Fundamentals of Agronomy-5

By Skumar

 

Fundamentals of Agronomy-5

WEEDS – MCQ TEST SERIES 


For MCAER PG CET | ICAR AIEEA | Agriculture Competitive Exams

🔹 PART A: Basics, Definition & Importance (Q.1–10)

1. A weed is best defined as

A. A plant with no economic value
B. A plant growing where it is not wanted
C. A harmful plant
D. A wild plant

✅ Answer: B
📌 Explanation: Any plant growing out of place and interfering with crop production is called a weed.

2. Term “weed” was first used by

A. De Candolle
B. Jethro Tull
C. Roxburgh
D. Liebig

✅ Answer: A
📌 Explanation: De Candolle introduced the term weed.

3. Weeds cause maximum loss in crops due to

A. Allelopathy
B. Competition
C. Acting as alternate hosts
D. Toxicity

✅ Answer: B
📌 Explanation: Competition for nutrients, water, light and space causes major yield loss.

4. Critical period of crop–weed competition refers to

A. Period of maximum weed growth
B. Period when weeds do not affect crop
C. Period when weeds must be controlled
D. Period after harvesting

✅ Answer: C
📌 Explanation: Weeds must be controlled during this period to prevent yield loss.

5. Yield loss due to weeds in India is approximately

A. 5–10%
B. 10–15%
C. 20–30%
D. 40–50%

✅ Answer: C
📌 Explanation: Average yield loss due to weeds is around 20–30%.

6. Weeds act as alternate hosts for

A. Insects only
B. Diseases only
C. Both insects and diseases
D. Rodents

✅ Answer: C
📌 Explanation: Many weeds harbor pests and pathogens.

7. Weeds increase cost of cultivation mainly due to

A. More fertilizers
B. More irrigation
C. Additional weed control measures
D. Harvesting losses

✅ Answer: C
📌 Explanation: Weed control adds extra labour and input costs.

8. Beneficial effect of weeds is

A. Yield reduction
B. Soil erosion control
C. Competition
D. Toxicity

✅ Answer: B
📌 Explanation: Some weeds help in preventing soil erosion.

9. The branch of agriculture dealing with weeds is

A. Agronomy
B. Weed science
C. Plant pathology
D. Botany

✅ Answer: B
📌 Explanation: Weed science deals with weed biology and management.

10. The study of weeds is known as

A. Ecology
B. Weedology
C. Weed science
D. Phytology

✅ Answer: C
📌 Explanation: Weed science is the correct scientific term.

🔹 PART B: Classification of Weeds (Q.11–25)

11. Classification of weeds based on life cycle includes

A. Annual, Biennial, Perennial
B. Broad-leaved, Grassy
C. Terrestrial, Aquatic
D. Crop weeds, Non-crop weeds

✅ Answer: A
📌 Explanation: Life cycle classification depends on duration of life.

12. Example of annual weed

A. Cyperus rotundus
B. Parthenium hysterophorus
C. Cynodon dactylon
D. Imperata cylindrica

✅ Answer: B
📌 Explanation: Parthenium completes life cycle within one season.

13. Example of perennial weed

A. Chenopodium album
B. Phalaris minor
C. Cyperus rotundus
D. Amaranthus viridis

✅ Answer: C
📌 Explanation: Cyperus propagates through tubers and persists year after year.

14. Biennial weeds complete their life cycle in

A. One season
B. Two seasons
C. Three seasons
D. Many years

✅ Answer: B
📌 Explanation: Biennials grow vegetatively in first year and reproduce in second.

15. Classification based on morphology includes

A. Annual, biennial
B. Grassy, broad-leaved, sedges
C. Aquatic, terrestrial
D. Parasitic, non-parasitic

✅ Answer: B
📌 Explanation: Morphological classification is based on plant structure.

16. Sedges can be identified by

A. Hollow stem
B. Round stem
C. Solid triangular stem
D. Jointed stem

✅ Answer: C
📌 Explanation: Sedges have solid, triangular stems.

17. Grassy weeds belong to family

A. Cyperaceae
B. Poaceae
C. Fabaceae
D. Asteraceae

✅ Answer: B
📌 Explanation: Poaceae is grass family.

18. Example of sedge weed

A. Echinochloa
B. Phalaris
C. Cyperus
D. Sorghum halepense

✅ Answer: C
📌 Explanation: Cyperus belongs to sedge family.

19. Aquatic weeds are classified as

A. Floating, submerged, emergent
B. Annual, perennial
C. Parasitic, non-parasitic
D. Broad-leaved, grassy

✅ Answer: A
📌 Explanation: Aquatic weeds grow in water bodies.

20. Example of floating weed

A. Hydrilla
B. Eichhornia
C. Vallisneria
D. Typha

✅ Answer: B
📌 Explanation: Eichhornia floats freely on water surface.

21. Parasitic weeds depend on host for

A. Water only
B. Nutrients only
C. Food only
D. All of the above

✅ Answer: D
📌 Explanation: Parasitic weeds derive water, nutrients and food from host.

22. Total parasitic weed is

A. Loranthus
B. Striga
C. Cuscuta
D. Orobanche

✅ Answer: C
📌 Explanation: Cuscuta lacks chlorophyll completely.

23. Partial parasitic weed is

A. Cuscuta
B. Orobanche
C. Striga
D. Chenopodium

✅ Answer: C
📌 Explanation: Striga has chlorophyll but depends on host roots.

24. Crop mimic weeds resemble

A. Crop in growth habit
B. Crop in seed
C. Crop in early growth stages
D. All of the above

✅ Answer: D
📌 Explanation: Mimicry helps weeds escape control.

