36. Plant Reproduction

Flowers

Fertilisation, zygote, embryo, germination | How do organisms reproduce | Biology | Khan Academy

How Pollination Works

DRAW IT Draw and label the parts of a flower.

Flower Anatomy

The Diversity and Pollination of Flowers

In angiosperms, are sperm and eggs produced by mitosis or meiosis? Which cells are spores? Which structures are gametophytes?

Plant Anatomy and Structure

 flower development depends on a sequence of three genes turning on in the correct order 

 No. The model suggests that different combinations of the genes are responsible for organ determination. 

 the A gene turns on sepals, the B gene turns on petals, the C gene turns on stamens, and all three are necessary for carpels to form 

 No. The model suggests that a combination of gene A and gene B is needed to form petals and gene B and gene C are needed to form stamens. 

 the A gene initiates the flower bud, the B gene initiates formation of the sterile parts, and the C gene initiates formation of the reproductive parts 

 No. The ABC model refers to organ identity genes, not floral initiation. 

 three mutations must occur at the shoot apical meristem for it to begin forming flower parts instead of leaves 

 No. The ABC model refers to organ identity genes, not phase change. 

 pairs of genes are required to form petals and stamens but a single gene can initiate sepals or carpels 

Review the ABC model of flower development.

The ABC model of flower formation suggests that __________.

Pollination Explained

Short Video: Bee Pollination

 No. The ovary is the site of ovum production, and ova are not transferred during pollination. 

 No. The stigma, style, and ovary are all parts of the carpel. 

 No. A sepal is a structure that encloses and protects the flower bud. 

 No. The stigma forms the portion of the carpel that receives the pollen from the male anther. 

Consider the male and female parts of flowers.

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

 No. Petals are often brightly colored to attract pollinators. 

 No. Sepals do not contain sporangia; they enclose and protect a floral bud prior to its opening. 

 Stamens, development of female gametophytes 

 No. Stamens are the sites at which male gametophytes develop. 

 Carpels, development of male gametophytes 

 No. Carpels are the sites at which female gametophytes develop. 

 Stamens, development of filament and anther 

You will want to review the structure and function of flowers.

Which of the following associations is correct?

A small flower with green petals is most likely
a. bee-pollinated.
b. bird-pollinated.
c. bat-pollinated.
d. wind-pollinated.

 No. This is a group of undifferentiated cells that forms at the end of a cut shoot. Adventitious roots develop from the callus. 

 No. This is the separation of a parent plant into parts, which develop into whole plants. 

 No. Clones are the result of fragmentation, or clones can be grown from cuttings. 

 No. Grafting occurs when a twig or bud from one plant is grafted onto a plant of a closely related species or a different variety of the same species. 

This is the type of reproduction that occurs in dandelions.

In this type of asexual reproduction, seeds are produced even without the joining of sperm and eggs.

S-genes are unique to plants and make them more susceptible to manipulation by bioengineers.

No. This is not an accurate description of S-genes.

S-genes make plants more resistant to pests.

If pollen from another species lands on the stigma of a plant, S-genes block the pollen tube growth.

No. S-genes are involved in stopping self-fertilization. Other mechanisms are involved in blocking interspecific fertilization.

 None of the listed responses is correct. 

 No. One of the other choices is correct. 

S-genes are involved in self-recognition. They prevent self-fertilization in many plant species.

"S" stands for "self."

Which statement below accurately describes the role of S-genes in plants?

Pollination: Trading food for fertilization in 3 minutes

Plants

Plant Reproduction in Angiosperms

Introduction to Seed Plants

Double fertilization means that
a. flowers must be pollinated twice to yield fruits and seeds.
b. every egg must receive two sperm to produce an embryo.
c. one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei.
d. every sperm has two nuclei.

Typical Structure of a Flower | Don't Memorise

 No. Flowers are produced by angiosperms; cones are produced by certain gymnosperms. 

 No. Anthers are male reproductive structures with chambers in which pollen grains are produced; it is the female reproductive structure that protects the seeds. 

 No. Sepals protect the entire flower bud as it develops. 

 No. Antheridia are male reproductive structures and are not associated with angiosperms. 

Does the male or female gametophyte house the seed?

Flowers bear seeds in protective chambers called __________.

Short Video: Bee Colony Decline

In a species showing sporophytic incompatibility, which 
type(s) of pollen could successfully fertilize an S2S3 flower?
(A) S1 pollen from an S1S3 flower
(B) S2 or S3 pollen from an S2S3 flower
(C) S3 pollen from an S1S1 flower
(D) S1 pollen from an S1S1 flower

Alteration of Generations

Types of Inflorescence | Morphology of Flowering Plants | Don't Memorise

Pollination: Trading Food for Fertilization

The Plants & The Bees: Plant Reproduction - CrashCourse Biology #38

Double Fertilization in Angiosperms

 No. A microsporocyte undergoes meiosis, producing four haploid microspores. Each microspore undergoes mitosis, resulting in two separate cells that become part of one pollen grain. Therefore, the division of four microspores results in four pollen grains. 

