CH 38 BIOL

Protoplasts can be screened for mutations that may improve the agricultural value of the plant.

Which statement below accurately describes protoplast fusion?

Dormancy allows a plant to remain protected and inactive until an appropriate time arrives for germination., imbibition of water

what is the benefit of seed dormancy? what is the first step in the germination of seed?

male pollen grain is two sperm cells, female is an embryo sac with 8 haploid nuclei.

what is the male gametophyte? what is the female gametophyte?

seed

Which of the following structures develops from the ovule after fertilization?

the seed

Which of the following structures develops from the ovule after fertilization?

one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei

Double fertilization means that __________.

scutellum.

A monocot embryo has one cotyledon. Grasses, such as maize and wheat, have a special cotyledon called a ____

pollen

A carpel / pistil has a long style with a stigma on which ____ may land.

It protects the enclosed seeds and aids in seed dispersal by wind or animals.

A fruit develops from the ovary.

a microspore undergoes mitosis and cytokinesis !!! When a microspore undergoes mitosis and cytokinesis, two separate cells are produced that, along with a spore wall, make up a pollen grain. Each anther contains four microsporangia, also known as pollen sacs. Within the microsporangia are many diploid cells called microsporocytes, or microspore mother cells. Each microsporocyte undergoes meiosis, forming four haploid microspores, each of which eventually gives rise to a haploid male gametophyte. Each microspore then undergoes mitosis, producing a male gametophyte consisting of only two cells: the generative cell and the tube cell. Together, these two cells and the spore wall constitute a pollen grain.

A generative cell and a tube cell originate when __________.

sporophyte

The gametophytes are reduced in size and depend on the __ for nutrients.

an ovary; an ovule

A pea pod is formed from __________. The pea inside the pod is formed from __________.

!!!!!

A simple fruit develops from a single carpel. An aggregate fruit develops from many separate carpels on one flower. An accessory fruit develops from tissues other than the ovary. The seed develops from the ovule.

pollen

A stamen consists of a filament topped by an anther with pollen sacs that produce __.

stock// scion

A twig or bud can be grafted onto a plant of a closely related species or variety. The _______ provides the root system. The ___ is grafted onto the stock.

callus

A____ is a mass of dividing undifferentiated cells that forms where a stem is cut and produces adventitious roots.

The ovary develops into a fruit enclosing the seed(s).

After double fertilization, each ovule develops into a seed.

Double fertilization results from the discharge of two sperm from the pollen tube into the embryo sac in the ovule.

After landing on a receptive stigma, a pollen grain produces a pollen tube that extends between the cells of the style toward the ovary.

Diploid (2n) sporophytes produce spores by meiosis 2n ---> n these spores (n) grow into haploid (n) gametophytes. Gametophytes produce haploid (n) gametes by mitosis fertilization of gametes produces a zygote = sporophyte cell (2n).

Alternation of Generations:

stamens and styles mature at different times or are arranged to prevent self pollination / self fertilization.

Floral Adaptations that prevent self-fertilization:

aggregated fruit: a fruit that develops from the merger of several ovaries that were separate in a single flower. In contrast, a simple fruit develops from one ovary. !!!!

An accessory fruit (sometimes called false fruit, spurious fruit, pseudofruit, or pseudocarp) is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue exterior to the carpel.

visual cues and volatile chemicals.

Angiosperm flowers can attract pollinators using

!!!!!!!

Anthers are structures that produce pollen. A pistil is a single carpel or two or more fused carpels. The style is the long neck of a carpel that leads to the ovary. The stigma is the sticky structure at the top of the style that captures pollen.

vegetative reproduction. --Asexual reproduction can be beneficial to a successful plant in a stable environment. However, a clone of plants is vulnerable to local extinction if there is an environmental change.

Asexual reproduction is also called

ovules.

At the base of the style is an ovary containing one or more

self-incompatibility,

Floral Adaptations that prevent self-fertilization: The most common is ___a plant's ability to reject its own pollen.

receptacle

Flowers are the reproductive shoots of the angiosperm sporophyte; they attach to a part of the stem called the .

sepals, petals, stamens, and carpels.

