Mendel's Experiments and Inheritance Principles

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Questions and Answers

What is the phenotype of a plant that has one dominant red allele and one recessive white allele?

Pink

All white

All red

Red with white spots (correct)

What type of genetic expression is demonstrated when a red and white flower produce pink offspring?

Incomplete dominance (correct)

Sex-linked inheritance

Codominance

Complete dominance

Which of the following genotypes could produce a child with type A blood if the father has type B blood and the mother has type AB blood?

IA i (correct)

IA IA

IB i

IA IB

If a homozygous red cow (RR) is crossed with a roan cow (Rr), what is the expected genotype of the offspring?

RR and Rr Signup and view all the answers

Which genotype corresponds to a continuous hairline in humans?

hh Signup and view all the answers

In a cross between two heterozygous individuals with widow's peaks and short fingers, which phenotype ratio is expected?

1:2:1 Signup and view all the answers

Which of the following is NOT a possible phenotype of the offspring when a red cow is mated with a roan cow?

White Signup and view all the answers

What is the term for a genetic cross that involves traits located on the same chromosome?

Linked genes Signup and view all the answers

What is the primary reason Mendel chose the garden pea for his experiments?

It had a wide variation in observable traits Signup and view all the answers

What are alleles?

Variants of a gene controlling the same trait Signup and view all the answers

According to Mendel's Law of Segregation, how do genes behave during gamete formation?

They segregate equally into gametes Signup and view all the answers

Which of the following best defines genotype?

The genetic makeup composed of both visible traits and non-expressed alleles Signup and view all the answers

What distinguishes phenotype from genotype?

Phenotype is always visible while genotype is not Signup and view all the answers

Which of the following traits was NOT studied by Mendel in his experiments?

Leaf color Signup and view all the answers

What does it mean for a gene to be dominant?

It masks the expression of a recessive gene Signup and view all the answers

What is the effect of the environment on genotype?

It can influence the expression of phenotype Signup and view all the answers

What is the primary difference between a dominant and a recessive allele?

A dominant allele will be expressed if present, while a recessive allele requires the absence of a dominant trait. Signup and view all the answers

Which genotype corresponds to an organism that has two identical dominant alleles?

Homozygous Dominant Signup and view all the answers

Which term describes an observable physical trait of an organism?

Phenotype Signup and view all the answers

What is the purpose of a Punnett Square?

To predict probabilities and possible genetic outcomes from a cross. Signup and view all the answers

If an organism is heterozygous for a trait, what does that signify?

It has one dominant and one recessive allele. Signup and view all the answers

What does a monohybrid cross involve?

Studying only one trait of a cross between two true-breeding organisms. Signup and view all the answers

Which of the following best describes Non-Mendelian inheritance?

Inheritance patterns that do not follow the principles established by Mendel. Signup and view all the answers

What is an example of incomplete dominance?

A red flower and a white flower producing a pink flower. Signup and view all the answers

Study Notes

Mendel's Experiments and Principles of Inheritance

Gregor Mendel, a Moravian monk, conducted experiments using pea plants (Pisum sativum) to study inheritance.
Selected seven characteristics for study due to the observable variations: flower color, flower position, stem length, seed shape, seed color, pod shape, and pod color.
Demonstrated that traits are passed from parents to offspring, introducing the concept of genes as the basic unit of inheritance.

Laws of Inheritance

Law of Segregation states that gene pairs segregate equally into gametes, resulting in offspring inheriting one allele from each parent.
A gene's transition to offspring is random, with the specific allele that is passed on varying by chance.
Alleles are variants of a gene that control specific traits and can be dominant or recessive.

Genotype vs. Phenotype

Genotype: The genetic makeup of an organism, including expressed and non-expressed alleles. Organisms with the same phenotype may have different genotypes.
Phenotype: The observable traits resulting from the genotype, influenced by the expression of certain genes (e.g., hair color, eye color).

Dominance in Alleles

Dominant Alleles: Expressed if present; represented by capital letters (e.g., A).
Recessive Alleles: Only expressed in the absence of a dominant allele; represented by lowercase letters (e.g., a).
One dominant allele is sufficient for expression, whereas two recessive alleles are required for expression.

Types of Genotypic Combinations

Homozygous Dominant: Two copies of dominant genes (AA).
Heterozygous: One dominant and one recessive allele (Aa).
Homozygous Recessive: Two copies of recessive genes (aa).

Monohybrid and Dihybrid Crosses

Monohybrid Cross: Involves a single trait between two true-breeding organisms.
Dihybrid Cross: Involves two traits, with parents having hybrid combinations for both traits.

Punnett Square

A tool created by Reginald Punnett to predict genetic outcomes and probabilities of offspring traits.

Non-Mendelian Inheritance

Refers to inheritance patterns that do not follow Mendel’s laws, often involving more complex genetic interactions and traits.
Main types include:
- Dominant Traits: Dominant phenotype if at least one dominant allele is present.
- Recessive Traits: Undisplayed unless both alleles are recessive.
- Codominance: Both alleles expressed distinctly (e.g., red and white spots).
- Incomplete Dominance: Intermediate expression of traits (e.g., pink from red and white parents).

Genetic Problems and Predictions

Applications of the concepts through problem-solving exercises to predict offspring genotypes and phenotypes using Punnett Squares.
Involves scenarios such as blood type inheritance and coat color in cattle to reinforce understanding of genetic principles.

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Description

This quiz explores Mendel's groundbreaking experiments with pea plants and the foundational principles of inheritance he established. Delve into the significance of these experiments and their impact on the field of genetics. Test your knowledge about Mendelian and non-Mendelian inheritance concepts.