Chapter 37: Plant Sensory Systems, Signals, and Responses

Amyloplasts

________ are organelles that contain starch granules; the starch is denser than water.

coleoptile

A(n) ________ is a modified leaf that forms a sheath protecting the emerging shoots of young grasses.

Abscisic acid

________, commonly abbreviated ABA, inhibits growth.

Responses

________ to attacks and infections in both plants and animals are called inducible defenses because they are triggered by the presence of a threat.

apical dominance

When ________ occurs, growth is restricted to the main stems; the lateral buds in the axils of each leaf remain dormant.

Photoperiodism

________ is any response by an organism that is based on ________- the relative lengths of day and night.

Francis Darwin

In 1881 Charles and ________ published one of the first experimental results on gravitropism " (gravity- turn)- "the ability to move in response to gravity.

proton

When ________ pumping lowers the pH of the wall to 4.5, cell wall proteins called expansins are activated.

separation of charges

The ________ creates a membrane voltage or membrane potential.

Stomatal closure

________ prevents more pathogen cells from entering the plant.

Expansins

________ "unzip "the hydrogen bonds at form between cellulose microfibrils and other polymers in the cell wall, loosening the structure.

HR

The ________ results in small brown spots in leaves- those cells dead by suicide that accumulate over the growing season.

Second messengers

________ are produced when receptor proteins trigger the production of intracellular signals or their release from storage areas.

Etiolation

________ describes the phenomenon in which plants have a pale yellow color and lengthen their stems and grow long, thin, and spindly when they are shaded or kept in dark conditions.

Dormancy

________ is a temporary state of reduced metabolic activity.

grains of sand

The ________ are called statoliths " (place- stones)

Disease causing agents

________ are termed pathogens.

Calcium ions

________ stored in the vacuole, ER, or cell wall are one of several ions or molecules that function as the second messenger in plants.

signal transduction

If the receptor is located in the plasma membrane, the subsequent process is called ________; the verb "transduce means convert from one form to another ..

auxin concentrations

Falling ________ are involved in the abscission, or shedding, of leaves and fruits, which is associated with the genetically programmed aging process called senescence.

movement

Directed ________ in response to light is called phototropism.

sensory cell

To travel from a(n) ________ to a response cell, electrical signals are propagated in a characteristic form called an action potential.

directional plant movement

Any ________ that occurs in response to a directional stimulus is considered a tropism.

Auxin

________ is the only plant hormone known to be transported through individual cells in one direction only.

Auxin transport

________ is polar, or unidirectional.

Phosphorylation

________ activates proteins involved in signal transduction cascades, causing them to ________ and activate a different set of proteins, which in turn catalyze the ________ and activation of still other proteins.

37.3 Red and Far-Red Light

Germination, Stem Elongation, and Flowering