Cell Communication Flashcards
(285 cards)
1
Q
What is favored in hot dry environments?
A
Phosphorus and photorespiration
This refers to the metabolic processes that are enhanced under such environmental conditions.
2
Q
What happens to the stomata in a C4 plant during the day?
A
The stomata are closed
This adaptation helps reduce water loss in hot environments.
3
Q
What occurs during the decarboxylation of the C4 acid?
A
Decarboxylation occurs during the day
This process is part of the C4 photosynthetic pathway.
4
Q
What is the first reaction of the Calvin cycle?
A
Combining CO2 with ribulose bisphosphate (RuBP)
This reaction is a carboxylation reaction.
5
Q
What is consumed during the reduction phase of the Calvin cycle?
A
NADPH produced from the light reactions
NADPH is crucial for the reduction of 3-phosphoglycerate to glyceraldehyde-3-phosphate.
6
Q
What should students do to estimate their grades?
A
Conduct a what-if analysis on Canvas
This allows students to input potential grades and see their impact on overall performance.
7
Q
How many points is the lab presentation assignment worth?
A
50 points
This is a separate assignment focused on presenting research.
8
Q
What is important to consider when selecting a gene for the lab presentation?
A
The gene must be relevant to the capabilities of Arabidopsis
Arabidopsis may not express certain traits, such as tuber formation.
9
Q
What types of proteins should be described in the lab presentation?
A
Three different types of proteins involved in the process
These can include enzymes, receptors, and structural proteins.
10
Q
What is the common name for Arabidopsis?
A
Thale crest
This name reflects its scientific classification.
11
Q
What does AGI stand for in the context of Arabidopsis?
A
Arabidopsis Genome Initiative
AGI numbers help identify genes within the Arabidopsis genome.
12
Q
What is the primary focus of the 2010 Project in plant biology?
A
To describe the function of every gene in Arabidopsis by 2010
Although it was an ambitious project, many genes remain uncharacterized.
13
Q
Fill in the blank: Phytochrome is involved in _______.
A
light signaling
Phytochromes are photoreceptors that regulate plant responses to light.
14
Q
What role does ethylene play in plants?
A
It is involved in ripening, defense responses, and programmed cell death
Ethylene is a key plant hormone with multiple roles.
15
Q
True or False: Arabidopsis can form tubers.
A
False
Arabidopsis is not capable of tuber formation.
16
Q
What should students do with their lab notebooks throughout the semester?
A
Keep them updated regularly
This practice is essential for maintaining accurate records and earning full credit.
17
Q
What is the main purpose of the Arabidopsis information resource?
A
To curate the Arabidopsis genome
This resource provides up-to-date genetic information and annotations.
18
Q
What type of information can be found on the Thale Nine website?
A
Genomic and protein information
This includes gene annotations, publications, and expression patterns.
19
Q
What is the significance of understanding cell signaling in plant roots?
A
It establishes patterns in growth and development
Cell signaling allows plants to respond to environmental cues and neighboring cells.
20
Q
What happens if a plant is overstimulated by touch?
A
It may stunt growth
Plants can misinterpret repeated touch as an attack by herbivores.
21
Q
What is the process by which a cell receives a signal and converts it into a response?
A
Signal transduction
Signal transduction involves the perception of a signal and the resulting change in cell behavior.
22
Q
What are the three main stages of a signal transduction pathway?
A
- Reception (perception)
- Transduction
- Response
23
Q
What is the role of receptors in signal transduction?
A
Receptors sense the signal and initiate the response
Receptors can be located on the cell surface or inside the cell.
24
Q
What is a primary messenger?
A
A molecule that initiates the signal transduction process
25
What are second messengers in the context of signal transduction?
Small molecules that amplify and distribute the signal within the cell
26
What type of response is characterized by a quick activation of existing proteins?
Fast response
27
What type of response requires the synthesis of new proteins and is typically slower?
Slow response
28
What is one example of a fast response in signal transduction?
Neural impulse transmission
29
What is the function of effector proteins in signal transduction?
They execute the change in cell behavior
30
What is phosphorylation in the context of signal transduction?
The addition of a phosphate group to a protein to activate or deactivate it
31
What enzyme is responsible for adding phosphate groups during phosphorylation?
Kinase
32
What enzyme removes phosphate groups from proteins?
Phosphatase
33
What is the role of G proteins in signal transduction?
They act as molecular switches that relay signals by binding GTP or GDP
34
What happens when a G protein is bound to GTP?
The G protein is active and can relay the signal
35
What does the intrinsic GTPase activity of a G protein do?
