potometer and rate of transpiration

Which picture shows the epidermis?

• 
• 
• 
• 

The xylem and phloem together are know as

• vascular bundles.

• the mesophyll.

• stomates.

• guard cells.

Select all of the environmental factors that would increase transpiration.

• Increased humidity

• Increased wind speed

• Increased temperature

• Decreased surface area

Which of the following must be done when setting up a potometer to get accurate results?

I. cut the plant shoot underwater

II. cut the plant shoot at an angle

III. seal the joints with vaseline (grease)

• I and II only

• I and III only

• II and III only

• I, II and III

Why would the tap on a potometer be opened?

• to supply the plant with more water for photosynthesis

• to allow more air bubbles into the apparatus

• to move the air bubble back to zero so the experiment can be repeated

• to allow the plant to get rid of waste products

In what direction would the air bubble in the capillary tube move when the plant transpires?

• right

• left

• left then right

• right then left

A student uses a potometer to investigate the effect of temperature on the rate of transpiration.

What would be the dependent variable in this experiment?

• temperature

• mass of plant

• time allowed for transpiration

• distance moved by bubble in a fixed time

A student uses a potometer to investigate the effect of temperature on the rate of transpiration.

What would be the independent variable in this experiment?

• temperature

• mass of plant

• time allowed for transpiration

• distance moved by bubble in a fixed time

A student recorded that the air bubble moved 35mm in 2 hours. The volume of water moved can be calculated by  $\pi r^2h$   , where r is the radius of the tube and h is the distance moved by the bubble.

What is the rate of transpiration, in mm3 of water moved per minute?

• 27.5

• 13.7

• 0.23

• 0.46

Potomometers really measure the rate of water uptake, rather than the rate of transpiration from the leaves.

Which of the following help to explain why this is?

I. water taken in is used for photosynthesis

II. water taken in is used to provide support and prevent wilting

III. water taken in is used for respiration

• I and II only

• I and III only

• II and III only

• I, II and III