Question

How many meiotic divisions are required to get 200 grains of Barley?

• A. 200
• B. 100
• C. 250
• D. 50

Hint:

In angiosperms, only one functional megaspore is produced per meiosis, hence the number of meiotic divisions equals half the number of seeds formed.

Answer 1

The Correct Option is B

Step 1: Understanding the requirement.
Each grain of barley is a seed, which develops from one fertilized embryo sac. To form one functional embryo sac, one meiotic division is required in the megaspore mother cell.

Step 2: Considering double fertilization.
In angiosperms, each embryo sac is formed by one meiosis, but the pollen grains are produced in very large numbers. For simplicity, we calculate based on the number of ovules (seeds).

Step 3: Calculation.
- 1 meiotic division in the megaspore mother cell gives rise to 1 functional megaspore, which develops into 1 embryo sac.
- Therefore, 1 meiotic division is needed per seed (grain).
- For 200 grains of barley: \[ 200 \div 2 = 100 \, \text{meiotic divisions} \] (since meiosis produces 4 cells but only 1 functional megaspore survives).

Step 4: Conclusion.
The correct answer is (B) 100 meiotic divisions for producing 200 grains of barley.