Review pollen grain formation, and remember how many products result from meiosis.

How many pollen grains can potentially result from one microsporocyte?

Angiosperm Life Cycle

Plant Structure

Flower - Types

Double Fertilization

 No. Sepals protect buds, but they are not related to reproduction. 

Review flower structure and angiosperm reproduction.

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

Plant Anatomy and Morphology

Flower: Sexual parts (unisexual & bisexual) | How do organisms reproduce | Biology | Khan Academy

Fertilisation in Flowering Plants -Class 12

Evaluate these statements about double fertilization. Select True or False for each sentence.
T/F Two zygotes are formed, but only one survives.
T/F One sperm fuses with an egg while the other sperm fuses with polar nuclei.
T/F It results in the formation of a diploid embryo and triploid endosperm.
T/F Both sperm involved in double fertilization form within the same pollen tube.

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other?

Why might it be advantageous for plants to promote cross-pollination? What are the advantages of self-pollination?

 Synergids divide, producing megaspores. 

 No. This is the role of megasporocytes. 

 Synergids divide, producing one large cell with eight haploid nuclei. 

 Synergids are the polar nuclei that share the cytoplasm of the large central cells of the embryo sac. 

 No. These are just known as polar nuclei. 

 Synergids help to attract and guide the pollen tube to the embryo sac. 

The synergids flank the egg at the entrance to the embryo sac.

What is the purpose of synergids in an ovule?

 No. The sporophyte develops from an embryo; a spore grows into a gametophyte. 

 the gametes are produced by the gametophyte through meiosis and cellular differentiation 

 No. Gametophytes are haploid and therefore do not undergo meiosis. 

 the spores are produced by the gametophyte by meiosis and cellular differentiation 

 the sporophyte is the haploid generation 

 No. The sporophyte is the diploid generation. 

 the gametes are produced by the gametophyte through mitosis and cellular differentiation 

Review angiosperm reproduction.

In the alternation of generations in plants, __________.

Animation: Sexual Reproduction in Angiosperms

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other?

In general, larger fruits tend to earn higher profits for farmers who grow cape gooseberries as a crop. Compared to self-pollinated flowers, what is the approximate percentage of difference in fruit size of bee-pollinated flowers?

Double Fertilization (Angiosperms)

 Sexual reproduction because it is always better to increase genetic variation 

 No. Asexual reproduction will ensure that gene combinations that adapt the plant well to the environment will be passed on to the next generation. Rolling the dice with sexual reproduction may produce poorly adapted offspring. 

 Sexual reproduction because it will ensure that the most advantageous genes are passed on to the next generation 

 No. Sexual reproduction is a roll of the dice. There is no way to ensure that the most advantageous genes will be passed on. 

 Asexual reproduction because it increases the genetic variation within the population 

 No. Asexual reproduction produces clones. It does not increase genetic variation. 

 Sexual reproduction because it requires less energy 

 No. In general, sexual reproduction requires more energy. 

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

Review the advantages and disadvantages of different types of reproduction.

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?

 No. This process results in the formation of four haploid microspores that later give rise to the generative cell and the tube cell. 

 No. Microsporocytes are diploid and undergo meiosis to give rise to four haploid microspores. 

 a microspore undergoes meiosis and cytokinesis 

 No. Microspores are haploid; they do not undergo meiosis. 

 microspore mother cells undergo mitosis and cytokinesis 

No. Microspore mother cells is another name for microsporocytes, which do not undergo mitosis.

 a microspore undergoes mitosis and cytokinesis 

How is a pollen grain formed?

A generative cell and a tube cell originate when __________.

Angiosperms: Flowering Plants

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other?

Researchers conducted controlled experiments to test for effects of different types of pollination on cape gooseberry fruit size and seed production. The types of pollination included self-pollination, cross-pollination by bees, and manual cross-pollination (transferring pollen from one plant to another by hand). Results are shown in the graphs here. Compared to self-pollination, do bees have a significant impact on fruit mass? How about on seed formation? <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/8d6e3220e59d2bef-1677305802279.jpg" style="width: 300px;">

Match questions 3–8 with options a–f. 


3. Attracts pollinator 

4. Develops into seed 

5. Protects flower before it opens 

6. Produces sperm 

7. Produces pollen 

8. Houses ovules 

a. pollen grain 
b. ovule 
c. anther 
d. ovary 
e. sepal 
f. petal

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other?

Considering the gooseberry flower shown here, what types of cues might attract bees to the plant? What type of rewards do bees seek?

