Plant Control Systems

Question 1

What causes external stimuli?

Answer 1

environmental cues

Question 2

What causes internal stimuli?

Answer 2

growth regulators

Question 3

What are the three steps when stimuli is detected?

Answer 3

Reception, Transduction, Response

Question 4

What is the definition of Etiolation

Answer 4

Energy allocation for growth in the dark

Question 5

What is the definition of De-Etiolation

Answer 5

When plants grown in the dark reach the light

Question 6

What is an example of a stimuli reacting process?

Answer 6

Photoreception

Question 7

In which stimuli step does phytochrome, a blue-green pigment found in many plants, in which it regulates various developmental processes, detect light?

Answer 7

Reception

Question 8

What is a Protein Kinase?

Answer 8

They are enzymes that regulate the biological activity of proteins

Question 9

During the Signal Transduction stage of Photoreception, what events occur?

Answer 9

Cyclic GMP and Calcium activate protein kinase, which become transcription factors.

Question 10

What is the response in Photoreception?

Answer 10

Plants greening- so De-Etiolation

Question 11

What are other response(s) to stimuli?

Answer 11

Mechanical

Question 12

What are the two types of mechanical stimuli? Give examples to both

Answer 12

Chronic
-Thigmomorphogenesis: response to touch, like wind
Acute
-Mimosa pudica: rapid leaf movements

Question 13

When herbivory occurs on a plant, what can a physical response be?

Answer 13

Spikes- like on a cactus

Question 14

How can plants respond to herbivory chemically?

Answer 14

They can release a chemical to attract predators to the organism eating it.

Question 15

How does predator recruitment work?

Answer 15

The plant is injured, which leads to signal transduction. The plant then releases a chemical to attract a predator (example: parasitic wasp) to lay its egg in the organism eating the plant (example: caterpillar)

Question 16

What is plant immunity?

Answer 16

Protection against pathogens

Question 17

What will bacteria/viruses often release in plant immunity?

Answer 17

Effector proteins

Question 18

R-proteins are another term for effector proteins- What creates them/ what is their function?

Answer 18

genes in plant genomes that convey plant disease resistance against pathogens by producing R proteins.

Question 19

In an infected leaf, what happens in the signal transduction phase?

Answer 19

Systematic signalling molecules are released.

Question 20

As the signalling molecules travel around the infected leaf’s plant, what do they do?

Answer 20

Induce signal transduction in other leaves.

Question 21

What type of stimuli response occurs in an infected leaf?

Answer 21

Acquired Resistance

Question 22

What are plant hormones?

Answer 22

long-term responses mediated by chemical signals

Question 23

Plant hormones are created in what area?

Answer 23

Active Growth Region

Question 24

What are the different kinds of plant hormones?

Answer 24

Auxin (Indolacetic Acid, IAA)
Cytokinins 
Gibberellins (GAs)  
Abscisic acid 
Ethylene

Question 25

What are the propertie(s) of plant hormones?

Answer 25

Concentration dependent Synergy Pleiotropy Redundancy

Question 26

What plant hormone property will have one gene code and control the phenotype or expression of several different and unrelated traits

Answer 26

Pleiotropy

Question 27

What is the definition of synergy?

Answer 27

interaction of biological structures or substances that produce an overall effect greater than the sum of individual effects

Question 28

The rate and extent of microorganism killing are a function of the antimicrobial concentration and are dependent on what?

Answer 28

Whether or not the concentration increases or decreases, therefore being concentration dependent

Question 29

What is the definition of redundancy?

Answer 29

Redundancy is when a given biochemical function is redundantly encoded by two or more genes

Question 30

What is the purpose of Auxin? Where is it produced?

Answer 30

To promote cell elongation. It is produced in the Shoot Apical Meristems, Root Apical Meristem and Leaf Primoridia.

Question 31

What are some other function(s) of auxin?

Answer 31

Growth Response (cell elongation), pattern development and promoting lateral roots

Question 32

There are two types of growth responses produced by auxin- what are they and what do they do?

Answer 32

Phototropism- when plant grows either towards (positive) or away (negative) from a source of light Gravitropism- differential growth in response to the force of gravity

Question 33

There are two types of pattern development produced by auxin- what are they and what do they do?

Answer 33

Branching Pattern- the way branching appears in positions along the bearing axis, the way branching appears over time and for rhythmic growth, the way it is distributed in growth units. Phyllotaxy- arrangement of leaves on an axis or stem

Question 34

What is the Acid-Growth Hypothesis?

Answer 34

The Acid-Growth Hypothesis is the ability of plant cells and plant cell walls to elongate or expand quickly at a low ph.

Question 35

During the process the Acid-Growth Hypothesis refers to, what is the membrane pumping?

Answer 35

Protons

Question 36

After the acidification of the cell walls during the cell elongation, what is activated? What does this do to the microfirbrils in the cell wall?

Answer 36

Expansion is activated, leading to the separation of microfibrils.

Question 37

During cell elongation what enzyme is activated after the expansion of the plant cells? What is cleaved during this process?

Answer 37

The wall enzyme is activated, leading to the cleavage of the crosslinked polysaccharides.

Question 38

What step in cell elongation follows the activation of the wall enzyme?

Answer 38

The cell wall loosens.

Question 39

True or False: During cell elongation the wall pressure is greater than the turgor pressure.

Answer 39

False: During cell elongation the wall pressure is less than the turgor pressure.

Question 40

Auxin plays a large part in the process of phototropism- when the plant is orientated towards the sun, does this mean the shoots are positive or negative?