25. Example of crop mimic weed in wheat

A. Chenopodium
B. Phalaris minor
C. Cynodon
D. Cyperus

✅ Answer: B
📌 Explanation: Phalaris resembles wheat seedlings.

🔹 PART C: Weed Control Methods (Q.26–45)

26. Manual weed control includes

A. Hoeing
B. Hand weeding
C. Mechanical weeding
D. All of the above

✅ Answer: D
📌 Explanation: All involve physical removal of weeds.

27. Mechanical weed control is best suited for

A. Sandy soils
B. Clay soils
C. Row crops
D. Broadcast crops

✅ Answer: C
📌 Explanation: Implements work effectively in row crops.

28. Cultural weed control includes

A. Herbicides
B. Crop rotation
C. Hand weeding
D. Burning

✅ Answer: B
📌 Explanation: Cultural practices suppress weeds naturally.

29. Crop rotation helps in weed control by

A. Increasing herbicide use
B. Breaking weed life cycle
C. Increasing fertilizer use
D. Increasing irrigation

✅ Answer: B
📌 Explanation: Different crops disturb weed survival.

30. Chemical weed control uses

A. Insecticides
B. Fungicides
C. Herbicides
D. Rodenticides

✅ Answer: C
📌 Explanation: Herbicides kill or suppress weeds.

31. Selective herbicides kill

A. All plants
B. Only crops
C. Only weeds
D. Specific weeds

✅ Answer: D
📌 Explanation: They target specific weed types.

32. Non-selective herbicide is

A. 2,4-D
B. Atrazine
C. Paraquat
D. Butachlor

✅ Answer: C
📌 Explanation: Paraquat kills all green vegetation.

33. Pre-emergence herbicides are applied

A. Before sowing
B. After sowing before crop emergence
C. After weed emergence
D. At flowering

✅ Answer: B
📌 Explanation: Applied before weeds emerge.

34. Post-emergence herbicides are applied

A. Before sowing
B. Before emergence
C. After weed emergence
D. At harvest

✅ Answer: C
📌 Explanation: Applied after weeds appear.

35. 2,4-D is effective against

A. Grassy weeds
B. Sedges
C. Broad-leaved weeds
D. All weeds

✅ Answer: C
📌 Explanation: 2,4-D controls dicot weeds.

36. Atrazine is commonly used in

A. Wheat
B. Rice
C. Maize
D. Cotton

✅ Answer: C
📌 Explanation: Atrazine controls weeds in maize.

37. Integrated weed management includes

A. Only herbicides
B. Only cultural methods
C. Combination of methods
D. Manual weeding only

✅ Answer: C
📌 Explanation: Integration improves efficiency and sustainability.

38. Biological weed control uses

A. Insects
B. Pathogens
C. Fish
D. All of the above

✅ Answer: D
📌 Explanation: Living organisms suppress weeds.

39. Zygogramma bicolorata controls

A. Lantana
B. Parthenium
C. Eichhornia
D. Cyperus

✅ Answer: B
📌 Explanation: It feeds on Parthenium leaves.

40. Chemical name of 2,4-D is

A. 2,4-dichlorophenoxy acetic acid
B. 2,4-dinitrophenol
C. 2,4-dichlorobenzene
D. 2,4-diethyl amine

✅ Answer: A
📌 Explanation: Full form is often asked in exams.

41. Herbicide resistance means

A. Crop resistance
B. Weed tolerance to herbicide
C. Soil resistance
D. Increased weed growth

✅ Answer: B
📌 Explanation: Continuous use selects resistant weeds.

42. Safeners are used to

A. Kill weeds
B. Protect crops from herbicide injury
C. Increase toxicity
D. Reduce dosage

✅ Answer: B
📌 Explanation: Safeners protect crop metabolism.

43. Weedicides should be applied when wind speed is

A. High
B. Moderate
C. Low
D. Very high

✅ Answer: C
📌 Explanation: Low wind prevents drift.

44. Drift injury is common with

A. Granular herbicides
B. Systemic herbicides
C. Volatile herbicides
D. Contact herbicides

✅ Answer: C
📌 Explanation: Volatile herbicides move with air.

45. Herbicide dosage is expressed as

A. Commercial product
B. Active ingredient
C. Acid equivalent
D. Both B and C

✅ Answer: D
📌 Explanation: Dosage is calculated in a.i. or a.e.

🔹 PART D: Advanced Concepts (Q.46–50)

46. Weed seed bank refers to

A. Stored weed seeds in soil
B. Seeds in granary
C. Seed certification
D. Seed treatment

✅ Answer: A
📌 Explanation: Soil contains viable weed seeds.

47. Dormancy in weeds helps in

A. Immediate germination
B. Avoiding adverse conditions
C. Increasing herbicide effect
D. Reducing survival

✅ Answer: B
📌 Explanation: Dormancy ensures long-term survival.

48. Allelopathy in weeds refers to

A. Physical competition
B. Chemical inhibition
C. Nutrient competition
D. Water competition

✅ Answer: B
📌 Explanation: Weeds release chemicals inhibiting crops.

49. Smother crops suppress weeds by

A. Chemical action
B. Dense canopy
C. Root exudates
D. Nutrient uptake

✅ Answer: B
📌 Explanation: They block sunlight.

50. Best long-term weed control strategy is

A. Manual weeding
B. Chemical control
C. Integrated weed management
D. Biological control

✅ Answer: C
📌 Explanation: IWM is sustainable and effective.


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