Question

34) What are the differences between primary and secondary growth? (4) 35) What is the name for the process by which xylem tissue transports water and minerals against gravity? (2)

Answer 1

34. DIFFERENCE BETWEEN PRIMARY AND SECONDARY GROWTH

PRIMARY GROWTH	SECONDARY GROWTH
Primary growth is the growth that occurs in the beginning by the action of primary meristem that increases the length of the stem.	Secondary growth is the growth that follows the primary growth by the action of cambium that increases the diameter of the plant.
Results in the growth in longitudinal axis	Results in radial growth
This growth stops after completion of tissue differentiation.	Only occurs in the mature parts
Occurs in all parts of the body	Occurs in both angiosperm and gymnosperms
Development of epidermis, cortex, primary vascular tissue occurs.	Development of bark, secondary phloem, secondary xylem occurs.

35. The process by which xylem tissue transports water and minerals from the roots to leaves against gravity without the use of pump is known as transpiration. When transpiration in plants occurs, water gets evaporated from the leaves. This results in more water being pulled from the root creating negative pressure or tension that draws the water upward from roots to stem which occurs due to sticking of water molecules with each other (cohesion) and thus causes more water molecules to fill the gap in the xylem as the top-most water is pulled toward the stomata.