chap 35 - 3. what is apical dominance? Explain how plants...

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3. what is apical dominance? Explain how plants generally grow, and why gardeners sometimes “pinch back” their plants. Apical dominance is when the terminal bud inhibits the growth of the axillary buds. Apical dominance increases the plants exposure to light further enabling photosynthesis. Removing the terminal buds, however, stimulates growth of the axillary buds. 6. what are the three types of plant tissues in plants? What are the functions and main components of each? The three main types of plant tissues are dermal, vascular, and ground. The dermal tissue is a thin layer of tightly packed cells that protects the young part of the plants. The function of these epidermis cells is relative to the organ it is covering. These cells secrete cuticle to help the aerial parts of the plant retain water. Vascular tissue enables transportation between the shoots and the roots. Xylem, the first type of tissue, transports water and dissolved minerals upward from the roots into the shoots. Tracheids and vessel elements are the components of xylem. When either a tracheid or vessel element disintegrates, the cell wall remains thicken, creating a nonliving passage through which water can flow. Pits are located within the secondary walls of both, enabling flow of water. Phloem, the second type, conveys food made in mature leaves to the roots and to nonphotosynthetic parts of the shoot system. Sieve-tube members allow for transport within the phloem. Ground tissue is tissue that is neither dermal nor vascular. Pith is the internal to the vascular, and cortex is the external to the vascular tissue. Ground tissue functions in photosynthesis, storage, and support. 7. compare and constrast collenchyma, parenchyma, and scelerchyma. Parenchyma cells have primary walls that are thin and flexible, and they lack a cell wall. Collenchyma have thicker primary walls, though unevenly thickened. Sclerenchyma cells have thick secondary walls usually strengthened by lignin and are more rigid than collenchyma. Parenchyma cells are the least specialized. They perform metabolic functionsm synthesizing and storing various organic products. Developing plant cells initiate as parenchyma cells before becoming specialized. Collenchyma cells help support young parts of the plant shoot. This support enables further growth due to lack of lignin and lack of secondary walls. Scelernchyma cells cannot elongate and they are located in regions that have stopped growing. The rigidness of their cell walls function as a skeleton to support the plant. Collenchyma cells are living and flexible at their mature stage, whereas sclerenchyma are dead. 8. explain what meristems are, their importance in plant growth, and how apical meristem affects plant structure. Be sure to explain what indeterminate growth is. Meristems, embryonic tissues, located in the growth region enable
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This note was uploaded on 09/27/2011 for the course BIOL 101 taught by Professor Fevzidaldal during the Fall '08 term at UPenn.

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chap 35 - 3. what is apical dominance? Explain how plants...

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