Alleles And Inheritance

Question 1

What did the experiments on pea plants determine about traits?

Answer 1

Traits are determined by alleles for any given characteristic.

Question 2

What does the combination of alleles in an organism represent?

Answer 2

Genotype.

Question 3

What is the expressed trait of an organism called?

Answer 3

Phenotype.

Question 4

What is the genotype of a yellow hybrid in pea plants?

Answer 4

Heterozygous (Yy).

Question 5

Fill in the blank: The parental generation in genetics is referred to as the _______.

Answer 5

P generation.

Question 6

What does homozygous mean?

Answer 6

Having two identical alleles for a given trait.

Question 7

What is the significance of the genotype in determining phenotype?

Answer 7

The genotype determines the expressed trait (phenotype).

Question 8

What does the Law of Segregation state?

Answer 8

During meiosis, the alleles of a gene separate randomly into individual gametes.

Question 9

What is the definition of genotype?

Answer 9

The genetic constitution of an organism, represented by alleles.

Question 10

What is the definition of phenotype?

Answer 10

The observable characteristics or traits of an organism.

Question 11

What is a Punnett Square?

Answer 11

A grid used to show the probability of offspring’s genotype and phenotype.

Question 12

What is the gamete genotype for a dominant yellow allele in pea plants?

Answer 12

Y

Question 13

What is the gamete genotype for a recessive green allele in pea plants?

Answer 13

y

Question 14

What is the phenotype ratio when two heterozygous pea plants are crossed?

Answer 14

75% yellow : 25% green (3:1)

Question 15

What is the genotype ratio for offspring from a cross of two heterozygous pea plants?

Answer 15

1 YY : 2 Yy : 1 yy (1:2:1)

Question 16

Fill in the blank: The dominant allele for color in pea plants is represented by _______.

Answer 16

Y

Question 17

Fill in the blank: The recessive allele for color in pea plants is represented by _______.

Answer 17

y

Question 18

What percentage of offspring will be homozygous dominant when crossing two heterozygous pea plants?

Answer 18

25%

Question 19

What percentage of offspring will be homozygous recessive when crossing two heterozygous pea plants?

Answer 19

25%

Question 20

What is a test cross?

Answer 20

To determine the presence of a recessive allele within an individual with dominant phenotype, by crossing them with a homozygous recessive individual

This helps identify if the dominant phenotype individual is homozygous or heterozygous.

Question 21

What are the genotypes and phenotypes of the offspring from a cross between BB and bb?

Answer 21

Genotype: 100% Bb, Phenotype: 100% brown

This scenario demonstrates a cross between homozygous dominant and homozygous recessive.

Question 22

What are the genotypes and phenotypes of the offspring from a cross between Bb and bb?

Answer 22

Genotype: 50% Bb, 50% bb; Phenotype: 50% brown, 50% blue

This scenario illustrates a cross between a heterozygous and a homozygous recessive individual.

Question 23

If an individual produces only offspring with a dominant phenotype, what can be concluded about that individual’s genotype?

Answer 23

The individual is homozygous dominant

This means they carry two dominant alleles.

Question 24

If an individual with a dominant trait produces even one offspring with a recessive phenotype, what can be concluded about that individual’s genotype?

Answer 24

The individual is heterozygous dominant

This means they carry one dominant allele and one recessive allele.

Question 25

What is the Law of Independent Assortment?

Answer 25

The principle that alleles for different traits segregate independently of one another during gamete formation.

This law is a key concept in genetics and was first formulated by Gregor Mendel.

Question 26

During which phase of meiosis does independent assortment occur?

Answer 26

Metaphase I.

In Metaphase I, homologous chromosomes align at the cell equator, allowing for independent assortment.

Question 27

What is the genotype of a dihybrid cross?

Answer 27

AaBb.

A dihybrid cross examines the inheritance of two different traits.

Question 28

What are the possible genotypes for a dihybrid cross between WwDd and WWdd?

Answer 28

• WWDd
• WwDd
• WWdd
• Wwdd

This is derived from combining the alleles of the two parents.

Question 29

What are genes located on the same chromosome called?

Answer 29

Linked genes

Linked genes do not segregate apart during meiosis and are often recombined together.

Question 30

What is the effect of linked genes on gamete genotypes?

Answer 30

Reduces the number of different possible gamete genotypes produced

This occurs because linked genes tend to be inherited together.

Question 31

What are the sex chromosomes in humans?

Answer 31

X and Y chromosomes

These chromosomes determine an individual’s biological sex.

Question 32

Where do most sex-linked traits occur?

Answer 32

On the X chromosome

This is typically represented as (X-linked) in Punnett squares.

Question 33

What are two examples of X-linked traits?

Answer 33

Colourblindness, hemophilia, baldness

These traits are affected by alleles located on the X chromosome.

Question 34

In X-linked traits, who is more affected by the recessive allele?

Answer 34

Males

Males have only one X chromosome, so they lack a second X chromosome that could mask the recessive allele.

Question 35

Fill in the blank: Genes located on the same chromosome are typically ______.

Answer 35

linked

Linked genes do not segregate apart during meiosis.

Question 36

True or False: All sex-linked traits are located on the Y chromosome.

Answer 36

False

Most sex-linked traits are located on the X chromosome.