Hydrolyzes GTP to GDP, turning the G protein off
36
Fill in the blank: A _______ is a signaling molecule that causes a change in cell behavior.
[signal]
37
What is the significance of the cellular response to seasonal cues for plants?
It helps plants adapt to changes in their environment
38
True or False: All receptors in plants are located on the cell surface.
False
39
What is the difference between extracellular and intracellular receptors?
Extracellular receptors are on the cell surface, while intracellular receptors are inside the cell
40
What are soluble receptors typically associated with?
Signals that can easily enter the cell, such as steroid hormones
41
What is the consequence of improper communication in cell signaling?
It can lead to diseases such as cancer or diabetes
42
What is the purpose of molecular switches in signaling pathways?
To toggle responses on and off
43
What type of molecules do soluble receptors typically perceive?
Small non-polar molecules
## Footnote
Examples include steroid hormones like estrogen.
44
What is the starting material for all steroid hormones?
Cholesterol
## Footnote
Cholesterol is also a steroid itself.
45
What role do transcription factors play in hormone signaling?
They activate transcription in response to hormone binding.
46
Where are soluble receptors typically located?
In the cytoplasm or nucleus.
47
What type of receptors are associated with the cell membrane?
Cell surface receptors.
48
What are the three broad classes of cell surface receptors?
1. G protein-coupled receptors
2. Enzyme-coupled receptors
3. Gated channels
49
What is the process of opening and closing channels called?
Gating.
50
What initiates the activation of G protein-coupled receptors?
The binding of a signal molecule.
51
What happens to GDP when a G protein is activated?
It is replaced by GTP.
52
What structure do all G protein-coupled receptors have?
Seven transmembrane alpha helices.
53
What type of enzyme is typically associated with enzyme-coupled receptors?
A protein kinase.
54
What amino acid is commonly phosphorylated by enzyme-coupled receptors?
Tyrosine.
55
What is the primary messenger in the epinephrine pathway?
Epinephrine.
56
What is the outcome of epinephrine binding to its receptor in the liver?
Release of glucose into the bloodstream.
57
What do second messengers do in a signaling pathway?
Amplify the signal and propagate cellular responses.
58
Name a common second messenger in signaling pathways.
Cyclic AMP.
59
What is the function of phosphodiesterase in relation to cyclic AMP?
Breaks down cyclic AMP.
60
What happens to inositol lipids during signaling?
They are cleaved to produce second messengers.
61
What is a key characteristic of calcium as a signaling molecule?
It is kept at low concentrations in the cytosol.
62
What do reactive oxygen species signal in the cell?
They can signal responses to pathogens and fortify the cell wall.
63
What effect does calcium influx have in a signaling pathway?
It can change cellular activity based on concentration.
64
What happens to calcium levels in response to a signal in cells?
Calcium levels flood into the cytoplasm from compartments like the apoplast, smooth ER, and vacuole
## Footnote
This influx is crucial for the cell to interpret the signal and respond appropriately.
65
What role do second messengers play in calcium signaling?
They propagate responses by activating proteins that amplify the original signal
## Footnote
Examples of second messengers include diacyl glyceride and calcium.
66
How do cells maintain calcium concentrations in the cytoplasm?
Calcium concentrations are kept low through pumps that move calcium into compartments
## Footnote
These compartments include the apoplast, smooth ER, and vacuole.
67
What is the significance of calcium in egg fertilization?
A flood of calcium occurs when a sperm enters the egg cell, preventing further sperm entry
## Footnote
This change alters the extracellular matrix to protect the egg from multiple fertilizations.
68
What technological advancement has aided in the visualization of calcium concentrations?
Fluorescent proteins that change colors with different calcium concentrations
## Footnote
This has enhanced understanding of calcium as a signaling molecule.
69
What is the role of glutamic acid in plant response to wounding?
It acts as a neurotransmitter that triggers calcium-based signals in response to damage
## Footnote
This signal travels quickly through the plant's vascular system.
70
How does calcium signaling help plants communicate danger?
Calcium waves activate defense hormones in response to stimuli like insect bites
## Footnote
This signaling allows plants to prepare for impending threats.
71
What are phytohormones?
Plant hormones that regulate various biological processes including growth and defense
## Footnote
Examples include auxin, cytokinin, abscisic acid, and jasmonic acid.
72
What is the difference between cytokinin and cytokines?
Cytokinins are plant hormones, while cytokines are inflammatory proteins in animals
## Footnote
They play different roles in their respective organisms.
73
What is dormancy in seeds?
A state during which seeds do not germinate despite favorable conditions
## Footnote
Hormones play a crucial role in regulating this state.
74
Where are some hormones synthesized and how do they travel?
