About Lesson
Sample Question
Q1.
(a) Describe secondary thickening in flowering plants
- Secondary thickening is facilitated by meristematic cells; called cambium; located between phloem and xylem in vascular bundles of the plant; the cambium divides radially; to form secondary phloem outside and secondary xylem inside; the ring cells forms intravascular cambium/cambium between vascular bundles divides to form secondary parenchyma; thereby increasing the growth of medullary rays; much more xylem is formed than phloem; thus pushing phloem and cambium ring outwards;üthe rate of secondary growth is dependent on seasons/rains; resulting in annual/rings; cork cambium divides to form new cork/bark tissue; to accommodate increased growth) on the outside and secondary cortex on the inside;
(b) Describe one method which can be used to measure the average growth rate of a single leaf on a plant
- Identify a young germinating seedling;ümark its radical with Indian ink or permanent ink at intervals e.g. of 2mm; Leave it to grow for some time e.g. 24 hours or overnight; Measure the distances between successive ink marks; and record; calculate the growth rate as;
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