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!
Answer:
Tidal volume is the amount of air breathed in with each normal breath. The average tidal volume is 0.5 litres (500 ml). Minute ventilation is the total volume of air entering the lungs in a minute. The average minute ventilation is 6 litres per minute.
Answer: 26.75 meters.
2πr = 84
2 * 3.14 * radius = 84
radius = 84/6.28
r= 13.375
So the diameter will be 13.375 + 13.375 which is 26.75 meters.