Guard cells close up to prevent water loss. These guard
cells will automatically open up if there is a need of water to go out of the
cell. An open stomate allows water to leave through transpiration, guard cells
control the opening and closing of a stomata, stomates will close to reduce
water loss and By opening and closing the stomata on the underside of the
leaves.
Well one is independent segregation of maternal and paternal chromosomes and another is crossing over