Theme 5 - Dr. Samuel Flashcards
What do Auxins do and where are they found?
-Promote plant growth
-govern responses to light and gravity
- Synthesized in apical meristems and young stems and leaves
What do Gibberellins do?
Stimulate growth including elongation of stems
What do cytokinins do?
Enhance growth and retard aging
What does Ethylene do?
It is a gaseous hormone and it regulates a range of responses including senescence
What do brassinosteroids do?
regulate plant growth responses
What does Abscisic acid do?
Suppresses growth and influences responses to environmental stress
What do Jasomonates do?
Regulate growth and have roles in defence.
What are the acid growth hypothesis steps?
a. Auxin acts on cell
b. Cross bridges break
c. Cell expansion
In the acid growth hypothesis, explain what goes on in order for the cell to expand.
a. Auxin triggers pumping of H+ into the cell wall
b. Activated expansion breaks cross bridges between cellulose microfibrils
c. Cellulose microfibrils loosen
What are phototropism and what is their effect?
- Growth responses to directional light source
- Blue light receptors trigger auxin transport
- Auxin triggers differential cell elongation.
What are the steps of phototropism in seedlings?
a. rays from the sun strike one side of a shoot tip
b. Auxin (red) diffuses down from the shoot tip to cells on it’s shaded side
c. The auxin stimulated cells elongate more quickly causing the seedling to bend.
What are some effects of Gibberellin?
-Bolting
-Fruit enlargement
What do plants defend against and what do they use to defend themselves?
Virus, bacteria, fungi, worms, parasites
They use physical and chemical deterrents
What is the potato blight?
Responsible for the Irish Potato famine
What is the hypersensitive response?
The unaffected cells around site of infection undergo cell death in turn containing the pathogen.
What happens during the hypersensitive response? (5)
- Strengthen cell wall
- close stomata
- selective plugging of the xylem
- Produce antimicrobial compounds
- Hypersensitive response
What is a Systemic Acquired Response?
Development of an immune response at the distal site
Describe what happens if one leaf on a plant is infected with TMV
After 7 days, there will be necrotic regions resulting from a hypersensitive response, and if another leaf is infected with TMV, there will be no visible signs of infection or disease.
How can plants attract insect allies?
Volatiles induce compounds in undamaged plants that made them less palatable
- Attract predatory insects that feed on the caterpillars or parasitize the eggs
What are Bt crops and what are their functions?
Bt crops are rows of crops where every other row is made with non-palatable compounds to guard against predation. Insects won’t evolve to attack these plants if they have palatable ones nearby.
What are Perfect Flowers?
Have both stamens and carpels
What are Imperfect Flowers?
Stamens OR carpels, not both. Either male or female.
What is critical to successful reproductive development?
Mate Recognition
What does pollination require?
Compatible pollen and female tissues