Some hormones are synthesized locally, while others like abscisic acid are transported long distances through the xylem
## Footnote
Transport mechanisms are vital for hormone functionality.
75
What type of receptors do plant hormones utilize?
Hormones have cell surface receptors, soluble receptors in the cytoplasm, or nuclear receptors
## Footnote
Different hormones have different receptor locations, affecting their actions.
76
How do transcription factors relate to hormone signaling?
Transcription factors can activate or repress gene expression in response to hormones
## Footnote
Hormones like jasmonic acid interact with these factors to regulate defense signaling.
77
What is phototropism?
Directional growth of plants towards a light source
## Footnote
It is a classic example of how plants respond to environmental stimuli.
78
What discovery did Darwin make regarding phototropism?
The tip of the coleoptile perceives light and sends a signal to the base for directional growth
## Footnote
This was a fundamental insight into plant behavior.
79
What is the significance of the coleoptile in plant growth?
It is a protective sheath that allows seedlings to bend towards light
## Footnote
The coleoptile's sensitivity to light is crucial for optimal growth.
80
What experiment distinguished the chemical nature of the signal in phototropism?
Experiments used gelatin and other materials to test the movement of the signal from the tip to the base
## Footnote
The results indicated a water-soluble substance was responsible for the growth response.
81
What is a characteristic of butter in relation to hydrophilic substances?
It is a fat that blocks hydrophilic substances but allows passage of lipids and hydrophobic molecules.
82
What was the result observed when the control was exposed to light?
The control bent towards the light.
83
What happened to the tip that was reconnected with gelatin?
It bent towards the light.
84
What was observed when the connection was blocked?
There was no movement.
85
What is required for movement in the experiment described?
A water soluble connection between the tip and the base.
86
What causes elongation and bending in the plant?
Movement from the tip.
87
Fill in the blank: The side connected to the tip was the one that ______.
elongated.
88
What was the role of the signal in the shaded side of the plant?
It caused elongation.
89
In the follow-up experiments, what was done with the tips?
They were harvested and put on a jello block.
90
What was the purpose of placing the jello block off-center?
To cause bending to occur.
91
What is the chemical identified as auxin?
Indole-3-acetic acid (IAA).
92
What amino acid is auxin derived from?
Tryptophan.
93
What is the most common chemical form of auxin?
IAA.
94
What class of compounds chemically resembles auxin?
Auxins.
95
True or False: Auxin is involved in all aspects of plant growth and development.
True.
96
What happens to a mutant that cannot make or sense auxin?
It has a total lack of auxin and is dead.
97
Fill in the blank: Auxin is a ______ hormone required for plant survival.
required.
98
What is the primary reason for the proposed new student success fee?
The budget crisis in California affects funding for the university.
99
Who must approve the new student success fee?
The students must approve the fee.
100
What is the importance of student engagement in the fee approval process?
Students need to be informed and vote to express their opinions.
101
What are the three different sessions mentioned for student engagement?
Sessions to hear about the proposed fee and engage with administrators.
102
What must students do to complain about the fee?
Students must vote.
103
What topics were covered in the plant physiology class?
Hormones, light signaling, and measuring different hormone phenotypes.
104
What is auxin also known as?
Indole 3-acetic acid (IAA).
105
What are the key aspects that contribute to hormone physiology?
* Synthesis of the hormone
* Breakdown of the hormone
* Transport of the hormone
106
What is polar auxin transport?
Directional transport of auxin in plants.
107
What is the role of auxin in phototropism?
Auxin moves to the shaded side of a plant to promote elongation, causing curvature towards light.
108
What is etiolated growth?
Spindly growth of plants when grown in low light conditions.
109
What determines whether auxin is protonated or deprotonated?
The pH level of the environment.
110
What are influx carriers responsible for in auxin transport?
Moving the protonated form of auxin into cells.
111
What are efflux carriers responsible for in auxin transport?
Moving the deprotonated form of auxin out of cells.
112
What is the significance of PIN proteins?
They are efflux carriers that facilitate directional auxin transport.
113
How does auxin concentration affect stem cell identity in roots?
High auxin concentration maintains stem cell identity and promotes cell division.
114
What is the auxin receptor complex responsible for?
Bringing together auxin and transcription factors for signaling.
115
True or False: There are no auxinless plants.
True.
116
Fill in the blank: The discovery that auxin is involved in phototropism was confirmed in ______.
2006.
117
What happens to auxin levels when plants are exposed to light?
Auxin synthesis is turned off, leading to shorter stems.
118
What type of growth response does auxin facilitate?
Cell elongation and growth responses.
