cHAPTER 25 - Biology Honors Prentice Hall Textbook by...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology Honors Prentice Hall Textbook by Miller/Levine 2/19/10 Chapter 25 HW 1. A 2. A 3. D 4. C 5. B 6. D 7. B 8. B 9. B 10. A 11. Auxins are produced in the apical meristems of plants, and they stimulate cell elongation. A higher concentration of auxins accumulates in the shaded part of a stem and cause the plant to bend toward a light source. 12. When light hits one side of the stem, a higher concentration of auxins develops in the shaded part of the stem. This change in concentration stimulates cells on the dark side to elongate. As a result, the stem bends away from the shaded side and toward the light. 13. Apical dominance is a phenomenon in which the closer a bud is to the stem’s tip, the more it’s growth is inhibited. This is because auxins produced in the apical mersitem, which as at the stem’s tip, inhibits the growth of lateral buds. For example, if you cut the tip off of a plant, then the shape of the plant will become fuller, because there will be no auxins to inhibit the lateral buds. 14. A tropism is the response of a plant to external stimuli. Gravitropism causes the roots of a plant to grow with the force of gravity and into the soil. Phototropism causes a plant to grow toward a light source. 15. Photoperiodism is the response of plants to periods of light and darkness. It is responsible for the timing of seasonal activities such as flowering and growth. This was discovered in the early 1920s, when scientists observed that tobacco plants flower according to the
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

cHAPTER 25 - Biology Honors Prentice Hall Textbook by...

This preview shows document pages 1 - 2. Sign up to view the full document.

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