Paper 2 - Transport

Question 1

How is water absorbed by root hair cells?

Answer 1

• Concentration gradient exists so water moves into root hair cell via osmosis
• Water potential changes to concentration gradient changes and water moves into the cortex via osmosis
• Water then diffuses into xylem via osmosis

Question 2

What is transpiration?

Answer 2

The evaporation of water from the surface of
a plant

Question 3

How does humidity affect the rate of transpiration?

Answer 3

• High humidity means high volume of water in the air
• Decreases water concentration gradient
• Slower rate of transpiration

Question 4

How does wind speed affect the rate of transpiration?

Answer 4

• High wind speed displaces water molecules away from leaf
• Increases water concentration gradient
• Faster rate of transpiration

Question 5

How does temperature affect the rate of transpiration?

Answer 5

• Water particles have more kinetic energy
• They move more rapidly
• Faster rate of transpiration

Question 6

How does light intensity affect the rate of transpiration?

Answer 6

• High light intensity triggers stomata to open
• So water molecules can exit easily
• Faster rate of transpiration

Question 7

Describe a practical to investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot

Answer 7

• Sample of a plant us cut underwater to prevent air entering the xylem
• Potometer is filled with water and all air bubbles are removed
• Leafy shoot is attached to Potometer, using petroleum jelly to form an airtight seal
• One air bubble is introduced by lifting capillarie tube out of beaker
• Use a ruler to measure the distance travelled by the air bubble
• Syringe full of water to reset the experiment
• The rate the distance the bubble has moved is used to find the volume of water
• Repeat with different light intensity, humidity, wind speed or temperature

Question 8

How does vaccination results in the manufacture of memory cells?

Answer 8

• Inactive pathogen introduced to immune system
  -Lymphocyte produces memory cells to remember the antigens of that pathogen
• So that thee next time the immune system in contact with that pathogen, antibodies can be produced faster, sooner and in greater quantity

Question 9

How are platelets are involved in blood clotting?

Answer 9

• Platelets rush to the site of the cut
• Form a physical barrier
• Preventing blood loss and the entry of micro-organisms