Test 2 Botany Review

Test 2 Botany Review - Test 2 Botany Review Chapter...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Test 2 Botany Review Chapter Summaries 11- Growth Growth is defined as “irreversible increase in volume due to the division and enlargement of cells” Development is a change in form as a result of growth and differentiation combined. Cells assume different shapes and forms, which adapt them to the problem involved in their total volume increasing at a greater rate than their total surface area. Some growth phenomena are influenced by hormones. Vitamins are organic molecules that function in activating enzymes; they are sometimes difficult to distinguish from hormones. Darwin and his son noticed in 1881 that coleoptiles bend toward a light source. Frits Went in 1926, followed up on the Darwinian observation and demonstrated that something in the coleoptiles tip moved out into agar when decapitated tips were placed on it. Three groups of plant hormones that promote the growth of plants have been found 1) Auxins stimulate the enlargement of cells and are involved in many other growth 2) Synthetic auxinlike compounds have been used as week killers and defoliants 3) Dioxin which has caused disease and defects in laboratory animals and is banned from the United States. Gibberellins promote stem growth without corresponding root growth Cytokinins promote cell division and can be used to stimulate the growth of axillary buds Abscisic acid causes buds to become dormant and apparently helps leaves respond to excessive loss of water Ethylene gas hastens ripening of fruits and is used commercially to ripen green fruits Senescence is the breakdown of cell parts that leads to the death of the cell Plant movements , such as nutations and nodding, twining, contractile, and nastic movements, are growth movements that result from internal stimuli Tropisims are permanent which direct growth directly from external stimuli- light, gravity, contact, and chemicals Turgor movements result from changes in internal water pressures Each species of plant has an optimum temperature for growth
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Photoperiodism is a response of plants to the duration of the day or night. Dormancy is a period of growth inactivity in seeds, bulbs, and other plant organs even when appropriate environmental conditions are met The change from dormancy to a state in which germination will occur in seeds is controlled by a variety of factors, including temperature, moisture, photoperiod, thickness of seed coat, enzymes, and growth inhibitors
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/23/2011 for the course BIOL 1401 taught by Professor Holaday during the Spring '08 term at Texas Tech.

Page1 / 6

Test 2 Botany Review - Test 2 Botany Review Chapter...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online