Answer 40

Positive

Question 41

In the phototropism of grasses, what part of the grass does the auxin affect?

Answer 41

The shoot apical meristem

Question 42

During auxin redistribution, which lateral side does the auxin travel to?

Answer 42

The auxin travels to the darker side of the plant- the part of the plant exposed to less light.

Question 43

During phototropism a plant appears to bend towards the light source- how does auxin contribute to this? Is the plant actually bending towards the light?

Answer 43

The plant is not actually bending towards the light. As the auxin redistributes to the dark of the plant, it causes those cells to elongate. This leads to unequal cell elongation in the plant, making the stem bend away from the elongated cells, and therefore towards the light source.

Question 44

True or False: During gravitropism the shoot is both positive and negative.

Answer 44

True

Question 45

The root cap of plants contains statoliths- what is its function?

Answer 45

Statoliths stimulates sensory receptors in response to gravity, to enable balance and orientation in the plant

Question 46

In a horizontal shoot, during gravitropism, statoliths will settle- what does this do to the plant cells cytoskeleton?

Answer 46

The cytoskeleton will become distorted

Question 47

Where will the auxin redistribute in gravitropism?

Answer 47

Downwards into the root

Question 48

In gravitropism what does auxin do to the root and shoot growth? Why does it do this?

Answer 48

Auxin inhibits root elongation, and instead encourages the growth of adventitious roots. It has the opposite effect on shoots, and makes it grow upwards. It does this to give the plant a good support system.

Question 49

What is the purpose of Cytokinins? Where is it produced?

Answer 49

The function of cytokinins is to stimulate cell division. It is produced in the root apical meristem, embryos and fruits.

Question 50

Give an example of where Cytokinin stimulates cell division.

Answer 50

Stimulates cell division in places like the meristem.

Question 51

What is a callus?

Answer 51

Crowing mass of unorganized plant Parenchyma cells. In living plants, callus cells are those cells that cover a plant wound.

Question 52

In the cytokinin:auxin ratio, what occurs when there is more cytokinins?

Answer 52

Shoot development

Question 53

In the cytokinin:auxin ratio, what occurs when there is more auxin?

Answer 53

Root development

Question 54

What is apical dominance?

Answer 54

The balance of two hormones.

Question 55

What gradient is produced in the terminal buds?

Answer 55

Auxin gradient

Question 56

What gradient is produced in the roots?

Answer 56

Cytokinin gradient

Question 57

What does the removal of the shoot apical meristem do?

Answer 57

Activate the axillary buds

Question 58

What will happen if you add auxin to a cut stem? What does it promote?

Answer 58

The stem will initiate roots at the cut. This promotes fruit growth

Question 59

What is the purpose of Gibberellins? Where is it produced?

Answer 59

It's purpose is to stimulate the growth of fruit, stem elongation and germination. It's produced in roots and young leaves

Question 60

How does gibberellins stimulate the stem and leaf growht? Give an example.

Answer 60

It loosens the cell wall. An example would be foolish rice and bolting cabbage.

Question 61

During germination, gibberellin imbibes the seed, making it break its dormancy. What does it mean to 'imbibe the seed'?

Answer 61

Uptake of water by dry seed is called imbibition (imbibition means to drink). The first part of the seedling to emerge from the seed coat is the root, or radical.

Question 62

During germination what produces gibberellin?

Answer 62

The embryo

Question 63

The gibberellin will travel to the aleurone. What is its function?

Answer 63

The aleurone stores protein as granules in plant seeds.

Question 64

What does the aleurone produce during germination? What does this product do?

Answer 64

The aleurone releases amylase to break down starch.

Question 65

What is the function of Abscisic Acid?

Answer 65

To slow growth

Question 66

How does abscisic acid affect seed dormancy?

Answer 66

It will wash out imbibition, and slow down embryo development.

Question 67

How does abscisic acid play a part in drought tolerance?

Answer 67

It closes the stomata and opens up the guard cells to accept potassium ions.

Question 68

What is the purpose of ethylene? Where is it found?

Answer 68

In response to stress it becomes a gaseous growth regulator. It is found in coal gas and is also produced by fruit.

Question 69

What kind of stress does ethylene respond to? What is it induced by?

Answer 69

It responds to drought, physical pressure, or injury. It is induced by auxin.

Question 70

Ethylene can also cause Senescence- what is this?

Answer 70

Programmed death

Question 71

What hormone does ethylene balance with in senescence?

Answer 71

Auxin

Question 72

In senescence ions are reclaimed- where are they found?

Answer 72

The leaves

Question 73

What does an auxin concentration exposed to ethylene lead to in senescence?

Answer 73

Cell wall break down

Question 74

What can cell wall break down lead to in senescence?

Answer 74

Leaf scars

Question 75

What does ethylene do in response to mechanical stress? Where is it produced?

Answer 75

It does something called triple response, which protects seedlings from getting damaged during germination. Its produced in the root tip.

Question 76

What morphological changes can a plant undergo when effected by ethylene under mechanical stress? What is it dependent on?

Answer 76

Obstacle avoidance- it is concentration dependent

Question 77

True or False: ethylene is produced by rotting fruit.

Answer 77

False: ethylene is produced by ripening fruit.

Question 78

What does ethylene effect in ripening fruit?

Answer 78

Cellulose, Starches, Scents and Colours

Question 79

Ethylene leads to ripening, as ripening leads to ___.

Answer 79

Ethylene