#1

CYK Lesson 38

1. Outline the wide diversity in the plant kingdom as exemplified by the structural differenes between bryophytes, filicinophytes, coniferophytes, and angiospermiophytes.

The wide variety of plants can easily be differentiated by the structural differences between the four categories of plants. Bryophytes have no roots, but they have something similar to roots called rhiziods. Mosses have simple leaves and stems and liverworts have a flat thallus. Filicinophytes have roots. They also have leaves and short non-woody stems. The leafs are usually curled up in a bud and are usually divided into pairs of leaflets. Coniferophytes are shrubs or trees that have roots, leaves, and woody stems. The leaves are usually narrow and have a thick cuitcle. Angiospermiophytes are flowering plants, they vary, but mostly they have roots, stems, and leaves. The stems that develop into shrubs and trees are woody.

#4

CYK Lesson 38

#4 Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues.

The main part of the leaf is the leaf blade or lamina. It ha a big surface area that absorbs sunlight, but it is very thin. Within the lamina is four tissues that make up the leaf. The palisade mesophyll consists of many chloroplasts. This is the main photosynthetic tissue and it is near the surface where light intensity is highest. This helps the process of photosynthesis because photosynthesis requires large amounts of sunlight. The upper epidermis is a layer of cells covered by a thick waxy cuticle. This part of the leaf prevents water loss from the upper surface. The xylem brings water to replace losses due to respiration. The phloem transports products from photosynthesis out of the leaf. Guard cells open and close the stoma and they control the amount of transpration. The stoma is a pore that allows carbon dioxide for photosynthesis to diffuse in and out to diffuse out. The spoongy mesophyll provides the main gas exchange surface.