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IB DP Biology Questions

9.2 Transport in the Phloem of Plants

Question 1

What is the primary role of the phloem in plants?

A. Transporting water and minerals from roots to leaves.

B. Transporting organic compounds from sources to sinks.

C. Facilitating gas exchange for photosynthesis.

D. Storing nutrients for later use.

Question 2

How does active transport contribute to the loading of sugars into the phloem sieve tubes?

A. It facilitates the passive diffusion of sugars into the sieve tubes.

B. It uses ATP to actively load sugars, creating a high solute concentration.

C. It decreases the solute concentration in the sieve tubes.

D. It prevents the uptake of water by osmosis.

Question 3

What drives the flow of sap in the phloem from the source to the sink?

A. Gravitational pull.

B. Transpiration pull.

C. Hydrostatic pressure gradient.

D. Active transport of water.

Question 4

Why does water enter the phloem at the source site?

A. Decreased solute concentration in the phloem.

B. Increased hydrostatic pressure in the phloem.

C. High concentration of solutes in the phloem leads to water uptake by osmosis.

D. Active transport of water into the phloem.

Question 5

Which of the following is true regarding the transport of solutes in the phloem?

A. Solutes move from areas of low pressure to areas of high pressure.

B. The incompressibility of water does not affect solute transport.

C. Solutes are transported along hydrostatic pressure gradients.

D. Active transport is not involved in solute loading into the phloem.

Question 6

a) Explain how plants transport organic compounds like sugars from their production sites (sources) to where they are used or stored (sinks) via phloem. [4]

b) Discuss the role of active transport in loading sugars into phloem sieve tubes at the source and how it requires energy in the form of ATP. [3]

Question 7

a) Elucidate how the incompressibility of water allows solutes to be transported in the phloem along hydrostatic pressure gradients. [3]

b) How does a high concentration of solutes in the phloem at the source site lead to water uptake by osmosis? [2]

Question 8

a) Discuss the significance of hydrostatic pressure gradients in the transport of solutes in the phloem of plants. [4]

b) How do environmental factors influence the rate of translocation of solutes in the phloem? Provide examples. [3]

Question 9

a) Describe the process of translocation in plants and explain how it is essential for the distribution of nutrients. [4]

b) How does the cohesion-tension theory relate to the transport of water in plants? [3]

c) Discuss the impact of environmental factors on the rate of translocation in plants. [3]

Question 10

a) Explain the role of active transport in loading sugars into the phloem. Why is ATP necessary for this process? [4]

b) How does the incompressibility of water facilitate the transport of solutes in the phloem? [3]

c) Discuss the mutualistic relationships between flowering plants and pollinators and their significance for plant reproduction. [3]

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