Question

How many meiotic divisions are required to produce 1600 seeds in an angiospermic plant?

• A. 1600
• B. 1800
• C. 3200
• D. 2000

Hint:

Formula for Meiotic Divisions to form $N$ seeds: \[ \text{Total Meiosis} = N \left(1 + \frac{1}{4}\right) = \frac{5N}{4} \] Example: For 100 seeds $\rightarrow 100 + 25 = 125$ meiosis.

Answer 1

The Correct Option is D

Step 1: Concept of Seed Formation:
One seed is formed from the fertilization of one female gamete (egg cell) by one male gamete. \[ 1 \text{ Seed} \leftarrow 1 \text{ Embryo Sac} + 1 \text{ Pollen Grain} \]
Step 2: Calculating Meiosis for Female Part (Megasporogenesis):
1 Megaspore Mother Cell (MMC) undergoes 1 Meiotic division to form 4 megaspores. Usually, only 1 becomes functional and forms the embryo sac. \[ \text{For 1 Egg/Seed} \rightarrow 1 \text{ Meiosis} \] For 1600 seeds $\rightarrow 1600$ Meiotic divisions.
Step 3: Calculating Meiosis for Male Part (Microsporogenesis):
1 Pollen Mother Cell (PMC) undergoes 1 Meiotic division to form 4 Pollen grains (Microspores). \[ \text{For 4 Pollens} \rightarrow 1 \text{ Meiosis} \] \[ \text{For 1 Pollen} \rightarrow \frac{1}{4} \text{ Meiosis} \] For 1600 seeds (requiring 1600 pollens): \[ 1600 \times \frac{1}{4} = 400 \text{ Meiotic divisions} \]
Step 4: Total Meiotic Divisions:
\[ \text{Total} = (\text{Meiosis for Eggs}) + (\text{Meiosis for Pollens}) \] \[ \text{Total} = 1600 + 400 = 2000 \]
Step 5: General Formula:
Total Meiosis ($M$) for $N$ seeds: \[ M = N + \frac{N}{4} = 1.25 N \] \[ M = 1.25 \times 1600 = 2000 \]