Plant Biology Quiz - Dormancy and Tropisms

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Questions and Answers

What is dormancy in plants primarily associated with in temperate zones?

Low temperatures and freezing conditions (correct)

Rapid growth of foliage

Increased sunlight and humidity

High levels of water availability

Which type of tropism involves the growth response of a plant to light?

Thigmotropism

Gravitropism

Hydrotropism

Phototropism (correct)

What is the primary effect of gravitropism in plants?

Roots do not respond to gravitational forces

Plants grow longer in length with no directional preference

Stems grow upwards while roots grow downwards (correct)

Roots grow upwards while stems grow downwards

In the study conducted by Irwin and Strauss on wild radish, what two populations were compared?

Bees created and randomly pollinated populations Signup and view all the answers

Which of the following correctly defines thigmotropism?

Response of plants to touch Signup and view all the answers

What type of reproduction do angiosperms primarily use in stable environments?

Asexual reproduction Signup and view all the answers

What is a characteristic feature of vegetative reproduction in plants?

Cloning from parent parts Signup and view all the answers

In sexual reproduction, what do male gametophytes develop into?

Pollen grains Signup and view all the answers

Which part of the flower is primarily associated with the female reproductive function?

Carpel Signup and view all the answers

What forms the network in rhizomatic vegetative reproduction?

Underground horizontal stems Signup and view all the answers

What is the haploid structure produced during the alternation of generations in flowering plants?

Gametophyte Signup and view all the answers

Which reproductive organs of angiosperms are produced seasonally?

Reproductive organs Signup and view all the answers

What part of the flower contains anthers at its tips?

Stamens Signup and view all the answers

What is the main requirement for effective pollination by animals?

Pollinators must visit plant individuals of the same species. Signup and view all the answers

What characteristic is common among flowers of wind-pollinated angiosperms?

They are small, green, and odorless. Signup and view all the answers

During fertilization, what occurs when the pollen tube reaches the embryo sac?

Two sperm cells are released; one fertilizes the egg and the other forms endosperm. Signup and view all the answers

What happens to the embryo after fertilization in angiosperms?

It becomes dormant after a period of active cell division. Signup and view all the answers

What forms the protective covering of the seed after fertilization?

The outer covering of the ovule. Signup and view all the answers

Which process must occur before germination can take place?

Water and oxygen must reach the embryo. Signup and view all the answers

What is meant by double fertilization in flowering plants?

One sperm fertilizes the egg and another fuses with polar nuclei. Signup and view all the answers

What begins after the pollen grains adhere to the stigma?

The growth of a pollen tube. Signup and view all the answers

What initiates the germination process of a seed?

Absorption of water Signup and view all the answers

In eudicots, which structure emerges from underground during germination?

Cotyledons Signup and view all the answers

Which dispersal method is most associated with fleshy fruits?

Animal excretion Signup and view all the answers

What role do plant hormones play in plant development?

They control the expression of some plant genes. Signup and view all the answers

What part of the carpel is responsible for containing the ovule?

Ovary Signup and view all the answers

Which statement about differentiation in plants is true?

Differentiation is reversible under certain conditions. Signup and view all the answers

What defines a plant as monoecious?

It has both male and female flowers on the same plant. Signup and view all the answers

Which of the following structures emerges first during seed germination?

Roots Signup and view all the answers

What is the primary function of the flower ovary during seed formation?

To develop into fruit Signup and view all the answers

What process occurs when microspore mother cells divide to form pollen grains?

Meiosis Signup and view all the answers

Which plant tissue is primarily responsible for growth and differentiation?

Meristematic tissues Signup and view all the answers

During egg formation, how many haploid megaspores are produced from a single megaspore mother cell after meiosis?

4 Signup and view all the answers

What is the result of self-pollination?

Self-fertilization Signup and view all the answers

What rewards do pollinators often receive from flowering plants?

Nectar Signup and view all the answers

What is known to influence the evolutionary traits of flower color and shape?

Attraction to pollinators Signup and view all the answers

What forms the pollen tube during pollen development?

Tube cell nucleus Signup and view all the answers

Which hormone has been identified as causing phototropism in plants?

Auxin Signup and view all the answers

What type of plants respond by flowering when the days become longer?

Long-day plants Signup and view all the answers

What impact do synthetic auxins have on plants?

They lead to the plant's death by reducing ATP production. Signup and view all the answers

What is photoperiodism?

The measured response of organisms to seasonal changes in light. Signup and view all the answers

What is the role of gibberellins in plants?

To stimulate cell division and elongation. Signup and view all the answers

Which statement accurately describes abscisic acid?

It is a hormone that regulates leaf and fruit drop. Signup and view all the answers

What tissue was used by F.C. Steward to successfully regenerate plants?

Phloem tissue Signup and view all the answers

Which category of plants flowers without concern for day length?

