Plant Transport

• Water Transport– 1. Enters root by osmosis– 2. Passes through cortex

(parenchyma) tissue by osmosis

– 3. Passes through endodermis• One way only• Combination of active

transport and osmosis

Plant Transport

• Water Transport (cont)4. Enters xylem• Cohesion-

– The attraction of water molecules to each other

• Transpiration-– The evaporation of

water from the leaves of plants

Plant Transport

• Water Transport (cont)– 5. Transpiration Pull-

• The force that pulls water upward.

• Cohesion holds the water column together as it moves upward through the xylem

Plant Transport

• Food Transport– Requires energy (active

transport)– Translocation-

• Movement of food through the phloem

– Pressure Flow Hypothesis (source-sink)• Food moves from an area

of high pressure to low pressure

Plant Transport

• Food transport– High Pressure (Source)-

• Could be leaves when food is formed

• Could be areas of food storage (root, stem, etc)

– Low Pressure (Sink)-• Could be where food is

used for growth.• Could be where food is

stored.

Plant Motions

• Auxins- – Plant hormones

• Stimulate or inhibit cells to grow

• Depends on the target organ

– Stem growth-• Auxins stimulate stem

cell growth

– Root growth-• Auxins inhibit root cell

growth

Plant Motions

• Tropism- – Response of a plant to

environmental stimuli– Positive-

• Respond toward the stimulus

– Negative- • Respond away from the

stimulus

Plant Motions

• Phototropism- – Response of plants to

light• Stem- positive

Plant Motions

• Gravitropism or geotropism-– Response of plants to

gravity• Stem- negative• Root- positive

Plant Motions

• Thigmotropism- – Response of plants to

touch• Tendril- positive

Flowering

• Photoperiodicity-– Response of flowering

plants to different light conditions

• Short day plants-– Flower when time

exposed to light is short– ex. chrysanthemums &

poinsettias

Flowering

• Long day plants-– Flower when the

amount of time exposed to light is long

– ex. clover, petunias, & hollyhocks

Flowering

• Day-neutral plants-– Length of light has no

effect on flowering– ex. corn & tomato

• Actually the amount of darkness, not light, that stimulates these plants