Chapter 11

Question 1

What did Gregor Mendel do and how was this significant to the scientific community

Answer 1

Gregor Mendel, an Austrian scientist, conducted groundbreaking experiments on pea plants in the mid-19th-century. He established the basic principles of hereditary, uncovering the laws of inheritance. His work laid the foundation for modern genetics and was crucial in understanding how traits are passed from one generation to the next

Question 2

Describe the relationship between genotypic and phenotypic ratios

Answer 2

The genotypic ratio represents the proportion of different genetic combinations resulting from a genetic cross, while the phenotypic ratio describes the proportion of observable traits within the offspring. In Mendelian inheritance, these ratios often exhibit a direct correspondence, but factors such as multiple gene involvement, epistasis, and environmental influences can lead to variations between genotypic and phenotypic ratios.

Question 3

What is the law of segregation?

Answer 3

The Law of segregation states that during the formation of gametes, the two alleles for a gene segregate or separate, so each gamete carries only one allele for each gene. This separation ensures that each offspring receives one allele from each parent during fertilization.

Question 4

How would you work through a test cross of mendelian traits?

Answer 4

To conduct a test cross, an individual with an unknown genotype (but expressing the dominant phenotype) is crossed with a homozygous recessive individual. Analyzing the phenotypic ratios of the offspring helps determine the unknown genotype.

Question 5

What ar alleles and how do they contribute to genetic diversity produced in meiosis?

Answer 5

Alleles are alternative forms of a gene, located at a specific position on a chromosome. They contribute to genetic diversity during meiosis by segregating and recombining, producing various combinations of alleles in gametes.

Question 6

What is the difference between a genotype and a phenotype?

Answer 6

Genotype refers to the genetic makeup of an organism, including the combination of alleles it carries. Phenotype is the observable physical or biochemical expression of the genotype.

Question 7

How would you work through a monohybrid cross? Dihybrid?

Answer 7

In a monohybrid cross, you examine the inheritance of a single trait. In a dihybrid cross, you study the inheritance of two traits simultaneously. Punnett squares can help predict the genotypic and phenotypic ratios of the offspring.

Question 8

What is the multiplication rule and how could you apply it to monohybrid crosses?

Answer 8

The multiplication rule states that the probability of two independent events occurring together is the product of their individual probabilities. In monohybrid crosses, you multiply the probabilities of individual allele combinations to determine the probability off a specific genotype.

Question 9

What is the addition rule and how could you apply it to monohybrid crosses?

Answer 9

The addition rule states that the probability of either of two mutually exclusive events occurring is the sum of their individual probabilities. In monohybrid crosses, you add the probabilities of different genotypes to determine the overall probability of a particular phenotype.

Question 10

What is the difference between incomplete dominance and codominance?

Answer 10

Incomplete dominance occurs when heterozygotes display an intermediate phenotype between the two homozygotes. Codominance occurs when both alleles are expressed fully in the heterozygote, resulting in a distinct phenotype.

Question 11

What is the relationship between dominance and phenotype?

Answer 11

Dominance determines the phenotypic expression of a particular allele. In a heterozygote, the dominant allele masks the expression of the recessive allele, leading to a specific phenotype.

Question 12

How are phenotypes affected by genes with more than two allelic forms?

Answer 12

When genes have more than two allelic forms, multiple alleles can influence the phenotype. However, an individual still carries two alleles at a specific gene locus.

Question 13

What is Pleiotropy

Answer 13

Occurs when a single gene influences multiple traits or has effects in different aspects of an organisms phenotype

Question 14

How does epistasis affect phenotypes?

Answer 14

Epistasis occurs when the expression of one gene masks or modifies the expression of another gene. it can alter the expected phenotype ratios in a dihybrid cross

Question 15

What is quantitative variation and how does this relate to polygenic inheritance?

Answer 15

involves traits that exhibit a range of phenotypes. Polygenic inheritance refers to the influence of multiple genes on a single trait, contributing to continuous variation in phenotypes.

Question 16

How are pedigree analyses created and used?

