Plant Biology BIOSCI II

Monocots

One cotyledon, parallel leaf venation, scattered vascular bundles, fibrous roots, flower parts in multiples of 3.

Dicots

Two cotyledons, net-like leaf venation, vascular bundles in a ring, taproot system, flower parts in multiples of 4 or 5.

Cohesion

(water molecules sticking together)

Adhesion

(water sticking to cell walls)

Tension

(negative pressure pulling water upward)

Evaporation

(water vapor loss from leaves)

How do you measure Transpiration rates?

potometer

Temperature

(higher temp increases transpiration)

Humidity

(higher humidity decreases transpiration)

Wind

(increases transpiration by removing water vapor)

Light intensity

(more light increases stomatal opening and transpiration)

Plants in low CO₂ environment

• have higher stomata density to maximize gas exchange.

Plants in high CO₂ environments

reduce stomata density to conserve water.

A mutants

Sepals → replaced by carpels, petals → replaced by stamens

B mutants

Petals → replaced by sepals, stamens → replaced by carpels

C mutants

Stamens → replaced by petals, carpels → replaced by sepals

Phototropism

(light)

Gravitropism

(gravity)

Thigmotropism

(touch)

Nyctinasty

(night movement, like closing leaves)

Thigmonasty

(response to touch, like Venus flytrap closing)