Biology Chapter 11 Flashcards

Questions and Answers

How could the botanist best determine whether the genotype of the green-pod plant is homozygous or heterozygous?

Cross the green-pod plant with a yellow-pod plant.

Which of Mendel's findings does the test cross of the green-pod plant illustrate if it is determined to be heterozygous (Gg)?

Law of segregation

During which part of meiosis do the two alleles of a gene separate?

Meiosis I, Anaphase

What are the genotypes and phenotypes of the four parent pea plants based on the F1 progeny?

Plant 1: Rryy; Plant 2: RrYy; Plant 3: RRYy; Plant 4: rryy Signup and view all the answers

What are the genotypes of the parent plants crossed with a plant grown from a round, yellow seed and a plant grown from a wrinkled, yellow seed?

Yellow round = RrYy; Yellow wrinkled = rrYy Signup and view all the answers

What are the predicted frequencies of each of the phenotypes in the F1 progeny?

Yellow round: 3/8; Yellow wrinkled: 3/8; Green round: 1/8; Green wrinkled: 1/8 Signup and view all the answers

Determine the relationship between the mutant allele and its corresponding wild-type allele for Twist, Forked, and Pale.

Twist: dominant; Forked: dominant; Pale: neither dominant nor totally recessive Signup and view all the answers

Identify the genotype of each F2 class based on the alleles for leaf color and leaf shape.

PP; F_; Pp; F_; pp; F_; PP; f+f+; Pp; f+f+; pp; f+f+ Signup and view all the answers

What statement best explains the outcome of the cross between the forked and twist lines?

The forked mutation and the twist mutation are codominant alleles of the same locus Signup and view all the answers

What designator is used for the twist allele to distinguish it from the forked allele?

F^(T) Signup and view all the answers

Which phenotype has the highest frequency based on the Punnett square?

The phenotype that results from having 3 dark-skin alleles Signup and view all the answers

What pattern does the distribution of frequency values show in the histogram?

A normal distribution, characterized by frequencies that are symmetrically distributed around one central peak value Signup and view all the answers

What is the best explanation for the curve's shape in the histogram?

Equal numbers of light-skin and dark-skin alleles result in a majority of the offspring having intermediate phenotypes. Signup and view all the answers

What are the phenotypic frequencies of the surviving offspring if one of the three genes is lethal when homozygous recessive?

0=0; 1=2; 2=9; 3=16; 4=14; 5=6; 6=1 Signup and view all the answers

How does the shape of the curve compare with the curve in Figure 2?

It is now skewed toward a higher number of dark-skin alleles. Signup and view all the answers

What does the example indicate about the distribution of phenotype frequencies in a population?

A lethal combination of alleles in a population will result in phenotype frequencies that do not have a normal distribution. Signup and view all the answers

Based on the inheritance pattern, which mode of inheritance is responsible for galactosemia?

Autosomal recessive Signup and view all the answers

What is the risk that Jane and John will have another child with galactosemia?

1/4 Signup and view all the answers

Which tests would be most useful for Jane and John regarding galactosemia?

Newborn screening (either assaying for the GALT enzyme or measuring excess galactose in the newborn's blood) Signup and view all the answers

How do quantitative characters differ from the characters investigated by Mendel in his experiments on peas?

Quantitative characters are due to polygenic inheritance, while a single gene affected all but one of the pea characters studied by Mendel. Signup and view all the answers

What is the chance that an individual taken at random from the F2 generation produces wrinkled seeds and yellow seeds?

25% for wrinkled; 75% for yellow Signup and view all the answers

Which statement about the homologous pair of chromosomes is correct?

These homologous chromosomes represent a maternal and a paternal chromosome. Signup and view all the answers

When a dominant allele coexists with a recessive allele in a heterozygote individual, how do they interact with each other?

They do not interact at all. Signup and view all the answers

Study Notes

Genetic Determination and Test Cross

Determine if a genotype is homozygous or heterozygous by conducting a test cross with a recessive phenotype.
A heterozygous genotype (Gg) illustrates Mendel's law of segregation.

Meiosis and Allele Separation

Alleles separate during meiosis I, specifically during the Anaphase phase.

Mendelian Traits in Pea Plants

Pea plants can show various phenotypes based on dominant and recessive alleles:
- Round (R) is dominant over wrinkled (r), yellow (Y) is dominant over green (y).
- Deductions about parental genotypes can be made from the phenotypes of F1 progeny.

Dihybrid Crosses

A round yellow seed plant (RrYy) crossed with a wrinkled yellow seed plant (rrYy) can produce offspring with various phenotypes.
Expected frequencies:
- Yellow round: 3/8
- Yellow wrinkled: 3/8
- Green round: 1/8
- Green wrinkled: 1/8

Allele Dominance and Relationships

Mutant alleles can show different relationships to wild-type alleles:
- Twist and Forked mutants are dominant over their respective wild types.
- Pale allele shows incomplete dominance.

Offspring and Punnett Squares

A Punnett square helps visualize offspring inheritance patterns.
Phenotypic frequencies change when lethal alleles are considered, leading to non-normal distributions.

Inheritance Patterns and Disorders

Galactosemia follows an autosomal recessive inheritance pattern.
If both parents are heterozygotes, the risk of having an affected child is 1/4.
Newborn screening for galactosemia is essential to manage affected individuals.

Quantitative vs. Mendelian Traits

Quantitative traits are influenced by multiple genes (polygenic inheritance) and show continuous variation, contrasting with Mendel's studies on traits influenced by single genes.

Chromosomal Alleles and Interactions

In a homologous chromosome pair, each chromosome carries different alleles for a trait, representing contributions from both parents.
Dominant and recessive alleles in heterozygotes do not interact functionally; one masks the effect of the other.

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Explore key concepts from Chapter 11 of Biology with these flashcards. Test your understanding of plant genetics, particularly focusing on the genotype determination of green-pod plants. Perfect for mastering Mendelian genetics.