What is Pollination?

Some plant species produce male and female individuals in 
which the males have an XY genotype and the females have 
an XX genotype. After double fertilization, what would be the 
genotypes of the embryos and endosperm nuclei?
(A) embryo XY/endosperm XXX or embryo XX/endosperm XXY
(B) embryo XX/endosperm XX or embryo XY/endosperm XY
(C) embryo XX/endosperm XXX or embryo XY/endosperm XYY
(D) embryo XX/endosperm XXX or embryo XY/endosperm XXY

The Reproductive Lives of Nonvascular Plants: Alternation of Generations - Crash Course Biology #36

In angiosperms, each pollen grain produces two sperm. What do these sperm do? 
a. Each one fertilizes a separate egg cell. 
b. One fertilizes an egg, and the other is kept in reserve. 
c. Both fertilize a single egg cell. 
d. One fertilizes an egg, and the other fertilizes a cell that develops into stored food.

Alternation of Generations

Make a sketch of a simplified flower with all four organs, and indicate how the pattern of expression for just two genes (e.g., “D” and “E”) could, hypothetically, regulate the development of each organ. Consider that what’s important is whether a gene is on or off and that a structure can be specified when neither gene is expressed.

 No. Sepals enclose and protect a floral bud prior to its opening. 

 No. Anthers are the sites of pollen production. 

 No. Fruits, which develop from ovaries, play a role in seed dispersal. 

What attracts a pollinator to a flower?

Like gymnosperms, many grasses and angiosperm trees are wind-pollinated. To conserve energy, these angiosperms do not produce complete flowers (complete flowers have all four of the basic parts). Which basic part would most likely be missing from wind-pollinated angiosperm flowers?

 No. Both of these are female structures. 

 No. Although stamens are the male structures, ovaries are female structures. 

 No. Although anthers are the male structures, ovules enclose the female gametophyte, the embryo sac. 

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

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other?

Global bee populations have been declining over the past decade. What impact might this have on the world’s human population?

ANGIOSPERM DOUBLE FERTILIZATION

 No. This is not the best answer. Ovules do bear sporangia, but only part of the stamen does. 

 No. Ovaries do house the ovules, which contain sporangia. The receptacle is the area where the four basic floral organs attach to the stem. 

 No. The sepal is a protective part of the flower, not reproductive. The filament is the part of the stamen that does not contain sporangia. 

 No. This is not the best answer. Anthers do bear sporangia, but only part of the ovary (the ovule) does. 

Sporangia are the structures from which spores are produced.

Which two structures of a flower bear sporangia?

What are the advantages and disadvantages of self-fertilization versus those of outcrossing?

Asexual Reproduction

Pollination

Name two kinds of asexual reproduction among plants. Explain two advantages of asexual reproduction over sexual reproduction. What is the primary drawback of asexual reproduction?

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other?

Based on the data in the graphs provided, approximately how many ovules are found in each gooseberry carpel?

 No. Not requiring a pollinator is an advantage of asexual reproduction, but it is not an underlying feature that enables asexual reproduction. 

 No. The ability to form adventitious roots depends on the presence of meristems and parenchyma cells, both of which are capable of giving rise to a variety of specialized cells. 

 No. The ability to form adventitious shoots depends on the presence of meristems and parenchyma cells, both of which are capable of giving rise to a variety of specialized cells. 

 They don't require genetic recombination. 

 No. This is a characteristic of asexual reproduction, but it is not an underlying feature that allows plants to reproduce asexually. 

 They have two types of cell capable of giving rise to a variety of specialized cells: undifferentiated meristems and parenchymal cells. 

This relates to stem cells.

What is the underlying feature that allows plants to reproduce asexually?

CBSE Class 12 Biology, Sexual Reproduction in Flowering Plants-2, Female Reproductive Organs

Some dioecious species have the XY genotype for male and XX for female. After double fertilization, what would be the genotypes of the embryos and endosperm nuclei?
a. embryo XY/endosperm XXX or embryo XX/endosperm XXY
b. embryo XX/endosperm XX or embryo XY/endosperm XY
c. embryo XX/endosperm XXX or embryo XY/endosperm XYY
d. embryo XX/endosperm XXX or embryo XY/endosperm XXY

 No. Although dioecious plants avoid self-fertilization, this is not the most common strategy. 

 The physical arrangement of stamens and carpels makes self-fertilization unlikely. 

 No. This strategy is used by many plants, but it is not the most common strategy. 

 Stamens and carpels on the same plant mature at different times. 

 No. Not all flowering plants require pollinators, but those that do have mechanisms to encourage pollinators. 

 They display self-incompatibility and reject their own pollen. 

It must be pretty important to increase genetic variability.

How do most flowering plants avoid self-fertilization?

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