119
What role does the pH difference between the cell wall and cytoplasm play in auxin transport?
It influences whether auxin is protonated or deprotonated, affecting its movement.
120
What is the function of auxin binding protein 1 (ABP1)?
Initially thought to be an auxin receptor, but later debunked.
121
What are the two main types of proteins involved in auxin transport?
* Influx carriers
* Efflux carriers
122
What happens to transcription factors in the presence of auxin?
They are ubiquitinated and marked for degradation.
123
What are oxide A proteins?
Transcription factors involved in auxin response
124
What is the role of the receptor complex in auxin signaling?
Acts as a molecular glue to bring together auxin and transcription factors
125
What happens to transcription factors when auxin is present?
They become ubiquitinated and are sent for degradation
126
What is an ARF?
Auxin Response Factor, a transcription factor activated by auxin
127
How quickly can auxin responsive genes change in response to auxin?
Within three minutes
128
What is the main type of response to auxin?
Transcriptional response
129
What is the significance of auxin in plant biology?
It is a developmental hormone controlling cell growth and pattern formation
130
What is polar auxin transport?
The process that influences how auxin gradients are established in plants
131
What is phyllotaxy?
The arrangement of leaves on a stem dictated by auxin maxima
132
What initiates lateral root formation?
Auxin concentrations in specific cells near vascular tissue
133
What is a morphogen?
A hormone that exists over a gradient in tissue influencing developmental patterns
134
What is cytokinin's role in plant development?
Promotes cell division and differentiation, and is involved in leaf senescence
135
How does cytokinin differ from auxin in terms of transport?
Cytokinin is made locally where it acts, while auxin is transported
136
What happens when you add only auxin to plant tissue culture?
It results in root formation
137
What happens when you add only cytokinin to plant tissue culture?
It results in shoot formation
138
What is callus tissue?
Undifferentiated tissue that forms when auxin and cytokinin are imbalanced
139
What compound is cytokinin derived from?
Adenine nucleotide
140
What is crown gall disease?
A condition caused by Agrobacterium tumefaciens leading to tumor formation
141
How does Agrobacterium tumefaciens cause crown gall disease?
By inserting genes into the plant genome that hijack hormone biosynthesis
142
What are TI plasmids?
Tumor inducing plasmids that carry genes for auxin and cytokinin biosynthesis
143
What is the relationship between Agrobacterium and plant biotechnology?
Agrobacterium is used to create transgenic plants by inserting desired genes
144
How can you insert genes into plant genomes using Agrobacterium?
By engineering the TI plasmid to carry the gene of interest
145
What is the significance of auxin and cytokinin in tissue culture?
They are critical for regenerating plants without sexual reproduction
146
True or False: Auxin is responsible for leaf senescence.
False
147
Fill in the blank: Auxin is primarily involved in _______.
Transcriptional responses
148
What influences the pattern of leaf emergence in plants?
Auxin maxima in the shoot apical meristem
149
What is the role of agrobacteria in the production of GMOs?
Agrobacteria insert new genes into mesophyll cells of plants
## Footnote
This process is a fundamental method for creating genetically modified crops.
150
What is cytokinin primarily known for in plant biology?
Cytokinin is important for hormone biosynthesis and cell differentiation
## Footnote
A significant amount of knowledge about cytokinin biosynthesis comes from studying agrobacteria.
151
How does cytokinin differ from auxin in terms of transport mechanisms?
Cytokinin does not have a polar transport mechanism like auxin
## Footnote
Cytokinin is primarily synthesized where it acts.
152
What type of signal is a paracrine signal?
A paracrine signal is made locally and diffuses out to act
## Footnote
Cytokinin can act both locally and as a long-distance signal in plants.
153
What is the mechanism of cytokinin signaling in eukaryotes?
Cytokinin signaling involves a phosphorelay mechanism
## Footnote
This mechanism is unique to eukaryotes and does not exist in animals.
154
What type of plant tissue development is influenced by cytokinin?
Cytokinin is crucial for the development of xylem and phloem tissues
## Footnote
It affects how vascular tissue develops in plants.
155
What is phyllotaxy in the context of plant growth?
Phyllotaxy refers to the arrangement of leaves on a stem
## Footnote
Cytokinin influences the patterns of leaf emergence from the apical meristem.
156
What was the result of a mutant corn strain in relation to phyllotaxy?
The mutant corn exhibited opposite phyllotaxy instead of alternate leaves
## Footnote
This change was linked to alterations in cytokinin signaling.
157
What is a compound leaf?
A compound leaf consists of multiple leaflets attached to a single node
## Footnote
Tomato plants are an example of plants with compound leaves.
