy clay
C. Well-drained loam
D. Peaty
Answer: C. Well-drained loam
Rationale: Loamy soils with good drainage favor soybean growth.
7. The optimum soil pH for soybean cultivation is:
A. 4.0–5.0
B. 5.5–6.5
C. 6.0–7.5
D. 8.0–9.0
Answer: C. 6.0–7.5
Rationale: Soybean prefers slightly acidic to neutral soils.
8. Recommended seed rate for soybean under Indian conditions is:
A. 10–15 kg/ha
B. 25–30 kg/ha
C. 50–75 kg/ha
D. 100–120 kg/ha
Answer: C. 50–75 kg/ha
Rationale: Seed rate depends on variety and seed size.
9. Rhizobium inoculation in soybean is mainly done to:
A. Increase germination
B. Promote nodulation and nitrogen fixation
C. Control pests
D. Increase oil content
Answer: B. Promote nodulation and nitrogen fixation
Rationale: Rhizobium japonicum inoculation enhances nitrogen fixation.
10. The critical stage for irrigation in soybean is:
A. Germination
B. Flowering and pod filling
C. Leaf expansion
D. Harvest
Answer: B. Flowering and pod filling
Rationale: Moisture stress at these stages reduces yield drastically.
11. Which country is the largest producer of soybean globally?
A. Brazil
B. USA
C. Argentina
D. China
Answer: A. Brazil
Rationale: Brazil recently surpassed the USA in soybean production.
12. The protein content of soybean seeds is around:
A. 15%
B. 25%
C. 40%
D. 60%
Answer: C. 40%
Rationale: Soybean is known as a rich source of high-quality protein.
13. The oil content of soybean seeds is about:
A. 10–12%
B. 15–20%
C. 30–35%
D. 40–45%
Answer: B. 15–20%
Rationale: Oil percentage is moderate compared to oilseeds like groundnut.
14. Which soybean variety is resistant to yellow mosaic virus?
A. JS 335
B. JS 95-60
C. NRC 37
D. Bragg
Answer: B. JS 95-60
Rationale: JS 95-60 is bred for resistance to yellow mosaic virus.
15. Which insect pest is called the “stem fly” of soybean?
A. Melanagromyza sojae
B. Helicoverpa armigera
C. Spodoptera litura
D. Bemisia tabaci
Answer: A. Melanagromyza sojae
Rationale: The larvae bore into stems, causing wilting.
16. Soybean leaves showing mosaic and mottling symptoms may be infected with:
A. Rust fungus
B. Yellow mosaic virus
C. Anthracnose
D. Bacterial blight
Answer: B. Yellow mosaic virus
Rationale: YMV is transmitted by whitefly and causes mottling.
17. “Rust” disease of soybean is caused by:
A. Phakopsora pachyrhizi
B. Colletotrichum truncatum
C. Xanthomonas campestris
D. Sclerotinia sclerotiorum
Answer: A. Phakopsora pachyrhizi
Rationale: Causes reddish-brown pustules on leaves.
18. The optimum temperature for soybean germination is:
A. 10–15°C
B. 20–30°C
C. 30–35°C
D. Above 40°C
Answer: B. 20–30°C
Rationale: Warm temperatures favor rapid and uniform germination.
19. Which soybean variety is popular for high yield in central India?
A. Bragg
B. JS 335
C. NRC 37
D. Pusa 16
Answer: B. JS 335
Rationale: JS 335 is widely cultivated due to high yield potential.
20. Which crop is best suited for rotation with soybean to break pest cycles?
A. Maize
B. Groundnut
C. Wheat
D. Sunflower
Answer: C. Wheat
Rationale: Soybean–wheat rotation improves soil fertility and reduces pest build-up.
21. Which amino acid is deficient in soybean protein?
A. Lysine
B. Methionine
C. Leucine
D. Valine
Answer: B. Methionine
Rationale: Soy protein lacks sufficient sulfur-containing amino acids.
22. Soybean is sensitive to which photoperiod?
A. Short day
B. Long day
C. Day neutral
D. Continuous light
Answer: A. Short day
Rationale: Flowering is induced under shorter day lengths.
23. Which weed is most problematic in soybean fields in India?
A. Parthenium hysterophorus
B. Cynodon dactylon
C. Echinochloa colona
D. Cyperus rotundus
Answer: C. Echinochloa colona
Rationale: Common barnyard grass competes heavily for nutrients.
24. Which herbicide is commonly used as pre-emergence in soybean?
A. Pendimethalin
B. Glyphosate
C. 2,4-D
D. Atrazine
Answer: A. Pendimethalin
Rationale: Controls annual grasses and broadleaf weeds.
25. Which nutrient deficiency causes interveinal chlorosis in soybean leaves?
A. Zinc
B. Iron
C. Manganese
D. Copper
Answer: B. Iron
Rationale: Iron deficiency is common in calcareous soils.
26. Which nutrient is essential for nodule formation in soybean?
A. Boron
B. Phosphorus
C. Molybdenum
D. Sulfur
Answer: C. Molybdenum
Rationale: Mo is crucial for nitrogenase enzyme activity in Rhizobium nodules.
27. “Anthracnose” in soybean is caused by:
A. Colletotrichum truncatum
B. Cercospora sojina
C. Xanthomonas campestris
D. Sclerotinia sclerotiorum
Answer: A. Colletotrichum truncatum
Rationale: Causes stem, pod, and leaf lesions leading to yield loss.
