Water transportation in plants

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Question 4h

How will the increasing CO2 in our atmosphere affect agricultural production?
a) the extra CO2 will encourage more growth in all crop plants
b) the extra CO2 will especially encourage growth in C4 crop plants
c) the extra CO2 will increase crop production provided no other necessities are limiting d) the extra CO2 will increase crop production by decreasing photorespiration in all plants

Explain your answer in one sentence

Question 4i

A first year student of biology is investigating photosynthesis. The plants for her control treatment (no light, no photosynthesis) are in her cellar, which is completely dark. She needs to visit these plants daily to water them. What colour cellophane should she attach to the front of her torchlight, so that her control treatment is not disturbed.

  1. a)  Any colour light will disturb her dark control plants
  2. b)  any colour will work as long as the torch is only on for a few seconds
  3. c)  blue
  4. d)  green
  5. e)  red

Explain your answer in one sentence:

C3, C4 and CAM photosynthesis

Question 5a

C4 and CAM photosynthesis differ from C3 photosynthesis in: a) timing of CO2 fixation

  1. b) location of CO2 fixation
    c) timing and location of CO2 fixation
    d) they don’t differ in their mechanism of CO2 fixation

Explain your answer in one sentence

Question 5b

C4 photosynthesis differs from C3 photosynthesis due to the following element(s)

  1. a)  CO2 fixation takes place during the night
  2. b)  CO2 fixation costs more energy
  3. c)  CO2 fixation is more efficient
  4. d)  C4 photosynthesis is more water conserving

Explain your answer(s) in one sentence

 

Question 5c

CAM photosynthesis differs from C3 photosynthesis due to the following element(s): a) timing of initial CO2 fixation

  1. b) location of initial CO2 fixation
    c) CAM is more water conservative
    d) they don’t differ in their mechanism of CO2 fixation

 

6a )Which of the below are important elements that contribute to our current understanding of how water moves to the top of tall trees

  1. a)  a metabolic pump that raises water to the top of trees
  2. b)  sturdy xylem vessels that can withstand the positive pressure of their content
  3. c)  sturdy xylem vessels that can withstand the negative pressure of their content
  4. d)  tensile strength of water
  5. e)  adhesive properties of water
  6. f)  cohesive properties of water
  7. g)  active transport of water by the roots
  8. h)  water movements due to gradients in water potential
  9. i)  turgor pressure in root cells

Explain how you can test one of the elements you circled above

Question 6b

Which of the below contribute(s) to our current understanding of how the products of photosynthesis are distributed within a plant

  1. a)  the phloem is under tension
  2. b)  the phloem is under pressure
  3. c)  water is actively pumped into the phloem to cause mass flow
  4. d)  sugars are actively pumped into the phloem
  5. e)  sugars move into the phloem by passive diffusion, with water following by osmosis
  6. f)  mass flow of phloem content occurs due to gravity

Explain how at least one the elements you chose above can be supported experimentally

Water and sugar transport in plants

Question 6c

What form of energy is used to (directly) drive water and sugar transport in plants? Where is the energy being put in?
Water transport: ………………………………….

Sugar transport: ………………………………………

Question 6d

Ringbarking kills a tree very slowly because
a) only the xylem is severed, so sugar transport still goes on
b) only the phloem is severed, so water transport still goes on
c) only the phloem is severed, but sugar transport still goes on
d) all of the transport systems are severed, but the tree has reserves

Explain your answer in one sentence

……………………………..

Question 6e

What type of transport (if any) continues after a tree has been ringbarked a) sugar transport still goes on
b) water transport still goes on
c) sugar and water transport still go on

  1. d) no transport continues after ringbarking Explain why ringbarking kills a tree very slowly

………………………………..

Question 6f

Which of the following cells are generally NOT under pressure during the day? a) root cells,

  1. b) leaf cells
    c) xylem cells d) phloem cells

Explain your answer in one sentence: …………

Question 6g

Which of the following cells are generally NOT under pressure at night? a) root cells

  1. b) phloem cells
    c) stomatal guard cells d) all of the above

Explain your answer in one sentence:

Question 6h.

Why does the water column in the xylem not fall down with the force of gravity when the stomata close at night?