158
How does cytokinin affect leaf complexity?
Increased cytokinin leads to greater leaf complexity
## Footnote
Conversely, reduced cytokinin results in simpler leaf structures.
159
What is the relationship between cytokinin and auxin in plant development?
Cytokinin and auxin work together to regulate developmental patterns
## Footnote
They influence processes like lateral root development.
160
What types of tumors are caused by agrobacterium?
Agrobacterium can cause shooty and rooty tumors
## Footnote
These tumors are linked to excessive production of cytokinin and auxin.
161
What should students focus on for their presentations in plant physiology?
Students should ensure their presentations are relevant to plant physiology
## Footnote
Biochemistry topics unrelated to plant physiology are discouraged.
162
163
What types of kinases transfer phosphate from ATP and oxygen?
Cytokine, ethylene, and BR kinases
## Footnote
These kinases play a crucial role in plant signaling and development.
164
What is the significance of polar oxygen gradients in plants?
They are important for organ development
## Footnote
Gradients help in establishing various physiological processes in plants.
165
True or False: High concentrations of cytokinin cause plants to bend towards light.
True
## Footnote
This bending is a result of asymmetric growth driven by cytokinin.
166
What is the only gaseous plant hormone?
Ethylene
## Footnote
Ethylene has various physiological effects, including fruit ripening.
167
What physiological outcomes is ethylene important for?
* Food ripening
* Programmed cell death (senescence)
* Leaf drop in deciduous plants
## Footnote
Ethylene mediates these processes, which are critical for plant life cycles.
168
What is the 'triple response' in plants?
An adaptive response involving a short, thick stem with an exaggerated hook
## Footnote
This response helps seedlings push through obstacles in the soil.
169
What happens to a seedling when it grows in the dark?
It develops an elongated stem and a hook to push out of the soil
## Footnote
This is a survival mechanism to reach light.
170
Fill in the blank: Ethylene is involved in the _______ response during seedling establishment.
triple
## Footnote
The triple response includes changes in stem growth to adapt to environmental obstacles.
171
What is the effect of ethylene on root growth?
Ethylene inhibits growth and promotes senescence
## Footnote
It can also lead to increased root hair formation but fewer lateral roots.
172
What is the role of auxin in plant growth?
Auxin is the master regulator of growth
## Footnote
It works in conjunction with other hormones like cytokinin and ethylene.
173
True or False: Ethylene production is a byproduct of fruit ripening.
False
## Footnote
Ethylene is actually the cause of fruit ripening.
174
How does ethylene affect the apical meristem during seedling growth?
It protects the apical meristem by causing the stem to hook
## Footnote
This adaptation helps prevent damage as seedlings push through the soil.
175
What is the relationship between ethylene and auxin in tropisms?
They work together to generate asymmetric cell elongation
## Footnote
This is crucial for responses like phototropism and gravitropism.
176
What experimental technique is used to measure ethylene production?
Gas chromatography
## Footnote
This method allows for precise measurement of gas levels in plant tissues.
177
What happens when ethylene binds to its receptor?
It turns the receptor off and the response on
## Footnote
This is the opposite of typical signaling pathways.
178
What is the significance of Arabidopsis in plant physiology studies?
It serves as a genetic model for understanding hormone signaling
## Footnote
Many discoveries about plant hormones originated from studies using Arabidopsis.
179
Fill in the blank: The Arabidopsis mutants that do not respond to ethylene are known as _______.
ethylene insensitive (EIN)
## Footnote
These mutants help researchers understand ethylene signaling pathways.
180
What do seedlings need to sense for proper growth direction?
Gravity
## Footnote
Seedlings must know up from down to grow shoots upwards and roots downwards.
181
What chemical is involved in tropisms and asymmetric elongation?
Auxin
## Footnote
Auxin plays a crucial role in plant response to gravity.
182
What happens to roots when plants are positioned horizontally?
Roots curve downwards
## Footnote
Roots can sense gravity and will grow downwards, even from a horizontal position.
183
What is the role of ethylene in relation to auxin?
Ethylene inhibits curvature caused by auxin
## Footnote
Ethylene and auxin have an antagonistic relationship in regulating gravity responses.
184
What is senescence in plants?
The process of aging and decline in plant organs
## Footnote
This is especially evident in flower parts after fertilization.
185
What is the significance of ethylene production during flower development?
It increases as flower petals senesce
## Footnote
Ethylene production spikes as petals fall off after fertilization.
186
How can cut flowers be preserved for longer?
Using ethylene inhibitors
## Footnote
Horticulturists use compounds that inhibit ethylene to prolong the life of cut flowers.