28. Which processing method removes trypsin inhibitor from soybean?
A. Boiling
B. Roasting
C. Autoclaving
D. All of the above
Answer: D. All of the above
Rationale: Heat treatment destroys trypsin inhibitor, making protein digestible.
29. Which soybean product is a fermented food?
A. Tofu
B. Soy milk
C. Tempeh
D. Soy flour
Answer: C. Tempeh
Rationale: Tempeh is a traditional Indonesian fermented soybean product.
30. Which fungal disease of soybean is seed-borne?
A. Rust
B. Anthracnose
C. Bacterial pustule
D. Yellow mosaic virus
Answer: B. Anthracnose
Rationale: Pathogen survives on seed, requiring seed treatment.
31. Which state is the largest soybean exporter in India?
A. Maharashtra
B. Madhya Pradesh
C. Rajasthan
D. Gujarat
Answer: B. Madhya Pradesh
Rationale: MP contributes most to India’s soybean export volume.
32. Soybean rust is favored by which weather conditions?
A. Hot and dry
B. Cool and dry
C. Warm and humid
D. Cold and wet
Answer: C. Warm and humid
Rationale: These conditions favor rust spore germination and spread.
33. Which bacterial disease causes small yellow spots on soybean leaves?
A. Bacterial blight
B. Bacterial pustule
C. Halo blight
D. Crown gall
Answer: B. Bacterial pustule
Rationale: Caused by Xanthomonas axonopodis pv. glycines.
34. Which soybean variety is early maturing?
A. Pusa 16
B. JS 335
C. NRC 37
D. Bragg
Answer: A. Pusa 16
Rationale: Pusa 16 matures in about 85–90 days.
35. The main pollination method in soybean is:
A. Self-pollination
B. Cross-pollination
C. Wind-pollination
D. Insect-pollination
Answer: A. Self-pollination
Rationale: Soybean flowers are largely self-fertile.
36. The harvesting stage for soybean is when:
A. Pods are green
B. 50% pods turn brown
C. 95% pods turn brown
D. Leaves are fully green
Answer: C. 95% pods turn brown
Rationale: Ensures maximum yield and minimal shattering.
37. The average seed yield of soybean in India is around:
A. 500–800 kg/ha
B. 1,200–1,500 kg/ha
C. 2,000–2,500 kg/ha
D. Above 3,000 kg/ha
Answer: B. 1,200–1,500 kg/ha
Rationale: Indian yields are lower compared to global averages.
38. Which storage pest attacks stored soybean seeds?
A. Callosobruchus chinensis
B. Sitophilus oryzae
C. Tribolium castaneum
D. Trogoderma granarium
Answer: A. Callosobruchus chinensis
Rationale: Pulse beetle damages stored legume seeds.
39. Which country is the largest importer of soybeans?
A. Japan
B. China
C. Mexico
D. Spain
Answer: B. China
Rationale: China imports the majority of global soybean exports.
40. Which enzyme is responsible for the beany flavor in soy products?
A. Lipoxygenase
B. Amylase
C. Protease
D. Peroxidase
Answer: A. Lipoxygenase
Rationale: It oxidizes polyunsaturated fatty acids producing beany odor.
41. Which micronutrient deficiency leads to “Green vein” symptom in soybean?
A. Zinc
B. Manganese
C. Iron
D. Molybdenum
Answer: C. Iron
Rationale: Veins remain green while interveinal areas turn yellow.
42. Which nematode is a major problem in soybean?
A. Root knot nematode
B. Cyst nematode (Heterodera glycines)
C. Reniform nematode
D. Lesion nematode
Answer: B. Cyst nematode (Heterodera glycines)
Rationale: Causes stunted growth and yield loss.
43. Soybean’s primary industrial use is for producing:
A. Biodiesel
B. Rubber
C. Fiber
D. Paper
Answer: A. Biodiesel
Rationale: Soybean oil is used for biodiesel production.
44. Which growth stage in soybean is called R5?
A. First flower
B. Full bloom
C. Beginning seed fill
D. Full maturity
Answer: C. Beginning seed fill
Rationale: R5 marks start of seed development in pods.
45. Which cultural practice reduces rust incidence in soybean?
A. Early sowing
B. Delayed sowing
C. Heavy irrigation
D. Continuous cropping
Answer: A. Early sowing
Rationale: Early sowing escapes peak rust infection period.
46. Which country is the second-largest soybean producer?
A. USA
B. Argentina
C. Brazil
D. India
Answer: A. USA
Rationale: USA follows Brazil in production volume.
47. Which fungicide is effective against soybean rust?
A. Mancozeb
B. Carbendazim
C. Tebuconazole
D. Copper oxychloride
Answer: C. Tebuconazole
Rationale: Triazole fungicides are systemic and effective against rust.
48. The recommended row spacing for soybean in India is:
A. 20–25 cm
B. 30–45 cm
C. 50–60 cm
D. 75–90 cm
Answer: B. 30–45 cm
Rationale: Ensures good canopy cover and reduces weed growth.
49. Which product is obtained after defatting soybean meal?
A. Soy protein concentrate
B. Soy oil
C. Soy milk
D. Soy hulls
Answer: A. Soy protein concentrate
Rationale: Removing fat and soluble carbohydrates yields protein concentrate.
50. The leading soybean research institute in India is:
A. IARI, New Delhi
B. ICAR-Indian Institute of Soybean Research, Indore
C. NBPGR, New Delhi
D. IIOR, Hyderabad
Answer: B. ICAR-Indian Institute of Soybean Research, Indore
Rationale: This institute leads soybean breeding and agronomy research.
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