Day-neutral plants Signup and view all the answers

Study Notes

Plant Reproduction and Growth

Angiosperms (flowering plants) can reproduce asexually or sexually.
Asexual reproduction is advantageous in stable environments, as it allows for rapid cloning of individuals from parts of the parent plant.
Vegetative reproduction creates new individuals simply by cloning from existing plant parts.
Asexual reproduction requires lower energy investment than sexual reproduction.

Forms of Vegetative Reproduction

Runners: Slender stems that grow along the soil surface (e.g., strawberries).
Rhizomes: Underground horizontal stems that create a network, giving rise to new shoots (e.g., irises, potatoes).
Suckers (or sprouts): Produced by roots and give rise to new plants (e.g., cherry, apple, raspberry).
Adventitious plantlets: Arise from meristematic tissue located in leaf notches (e.g., Kalanchoë daigremontiana).

Sexual Reproduction in Angiosperms

Involves an alternation of generations.
The diploid sporophyte generation produces a haploid gametophyte generation, enclosed within the sporophyte.
Male gametophytes are pollen grains, developing from microspores.
Female gametophytes are the embryo sacs, developing from megaspores.
Gametophytes are produced in specialized structures of the flower.
Reproductive organs are produced seasonally.

Flower Structure

Most flowers contain male (stamens) and female (carpels) parts.
Stamens have anthers at their tips.
Carpels consist of an ovary, style, and stigma.
Imperfect flowers contain either only male or only female parts.
Monoecious plants have imperfect flowers of both male and female on the same plant.

Pollen Formation

Pollen sacs within anthers contain microspore mother cells.
Meiosis in microspore mother cells produces haploid microspores.
Mitosis transforms microspores into pollen grains, containing a generative cell and a tube cell nucleus.
The tube cell nucleus forms the pollen tube, and the generative cell later divides into two sperm cells.

Egg Formation

Ovules within the ovary contain diploid megaspore mother cells.
Meiosis produces haploid megaspores.
One megaspore survives and undergoes repeated mitotic divisions to form eight haploid nuclei within the embryo sac.

Pollination

Pollen transfer from anther to stigma.
Self-pollination occurs when pollen from a flower's anther pollinates the same flower's stigma.
Many angiosperms use animals (like insects, birds) for pollination, often rewarding them with food (e.g., nectar).
Flower color and form are evolutionary adaptations to attract pollinators.
Wind pollination is common in some angiosperms and most gymnosperms, characterized by small, green, odorless flowers.

Fertilization

Pollen grains germinate and grow a pollen tube.
The pollen tube reaches the ovule in the ovary.
The pollen tube releases two sperm cells into the embryo sac.
One sperm fertilizes the egg, forming a zygote, and the other fuses with polar nuclei to form the endosperm (nutrient tissue).
This process is double fertilization.

Seeds

After fertilization, cell division forms an embryo.
Embryo development stops and enters dormancy, usually after apical meristems and cotyledons have developed, as a result of drying.
The seed coat forms from the outer covering of the ovule.
Seeds contain a dormant embryo and food source.
Germination occurs when the seed absorbs water and metabolic activities resume due to access to water and oxygen.

Fruit

The flower ovary develops into fruit during seed formation.
Fruits form in various ways and are diverse in form.
Fleshy fruits are usually dispersed by birds and other vertebrates.
Some fruits disperse by wind or attaching to mammals/birds.
Some fruits disperse by water.

Plant Germination

Seed absorbs water.
Aerobic respiration begins.
Roots emerge first.
In eudicots, cotyledons emerge with the stem; in monocots, the coleoptile emerges from underground.

Plant Hormones

Growth and differentiation continue after germination in a repeated cyclical manner.
Plants can be regrown from isolated differentiated tissues.
Plant development is regulated by meristematic tissues, which are coordinated by plant hormones.
Hormones act in plants, not just in specialized tissues.
Various specialized plant hormones are found in plants (auxin, gibberellins, cytokinins, ethylene, abscisic acid).

Phototropism (Auxin)

Phototropism is the growth of plants toward light.
Charles Darwin's experiments suggested the existence of a plant growth substance (later identified as auxin) involved in bending toward light.
Frits Went discovered that auxin causes tissues on the side of a seedling facing light to grow more than the opposite side, driving the bending.
Synthetic auxins are used to control weeds.

Photoperiodism and Dormancy

Photoperiodism is a mechanism plants use to detect seasonal changes in day length.
Plants’ flowering responses are categorized based on their day length requirements (long-day plants, short-day plants, day-neutral plants).
Dormancy is the temporary cessation of growth in plants to survive unfavorable conditions, such as winter in temperate zones.

Tropisms

Tropisms are directional growth responses to external stimuli.
Phototropism is the growth of plants toward light.
Gravitropism is the growth of plants in response to gravity (stems upward, roots downward).
Thigmotropism is the response of plants to touch.

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Description

Test your knowledge on key concepts in plant biology, including dormancy, tropisms, and specific studies on wild radish. This quiz addresses important mechanisms through which plants respond to their environment. Perfect for students studying plant sciences or biology.