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Questions and Answers
Which term describes the complete halt of growth in plants due to unfavorable conditions?
Which term describes the complete halt of growth in plants due to unfavorable conditions?
What is the primary response of plants under the influence of phototropism?
What is the primary response of plants under the influence of phototropism?
Which of the following accurately describes gravitropism?
Which of the following accurately describes gravitropism?
In the study of wild radish flower color, what was the purpose of creating a population through hand pollination?
In the study of wild radish flower color, what was the purpose of creating a population through hand pollination?
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What defines thigmotropism in plants?
What defines thigmotropism in plants?
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What is the main advantage of asexual reproduction in angiosperms?
What is the main advantage of asexual reproduction in angiosperms?
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Which of the following structures is involved in the male gametophyte development in angiosperms?
Which of the following structures is involved in the male gametophyte development in angiosperms?
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What distinguishes a rhizome from other forms of vegetative reproduction?
What distinguishes a rhizome from other forms of vegetative reproduction?
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In the alternation of generations within angiosperms, which phase is diploid?
In the alternation of generations within angiosperms, which phase is diploid?
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What part of the flower is primarily responsible for producing the male gametophytes?
What part of the flower is primarily responsible for producing the male gametophytes?
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Which vegetative reproduction method produces new plants from root sprouts?
Which vegetative reproduction method produces new plants from root sprouts?
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What is the function of the carpel in angiosperms?
What is the function of the carpel in angiosperms?
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Which statement about the generation of angiosperms is correct?
Which statement about the generation of angiosperms is correct?
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Which of the following hormones is responsible for phototropism in plants?
Which of the following hormones is responsible for phototropism in plants?
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What type of plants flowers when days become longer in summer?
What type of plants flowers when days become longer in summer?
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What effect do synthetic auxins like 2,4-D have on plants?
What effect do synthetic auxins like 2,4-D have on plants?
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What aspect of plants does photoperiodism specifically measure?
What aspect of plants does photoperiodism specifically measure?
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What is required for effective pollination by animals?
What is required for effective pollination by animals?
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In which tissue did F.C.Steward successfully regenerate plants?
In which tissue did F.C.Steward successfully regenerate plants?
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What characterizes the flowers of wind-pollinated angiosperms?
What characterizes the flowers of wind-pollinated angiosperms?
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Which type of hormone has a role in the process of dormancy in plants?
Which type of hormone has a role in the process of dormancy in plants?
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What initiates the growth of a pollen tube after pollen grains adhere to the stigma?
What initiates the growth of a pollen tube after pollen grains adhere to the stigma?
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What is the primary function of the style in the carpel?
What is the primary function of the style in the carpel?
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How do auxins cause a plant to bend toward light?
How do auxins cause a plant to bend toward light?
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In the process of double fertilization, what role does one of the sperm cells play?
In the process of double fertilization, what role does one of the sperm cells play?
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Which of the following is NOT considered a major plant hormone?
Which of the following is NOT considered a major plant hormone?
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What happens to the embryo after fertilization?
What happens to the embryo after fertilization?
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What is the outcome of meiosis in the microspore mother cells?
What is the outcome of meiosis in the microspore mother cells?
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What does the outer covering of the ovule develop into?
What does the outer covering of the ovule develop into?
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Which of the following statements about imperfect flowers is correct?
Which of the following statements about imperfect flowers is correct?
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During pollen formation, what occurs after the formation of microspores?
During pollen formation, what occurs after the formation of microspores?
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What must occur for germination to take place?
What must occur for germination to take place?
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What occurs during the active cell division following fertilization?
What occurs during the active cell division following fertilization?
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In the ovule's structure, how many haploid nuclei are produced after the megaspore undergoes mitotic divisions?
In the ovule's structure, how many haploid nuclei are produced after the megaspore undergoes mitotic divisions?
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What defines monoecious plants in terms of flower composition?
What defines monoecious plants in terms of flower composition?
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What is the main role of pollinators in angiosperm reproduction?
What is the main role of pollinators in angiosperm reproduction?
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What results from self-pollination in flowers?
What results from self-pollination in flowers?
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What is primarily responsible for the dispersal of fleshy fruits?
What is primarily responsible for the dispersal of fleshy fruits?
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Which part of the plant first emerges during germination?
Which part of the plant first emerges during germination?
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What initiates the process of aerobic respiration in a seed?
What initiates the process of aerobic respiration in a seed?
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What is a characteristic feature of differentiated plant cells?
What is a characteristic feature of differentiated plant cells?
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How does a plant's development primarily depend on its environment?
How does a plant's development primarily depend on its environment?
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Which of the following best describes cotyledon emergence in eudicots?
Which of the following best describes cotyledon emergence in eudicots?
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What role do plant hormones play in the growth of a plant?
What role do plant hormones play in the growth of a plant?
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Which mechanism is NOT commonly associated with the dispersal of seeds?
Which mechanism is NOT commonly associated with the dispersal of seeds?
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Study Notes
Plant Reproduction and Growth
- Angiosperms (flowering plants) can reproduce asexually or sexually.
