Formative Practice 1.2 (Form 5 Biology Textbook Exercise and Answer)

Question 1:
Name the three zones of cell growth.

The three zones of cell growth are the zone of cell division, zone of cell elongation and zone of cell differentiation.

Question 2:
The figure below shows a cross-section of a plant stem that undergoes secondary growth.

(a) Label the primary xylem, primary phloem, secondary xylem and secondary phloem.
(b) Explain the formation of secondary xylem and secondary phloem.


Secondary growth occurs when the vascular cambium divides actively through mitosis. The cells in the cambium ring divide inwards to form new xylem and outwards to form new phloem. The new xylem tissues become secondary xylem and the new phloem tissues become secondary phloem.

Question 3:
Why is secondary growth important to plants?

The importance of secondary growth:
• To provide stability to plants by increasing the stem and root diameters to suit the height of plants.
• To produce more xylem and phloem tissues.

Question 4:
Secondary growth supports primary growth.

Using your knowledge in biology, support the above statement.

The primary growth of woody plants is followed by the secondary growth which increases the diameter or circumference of plant stems. The more growth, the more vascular and cork tissues.

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