Formative Practice 4.3 (Form 5 Biology Textbook Exercise and Answer)

Question 1:
State the definition of translocation.

The process of transporting organic substances such as sucrose, amino acids and hormones in the phloem from the leaves to other parts of the plant such as the roots and stem.

Question 2:
What is the role of translocation in plants?

Translocation helps in transporting photosynthetic products from the leaves to other parts of the plant that need them for growth and respiration such as roots, fruits, tip of shoots or developing flowers. Other than that, translocation also transports excess photosynthetic products to other parts of the plants such as rhizomes, tubers and bulbs.

Question 3:
How does translocation occur from the leaves to the roots? Explain.

Sucrose is actively transported into the sieve tube. The transport of sucrose into the sieve tube through the companion cell from the leaf reduces the water potential in the sieve tube. This causes water to diffuse from the xylem into the sieve tube via osmosis. The water diffusion increases the hydrostatic pressure in the sieve tube. The increase in the hydrostatic pressure causes the phloem sap to be pushed along the sieve tubes to other organs of the plant. The phloem sap (sucrose) is transported from the sieve tubes to others parts such as stems, roots, shoots, fruits and tubers by active transport. The high water potential in the phloem causes the water to diffuse in order for it to return into the xylem by osmosis. Transpiration pulls water along the xylem vessel against the direction of gravitational pulls.

Question 4:
Compare sucrose concentration in a leaf cell and sieve tube. What is the effect of the difference?

The concentration of sucrose in leaf cells is higher than in sieve tubes. The hydrostatic pressure in the sieve tubes increases, causes the phloem sap (sucrose) to move into the sieve tube actively.

Question 5:
How does translocation affect a plant’s yield?

An efficient translocation from the leaf to the storage organs such as fruit will increase the size of fruit or the tuber.

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