Lecture 11: Plant Chemistry 1

Question 1

What do plants activate during the winter?

Answer 1

Abscisic acid(also dormin) that inhibits growth. In addition, it also closes the stomata to conserve water. It also promotes seed dormancy.

Question 2

What do plants activate during the spring?

Answer 2

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.

Question 3

What do plants release during the summer?

Answer 3

Auxin where it stimulates shoot/root elongation and fruit growth. In addition, also phototropism. Also establishes apical dominance and inhibits leaf abscission.

Question 4

What phototropism?

Answer 4

Growth in response to light.

Question 5

What is negative phototropism?

Answer 5

Roots grow down away from light or sun(roots)

Question 6

What is positive phototropism?

Answer 6

Stem growth toward the light or sun(shoots)

Question 7

What is another hormone that is released from plants during the summer?

Answer 7

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.

Question 8

What hormone is released during the fall?

Answer 8

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.

Question 9

What is senescence?

Answer 9

It means to “grow old” or deteriorate with age

Question 10

What is leaf abscission in the fall?

Answer 10

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

Question 11

What is light detection?

Answer 11

The determining of passage of days/seasons. It can also detect the presence of light, direction, intensity, and color.

Question 12

What do plants need for healthy development?

Answer 12

Red and blue light

Question 13

What is phototropin?

Answer 13

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.

Question 14

What is phytochrome?

Answer 14

The red light photoreceptor. It gives the plant the ability to detect red and far red light.

Question 15

What are the two forms of phytochrome?

Answer 15

1. Pr which reacts to red light.
2. Pf reacts to far red light

Question 16

What light is better for plants?

Answer 16

Red light>far red light.

Question 17

Why is red light better to a plant?

Answer 17

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.

Question 18

What happens where there is more red light?

Answer 18

Pr–>Pfr

Question 19

What happens when there is more far red light than red light?

Answer 19

Pfr–>Pr

Question 20

Why is far red light not good?

Answer 20

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.

Question 21

What are the function of the circadian rhythm in plants?

Answer 21

It automates responses that are automatic and oscillate. This does not occur from any outside variables and occurs even during artificial light indoors.

Question 21

What is the circadian rhythm in plants?

Answer 21

It is the their biological clock.

Question 22

What do plants do during the night?

Answer 22

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.

Question 23

How do plants set their circadian rhythm to 24 hours a day?

Answer 23

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.

Question 24

What is photoperiodism?

Answer 24

The ability to tell the seasonsor a response to it

Question 25

What is phenology?

Answer 25

The timing of seasonal events

Question 26

Why is photoperiodism and phenology important to plants?

Answer 26

It lets plants/flowers know when to produce them for when pollinators are present.

Question 27

What are spring/summer plants?

Answer 27

Long day plants where there is more than 14 hours of sunlight.

Question 28

What are some examples of spring/summer plants?

Answer 28

Radish, lettuce, iris, cereals

Question 29

What are the stimulus of spring/summer plants?

Answer 29

Short nights where there are less than 8 hours of darkness

Question 30

What are fall/winter plants?

Answer 30

Short day plants where there are less than 14 hours of sunlight.

Question 31

What are examples of fall/winter plants?

Answer 31

Chrysanthemum, poinsettia, soybean

Question 32

What is the stimulus of fall/winter plants?

Answer 32

Long nights of more than 8 hours of darkness

Question 33

What is gravitropism?

Answer 33

When plants respond to gravity

Question 34

What is negative gravitropism?

Answer 34

When the plant is against gravity.

Question 35

What is an example of negative gravitropism?

Answer 35

The stem that is going up rather than down

Question 36

What is positive gravitropism?

Answer 36

When the plant is going toward gravity.

Question 37

What is an example of positive gravitropism?

Answer 37

The roots where they are going down with gravity

Question 38

What are statoliths?

Answer 38

Specialized organelle in plants that tell them about gravity. They contain dense starch grains where they settle to the bottom of cell because of gravity.

Question 39

What is thigmotropism?

Answer 39

The plants response to touch

Question 40

What does thigma mean?

Answer 40

touch

Question 41

What is an example of thigmotropism?

Answer 41

Trees that grow stocky(wider) because of the wind. Also similar to vine tendrils that coil around when they find support. Also, a venus fly trap that feels prey. Another example, are touch-me-not where they close their leaves when touched

Question 42

What is an action potential in plants?

Answer 42

A nerve impulse response that sends electrical signals to the plants.

Question 43

How are action potentials used in plants?

Answer 43

When they feel attacked and they alarm other leaves to prepare for when an herbivore attacks again.

Question 44

Can plants hear?

Answer 44

Yes through sound vibrations like humans but instead it is their trichomes.

Question 45

How do plants communicate?

Answer 45

Plants communicate through volatile organic compound (VOC) where they release gas that diffuses in the air and warns neighboring plants of herbivores.

Question 46

How do plants have friends?

Answer 46

Through a shared root system where plants share nutrients. Example is the New Zealand stump that is cut and is alive because of the sharing of resources from its friends.