Flowers consist of four floral organs:

fermentation and distillation

Biofuels are made by the __________________ of plant materials such as cellulose. Biofuels can be produced by rapidly growing crops and reduce dependency on fossil fuels.

flies

Chemical signal: Odor attracts

inflorescences.

Clusters of flowers are called

bees and dandelions

Color = visual cue / signal to attract pollinators

Incomplete flowers lack one or more floral organs, for example stamens or carpels.

Complete flowers contain all four floral organs.

After landing on a receptive stigma (receptive tip of carpel), the pollen grain produces a tube that extends through the style to the ovary. Here, it discharges two sperm into the embryo sac. One sperm fertilizes the egg, the other gives rise to the nutritive material (endosperm!) on which the embryo will feed.

Describe the process of double fertilization.

The possibility of introducing genes escaping into related weeds through crop-to-weed hybridization which will result in "super weeds" that would be resistant to many herbicides. -Male sterility -Apomixis -Transgenes into chloroplast DNA -Strict self-pollination

Discuss the risks of trangenic crops and describe four strategies that may prevent transgene.

Male sterility Apomixis (asexual reproduction in plants, in particular agamospermy) Transgenes into chloroplast DNA (not transferred by pollen) Strict self-pollination.

Efforts are underway to prevent this by introducing:

Water Wind Animals

Fruit dispersal mechanisms include:

Simple, a single or several fused carpels. Aggregate, a single flower with multiple separate carpels. Multiple, a group of flowers called an inflorescence.

Fruits are also classified by their development:

The radicle (embryonic root) emerges first. Next, the shoot tip breaks through the soil surface.

Germination depends on imbibition, the uptake of water due to low water potential of the dry seed.

They have self-incompatibility and reject their own pollen.

How do most flowering plants avoid self-fertilization?

generative nucleus ---> 2 SPERM, and tube nucleus ---> produces a pollen tube that grows down into the ovary and discharges 2 sperm near the embryo sac. The pollen grain consists of the two-celled male gametophyte and the spore wall.

If pollination succeeds, a pollen grain:

fragmentation

In a potato, the "eyes" are vegetative buds. These buds can develop into an entirely new plant. This is an example of _________.

Asexual reproduction, because it ensures that the genes that have proven to adapt the plant well to the environment will be passed on to the next generation

In an environment that is very stable, with reliable moisture and temperature, what type of reproduction would be most advantageous for a plant and why?

anther to stigma (male -> female).

In angiosperms, pollination is the transfer of pollen from:

sporophyte

In angiosperms, the ____ is the dominant generation, the large plant that we see.

the upper part (scion) of one plant grows on the root system (rootstock) of another plant.

In grafting,

In other eudicots, the food reserves of the endosperm are exported to the cotyledons

In most monocots and some eudicots, endosperm stores nutrients that can be used by the seedling.

Below the cotyledons the embryonic axis is called the hypocotyl and terminates in the radicle (embryonic root); above the cotyledons it is called the epicotyl.

In some eudicots, such as the common garden bean, the embryo consists of the embryonic axis attached to two thick cotyledons (seed leaves)

the gametes are produced by the gametophyte through mitosis and cellular differentiation !!!!! In the alternation of generations in plants, the gametes are produced by the gametophyte through mitosis and cellular differentiation. The life cycles of plants are characterized by an alternation of generations, in which multicellular haploid (n) and diploid (2n) generations take turns producing each other. The diploid plant, the sporophyte, produces haploid spores by meiosis. These spores divide by mitosis, giving rise to the multicellular gametophytes, the male and female haploid plants that produce gametes (sperm and eggs). Fertilization, the fusion of gametes, results in diploid zygotes, which divide by mitosis and form new sporophytes.

In the alternation of generations in plants, __________.

a bud is taken from one plant and grown on another.

