IGCSE Biology Paper-1: Specimen Questions with Answers 111 - 111 of 208

Answer

Explanation

Cambium: - Meristematic tissue responsible for lateral (outward) growth in plants is known as cambium. There are two kinds of cambium in woody plant stems, both of which increase the diameter of stems. First type of cambium is vascular cambium found in the center of the stem; its division produces the plant’s secondary vascular tissue (xylem and phloem cells. ) The outer ring or near the epidermis the bark of a woody plant also contains a cambium called secondary cambium or cork cambium, which creates cork cells of the outer layer and responsible to give rise the bark. The cambium layer consists of a single layer of cell and these cells divide in a direction parallel with epidermis. Each time it divides into two cells and one of the two new cells one remains meristematic and the other differentiates into permanent tissue. If the newly formed cell is near the xylem it will form secondary xylem and if newly formed cell is towards phloem it will develop in secondary phloem. The activity of cambium thus increases, and the enlargement of stem takes place and the activity of cambium remains for a considerable long period of time.

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