- Asexual reproduction is advantageous in stable environments, allowing new individuals to be cloned from parts of the parent plant.
- Vegetative reproduction is a type of asexual reproduction where new plants are produced from stems, roots, or leaves.
- Forms of vegetative reproduction include runners (e.g., strawberry plants), rhizomes (e.g., irises, potatoes), suckers (e.g., cherry, apple, raspberry plants), and adventitious plantlets (e.g., Kalanchoë daigremontiana).
- Sexual reproduction in plants involves alternation of generations.
- The diploid sporophyte generation produces a haploid gametophyte generation enclosed within the sporophyte.
- Male gametophytes are pollen grains that develop from microspores.
- The female gametophyte is the embryo sac, which develops from a megaspore.
- Angiosperm reproductive organs (flowers) are produced seasonally.
- Most flowers contain male parts (stamens) and female parts (carpels).
- Stamens have anthers at their tips.
- Carpels consist of an ovary, style, and stigma.
- Flowers with only male or female parts are imperfect.
Pollen Formation
- Pollen sacs within anthers contain microspore mother cells.
- Microspore mother cells undergo meiosis to form four haploid microspores.
- Microspores undergo mitosis to form pollen grains containing a generative cell and a tube cell nucleus.
- The tube cell nucleus forms the pollen tube.
- The generative cell divides to form two sperm cells.
Egg Formation
- The ovary, located at the base of the carpel, contains ovules.
- Each ovule has a diploid megaspore mother cell.
- Meiosis in the megaspore mother cell produces four haploid megaspores.
- Only one megaspore survives and undergoes repeated mitotic divisions to produce eight haploid nuclei.
- These nuclei form the embryo sac.
Pollination
- Pollination is the transfer of pollen from the anther to the stigma.
- If pollen from a flower pollinates the same flower's stigma, self-pollination occurs, which can lead to self-fertilization.
- Many angiosperms use animals (pollinators) to carry pollen grains from flower to flower, often rewarded with food like nectar.
- Flower color and form have evolved to attract specific pollinators.
- Effective pollination by animals requires a particular insect or animal to visit plant individuals of the same species.
Wind Pollination
- In some angiosperms and all gymnosperms, pollen is dispersed by wind and passively reaches the stigma.
- Plants dispersed by wind have small, green, and odorless flowers.
- Individuals of a given species need to grow where there's ample wind and relatively close to each other.
Fertilization
- Pollen grains adhere to the stigma, grow a pollen tube, and penetrate the style, reaching the ovule.
- The pollen tube releases two sperm cells.
- One sperm fertilizes the egg, and the other sperm fuses with polar nuclei to form endosperm (nutritive tissue).
- This process of using two sperm cells in fertilization is called double fertilization.
Seeds
- After fertilization, active cell division forms an embryo.
- The embryo becomes dormant after drying.
- The outer covering of the ovule develops into a seed coat, an impermeable layer that encloses the dormant embryo and food supply.
- Germination, resumption of metabolic activities, occurs when water and oxygen reach the embryo.
- Germination ensures that seeds germinate under favorable conditions.
Fruits
- During seed formation, the flower ovary develops into fruit.
- Fruits form in various ways and have diverse forms.
- Fleshy fruits are usually dispersed by birds and animals after excreting.
- Other fruits are dispersed by wind or by attaching themselves to the fur of mammals or the feathers of birds or water.
Germination
- A seed absorbs water when appropriate conditions are met.
- Aerobic respiration begins once the seed coat ruptures.
- The roots emerge first, followed by the stem and cotyledons (seed leaves) in eudicots, or the coleoptile in monocots.
Plant Hormones
- Plant development depends on the activities of meristematic tissues interacting with the environment via hormones.
- Differentiation in plants is largely reversible.
- Cells can express their hidden genetic information when provided with appropriate environmental cues.
- Plant hormones influence the expression of some plant genes.
Auxins
- Auxin is a plant hormone involved in phototropism.
- Phototropism is the growth of plants towards light.
- Experiments by Darwin and his son suggested a substance, later identified as auxin, was responsible for plant bending.
- Auxin causes the tissues on the shaded side of a seedling to grow more than those on the opposite side, bending the plant toward light.
- Synthetic auxins are used to control weeds.
- Synthetic auxins work by causing plants to grow to death, reducing ATP production.
Photoperiodism and Dormancy
- Photoperiodism is a mechanism that allows organisms to measure seasonal changes in day and night length.
- Plant flowering responses are categorized by their relation to day length: long-day, short-day. and day-neutral plants.
- Dormancy is a period when plant growth stops.
- Dormancy is often associated with winter in temperate zones due to low temperatures and water freezing.
Tropisms
- Tropisms are directional and irreversible growth responses to external stimuli, like phototropism, gravitropism and thigmotropism.
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Description
Explore the fascinating world of plant reproduction, focusing on both asexual and sexual methods. Learn about vegetative reproduction and the roles of gametophytes and sporophytes in angiosperms. This quiz will deepen your understanding of how flowering plants propagate and thrive in their environments.