In the budding process,

anther; stigma In the process of pollination, pollen grains are transferred from the anther to the stigma. Pollen is produced within the anther and is transferred to the stigma, from which it can migrate to the ova. A stamen consists of a stalk called the filament and a terminal structure called the anther; within the anther are chambers called microsporangia (pollen sacs) that produce pollen (male gametophytes). A carpel, a female structure, has an ovary at its base and a long, slender neck called the style. At the top of the style is a generally sticky structure called the stigma that captures pollen. Within the ovary are one or more ovules (female gametophytes); the number of ovules depends on the species. The term pistil is sometimes used to refer to a single carpel or two or more fused carpels. In angiosperms, pollination is the transfer of pollen from an anther to a stigma. It is accomplished by wind, water, or animals. If pollination is successful, a pollen grain produces a pollen tube, which then grows down into the ovary via the style. Stamens and carpels are reproductive organs, whereas sepals and petals are sterile. Sepals, which enclose and protect unopened floral buds, are usually leafier in appearance than the other floral organs. Petals are typically more brightly colored than sepals and advertise the flower to insects and other pollinators.

In the process of pollination, pollen grains are transferred from the __________ to the __________.

artificial selection

Maize, a product of ______, is a staple in many developing countries.

Sexual reproduction results in offspring that are genetically different from their parents. Asexual reproduction results in a clone of genetically identical organisms.

Many angiosperm species reproduce both asexually and sexually.

Dioecious species have staminate and carpellate flowers on separate plants.

Many angiosperms have mechanisms that make it difficult or impossible for a flower to self-fertilize.

and

Many angiosperms reproduce sexually ____ asexually.

cuttings.

Many kinds of plants are asexually reproduced from plant fragments called

attracts birds

Nectar = chemical attractant

vitamin A

Nutritional quality of plants is being improved. "Golden Rice" is a transgenic variety being developed to address _________deficiencies among the world's poor.

triploid (3n) food-storing endosperm.

One sperm fertilizes the egg, and the other combines with the polar nuclei, giving rise to the ____________

- it refers to innovations in the use of plants to make useful products. -In a specific sense, it refers to use of GM organisms in agriculture and industry.

Plant biotechnology has two meanings:

microsporangia, or pollen sacs, of anthers.

Pollen develops from microspores within the ____

wind, water, bee, moth and butterfly, fly, bird, bat, or water.

Pollination can be aided by environmental agents such as:

Which of the following structures is not part of a seed?

Radicle Hypocotyl Epicotyl Embryo THE CORRECT ANSWER Stamen Endosperm

a block in growth of a pollen tube.

Recognition of self pollen triggers a signal transduction pathway leading to

The breaking of seed dormancy often requires environmental cues, such as temperature or lighting changes.

Seed dormancy increases the chances that germination will occur at a time and place most advantageous to the seedling.

However, only a fraction of seedlings survive.

Sexual reproduction generates genetic variation that makes evolutionary adaptation possible.

artificial selection.

Since the beginning of agriculture, plant breeders have genetically manipulated traits of wild angiosperm species by

One concern is that genetic engineering may transfer allergens from a gene source to a plant used for food. unforeseen effects on nontarget organisms. most serious concern is transgene escape******** = the possibility of introduced genes escaping into related weeds through crop-to-weed hybridization.

Some biologists are concerned about risks of releasing GM organisms into the environment:

zygote 2n

Sperm + egg =

endosperm 3n

Sperm + two polar nuclei =

The seedlings might not develop after germination due to a lack of nutrients. After double fertilization, each ovule develops into a seed. Meanwhile, the ovary develops into a fruit, which encloses the seeds and aids in their dispersal by wind or animals. As the sporophyte embryo develops from the zygote, the seed stockpiles proteins, oils, and starch to varying degrees, depending on the species. This stockpiling is why seeds are such a major nutrient drain. Initially, carbohydrates and other nutrients are stored in the seed's endosperm. Germination depends on imbibition, the uptake of water due to the low water potential of the dry seed. Imbibition causes the seed to expand and rupture its coat and triggers changes in the embryo that enable it to resume growth. Following hydration, enzymes digest the stored materials of the endosperm or cotyledons, and the nutrients are transferred to the growing regions of the embryo. The lack of endosperm would likely prevent the seed from germinating into a seedling. Without endosperm, which provides nutrients to the embryo, the embryo would not develop faster. Germination of seeds depends more on water than on the endosperm. Plants have either one or two cotyledons. The lack of endosperm is unlikely to cause a plant to have more than two cotyledons.

