Unit 3 (Gas Exchange): Introducing Plant Parts and Stomata's Functions

plant organs

roots, stems, leaves

root system

parts of a plant below ground

shoot system

parts of a plant above ground

root

anchors a vascular plant in the soil and helps with absorption of minerals and water

taproot

the main vertical root that penetrates the soil deeply

lateral roots

branches off the taproot and allows for better absorption

root hairs

thin, finger-like extensions of root epidermal cells

stem

connects leaves and buds, elongates the shoot

nodes

the points at which leaves are attached

internodes

segments between the nodes (stem)

apical bud

located at the very top, responsible for continuous growth

axillary bud

can potentially form a branch, thorn, or flower

leaf

plant organ responsible for photosynthesis

blade

the flat part of the leaf

petiole

connects leaf to stem

veins

vascular tissue of leaves

dermal tissue

plant’s outer-protective layer, first line of defense against damage

epidermis

makes up the dermal tissue in nonwoody plants, a single layer of cells

periderm

replaces epidermis as woody plants mature because it’s thicker/more protective

cuticles

secretes wax to prevent water loss

vascular tissue

xylem(water and minerals) and phloem(products of photosynthesis)

ground tissue

tissues that are neither dermal or vascular

pith

ground tissue that surrounds vascular tissue

cortex

ground tissue external to the vascular tissue

stomata

aids in absorbing CO2 and releasing O2—also contributes to water loss

guard cells

control the diameter of the stomata by changing the shape

what does water loss depend on

number of stomata and size

guard cells absorbing water

as guard cells absorb, they become more structured/turgid, bow-like

guard cells losing water

as guard cells release water , they become less bowed and close the pores

turgor pressure

pressure exerted by the fluid in the plant cell against its cell wall, gives the plant its rigidity

abiscisic acid (ABA)

produced in roots and leaves, signals guard cells to close stomata

xerophytes

plants adapted to arid environments

crassulaccean acid metabolism(CAM)

special photosynthesis found in succulents to take in CO2 at night and close stomata in the day where evaporation is more likely