Lecture 11: Plant Chemistry 1 Flashcards
(47 cards)
What do plants activate during the winter?
Abscisic acid(also dormin) that inhibits growth. In addition, it also closes the stomata to conserve water. It also promotes seed dormancy.
What do plants activate during the spring?
Gibberellins where it breaks seed dormancy and allows it to germinate and sprout(also stem elongation and fruit development). In addition, it also induces amylase synthesis where it breaks down starch into glucose.
What do plants release during the summer?
Auxin where it stimulates shoot/root elongation and fruit growth. In addition, also phototropism. Also establishes apical dominance and inhibits leaf abscission.
What phototropism?
Growth in response to light.
What is negative phototropism?
Roots grow down away from light or sun(roots)
What is positive phototropism?
Stem growth toward the light or sun(shoots)
What is another hormone that is released from plants during the summer?
Cytokinins where it promotes cell division shoot/root. It is works with auxin for plant growth. However, it counters apical dominance and lateral buds are promoted. In addition, it inhibits leaf senescence.
What hormone is released during the fall?
Ethelene. It promotes fruit ripening and inhibits shoot elongation(stops growth) and promotes lateral expansion. Also experiences senescence where the leaves die and are recycled. There is also the breakdown of chlorophyll and nutrients are stored away in the stems. In addition, it has leaf abscission.
What is senescence?
It means to “grow old” or deteriorate with age
What is leaf abscission in the fall?
It means to “cut away” or loss of leaves. In the fall weight of the leaf causes it to fall of and layers of cork are formed to prevent infections. There are also enzymes that hydrolyze cell walls at base of petiole
What is light detection?
The determining of passage of days/seasons. It can also detect the presence of light, direction, intensity, and color.
What do plants need for healthy development?
Red and blue light
What is phototropin?
The blue light photoreceptor that gives the plant the ability to see blue light. It also induces phototropism, opening of the stomata, and chloroplast movements. It also responded to changing light intensity. It is also used to optimize photosynthetic efficiency.
What is phytochrome?
The red light photoreceptor. It gives the plant the ability to detect red and far red light.
What are the two forms of phytochrome?
- Pr which reacts to red light.
- Pf reacts to far red light
What light is better for plants?
Red light>far red light.
Why is red light better to a plant?
It means there is good quality light. In seeds, it promotes seed germination and vertical growth. In adults, it inhibits vertical growth and promotes horizontal growth. Also, spreads out and increases surface area to capture more sunlight.
What happens where there is more red light?
Pr–>Pfr
What happens when there is more far red light than red light?
Pfr–>Pr
Why is far red light not good?
It means there is shade. For a seed, it inhibits germination and is better for the seed to wait. For an adult, it means to avoid the shade. This promotes growth to leave the shade and to grow taller to break to the top and get the light. Or it can also mean to grow wider to get out of the shadow.
What are the function of the circadian rhythm in plants?
It automates responses that are automatic and oscillate. This does not occur from any outside variables and occurs even during artificial light indoors.
What is the circadian rhythm in plants?
It is the their biological clock.
What do plants do during the night?
The sleep and lower their leaves for a cycle of 26 hours. They go back up during the day and can change if they are kept indoors.
How do plants set their circadian rhythm to 24 hours a day?
By reacting to its phytochrome. In the night, all Pfr is converted to Pr. During the day, the Pr is converted to Pfr. With this, the plant knows the morning has occurred and the first light has happened. As a results, plants will sleep 16 hours after dawn.