Suppose a mutation in which the endosperm does not develop occurs in a plant. What might be the effect on the development of the seeds or seedlings of that plant?

flowers, double fertilization, and fruits.

The angiosperm life cycle is characterized by "three Fs":

both an aggregate fruit and an accessory fruit

The black dots that cover strawberries are actually individual fruits. The fleshy and tasty portion of a strawberry derives from the receptacle of a flower with many separate carpels. Therefore, a strawberry is __________.

seed coat

The embryo and its food supply are enclosed by a hard, protective ____

carpels; ovules

The female structures of angiosperms are called __________, and they produce __________.

anthers// pollen

The male structures of angiosperms are called __________, and they produce __________.

!!!!!!

The seed develops from the ovule. Pollen develops from the microsporangium. An egg develops from the megasporangium. The gametophyte develops from the sporophyte.

dioecious

This contrasts with the translation of _______, which is "double house." This means that male flowers are on one plant and female flowers are on another plant.

Produce proteins to defend them against insect pests Tolerate herbicides Resist specific diseases.

Transgenic crops have been developed that:

common garden bean and maize corn

Two common types of seed germination

coleoptile//coleorhiza

Two sheathes enclose the embryo of a grass seed: a __________ covering the young shoot and a ___________ covering the young root.

A gene that causes the plants to produce a chemical that becomes toxic within insect guts.

What does the "Bt" in Bt maize refer to?

They allow farmers to "weed" with herbicides, cutting down on soil tillage and erosion. genetic engineers have created "Golden Rice," a transgenic variety supplemented with two daffodil genes that enable it to produce grain containing beta-carotene, a precursor of vitamin A.

What is a major advantage of herbicide-resistant crops?

The fruit

Which of the following structures develops from the ovary after fertilization?

self-recon and prevent self fertilization

What is the function of S-genes in plants?

The gametes of the individual plant would self-fertilize.' The effect of a mutation that deactivates an S-gene in a plant in which gametic incompatibility typically occurs, might be that the gametes of the individual plant would self-fertilize. If an S-gene is deactivated, it is unlikely that self-fertilization would still be blocked. Even though the S-gene was deactivated, the plant could still be fertilized by gametes from another plant. Self-fertilization does not increase genetic variability in a plant's offspring; instead, it would reduce it.

What might be the effect of a mutation that deactivates an S-gene in a plant in which gametic incompatibility typically occurs?

Ovaries located inside receptacles (an enlarged area at the apex of a stem that bears the organs of a flower or the florets of a flower head.) Fusion of floral parts Reduction in the number of floral parts Bilateral symmetry (Bilateral symmetry is a characteristic of animals that are capable of moving freely through their environments)

Which of the following characteristics correctly identify/ies general trends in the evolution of flowers?

A multiple fruit develops from the many carpels of the many flowers that form an inflorescence.!!

Which of the following statements correctly describes a multiple fruit?

A megasporangium is found in the ovary of a flower, and a microsporangium is found in the anther of a flower.

Which of the following statements correctly describes one difference between a megasporangium and a microsporangium?

Complete flowers contain all four basic floral organs: stamen, carpel, petal, and sepal.

Which of the following statements correctly describes the structure of a complete flower?

Some seeds require light to break dormancy. Some seeds require high temperatures to break dormancy. Seeds of many plants remain dormant until a specific environmental cue breaks dormancy. Some seeds require large amounts of rainfall to break dormancy. During the last stages of its maturation, the seed dehydrates until its water content is only about 5-15% of its weight.The embryo, which is surrounded by a food supply (cotyledons, endosperm, or both), enters dormancy; that is, it stops growing and its metabolism nearly ceases.

