Genetics: Punnett Squares and Independent Assortment (hard difficulty)

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Questions and Answers

What is the principle stated by Mendel's Second Law of Independent Assortment?

The segregation of different allele pairs is dependent.

The inheritance of an allele of one gene influences which allele is inherited at a second gene.

The alleles of each gene segregate independently. (correct)

The alleles of each gene segregate dependently.

In a dihybrid cross, what is the ratio of phenotypes in the F2 generation?

1:1:1:1

9:3:3:1 (correct)

3:1:1:1

1:2:1:2

What is the purpose of pedigree analysis?

To determine the dominant allele of a gene

To determine the genotype of an individual

To determine the inheritance pattern of a trait (correct)

To determine the phenotype of an individual

What is a dihybrid cross?

A cross between two parents with two differing traits Signup and view all the answers

What is the definition of independent assortment?

The segregation of alleles of different genes during gamete formation Signup and view all the answers

What is a defective copy of a gene called?

Mutation Signup and view all the answers

What is the purpose of a Punnett square?

To predict the possible genotypes and phenotypes of offspring Signup and view all the answers

What is the ratio of round yellow to wrinkled green phenotypes in the F2 generation of a dihybrid cross?

9:3 Signup and view all the answers

What was Mendel's approach to understand the formation of hybrids?

To deduce empirical laws through quantitative analysis Signup and view all the answers

What is the term for a cross between two variants of the same characteristic?

Monohybrid cross Signup and view all the answers

In a dihybrid cross, how many characters are being observed?

Two Signup and view all the answers

What is the term for a variety that produces the same trait over several generations?

True-breeder Signup and view all the answers

What is the difference between a character and a trait?

A character is a general property, while a trait is a specific property Signup and view all the answers

What is the purpose of Mendel's experiments?

To understand the formation of hybrids and hereditary traits Signup and view all the answers

What is the term for the crossing of individual plants that differ in two characters?

Dihybrid cross Signup and view all the answers

What is the significance of Mendel's experiments in understanding hereditary traits?

They established empirical laws that govern hereditary traits Signup and view all the answers

What is the reason for the absence of a blending mechanism of heredity in the F2 generation?

The F2 generation showed an ~ 3:1 ratio of the two parental traits Signup and view all the answers

What is the particulate theory of inheritance?

The genetic determinants that govern traits are inherited as discrete units that remain unchanged as they are passed from parent to offspring Signup and view all the answers

What is true about the two factors of a single character when they are different and present in the same plant?

One variant is dominant and its effect can be seen, and the other variant is recessive and is not seen Signup and view all the answers

What is the ratio of the two parental traits in the F2 generation?

3:1 Signup and view all the answers

What is true about the F1 generation?

The F1 generation showed only one of the two parental traits Signup and view all the answers

What is Mendel's postulate about a pea plant?

A pea plant contains two discrete hereditary factors for a given character Signup and view all the answers

What does the particulate theory of inheritance explain?

How traits are inherited as discrete units that remain unchanged as they are passed from parent to offspring Signup and view all the answers

What is the significance of the 3:1 ratio in the F2 generation?

It refutes the blending mechanism of heredity Signup and view all the answers

Study Notes

Punnett Squares

Punnett squares are used to show the possible genotypes of offspring by combining the alleles of gametes.

Mendel's Second Law of Independent Assortment

Two genes on different chromosomes segregate their alleles independently.
The inheritance of an allele of one gene does not influence which allele is inherited at a second gene.
In a dihybrid cross, the alleles of each gene assort independently.
The segregation of different allele pairs is independent.
Independent alignment of different homologous chromosome pairs during metaphase I leads to the independent segregation of different allele pairs.

Independent Assortment of Two Traits

In a dihybrid cross, parents with two differing traits are crossed.
The alleles of each gene are independent, and the segregation of different allele pairs is independent.
The F2 generation shows all four possible phenotypes in a set ratio of 9:3:3:1.
The ratio of phenotypes can be explained by the independent assortment of two traits.

Modern Genetics

A defective copy of a gene is a mutation.
Pedigree analysis is used to determine the inheritance pattern of a trait.
Symbols are used in pedigree analysis to represent different individuals and their relationships.

Interpreting the Data

The F1 generation showed only one of the two parental traits.
The F2 generation showed an approximately 3:1 ratio of the two parental traits.
The results refuted a blending mechanism of heredity and suggested a particulate theory of inheritance.
Mendel postulated that a pea plant contains two discrete hereditary factors for a given character, one from each parent.

Mendel's Experiments

Mendel studied seven characters that bred true.
The morphological characteristics of an organism are termed characters.
A variety that produces the same trait over several generations is termed a true-breeder.
Mendel did not have a hypothesis to explain the formation of hybrids, but rather believed that a quantitative analysis of crosses may provide mathematical relationships that govern hereditary traits.
Mendel's experiments involved crossing two variants of the same characteristic, and he also performed dihybrid crosses, crossing individual plants that differ in two characters.

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Description

Learn about Punnett squares and Mendel's Second Law of Independent Assortment, understanding how alleles combine and segregate independently in genetics.