1 / 17

Higher Biology

Learn the adaptations of xerophytes and hydrophytes to survive in harsh habitats or aquatic environments, facing and overcoming challenges unique to each. Explore structural and physiological strategies these plants employ.

geraldallen
Download Presentation

Higher Biology

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. Higher Biology Adaptation Part 4

  2. Adaptation 4 By the end of this lesson you should be able to: • Know what a xerophyte is. • Describe the problems that xerophytes face. • Describe how xerophytes are adapted to survive in • their environment. • Know what a hydrophyte is. • Describe the problems that hydrophytes face. • Describe how hydrophytes are adapted to survive in their environment.

  3. Xerophytes Moorlands- exposed and windy • Xerophytes are plants that have become adapted to survive in habitats where transpiration rates are very high. • Examples of habitats are: Deserts- hot and dry

  4. Xerophytes • There are 3 categories of xeromorphic adaptations: Structural adaptations- reduce transpiration rate Structural adaptations- resisting drought Physiological adaptations

  5. Structural adaptations To reduce transpiration rate: • Leaves have a reduced number of stomata. • Leaves have a thick cuticle. • Leaves can be rolled and/or hairy. • Leaves have sunken stomata in pits. • Leaves can be small and circular. • Leaves are reduced to spines.

  6. Structural adaptations To reduce transpiration rate: Marram Grass (T.S.) Rolled leaf Hairs Thick cuticle

  7. Structural adaptations To reduce transpiration rate: Cactus surface Sunken stomata in pits Thick cuticle

  8. Structural adaptations To resist drought: • Long roots. • Extensive system of superficial roots. • Storing water in succulent tissues. • Folded stems.

  9. Physiological adaptations To reduce water loss: • Reversed stomatal rhythm- closed during the day and open at night. They take in CO2 during the night and store it for use in photosynthesis during the day. • Ceasing vegetative activity during dry times- e.g. existing in a desiccated state (seed) and only germinating when water becomes available. • Insert and complete the “Xerophytes” summary sheet .

  10. Hydrophytes Partially submerged e.g. water lily • Hydrophytes are plants that live either partially or completely submerged in water. Completely submerged e.g. water milfoil

  11. Hydrophytes • These have evolved adaptations to help them survive in an aquatic environment.

  12. Hydrophytes- adaptations Specialised leaves • Submerged leaves have no stomata. • Floating leaves have all their stomata on the upper surface. • Floating leaves have long leaf stalks (petioles) to enable the leaves to move up and down in response to changes in water level. • Submerged leaves are narrow or finely divided.

  13. Hydrophytes Floating leaves- stomata on top surface e.g. water lily Narrow, finely divided leaves e.g. water milfoil

  14. Hydrophytes adaptations Reduced Xylem: • Not required since water provides the support for submerged plants. • Any xylem is found at the centre of the stem- to allow flexibility in response to water movements.

  15. Hydrophytes adaptations Extensive air spaces: • Store O2produced during photosynthesis for use in respiration. • Provide buoyancy for leaves- keeps them near the surface for maximum exposure to light. • Insert and complete the “Hydrophytes” summary sheet.

  16. Practice Questions • Torrance • TYK page 183 Q1-5 • AYK page 184 Q4-6

  17. Adaptation 4 Can you do it? • Know what a xerophyte is. • Describe the problems that xerophytes face. • Describe how xerophytes are adapted to survive in • their environment. • Know what a hydrophyte is. • Describe the problems that hydrophytes face. • Describe how hydrophytes are adapted to survive in their environment.

More Related