Which of the following statements is/are correct regarding seed dormancy?

Many species of flowering plants evolved without specific pollinators.:false

Which of the following statements regarding pollination are incorrect? About 65% of all flowering plants require insects for pollination. Approximately 80% of all angiosperm pollination is biotic. Fly-pollinated flowers usually smell like rotten meat in order to attract flies. Many species of flowering plants evolved with specific pollinators.

Ovaries

Which of the following structures contain(s) and protect(s) the seeds in an angiosperm plant?

Imbibition of water causes the seed coat to swell and allows the cells of the embryo to rehydrate. Germination depends on imbibition, the uptake of water due to the low water potential of the dry seed. Imbibing water causes the seed to expand and rupture its coat and also triggers metabolic changes in the embryo that enable it to resume growth. Following hydration, enzymes begin digesting the storage materials of the endosperm or cotyledons, and the nutrients are transferred to the growing regions of the embryo. The first organ to emerge from the germinating seed is the radicle, the embryonic root. Next, the shoot tip must break through the soil surface. In garden beans and many other eudicots, a hook forms in the hypocotyl, and growth pushes the hook above ground. In response to light, the hypocotyl straightens, the cotyledons separate, and the delicate epicotyl, now exposed, spreads its first true leaves (as distinct from the cotyledons, or seed leaves). These leaves expand, become green with chlorophyll, and begin making food by photosynthesis. The cotyledons shrivel and fall away from the seedling, their food reserves having been exhausted by the germinating embryo.

Why do seeds need water to germinate?

meiosis

Within an ovule, megaspores are produced by ___ and develop into embryo sacs, the female gametophytes.

Protoplast fusion

__ is used to create hybrid plants by fusing protoplasts, plant cells with their cell walls removed.

Transgenic plants

___________ are genetically modified (GM) to express a gene from another organism.

Fragmentation,

______________, a separation of a parent plant into parts that develop into whole plants, is a very common type of asexual reproduction.

Apomixis

________is the asexual production of seeds from a diploid cell.

Symbiotic relationships

are common between plants and other species.

apomixes

asexual reproduction in plants, in particular agamospermy.

The microsporangia mother cell undergoes meiosis to become 4 haploid microspore cells and each pollen grain/microspore undergoes mitosis and produce two cells the generative cell and the tube cell. The generative cell contains two sperm and the tube cell becomes the pollen grain ---------------------------- The megaspore mother cell undergoes meiosis and produces 4 megaspores only 1 survives the megaspore undergoes mitosis 3 times and the produces a large cell with 8 nucleis

at the conclusion of meiosis and mitosis in plants, what are the end products?

monoecious

both staminate and pistillate flowers are found on the same plant, the plant is said to be

After double fertilization, each ovule develops into a seed. The ovary develops into a fruit enclosing the seed(s). Endosperm development usually precedes embryo development providing and immediate source of nutrient .

describe the fate and function of the ovule, ovary and endosperm after fertilization

Pollination - The process of pollen transfer from an anther to a stigma. Fertilization - The fusion of a male gamete with a female gamate

distinguish between pollination and fertilization

Asexual Reproduction **Advantages: Beneficial to stable plant in a stable environment, No need to search for mate, No need for pollinator, requires less energy **Disadvantages: Vunerable to local extinction, ------------------------------------------------ Sexual Reproduction **Advantages: generate genetic variation that makes evolutionary adaption possible; organism is more protected **Disadvantages: Requires two organisms, requires more energy

explain the advantages and disadvantages of reproducing sexually and asexually

Hybridization

is common in nature and has been used by breeders to introduce new genes.

Fragmentation-A means of asexual reproduction whereby a single parent breaks into parts that regenerate into whole new individuals. ------ Apomixis-any of several kinds of reproduction without fertilization. ----- Grafting - implanting a branch or bud from one plant onto another. ----- Clones from cutting-Many plants are asexually reproduced from plant fragments.

name and describe several natural and artificial mechanisms of asexual reproduction