  1. a) stomata do not completely close at night b) the cohesive property of water
    c) the adhesive property of water
    d) water is constantly pushing into the roots

Explain your answer in one sentence

Question 6i

Water does not fall down in the xylem vessels at night because it adheres to the vessel walls. Give a different, day-to-day example where this adhesive property of water is shown or used

 

Question 6k

Water can be drawn up through a xylem vessel due to its molecules being attracted to each other. Give a day-to-day example (other than a drinking straw) where this cohesive property of water is shown or used ……..

Question 6l

After you cut flowers for a birthday arrangement, why does the cut stems not bleed any liquid from the xylem? ……………..

Question 6m

After you buy cut flowers from the florist and bring them home, why is it a good idea to cut one or two centimetres off the stem’s lower end, before placing the flowers in water? ……………………………………………

Question 7: About water potential and water movement

Water potential and water movement

Question 7a

If a soil in a paddock was getting saltier (e.g. due to effects of irrigation), what could plants do to continue attracting water to their roots?

  1. a)  grow more roots
  2. b)  manufacture solutes for their roots to decrease their water potential
  3. c)  close their stomata more frequently during the day
  4. d)  increase the water potential of their roots to keep up the gradient

Explain your answer in one sentence: …………………….

Question 7b

Mangroves which grow in sea water must have special adaptations to attract water to their roots. What would you expect to find in the roots of mangroves? You may choose more than one option

  1. a)  a low concentration of salt
  2. b)  a high water potential
  3. c)  a high concentration of solutes
  4. d)  a low water potential

Explain your answer(s) in one sentence: …………………………………………….

Question 7c

Mangroves, which grow in seawater, have special adaptations to attract water into their roots.

However, why for example, would a tulip, fail to survive in seawater? More than one option may apply

  1. a)  Incoming salts would be toxic
  2. b)  its roots would be in the equivalent of a drought
  3. c)  the water potential in its roots would not be low enough to attract water
  4. d)  the water potential in its roots would not be high enough to attract water

Explain your answer in one sentence: …………………………

Question 7d

In the diagram below, what might be the salt concentrations of the different solutions surrounding these cells (going from left to right), relative to the salt concentration inside the three cells?

  1. a)  the outside solutions are of lower, higher, equal concentrations
  2. b)  the outside solutions are of higher, lower, equal concentrations
  3. c)  the outside solutions are of lower, equal, higher concentration
  4. d)  the outside solutions are of higher, equal, lower concentration

Explain your answer in one sentence…………

Question 7e

In the diagram below, what might be the water potential of the three solutions surrounding these cells (going from left to right), relative to the water potential inside the three cells?

  1. a)  the three outside solutions have a lower, equal, higher water potential
  2. b)  the three outside solutions have a higher, equal, lower water potential
  3. c)  the three outside solutions have a lower, higher, equal water potential
  4. d)  the three outside solutions have a higher, lower, equal water potential

Explain your answer in one sentence ……………..

Question 7f

Why can water travel up to the top of tall trees?
a) the water potential gets constantly lower

  1. b) the water potential gets constantly higher
    c) the concentration of solutes is constantly increasing d) the pressure is constantly decreasing

Besides your answer above, what two critical properties of water allow it to move to such immense heights:

  1. ………..2. ……………

Question 7g

Why can water travel up to the top of tall trees?
a) the water potential gets constantly lower

  1. b) the water potential gets constantly higher
    c) the concentration of solutes is constantly increasing d) the pressure is constantly decreasing

Name two circumstances under which water transport stops

Question 7h

On an overcast day with 100% humidity, how fast would you expect xylem sap to move within the plant?

  1. a) 40cm/hour b) no movement c) 10cm/hour

Explain your answer in one sentence: …………………………

Question 7i

Which way would water move between soil and root cells in the following three scenarios. Indicate your answer by adding an arrowhead to the relevant horizontal line

yosmotic = –0.9 MPayosmotic = –1.0 MPayosmotic = –0.9 MPa

…………………………

Question 7j

Which way would water move between soil and root cells in the following three scenarios. Indicate your answer by adding an arrowhead to the relevant horizontal line

yosmotic = –1.0 MPayosmotic = –1.0 MPayosmotic = –0.7 MPa

Question 7k

Make a sentence (or two) using at least the following words: cell wall, membrane, vacuole, turgor pressure, solution, solute.

 

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