Ch. 38 - Angiosperm Reproduction and Biotechnology

Campbell - Campbell Biology 12th Edition

Urry12th EditionCampbell BiologyISBN: 9785794169850Not the one you use?Change textbook

Urry 12th Edition

Ch. 38 - Angiosperm Reproduction and Biotechnology

Problem 5

Chapter 38, Problem 5

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

Verified step by step guidance

Step 1: Understand the concept of double fertilization in plants. Double fertilization involves two sperm cells from the pollen grain. One sperm cell fertilizes the egg cell to form the embryo, while the other sperm cell fertilizes the central cell (which contains two nuclei) to form the triploid endosperm.

Step 2: Analyze the genotypes of the male and female individuals. Males have an XY genotype, and females have an XX genotype. This means the sperm cells produced by males can carry either an X or a Y chromosome, while the egg cells produced by females will always carry an X chromosome.

Step 3: Determine the possible genotypes of the embryo. The embryo is formed by the fusion of one sperm cell and one egg cell. If the sperm cell carries an X chromosome, the embryo will have an XX genotype (female). If the sperm cell carries a Y chromosome, the embryo will have an XY genotype (male).

Step 4: Determine the possible genotypes of the endosperm nuclei. The endosperm is formed by the fusion of the second sperm cell with the two nuclei in the central cell. If the sperm cell carries an X chromosome, the endosperm will have an XXX genotype. If the sperm cell carries a Y chromosome, the endosperm will have an XXY genotype.

Step 5: Match the possible combinations of embryo and endosperm genotypes to the given options. Based on the analysis, the embryo can be XX with an XXX endosperm or XY with an XXY endosperm. This matches option d: Embryo XX/endosperm XXX or embryo XY/endosperm XXY.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Double Fertilization

Double fertilization is a unique process in angiosperms where one sperm cell fertilizes the egg cell to form the zygote, while another sperm cell fuses with two polar nuclei to form the triploid endosperm. This endosperm provides nourishment to the developing embryo. Understanding this process is crucial for determining the genotypes of both the embryo and the endosperm in the context of the question.

Genotype and Phenotype

Genotype refers to the genetic constitution of an organism, represented by the alleles it possesses, while phenotype is the observable expression of those genes. In the context of the question, knowing the genotypes of the male (XY) and female (XX) plants helps predict the possible genotypes of the resulting embryos and endosperm after fertilization.

Plant Reproduction and Sex Determination

In some plant species, sex determination can be based on specific genotypes, such as XY for males and XX for females. This genetic basis influences the offspring's sex and genotype. Recognizing how these genotypes contribute to the formation of embryos and endosperm is essential for answering the question regarding the potential outcomes of fertilization.

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Related Practice

Textbook Question

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

Textbook Question

'Bt maize'

a. Is resistant to various herbicides, making it practical to weed rice fields with those herbicides.

b. Contains transgenes that increase vitamin A content.

c. Includes bacterial genes that produce a toxin that reduces damage from insect pests.

d. Is a 'boron (B)-tolerant' transgenic variety of maize.

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Textbook Question

Which statement concerning grafting is correct?

a. Stocks and scions refer to twigs of different species.

b. Stocks and scions must come from unrelated species.

c. Stocks provide root systems for grafting.

d. Grafting creates new species.

Textbook Question

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

Textbook Question

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

a. A simple fruit with many seeds

b. Both a multiple fruit and an accessory fruit

c. Both a simple fruit and an aggregate fruit

d. Both an aggregate fruit and an accessory fruit

Textbook Question

Draw and label the parts of a flower.

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