187
What are the differences between unripened and ripened fruit?
Taste, texture, and sweetness
## Footnote
Ripened fruit is sweeter, softer, and more flavorful than unripened fruit.
188
What changes occur in cell walls during fruit ripening?
Cell wall modifications leading to softening
## Footnote
The transition from hard to soft fruit involves significant changes in cell wall structure.
189
What is post-harvest physiology?
The study of fruit physiology after harvesting
## Footnote
This field focuses on maintaining the quality of fruits before they reach consumers.
190
How are fruits often treated during shipping to ensure quality?
Picked green and treated with ethylene inhibitors
## Footnote
This process allows fruits to ripen at their destination without spoiling during transport.
191
What is jasmonic acid's role in plants?
Defense against herbivores and pathogens
## Footnote
JA is crucial for signaling responses to threats that might damage the plant.
192
What is the relationship between jasmonic acid and flower development?
JA is involved in flower and seed development
## Footnote
Jasmonic acid influences reproductive functions and fertility in plants.
193
What is the effect of jasmonic acid on herbivory?
It triggers defense responses in plants
## Footnote
JA is produced in response to physical damage or herbivore attacks.
194
What happens to transcription factors in the presence of jasmonic acid?
JAZ proteins are degraded, allowing gene expression
## Footnote
This degradation activates the plant's defense mechanisms.
195
What happens when plants are under stress from herbivores?
Energy is reallocated from growth to defense
## Footnote
Plants prioritize defense mechanisms over growth when facing threats.
196
What are the visual indicators of jasmonic acid signaling in plants?
Rapid degradation of JAZ proteins
## Footnote
This allows for a quick response to environmental signals.
197
What is JA important for in plants?
JA is really important for herbivory responses.
## Footnote
JA stands for jasmonic acid, which is a plant hormone involved in defense mechanisms.
198
What do proteinase inhibitors do?
Proteinase inhibitors inhibit the digestive enzymes in the gut of herbivorous insects.
## Footnote
They prevent the breakdown of proteins consumed by the insects, hindering their growth.
199
What is the role of abscisic acid (ABA) in plants?
ABA is a stress hormone involved in water balance, regulating guard cell biology, seed development, and response to abiotic stresses.
## Footnote
Abiotic stresses include water stress, osmotic stress, and heat stress.
200
Where is zeaxanthin primarily made?
Zeaxanthin is mostly made in plastids and the cytosol.
## Footnote
It is an accessory pigment and a precursor to ABA biosynthesis.
201
How does ABA affect guard cells?
ABA signals guard cells to close stomata, reducing transpiration and conserving water.
## Footnote
This is crucial for maintaining water balance in vascular plants.
202
True or False: ABA promotes germination in seeds.
False.
## Footnote
ABA inhibits germination while gibberellic acid promotes it.
203
What happens to ABA levels as seeds mature?
ABA accumulates as seeds dry down and protects them from desiccation.
## Footnote
As seeds become less dormant, ABA levels decrease.
204
What is the relationship between ABA and gibberellic acid (GA)?
ABA inhibits germination and dormancy, while GA promotes germination and inhibits dormancy.
## Footnote
They have antagonistic roles in seed development.
205
Fill in the blank: ABA is involved in _____ stress responses in plants.
abiotic
## Footnote
ABA plays a significant role in responding to various environmental stresses.
206
What is the effect of ABA on leaf temperature?
When stomata are open, transpiration cools the leaf surface.
## Footnote
High transpiration rates lead to lower leaf temperatures.
207
What is vivipary in the context of seeds?
Vivipary is premature germination of seeds.
## Footnote
It is often studied in corn genetics.
208
What do osmoprotectants do?
Osmoprotectants protect proteins from denaturing and DNA from oxidative stress.
## Footnote
Examples include sugars and proline.
209
How does ABA affect root development during water deficiency?
ABA reallocates energy towards root development when water is deficient.
## Footnote
This adaptation helps plants search for water sources.
210
What role do heat shock proteins play in plants?
Heat shock proteins protect other proteins from denaturing due to heat stress.
## Footnote
They are crucial for maintaining protein stability under stress conditions.
211
What are ABI mutants?
ABI mutants are ABA insensitive mutants that affect ABA signaling pathways.
## Footnote
These mutants were important in understanding ABA receptor functions.
212
What is the primary function of guard cells in plants?
Guard cells regulate the opening and closing of stomata.
## Footnote
This regulation is vital for gas exchange and water conservation.
213
What happens to protease activity when insects feed on plants with proteinase inhibitors?
Protease activity is inhibited, affecting the insect's digestion and growth.
