Plants Response To Internal And External Signals

Question 1

Exogenous signal

Answer 1

A signal coming from outside the body such as light

Question 2

Endogenous signal

Answer 2

A chemical signal within the body

Can be hormones or neurotransmitters

Question 3

What did Darwin notice with plants ( what was his experiment)

Answer 3

That they bend towards light

This led to the question of what pet was responsible in bending the plant towards the light. They thought the tip so the cut it off. To further support they put an opaque cap that covered light and the plant didn’t respond. To go even further they got a translucent cap and the plant did bend. Adding a collar to the middle of the plant didn’t prevent the bending either further supporting the tip of the plant causing the bend

Question 4

Boysen jenson experiment

Answer 4

Used gelatin slaps because it’s not solid so molecules can diffuse through it. They tested if the tip senses the light and then sends a signal in the form of a molecule to the other part of the plant. They cut the tip off and put a slap of gelatin between stock and tip and put it back in place. Even though tip was removed the stem still bender towards the light further supporting the tip sensing the light for the bend. Solid mica slab was also used in the same way and no bending occurred so it is most likely molecular signal.

Question 5

Signal transduction

Answer 5

Tone signal get converted in another signal. Light to plant that causes the plant to release a signal to bend

Question 6

Agar cubes allowed for

Answer 6

The plant tip to be put on and left for a while so the molecule could be absorbed and then the agar cube was put on to the cut stem and the plant still bent without its tip.

Question 7

What are chemical signals

Answer 7

Just molecules

They have no effect unless there is a specific receptor where a chemical signal can bind

Question 8

How are chemical signal categorized

What are the ones in humans

Answer 8

How they work

Hormones

and neurotransmitters

Question 9

Neurotransmitters

Answer 9

They work locally ( cell to cell) and release by Newton’s and work right next to that

Question 10

Hormones

Answer 10

Work through the bloodstream to broadcast a signal.

Question 11

What kinds of molecules are receptors

Answer 11

Proteins

Question 12

Auxin (IAA)

Answer 12

First hormone discovered
(Indolasedic acid)

Growth hormone -stem elongation from low concentration only(

Promotes lateral and adventitious roots

Enhances apical dominance

Rudimentary releases and the receptor turns on a proton pump that pumps proton near cell wall make the fluid on the outside more acidic. Acidity promotes enzymes that clip parts of the cell way but only happens on the sides and not the ends so stretches for stem elongation

Question 13

Does how much of a hormone matter to the effect

Answer 13

Yes certain concentration of the same hormone can do different or opposite things. Can do different things to the body possibly based on the receptor

Question 14

Cytokinins

Answer 14

Plant hormone

Regulate cell division In Roots and shoots

Question 15

Gibberelellins

Answer 15

Stimulates growth and fruit growth

Used to make grapes way bigger without molding by also growing the stems

Can cause booting in certain kinds of species and stem elongation

In seeds these chemical signal is release by the endosperm and reaches the aluerone cells that respond to the chemical and make amylase which break down glucose to break down starch in the embryo to feed the embryo

Question 16

Brassinosteroids

Answer 16

Phytosterol.

At high concentrations they inhibit root growth and at low concentration they promote root growth

Question 17

What are the major steroid hormones in humans

Answer 17

Sex hormones

Initial steroid that gets modified and turns into something else is cholesterol

Question 18

What get slightly modified in animals regarding their steroids

Answer 18

Cholesterol is the base of all steroids

Question 19

For plants what is the base of their steroids

Answer 19

Phytosterol

Question 20

Abscisic Avis (ABA)

Answer 20

Named for the process of abscission which is the loss of leaves.

But doesn’t cause leaves to fail so misnomer

Inhibits growth
Stomata closure
Promote leaf senescence or aging

Question 21

Ethylene

Answer 21

Responsible for the ripening of fruit

Question 22

Bolting In plate is what

Answer 22

Very rapid growth

Question 23

What tells seeds to germinate

Answer 23

A sufficient amount of water. Which is an exogenous signal

Question 24

What is starch made out of

Answer 24

Glucose

Question 25

Ethylene controlls the

Answer 25

Triple response

Question 26

What are the triple responses

Answer 26

The root slows down its lengthening and get wider. The root is shoot with start growing horizontally for a while and will then grow down if a root if it can These are cause by ethylene

Question 27

Constitutive triple response

Answer 27

Always turned on gene Turn a gene on when it shouldn’t always be on so can cause a root or shoot to think ethylene is there are will always undergo triple response

Question 28

Abscission is caused by how many hormones

Answer 28

Two Ethylene and Auxin

Question 29

Abscission

Answer 29

Ethylene Auxin ratio causes it Leaf produces auxin and stem produces ethylene Petiole has a ratio Leaf my produce less auxin and the and the same ethylene by the stem so the ratio gets bigger cause the leaf to gradually fall off

Question 30

Photomorphogenesis

Answer 30

The bringing about a change in shape in response to light. This is what happens in potatoes. If you put them in light they will sprout green leaves and stems but In dark they grow white stout stems because it thinks its growing through the ground in the dark

Question 31

Blue light receptors

Answer 31

Responds to blue light

Question 32

Phytochrome’s

Answer 32

Responds to red light or red light receptors Can cause a seed to germinate but if far red light( light past red we can see) is shined onto a seed then the seed will not germinate. Only if you shine the red light again without the far red after will it germinate. The receptors act as light switches for germination It is a protein, operates based on its shape or conformation. One shape that is for red light is called Pr and Pfr shape is for far red light Shinning light on Pr will change its shape to Pfr and viceversa

Question 33

Tropism ( phototropsim

Answer 33

Refers to a response to a signal so phototropism means response to light

Question 34

Circadian rhythms

Answer 34

Built in clocks in rhythms that are not exactly a day per day clock. Organisms reset their clocks so they are exactly 24 hours Plants use light to reset

Question 35

Circanual rhythms

Answer 35

Animals have these sometime for mating seasons. Plants need these to know what time of year it is. Phytocromes also reset these life through the presence of light and how long it light or dark

Question 36

Angiosperms can be classified based on their flowers that move

Answer 36

Short day or long night plants Unless night is long enough the plant will produce a flower Long day plants and short night plants Won’t produce a flower unless night is short. They can be fooled by a blast of light by either thinking there is 2 short night so will produce or not produce flowers based on what type of response they have

Question 37

Gravitropism

Answer 37

A response to gravity Roots that response to this are positive tropism

Question 38

Positive and negative tropism

Answer 38

The response to that stimulus is towards that stimulus - positive The response to the stimulus is away from it -negative

Question 39

How do roots sense gravity

Answer 39

Statoliths - is a little gradual of densely packed starch that is there to make the statolith dense so it’s heavier than its surrounding. It falls to the bottom of the cell and wherever it lands tells the cell that is down. Can tell plant where to drop roots and shoots

Question 40

Otoliths in humans

Answer 40

Little sand like particles in our ears that are responsible for telling our brain what position our head is in space.

Question 41

Thigmatopism

Answer 41

Is the response to touch Leaflets that fold up on a certain plant

Question 42

Electrochemical signals used in organism are called

Answer 42

Used in neurons and muscle cells are called action potentials. Voltage signals because they vary ions which have charge Very fast in animals but not as fast in plants

Question 43

Drought is a

Answer 43

Environmental stressor. Plants deal with this by producing abscisic acid because they control the opening and closing of stomata

Question 44

Saturated fatty acids don’t have any

Answer 44

Bends in them Unsaturated fates have bend in them and can loosen up sell membrane allowing them to live in cold places