Answer 16

Pedigree analyses are visual representations of a family’s genetic history. They help trace the inheritance of traits and disorders across generations, aiding in the identification of patterns and carriers.

Question 17

How does a recessively inherited disorder look in a pedigree analysis?

Answer 17

In a pedigree analysis, a recessively inherited disorder often appears when two carriers (heterozygotes) have affected offspring. This disorder may skip generations and show up when two carriers have children.

Question 18

What are multifactorial disorders?

Answer 18

multifactorial disorders result from the interaction of genetic and environmental factors. They often involve the contribution of multiple genes, making prediction and prevention more complex.

Question 19

How are dominantly inherited disorders passed on through generations?

Answer 19

They appear in every generation, as individuals with even one copy of the dominant allele express the disorder. Affected individuals usually have an affected parent.

Question 20

Allele

Answer 20

An allele is one of the alternative forms of a gene that occupies a specific position (locus) on a chromosome. Alleles can exist in multiple variations, influencing the expression of a particular trait.

Question 21

Dihybrid Cross

Answer 21

A dihybrid cross involves the simultaneous examination of the inheritance of two different traits. It helps predict the genotypic and phenotypic ratios of offspring when parents differ in two specific characteristics.

Question 22

Gene

Answer 22

A gene is a segment of DNA that contains the instructions for building one or more molecules that help determine an organism’s traits. Genes are located at specific positions on chromosomes.

Question 23

Genetic Cross

Answer 23

A genetic cross is an experimental breeding between individuals to study the inheritance of traits and predict the genetic makeup of their offspring.

Question 24

Locus

Answer 24

The specific position of a gene on a chromosome

Question 25

Monohybrid cross

Answer 25

A monohybrid cross involves the examination of the inheritance of a single trait. It helps predict the genotypic and phenotypic ratios of offspring from parents differing in one characteristic.

Question 26

P, F1, and F2

Answer 26

P represents the parental generation, F1 is the first filial generation (offspring of the P generation), and F2 is the second filial generation (offspring of the F1 generation).

Question 27

Progeny

Answer 27

Progeny refers to the offspring or descendants produced by parents in a genetic cross

Question 28

Testcross

Answer 28

A testcross involves breeding an individual with an unknown genotype (expressing a dominant phenotype) with a homozygous recessive individual to reveal the unknown genotype.

Question 29

True Breeding

Answer 29

True-breeding organisms are those that, when self-fertilized or cross-fertilized with another true-breeding individual, produce offspring with the same traits as the parents.

Question 30

Product Rule

Answer 30

used to calculate the probability of two independent events occurring together. In genetics, it helps determine the probability of a specific GENOTYPE in offspring.

Question 31

Sum Rule

Answer 31

The sum rule is used to calculate the probability of either of two mutually exclusive events occurring. In genetics, it helps determine the probability of a specific PHENOTYPE in offspring.

Question 32

Mutually Exclusive Events:

Answer 32

Mutually exclusive events are events that cannot occur simultaneously. In genetics, mutually exclusive events refer to the inheritance of one trait excluding the inheritance of another trait.

Question 33

Pedigree

Answer 33

A pedigree is a graphical representation of the genetic relationships within a family over several generations. It helps trace the inheritance of traits or genetic disorders.

Question 34

Carrier

Answer 34

A carrier is an individual who carries and can transmit a recessive allele for a genetic disorder but does not express the disorder themselves.

Question 35

Pleiotropy:

Answer 35

the production by a single gene of two or more apparently unrelated effects.

Question 36

Epistasis

Answer 36

Epistasis is a genetic interaction where the expression of one gene masks or influences the expression of another gene.

Question 37

Co-dominance

Answer 37

Co-dominance occurs when both alleles in a heterozygous individual are fully expressed, resulting in a phenotype that shows characteristics of both alleles.

Question 38

Polygenic inheritance

Answer 38

Polygenic inheritance involves the influence of multiple genes on a single trait, leading to a wide range of phenotypic variations.

Question 39

Incomplete dominance

Answer 39

Incomplete dominance occurs when the heterozygous phenotype is an intermediate blend of the homozygous phenotypes, neither allele being fully dominant.