Question

1. How do guard cells help in opening and closing of stomata?

Answer 1

There's a inflow of water in the guard cells which makes them swell thus opening the stomatal pore and when the water flows out the guard cell shrinks closing the stomatal pore.

Hope it works :)

Answer 2

The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pore to open. Simillarly the pore closes if the guard cells shrink