Chapter 25.4 and 25.5

Question 1

System Acquired Resistance

Answer 1

A defence response to infections and injured tissues. Cells in an affected tissue release signalling molecules that call for the synthesis and release of organic compounds that will protect the plant against attacks.

Question 2

Compartmentalization

Answer 2

Trees will wall off the damaged tissue, release phenols (and other toxic compounds) and often secrete resins. Compartments form around injured, infected, or poisoned tissues, and new tissues grow overtop.

Question 3

Leaf folding

Answer 3

A controlled response by Lupinus arboreus to changing conditions. Response minimizes heat absorption.

Question 4

Circadian Rhythm

Answer 4

Biological activity pattern that recurs with an approximate 24-hour cycle. Phytocrome helps control this.

Question 5

Homeostasis in Plants

Answer 5

There are control mechanisms (compartmentalization, system acquired resistance, and rhythmic leaf movements) that help maintain homeostasis, but they are not centrally controlled like in animals.

Question 6

Things involved in Communication Among Distant Cells

Answer 6

Amino acids, peptides, proteins, lipids, and gases. Some other signals diffuse through interstitial fluid, or through blood vessels or vascular tissues.

Question 7

Molecular Mechanisms in Cell Communication

Answer 7

Often have three steps:

1. Specific Receptor is activated
2. Signal is transduced (converted into a form that can operate inside the cell)
3. Cell makes a response to the signal (ex. altering its metabolism or which genes it expresses)

Question 8

Responses to Molecular Signals

Answer 8

Many receptors that respond are membrane proteins, and once activated some will activate an enzyme that will activate more of a different kind of enzyme, and so on.

Question 9

Cascading Reactions

Answer 9

Amplify the response to one signal many times over

Question 10

Apoptosis

Answer 10

The process of programmed cell death. Example of a response to signal reception.