Agronomy Crop Physiology 2 — Questions and Answers
Question 1: What is the water potential of pure water at standard conditions?
- -1 MPa
- +1 MPa
- 0 MPa (Correct answer)
- 0.5 MPa
Correct answer: 0 MPa
Pure water has a water potential of 0 MPa by definition; adding solutes lowers water potential below zero, driving water movement into cells via osmosis.
Question 2: Which photosynthetic adaptation allows cacti and pineapples to open their stomata at night to fix CO2?
- C3 photosynthesis
- Photorespiration
- CAM photosynthesis (Correct answer)
- C4 photosynthesis
Correct answer: CAM photosynthesis
Crassulacean Acid Metabolism (CAM) allows desert plants to open stomata at night, storing CO2 as malic acid, then using it for photosynthesis during the day with stomata closed to minimize water loss.
Question 3: What is vernalization in crop production?
- Application of fertilizers in early spring
- A period of cold temperature exposure required to induce flowering (Correct answer)
- The process of seed germination under warm temperatures
- Treatment of seeds with hormones to break dormancy
Correct answer: A period of cold temperature exposure required to induce flowering
Vernalization is the process by which prolonged exposure to cold temperatures promotes flowering in certain crops, such as winter wheat, allowing them to flower in spring.
Question 4: What is the primary function of xylem tissue in crop plants?
- Transport of sugars from leaves to roots
- Storage of starch reserves
- Transport of water and minerals from roots to shoots (Correct answer)
- Gas exchange in leaves
Correct answer: Transport of water and minerals from roots to shoots
Xylem is the vascular tissue that conducts water and dissolved minerals upward from the roots to the rest of the plant through lignified, hollow dead cells.
Question 5: Which plant hormone promotes seed germination, stem elongation, and is applied commercially to increase grape berry size?
- Ethylene
- Abscisic acid
- Cytokinin
- Gibberellin (Correct answer)
Correct answer: Gibberellin
Gibberellins promote stem elongation, seed germination, and fruit set; commercial applications to grapes increase berry size and are used to produce seedless varieties.
Question 6: What term describes the transport of photosynthates (sugars) through the phloem from leaves to roots or fruits?
- Cohesion-tension
- Translocation (Correct answer)
- Osmosis
- Transpiration
Correct answer: Translocation
Translocation is the movement of sugars, amino acids, and other organic solutes through the phloem from source tissues (leaves) to sink tissues (roots, fruits, seeds) via pressure flow.
Question 7: Which mineral nutrient is essential for chlorophyll synthesis and is found at the center of the chlorophyll molecule?
- Calcium
- Potassium
- Iron
- Magnesium (Correct answer)
Correct answer: Magnesium
Magnesium is the central atom in the chlorophyll molecule's porphyrin ring; deficiency causes interveinal chlorosis because plants cannot synthesize adequate chlorophyll.
Agronomy Crop Physiology 2
What is the water potential of pure water at standard conditions?