Chapter 11: Plants

Multicellular, eukaryotic, photosynthetic autotrophs.

• Cell walls • Roots and root hairs • Cutins • Stomates • Xylem and Phloem • Seeds and pollen

Maximizes sugar production while minimizing water loss. Has a palisade layer (tightly packed) and spongy mesophyll (to allow easy transfer of gases).

Epidermal cells that contain chloroplasts, stomates, and are photosynthetic.

The openings where plants lose water by transpiration. When the stomata cells absorb water and become turgid they curve and open the stomate, and the stomate closes when the cells lose water and become flaccid.

• Diffusion • Osmosis • Aquaporins (Osmosis of water) • Cell swelling (Stomates)

• Bulk flow: movement from high to lower pressure. • Phloem: transports sugars from photosynthesis. • Transpirational pull: Fluid in the xylem can be pulled upwards. • Root pressure: fluid in the xylem can be pushed down.

The evaporation of water from the leaves.

The attraction of water to water. Makes it possible to pull a column of water from above within the xylem.

For every molecule that is evaporated at the leaf through transpiration, another is pulled in at the root to replace it.

• High humidity will slow down transpiration, and vice versa. • Strong winds can reduce humidity, thus increasing transpiration. • Increased light intensity can increase transpiration. • Closed stomates will stop transpiration.

Can affect the growth, development, and responses to environmental stimuli. Hormones usually do not depend on the raw amount given, but on the relative amounts. Examples include auxin, gibberellins, abscisic acid, cytokinins and ethylene gas.

Can amplify the hormonal signal.

Growth of a plant towards or away from a stimulus. Toward a stimulus is a positive tropism, and away is a negative tropism.

Result from an unequal distribution of auxins on once side of plant away from the light. Since auxins cause growth, the cells on the shady side enlarge, which cause the plant to move toward the light.

The interaction of auxins and statoliths.

The psychological response to a photoperiod.

The environmental stimulus that lets the plant know of the season and time of day.

Most plants have this, which is a 24 hour biological clock.

Will only flower when the light period is longer than a certain number of hours.

Will flower regardless of the length of day.

The photoreceptor responsible for keeping track of the length of day and night.