1 / 11

Chapter 8 Section 5

Chapter 8 Section 5. Plant responses and Growth. Tropism. A plants growth response toward or away from a stimulus Plant grows toward a stimulus: positive tropism Plant grows away from a stimulus: negative tropism Three important stimuli Touch Light Gravity. Examples of Tropisms.

cody
Download Presentation

Chapter 8 Section 5

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 8 Section 5 Plant responses and Growth

  2. Tropism • A plants growth response toward or away from a stimulus • Plant grows toward a stimulus: positive tropism • Plant grows away from a stimulus: negative tropism • Three important stimuli • Touch • Light • Gravity

  3. Examples of Tropisms • Plant showing response to touch • Thigmotropism • Positive tropism • Grows toward object they are touching • Example: bladderworts, grapes, morning glories

  4. Examples of Tropisms • Plant showing response to light • Phototropism • Positive tropism • Grows toward light

  5. Examples of Tropisms • Plants showing response to gravity • Gravitropism • Negative tropism on stem • Gravity it pulling down, yet plant grows up • Positive tropism on roots • Roots grow down, direction gravity pulls

  6. Hormones and Tropisms • Hormones • Produced by a chemical that affects how the plant grows and develop • Auxin • Speeds up the rate at which a plant’s cell grows • Plants hormones also control… • Tropism • Germination • Formation of leaves, stems, roots • Shedding of leaves • Development/ripening of fruit

  7. How does auxin control a plants response to light • Auxin builds up in shaded side of a stem • Cells on shaded side of the stem begin to grow faster • Cells on stem’s shaded side are longer than those on sunny side • Stem bends toward light

  8. Seasonal Changes: Photoperiodism • What triggers a plant to flower? • The amount of DARKNESS a plant receives • Photoperiodism • A plant’s response to seasonal changes in length of night and day • Critical night length • The number of hours of darkness that determines whether or not a plant will flower

  9. Long-Day/Short-Day Plant • Short-day plants • Flower when nights are longer than a critical length (fall/winter) • Long-day plants • Flower when nights are shorter than a critical length (spring/summer) • Day-neutral plants • Flowering cycle is not sensitive to period of light and dark

  10. Dormancy • A period when an organism’s growth or activity stops

  11. Life SpanS of Angiosperms • Annuals • Angiosperms that complete a life cycle within one growing season • Most have herbaceous stems • Biennials • Angiosperms that complete a life cycle in two years • Once flowers produce seeds, the flower dies • Perennials • Angiosperms that live for more than two years • Ex. peony

More Related