## Footnote
This serves as a defense mechanism for the plant.
214
What is vivipary?
Premature germination of seeds
## Footnote
Vivipary occurs when seeds germinate while still attached to the parent plant, as seen in corn and tomatoes.
215
What happens to seeds in viviparous mutants?
They never dry down and immediately germinate
## Footnote
This phenomenon makes it challenging to collect and store seeds.
216
What is the role of gibberellic acid in plants?
Promotes elongation and is important for seed germination
## Footnote
Gibberellic acid has an antagonistic role with abscisic acid (ABA).
217
Where was brassinolide originally discovered?
In pollen
## Footnote
It was isolated from mustard pollen, leading to its classification as a brassinosteroid.
218
What is the relationship between brassinosteroids and cell elongation?
Brassinosteroids are involved in promoting cell elongation
## Footnote
They work together with auxin in growth pathways.
219
What is the significance of grafting in plant propagation?
It allows for the combination of different root systems and shoots
## Footnote
Grafting is commonly used for horticultural varieties to enhance hardiness.
220
What is the main difference between animal steroid hormone receptors and brassinosteroid receptors?
Brassinosteroid receptors are located at the cell surface
## Footnote
In contrast, animal steroid hormones typically have soluble receptors that act as transcription factors.
221
Fill in the blank: The hormone _______ is involved in the differentiation of vascular tissues.
brassinosteroid
222
True or False: Gibberellic acid is produced endogenously by most plant species.
True
223
What is the name of the fungus that causes foolish seedling disease in rice?
Gibberella fujikuroi
224
What are the characteristics of dwarf plants in relation to gibberellic acid?
They are GA deficient mutants
## Footnote
Mendel's experiments in the 1860s identified these dwarf mutants, which were later linked to GA deficiency.
225
What is the primary effect of gibberellic acid on plant growth?
It promotes stem elongation and influences flowering
## Footnote
Gibberellic acid is crucial during various developmental stages in plants.
226
Fill in the blank: The discovery of _______ was significant for agricultural advancements in wheat production.
GA-deficient varieties
227
What is the impact of brassenolide on the plant's response to light?
It plays a crucial role in how plants respond to light
## Footnote
Brassinosteroids influence physiological responses related to light exposure.
228
What happens to pollen tubes during germination?
They elongate to deliver sperm nuclei to the egg cells
## Footnote
This process is essential for successful fertilization in flowering plants.
229
What is the main goal of developing new varieties of agricultural plants like wheat?
To produce a lot of product with less waste.
230
Who introduced different wheat species that contributed to the green revolution?
Norman Borlaug.
231
What characteristic defines the semi-dwarf varieties of wheat developed during the green revolution?
They are GA insensitive dwarfs.
232
What does GA stand for in the context of plant biology?
Gibberellic acid.
233
How do GA deficient mutants appear?
They are dwarfy looking plants.
234
What is paclobutrazole and how does it function?
An herbicide that inhibits gibberellic acid biosynthesis.
235
What is the role of auxin in plant growth?
It is the only hormone transported in a polar way.
236
True or False: GA is transported in a polar way.
False.
237
What happens to GA deficient morphs when grafted onto wild type rootstocks?
They restore the phenotype.
238
What is the relationship between ABA and GA during seed germination?
They have an antagonistic relationship.
239
Fill in the blank: The embryo in a seed needs a source of energy before it can fully _______.
photosynthesize.
240
What enzyme is responsible for breaking down starch during seed germination?
Amylase.
241
What is the significance of gibberellic acid (GA) in seedling establishment?
It is important for breaking down starch into sugars for energy.
242
What environmental cues do plants use to determine flowering time?
Light and photoperiod.
243
What is phototropism?
The growth of plants in response to light direction.
244
How do blue light receptors affect plant growth?
They stimulate auxin synthesis and asymmetric elongation.
245
What are phototropins?
A type of blue light receptor that regulates phototropism.
246
What class of blue light receptors work in the cytoplasm and nucleus?
Cryptochromes.
247
Define fluence in the context of light.
The number of photons absorbed in a particular surface area over time.
248
True or False: Light behaves only as a particle.
False.
249
What is one of the applications of gibberellic acid in brewing?
To start the process of fermentation in barley.
250
What happens to chloroplasts in high light conditions?
They move out of the direct path of light to avoid damage.
251
What is the primary role of the endosperm during seed germination?
To store starch that is broken down into sugars for the embryo.
252
What is the relationship between seed dormancy and winter conditions?
Some seeds require winter conditions to break dormancy.
253
What happens when gibberellic acid is applied to long day plants in short day conditions?
It can induce flowering despite short day conditions.
254
What is micromoles?
A quantitative number representing an amount of something
## Footnote
Micromoles are often used in measuring the amount of photons absorbed onto a surface.
255
What does irradiance refer to?
The amount of energy associated with light
## Footnote
Energy depends on the wavelength, with shorter wavelengths having more energy.
256
How do plants respond to low fluence light?
They exhibit very dim light responses
## Footnote
These responses are primarily red light responses.
257
What is photoreversibility?
The ability of red light to promote germination and far red light to reverse it
## Footnote
This phenomenon was observed in seeds, such as lettuce seeds.
258
What is the action spectrum range for red light?
625 to 700 nanometers
## Footnote
Far red light ranges from 700 to 800 nanometers.
259
What is photomorphogenesis?
The developmental process where plants stop elongating and expand their leaves in response to light
## Footnote
This process is triggered by red light.
260
What are phytochromes?
The receptors for red light and far red light in plants
## Footnote
In Arabidopsis, there are five types: A, B, C, D, E.
261
What are the two physical forms of phytochromes?
PR form (inactive) and PFR form (active)
## Footnote
PR absorbs red light, while PFR absorbs far red light.
262
What is the significance of the ratio of PR to PFR forms?
It helps plants sense the brightness and duration of light
## Footnote
This ratio changes depending on the light conditions.
263
What is shade avoidance?
The growth response of plants to grow taller when shaded by neighbors
## Footnote
This adaptation helps plants compete for light.
264
What is photoperiodism?
The physiological response of plants to the length of day and night
## Footnote
Plants can sense seasonal changes based on photoperiod.
265
What are short day plants?
Plants that flower under short days and long nights
## Footnote
They complete their life cycle during periods of shorter daylight.
266
What are long day plants?
Plants that flower under long days and short nights
## Footnote
They typically bloom in the summer when days are longer.
267
What are day neutral plants?
Plants that can flower regardless of day length
## Footnote
These plants are commonly found near the equator where day and night lengths are consistent.
268
Fill in the blank: The units used to measure light intensity are called _______.
Einsteins
269
True or False: Plants are equally sensitive to both red and far red light.
False
## Footnote
Plants respond differently to these wavelengths, with red light promoting certain responses and far red light reversing them.
270
What are day neutral plants?
Plants that do not have a specific requirement for day length to flower or germinate.
## Footnote
They can flower under a wide range of day lengths.
271
Where on the planet is the amount of day and night the same year-round?
At the equator.
## Footnote
The equator experiences equal amounts of daylight and darkness throughout the year.
272
What is a long day plant?
A plant that requires long daylight hours to germinate or flower.
## Footnote
Example: Kopelberg, which requires 16 hours of sunlight.
273
What is the daylight requirement for tobacco plants?
12 hours of light.
## Footnote
Tobacco is classified as a short day plant.
274
In Winnipeg, Canada, how many hours of light are there in January?
8 hours of light.
## Footnote
This results in 16 hours of darkness during winter.
275
What unique light conditions do plants experience at the North Pole?
24 hours of light or 24 hours of darkness, depending on the season.
## Footnote
This phenomenon occurs during summer and winter solstices.
276
What is photoperiodism?
The response of plants to the lengths of day and night.
## Footnote
It affects flowering and other developmental processes.
277
What type of plant is a chrysanthemum?
A short day plant.
## Footnote
It flowers when the day length is about 10 hours.
278
What happens to a chrysanthemum when it receives a red light pulse at night?
It perceives the night as interrupted and does not flower.
## Footnote
This indicates how sensitive plants are to light interruptions.
279
What is the effect of far red light on a chrysanthemum after a red light pulse?
It can reverse the inhibition of flowering.
## Footnote
This allows the plant to flower as it perceives proper night conditions.
280
What environmental factor besides light influences plant development?
Temperature.
## Footnote
Seasonal temperature cues can affect flowering and dormancy.
281
What confusion can arise in plants due to temperature changes?
Plants may bud out or prepare to flower during unseasonably warm periods.
## Footnote
This can lead to frost damage if temperatures drop again.
282
What is the role of phytochrome in plants?
It is involved in sensing light and temperature.
## Footnote
Phytochrome helps regulate responses to environmental cues.
283
What happens to phytochrome distribution in response to light?
It concentrates in the nucleus.
## Footnote
This distribution is also influenced by temperature.
284
What is the consequence of having seasonal cues out of sync for plants?
It can lead to incorrect growth responses, such as premature flowering.
## Footnote
This misalignment can be detrimental to crops.
285
True or False: Irises are considered short day plants.
False.
## Footnote
Some species of irises are long day plants.
