Biology Honors Prentice Hall Textbook by Miller/Levine
11. The two types of vascular tissues are xylem and phloem. Xylem consists of tracheids and
vessel elements and it is a water conducting tissue. Phloem consists of sieve tube
elements and companion cells and it is a food conducting tissue.
12. Parenchyma, Collenchyma, and Sclerenchyma are Parenchyma cells have thin cell walls
and large central vacuoles surrounded by a thin layer of cytoplasm. Collenchyma cells
have strong flexible cell walls that help support larger plants. Sclerenchyma cells have
extremely thick, rigid cell walls that make ground tissue tough and strong.
13. In root cross sections, the vascular tissue is arranged vertically, but in stem cross
sections, the vascular tissue is arranged in a circular pattern.
14. Root hairs penetrate
the surface between soil particles and produce a large surface area
through which water can enter the plant.
15. During secondary growth, vascular cambium appears as a thin layer situated between
phloem and xylem. Divisions in the vascular cambium give rise to new layers of xylem
and phloem, and causes the stem to grow thicker.
16. Bark develops from phloem, which transports nutrients, cork cambium, which produces a
thick protective layer, and cork, which prevents loss of water.
17. The three main functions of leaves are photosynthesis, which produces food,
transpiration, which is the loss of water through leaves, and gas exchange, which
maintains a balance for photosynthesis and transpiration.
18. The epidermis and cuticle cells form a waterproof barrier that protects tissues and limits
the loss of water due to evaporation. The pore like openings allow photosynthesis to take
place but not so much so that the leaves lose an excessive amount of water.
19. The combination of root pressure, capillary action (adhesion), and transpiration provides
enough force to move water through the xylem tissue of plants.
20. When water is abundant, it flows into the leaf, raising water pressure in the guard cells
which the open the stomata When water is scarce, the water pressure in the leaf falls, and
the guard cell close the stomata.
21. Phloem carries out the seasonal movement of sugars within a plant. These sugars are