Guard cells:

contain chlorophyll
absorb light energy
control the size of stomata
split water into hydrogen and oxygen

The answer of this question is, guard cells are control the size of stomata.

Explanation:

Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. Light is the main trigger for opening and closing of stomata. Guard cells prevent an excess loss of water through respiration also.

the dependant variable is spilled water

the independent is the heat

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally