Podcast
Questions and Answers
What is the primary function of auxins in plants?
What is the primary function of auxins in plants?
- Promoting cell elongation (correct)
- Inhibiting stem elongation
- Closing stomata during drought
- Promoting seed dormancy
Which hormone is often referred to as the 'stress hormone' in plants?
Which hormone is often referred to as the 'stress hormone' in plants?
- Gibberellin
- Cytokinin
- Auxin
- Abscisic Acid (ABA) (correct)
What role do gibberellins play in seed germination?
What role do gibberellins play in seed germination?
- Inhibiting germination under all conditions
- Maintaining seed dormancy
- Breaking seed dormancy and initiating germination (correct)
- Preventing the mobilization of stored nutrients
How do synthetic auxins help in weed control?
How do synthetic auxins help in weed control?
What is the primary function of abscisic acid (ABA) during drought conditions?
What is the primary function of abscisic acid (ABA) during drought conditions?
How do auxins contribute to phototropism in plants?
How do auxins contribute to phototropism in plants?
What is the role of tannins in plant defense?
What is the role of tannins in plant defense?
Which of the following best describes the function of phytoalexins?
Which of the following best describes the function of phytoalexins?
How do thorns, spines, and prickles protect plants?
How do thorns, spines, and prickles protect plants?
What is the primary difference between thorns and prickles?
What is the primary difference between thorns and prickles?
Which plant structure serves as a defense mechanism and also reduces water loss in arid environments?
Which plant structure serves as a defense mechanism and also reduces water loss in arid environments?
What triggers abscission (leaf drop) in plants during autumn?
What triggers abscission (leaf drop) in plants during autumn?
How do volatile organic compounds (VOCs) produced by some plants contribute to their defense?
How do volatile organic compounds (VOCs) produced by some plants contribute to their defense?
Auxins produced at the stem's tip inhibit the growth of lateral buds, ensuring the plant grows taller rather than wider. What is this phenomenon known as?
Auxins produced at the stem's tip inhibit the growth of lateral buds, ensuring the plant grows taller rather than wider. What is this phenomenon known as?
A cereal crop is being attacked by broadleaf weeds. Which hormone would be the MOST effective and selective to apply to the crop to remove the broadleaf weeds without damaging the cereal crop?
A cereal crop is being attacked by broadleaf weeds. Which hormone would be the MOST effective and selective to apply to the crop to remove the broadleaf weeds without damaging the cereal crop?
To develop a seedless fruit, which hormone would agricultural scientists MOST likely use?
To develop a seedless fruit, which hormone would agricultural scientists MOST likely use?
A plant is infected with a fungal pathogen. Which defensive response is MOST likely to occur?
A plant is infected with a fungal pathogen. Which defensive response is MOST likely to occur?
A plant physiologist discovers a mutant plant that is unable to produce abscisic acid (ABA). Which of the following is the MOST likely consequence?
A plant physiologist discovers a mutant plant that is unable to produce abscisic acid (ABA). Which of the following is the MOST likely consequence?
A botanist is studying a newly discovered desert plant with extremely reduced leaves and a high density of spines. What is the MOST likely explanation for these adaptations?
A botanist is studying a newly discovered desert plant with extremely reduced leaves and a high density of spines. What is the MOST likely explanation for these adaptations?
If a plant is genetically modified to overproduce alkaloids, which of the following ecological consequences is MOST likely to occur?
If a plant is genetically modified to overproduce alkaloids, which of the following ecological consequences is MOST likely to occur?
What is a key distinction between plant hormones and animal hormones in terms of their action?
What is a key distinction between plant hormones and animal hormones in terms of their action?
If the apical bud of a plant is removed, what is the MOST likely outcome due to altered auxin distribution?
If the apical bud of a plant is removed, what is the MOST likely outcome due to altered auxin distribution?
Which of the following agricultural applications is MOST directly related to the function of gibberellins?
Which of the following agricultural applications is MOST directly related to the function of gibberellins?
How does abscisic acid (ABA) help plants respond to water scarcity?
How does abscisic acid (ABA) help plants respond to water scarcity?
Why are synthetic auxins used as herbicides?
Why are synthetic auxins used as herbicides?
In phototropism, what causes a plant to bend towards a light source?
In phototropism, what causes a plant to bend towards a light source?
A plant is experimentally treated with a chemical that blocks the production of tannins. What is the MOST likely consequence?
A plant is experimentally treated with a chemical that blocks the production of tannins. What is the MOST likely consequence?
How do volatile organic compounds (VOCs) assist in plant defense?
How do volatile organic compounds (VOCs) assist in plant defense?
What is the evolutionary advantage of spines on desert plants?
What is the evolutionary advantage of spines on desert plants?
Which of the following is the MOST accurate distinction between thorns and spines as plant defense mechanisms?
Which of the following is the MOST accurate distinction between thorns and spines as plant defense mechanisms?
How do plants utilize tannins as a defense mechanism against herbivores?
How do plants utilize tannins as a defense mechanism against herbivores?
A researcher discovers a plant species that exhibits an unusually high concentration of alkaloids in its leaves. What inference can be made about this plant?
A researcher discovers a plant species that exhibits an unusually high concentration of alkaloids in its leaves. What inference can be made about this plant?
A plant is subjected to a prolonged drought. What hormonal change is MOST likely to occur?
A plant is subjected to a prolonged drought. What hormonal change is MOST likely to occur?
Which of the following plant structures offers protection by reducing water loss AND deterring herbivores?
Which of the following plant structures offers protection by reducing water loss AND deterring herbivores?
During autumn, what physiological process is directly influenced by increased levels of abscisic acid (ABA)?
During autumn, what physiological process is directly influenced by increased levels of abscisic acid (ABA)?
A botanist discovers a new plant species in a rainforest. The plant has no thorns, spines, or prickles, but it is almost never eaten by herbivores. What is the MOST likely defense mechanism this plant employs?
A botanist discovers a new plant species in a rainforest. The plant has no thorns, spines, or prickles, but it is almost never eaten by herbivores. What is the MOST likely defense mechanism this plant employs?
Plants use a variety of defense mechanisms against herbivores. Which of the following traits would offer simultaneous protection from both herbivory and excessive sunlight?
Plants use a variety of defense mechanisms against herbivores. Which of the following traits would offer simultaneous protection from both herbivory and excessive sunlight?
A plant is genetically engineered to have a perpetually high level of gibberellins. Which of the following environmental conditions would MOST challenge its survival?
A plant is genetically engineered to have a perpetually high level of gibberellins. Which of the following environmental conditions would MOST challenge its survival?
A species of grasshopper is able to digest tannins without any negative effects and preferentially feeds on plants rich in these compounds. What evolutionary pressure might these plants experience?
A species of grasshopper is able to digest tannins without any negative effects and preferentially feeds on plants rich in these compounds. What evolutionary pressure might these plants experience?
A research team discovers a plant virus that inhibits the production of phytoalexins in infected plants. What is the MOST likely consequence of this viral infection?
A research team discovers a plant virus that inhibits the production of phytoalexins in infected plants. What is the MOST likely consequence of this viral infection?
What is the MOST direct effect of auxins on cell walls that promotes cell elongation?
What is the MOST direct effect of auxins on cell walls that promotes cell elongation?
Which of the following is a commercially important application of gibberellins in fruit production?
Which of the following is a commercially important application of gibberellins in fruit production?
Why might a plant with a mutation that impairs abscisic acid (ABA) synthesis be more susceptible to disease?
Why might a plant with a mutation that impairs abscisic acid (ABA) synthesis be more susceptible to disease?
How might increased levels of abscisic acid (ABA) affect the process of transpiration in plants during drought?
How might increased levels of abscisic acid (ABA) affect the process of transpiration in plants during drought?
What is the primary mechanism by which tannins protect plants from herbivores?
What is the primary mechanism by which tannins protect plants from herbivores?
Which statement accurately describes the physical location and origin of prickles on a plant?
Which statement accurately describes the physical location and origin of prickles on a plant?
What is the primary role of phytoalexins in plant defense against pathogens?
What is the primary role of phytoalexins in plant defense against pathogens?
In what way might a plant benefit from producing volatile organic compounds (VOCs) when attacked by herbivores?
In what way might a plant benefit from producing volatile organic compounds (VOCs) when attacked by herbivores?
What is the MOST likely consequence of applying a synthetic auxin to a plant at a concentration significantly higher than typically used?
What is the MOST likely consequence of applying a synthetic auxin to a plant at a concentration significantly higher than typically used?
What adaptive advantage do plants with thorns or spines MOST likely have in environments with high herbivore pressure?
What adaptive advantage do plants with thorns or spines MOST likely have in environments with high herbivore pressure?
A plant is observed to have very high levels of alkaloids. What might this indicate about its ecological interactions?
A plant is observed to have very high levels of alkaloids. What might this indicate about its ecological interactions?
How does the production of tannins aid in a plant's survival?
How does the production of tannins aid in a plant's survival?
A researcher discovers a plant that exhibits constitutive expression of phytoalexin biosynthesis genes. How might this affect the plant's interactions with its environment?
A researcher discovers a plant that exhibits constitutive expression of phytoalexin biosynthesis genes. How might this affect the plant's interactions with its environment?
What is the MOST direct effect of abscisic acid (ABA) on guard cells during a drought?
What is the MOST direct effect of abscisic acid (ABA) on guard cells during a drought?
A plant species is found to have unusually small leaves covered in dense, hair-like structures. What environment is it MOST likely adapted to?
A plant species is found to have unusually small leaves covered in dense, hair-like structures. What environment is it MOST likely adapted to?
How do synthetic auxins act as selective herbicides?
How do synthetic auxins act as selective herbicides?
In the context of phototropism, what is the primary mechanism by which auxins contribute to a plant bending towards light?
In the context of phototropism, what is the primary mechanism by which auxins contribute to a plant bending towards light?
If a plant is genetically modified to produce excessive amounts of tannins in its leaves, what is ONE likely consequence?
If a plant is genetically modified to produce excessive amounts of tannins in its leaves, what is ONE likely consequence?
Which of the following scenarios would MOST likely result in a plant exhibiting strong apical dominance?
Which of the following scenarios would MOST likely result in a plant exhibiting strong apical dominance?
A plant experiences a sudden and prolonged drought. Which of the following hormonal responses is MOST likely to occur at the transcriptional level in root cells?
A plant experiences a sudden and prolonged drought. Which of the following hormonal responses is MOST likely to occur at the transcriptional level in root cells?
Flashcards
Plant Hormones (Phytohormones)
Plant Hormones (Phytohormones)
Chemicals that regulate a plant's growth and response to environmental stimuli.
Auxins
Auxins
Plant hormones that promote cell elongation and regulate fruit development, suppressing lateral bud growth.
Gibberellins
Gibberellins
Plant hormones that stimulate stem elongation, seed germination, and fruit enlargement.
Abscisic Acid (ABA)
Abscisic Acid (ABA)
Signup and view all the flashcards
Geotropism
Geotropism
Signup and view all the flashcards
Phototropism
Phototropism
Signup and view all the flashcards
Plant Defense Mechanisms
Plant Defense Mechanisms
Signup and view all the flashcards
Chemical Defenses (Plants)
Chemical Defenses (Plants)
Signup and view all the flashcards
Alkaloids
Alkaloids
Signup and view all the flashcards
Tannins
Tannins
Signup and view all the flashcards
Phytoalexins
Phytoalexins
Signup and view all the flashcards
Mechanical Defenses (Plants)
Mechanical Defenses (Plants)
Signup and view all the flashcards
Thorns
Thorns
Signup and view all the flashcards
Prickles
Prickles
Signup and view all the flashcards
Spines
Spines
Signup and view all the flashcards
Apical Dominance
Apical Dominance
Signup and view all the flashcards
Hormone Weed Control
Hormone Weed Control
Signup and view all the flashcards
Gibberellins Role
Gibberellins Role
Signup and view all the flashcards
ABA in Seed Dormancy
ABA in Seed Dormancy
Signup and view all the flashcards
Abscission
Abscission
Signup and view all the flashcards
Plant Surface Defenses
Plant Surface Defenses
Signup and view all the flashcards
Volatile Organic Compounds (Plants)
Volatile Organic Compounds (Plants)
Signup and view all the flashcards
What is geotropism?
What is geotropism?
Signup and view all the flashcards
What is phototropism?
What is phototropism?
Signup and view all the flashcards
Study Notes
- Plant hormones, or phytohormones, are chemicals regulating plant growth and environmental responses.
- Unlike animal hormones, plant hormones can act where produced or be transported to other regions.
- Plant hormones are essential for germination, flowering, fruit setting, and aging.
Auxins
- Auxins promote cell elongation, suppress lateral bud growth (apical dominance), and regulate fruit development.
- They are produced in stem and root tips and move to other plant parts.
- Auxins are involved in phototropism (growth towards light) and geotropism (growth in response to gravity).
- In apical dominance, auxins inhibit lateral bud growth, promoting taller growth.
- Removing the stem tip reduces auxin, allowing lateral buds to grow, resulting in bushier plants.
Gibberellins
- Gibberellins stimulate stem elongation, seed germination, and fruit enlargement.
- They break seed dormancy and initiate germination by mobilizing stored nutrients.
- Gibberellins promote flowering and fruit development without fertilization, useful in breeding programs.
Abscisic Acid (ABA)
- Abscisic acid is the "stress hormone," involved in stress responses.
- ABA closes stomata during drought to reduce water loss.
- ABA promotes seed dormancy, ensuring germination under optimal conditions.
- Increased ABA levels in autumn lead to leaf drop (abscission), preparing the plant for winter.
Control of Weeds Using Plant Hormones
- Weed control uses plant hormones by exploiting different species sensitivities.
- Synthetic auxins selectively kill broad-leaved weeds in lawns or cereal crops without harming grass or crops.
- This selective action is due to differences in hormone sensitivity between broad-leaved weeds and narrow-leaved plants.
Role of Auxins in Geotropism and Phototropism
-
Auxins are central to geotropism and phototropism, growth responses to gravity and light.
-
In geotropism, auxins accumulate on the lower side, causing less cell elongation and upward shoot growth.
-
Roots grow downward in geotropism due to auxin accumulation.
-
In phototropism, auxins accumulate on the shaded side, causing more cell elongation and bending towards light.
-
Plant hormones regulate key processes determining plant form and vitality.
-
Understanding hormone functions illuminates plant biology and provides tools for agricultural practices.
-
Geotropism and phototropism demonstrate plant adaptation to ensure survival and reproduction.
Plant defence mechanisms
- Plants have structural and chemical defenses against herbivores, pathogens, and environmental stresses.
- These strategies are crucial for survival, reproduction, and maintaining ecological niches.
- Plants developed defenses due to their inability to escape predators or unfavorable conditions.
Chemical Defenses
- Plants produce chemical compounds for defense, including toxins, repellents, and antinutritional substances.
- These chemicals protect against herbivores, insects, and pathogens like bacteria, viruses, and fungi.
- Alkaloids are bitter-tasting compounds, like nicotine and caffeine, that can be toxic to herbivores.
- Tannins bind to proteins, making plant tissue indigestible to discourage herbivores from feeding.
- Phytoalexins are antimicrobial compounds synthesized in response to pathogen invasion.
- Plants secrete sticky or slippery substances to deter insects and produce volatile organic compounds to attract predators of herbivores.
Mechanical Defenses
-
Plants use mechanical or physical strategies for protection.
-
Thorns, spines, and prickles are recognizable plant defense structures.
-
Thorns are modified branches or stems that provide a barrier against large herbivores.
-
Prickles are outgrowths from the epidermis or cortex, deterring animals and providing a mechanical barrier.
-
Spines are modified leaves that reduce surface area, minimize water loss, deter herbivores, and offer shade.
-
Plant defense mechanisms include chemical production and physical barriers.
-
Adaptations help plants survive, ward off attackers, and compete for resources.
-
Understanding these mechanisms is crucial for pest and disease management, reducing the need for chemical pesticides for more sustainable farming.
-
Studying plant defenses uncovers plant interactions with the environment.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
