In the protein adenylate kinase, the c-terminal region is a -helical, with the sequence val- asp-asp- val- phe-ser- gln- val- cys- thr- his- leu- aspthr- leu-lys- the hydrophobic, residues in this sequence are presented in boldface type. suggest a possible reason for the periodicity in their spacing

Hey there!

The purpose of guard cells is to control the opening and closing of the Stomata, keeping it the correct width, or size.

Therefore, your correct answer would be Option 3, control the size of the Stomata.

Hope this helps!

Read more on -

it's unlikely a majority of a large population would agree on issues

hope this : )