Gas Exchange in Flowering Plants

___ and ___ ___ of flowering plants must exchange gases with the surrounding environment.

Leaves and green stems

What are the tightly regulated pores that enable gas exchange in flowering plants?

Stomata

How do CO2, H2O, and other gases diffuse through open stomata?

From higher concentration to lower concentration

Why is the precise control of stomata important?

To conserve water

The leaves from flowering plants must acquire carbon dioxide (CO2) molecule from the environment. Why?

To enable the Calvin Cycle reactions of photosynthesis to make carbohydrates by converting CO2 to carbohydrate.

Why do the living cells in the roots of flowering plants require a supply of oxygen (O2) molecules from the environment?

To enable cellular respiration to make ATP

Which specialized cells regulate the opening and closing of the stomata in leaves and green stems?

(Two) Guard cells

Which environmental stimulus induces the stomata in the leaf to open?

Blue Light

Which stimulus induces the stomata in the leaf to close?

• No blue light (No sunlight)

• Water stress

• High CO2, levels within the leaf

• Pathogen detection

• All the above

All the above

Which structures in the bark surrounding the stem enable oxygen and carbon dioxide molecules to diffuse through the bark?

Lenticels

Which structures in the bark enable the oxygen molecules in the soil to diffuse through the bark to enter the roots?

Lenticels

Why is it critical for the lenticels on the surface of developing fruit to enable oxygen (O2) molecules to diffuse into the fruit?

To enable cells to make ATP by cellular respiration

Carbon dioxide (CO2) molecules have diffused into the leaf through open stomata. What enables these gas molecules to diffuse to all the photosynthetic cells in the leaf?

Empty spaces between the cells

Gamma grass can tolerate drought conditions because their roots grow deep into the soil where water is available. Which tissue enables oxygen (O2) molecules to diffuse from the stem into the deep roots?

Aerenchyma

In water lilies, oxygen (O2) produced in the leaf must diffuse into the submerged stem and roots. Which internal air tubes in the stem enable O2 to diffuse to the root system?

Lacunae

We depend on O₂ that photosynthetic species produce during the light reactions of photosynthesis. Which highly regulated structures enable O₂ to diffuse from the leaves of green stems of flowering plants into the environment?

Stomata

Low CO₂ in leaves causes…

Stomata (of leaves and green stems) to open

High CO₂ level in leaves causes…

Stomata (of leaves and green stems) to close

Pathogen detection causes…

Stomata (of leaves and green stems) to close

Water stress causes…

Stomata (of leaves and green stems) to close

Which structures enable gases to diffuse through the bark that surrounds the organs of woody plants?

Lenticels

Which internal anatomical feature enables O₂ and CO₂ molecules to diffuse to all cells in each plant organ?

Empty spaces between cells enable gas diffusion

How are the signals that regulate stomata recognized?

Guard cells surrounding stomata have receptors that recognize the signals that regulate stomata.

What has receptors that recognize the signals that regulate stomata?

Guard cells surrounding stomata

Stimuli that induces stomata to open cause —

• Guard Cells to uptake H2O molecules by ___

• Guard cells to ___ and change ___

• The stomatal ___ to open.

• Guard Cells to uptake H2O molecules by osmosis

• Guard cells to swell and change shape

• The stomatal pore to open.

Large intercellular spaces in ___ enable gas diffusion

Bark (Lenticels)

The bark surrounding the organs (branches, roots, stems) of woody plants is ___ and ___.

Gasproof and Waterproof

What porous tissue enables O₂ to diffuse from the leaves, through the stem, to roots?

Arenchyma

Roots can grow into anaerobic, deeper soils with H₂O. What porous tissue helps these roots receive diffused oxygen from the leaves?

Aerenchyma

Some wetland-adapted species that have roots extended far into the soil have what kind of porous tissue?

Aerenchyma

The water lily’s roots and stem have hollow canals in Aerenchyma tissue called…

Lacunae