1. crossing over
1. Microspore pollen
2. Megaspore mother cell megaspore
3. Secondary spermatocyte spermatid
4. Oogoniumprimary ppcyte
1. permeability
2. active transport
3.
4.
ก.
ข.
1.
2.
3. ,
4. ,
1.
2.

2. 3.
4.