Agronomy Agronomy MCQ 2 — Questions and Answers
Question 1: Which soil texture class has the highest water-holding capacity?
- Sandy loam
- Clay (Correct answer)
- Silt loam
- Coarse sand
Correct answer: Clay
Clay soils have the highest water-holding capacity due to their small particle size and large surface area.
Question 2: The process by which atmospheric nitrogen is converted into ammonia by microorganisms is called:
- Nitrification
- Denitrification
- Biological nitrogen fixation (Correct answer)
- Ammonification
Correct answer: Biological nitrogen fixation
Biological nitrogen fixation is performed by microorganisms like Rhizobium that convert N₂ gas into ammonia (NH₃).
Question 3: What is the primary purpose of crop rotation in agronomic systems?
- Increase soil pH
- Break pest and disease cycles (Correct answer)
- Reduce irrigation needs
- Increase soil temperature
Correct answer: Break pest and disease cycles
Crop rotation disrupts the life cycles of pests, pathogens, and weeds that are host-specific to a single crop.
Question 4: Which nutrient deficiency causes interveinal chlorosis in young leaves?
- Nitrogen
- Potassium
- Iron (Correct answer)
- Phosphorus
Correct answer: Iron
Iron deficiency causes interveinal chlorosis in young (newest) leaves because iron is immobile in the plant.
Question 5: The C4 photosynthetic pathway is advantageous over C3 in which condition?
- Low light intensity
- Cool, moist climates
- High temperature and high light intensity (Correct answer)
- Shaded environments
Correct answer: High temperature and high light intensity
C4 plants like corn and sorghum use a carbon-concentrating mechanism that reduces photorespiration under hot, high-light conditions.
Question 6: What does the term 'photoperiodism' refer to in crop production?
- Rate of photosynthesis per day
- Plant response to relative lengths of day and night (Correct answer)
- Sensitivity of crops to light intensity
- Daily water use driven by sunlight
Correct answer: Plant response to relative lengths of day and night
Photoperiodism is a plant's physiological response to the ratio of light to dark periods, which controls flowering in many crops.
Question 7: Which of the following is considered a legume cover crop used to improve soil nitrogen?
- Winter rye
- Hairy vetch (Correct answer)
- Oats
- Buckwheat
Correct answer: Hairy vetch
Hairy vetch (Vicia villosa) is a legume cover crop that fixes atmospheric nitrogen through its symbiotic relationship with Rhizobium bacteria.
Agronomy Agronomy MCQ 2
Which soil texture class has the highest water-holding capacity?