Transpiration

Question 1

Define transpiration

Answer 1

Loss of water from the plant

Question 2

Where does most transpiration take place?

Answer 2

In the leaves

Question 3

What does the transpiration stream carry?

Answer 3

Carries minerals dissolved in water

Question 4

4 factors that affect transpiration rate

Answer 4

Light intensity, temperature, air flow and humidity

Question 5

Explain transpiration

Answer 5

It’s caused by evaporation of water from a plants surface (mainly leaves).
Loss of water creates concentration gradient causing more water to be drawn through the xylem from the roots

Question 6

What does NPK stand for

Answer 6

Nitrates, phosphates, potassium

Question 7

Why do we need npk and what would happen if plants are deficient in any of these?

Answer 7

Nitrates - makes amino acids and proteins.
*Stunted growth
Phosphates - Makes dna and cell membranes
*Poor root growth and purple leaves
Potassium - enzymes (respiration and photosynthesis)
*yellow leaves, poor flower and fruit growth

Question 8

Describe the effect of temperature on transpiration rate

Answer 8

As temperature increases, transpiration rate increases as the water particles have more energy to evaporate and diffuse out of the stomata

Question 9

Describe the effect of lower light intensity on transpiration rate

Answer 9

Decreases transpiration rate as stomata close in darker conditions. Therefore very little water can escape

Question 10

Describe the effect of lower humidity on transpiration rate

Answer 10

Faster transpiration rate as there is a greater difference in the water concentration inside the leaf compared to outside

Question 11

Describe the effect of air flow on transpiration rate

Answer 11

Better airflow, the greater transpiration rate. If airflow around leaf is poor, water vapour surrounds the leaf. High concentration of water particles outside and inside leaf. Diffusion doesn’t happen quickly

Question 12

Calculate transpiration rate if the bubble on the photometer moved 35mm in 10 mins

Answer 12

Speed = distance moved / time taken
35/10 = 3.5mm/min

Question 13

Describe the method to estimate transpiration rate

Answer 13

1. Set up potometer
2. Record the starting position of the air bubble
3. Start a stopwatch and record the distance moved by the bubble per unit time (hour)
4. Calculate the speed using distance moved/time taken