Question 1

Brown eyes are dominant over blue eyes. Suppose that two brown-eyed parents gave birth to a blue-eyed child. It may be inferred that

Accepted Answer

Since brown eyes are dominant over blue eyes, a child can only have blue eyes if they inherit two recessive alleles for eye color. Therefore, both the mother and father must be heterozygous for brown/blue eyes, meaning they each have one dominant brown allele and one recessive blue allele. When they both pass down their recessive blue allele to their child, the child ends up with two recessive alleles for eye color, resulting in blue eyes. It is possible for two brown-eyed parents who are carriers of the recessive blue allele to have a blue-eyed child.

Question 2

The genetic characteristics of the ____ determine the baby's sexual identity.

Accepted Answer

A baby's sexual identity is determined by the sex chromosomes in the father's sperm. The sperm can carry either an X chromosome or a Y chromosome, while the mother's ovum always carries an X chromosome. If the fertilizing sperm carries an X chromosome, the resulting baby will be female (XX), and if it carries a Y chromosome, the baby will be male (XY). Therefore, the best choice is B - father's sperm.

Question 3

When a person is homozygous for an inherited trait, the alleles inherited from mother and father are

Accepted Answer

Homozygous means having two identical alleles for a particular gene. Therefore, if a person is homozygous for an inherited trait, both alleles inherited from the mother and father are the same.

Question 4

Genes have all the following functions EXCEPT

Accepted Answer

Genes do not determine the content of what is learned. Learning and environmental factors play a significant role in shaping a person's knowledge and experiences. Genes primarily function in controlling the expression of traits and features, guiding cellular differentiation, and producing specific amino acids for protein synthesis.

Question 5

DOMINANT TRAIT is to RECESSIVE TRAIT as ____ is to ____ in phenotypes.

Accepted Answer

Dominant traits are more likely to appear in the phenotype than recessive traits, making them more common, while recessive traits are less common or rare in occurrence.

Question 6

Two parents whose phenotypes both show a dominant trait will have a child who shows the recessive version of the trait

Accepted Answer

Both parents must carry a recessive allele for the trait in order for the child to receive two copies of the recessive allele, leading to expression of the recessive trait. This is known as a homozygous recessive genotype.

Question 7

Nature's principle for genetic sexual identity is,

Accepted Answer

The presence or absence of a Y-chromosome determines the genetic sex of an individual. If a person has an XY combination of chromosomes, they will develop as a male, and if they have an XX combination, they will develop as a female. Thus, the absence of a Y-chromosome means that the individual will develop as a female. Therefore, option B, "In the absence of a Y-chromosome, develop as a girl," is the correct answer.

Question 8

Mendel's experiments on the inheritance of dominant vs. recessive traits in pea seeds showed that

Accepted Answer

Mendel's experiments showed that the offspring's traits are not simply a blend of the parents' traits, but instead follow predictable patterns of inheritance based on the presence or absence of dominant and recessive alleles. This led to the development of Mendelian genetics and the understanding that traits are inherited through the passing down of specific genes. The options A, B, and C are incorrect because they do not accurately reflect the results or conclusions of Mendel's experiments.

Question 9

A baby's genetic sexual identity is determined when

Accepted Answer

A baby's genetic sexual identity is determined at conception when the sperm carrying either an X or Y chromosome successfully fertilizes the egg. If the sperm carries an X chromosome, the baby will develop as female, and if the sperm carries a Y chromosome, the baby will develop as male.

Question 10

A person who carries two dominant or two recessive genes is said to be ____ for that trait.

Accepted Answer

A person who carries two dominant or two recessive genes is homozygous for that trait. Heterozygous refers to a person who carries one dominant and one recessive gene for a particular trait. Codominant refers to two alleles that are equally dominant and are both expressed in the phenotype. Corecessive is not a term used in genetics.

Question 11

Genes exert their influences on development by

Accepted Answer

Genes manage the production of proteins, including amino acids, which are essential for cell development. Thus, genes control the development of the organism by directing the production of the necessary building blocks for cellular function and growth.

Question 12

One trait that illustrates the concept of simple dominant/recessive inheritance is

Accepted Answer

The answer of One trait that illustrates the concept of...

Question 13

During the 1800s, Gregory Mendel studied the inheritance of traits that are

Accepted Answer

Mendel's work focused on traits that were controlled by single pairs of genes. He studied pea plants and observed patterns of inheritance for traits such as flower color, seed shape, and plant height. His discoveries laid the foundation for the modern understanding of genetics.

Question 14

One notion of biological inheritance is that traits of the two parents are blended, like mixing paint colors, to form the phenotypic traits of the offspring. This notion was ____ Mendel's experimental results with peas.

Accepted Answer

Mendel's experimental results with peas showed that traits are inherited in a particulate (non-blended) manner, which disconfirmed the notion of blended inheritance.

Question 15

When a trait appears in an all-or-none fashion in the phenotype, then it is known that the trait

Accepted Answer

When a trait appears in an all-or-none fashion in the phenotype, it is mostly likely controlled by a single pair of genes, also known as a Mendelian trait. This is because the expression of the trait is either present or absent, which is determined by the presence or absence of the dominant allele in the gene pair. If the trait was controlled by a group of many pairs of genes, it would result in a more continuous variation rather than an all-or-none expression. The other options, such as learned experience and nutritional food intake, do not directly influence the genetic expression of a trait.

Question 16

A recessive trait will appear in the offspring's phenotype when its allele is inherited from

Accepted Answer

A recessive trait will only appear in the offspring's phenotype when both copies of the gene are inherited, one from the father and one from the mother. Therefore, the correct answer is D, both father and mother.

Question 17

Brown eyes are dominant over blue eyes. Two brown-eyed parents could have a blue-eyed child

Accepted Answer

Brown eyes are dominant, meaning a person needs only one brown-eyed allele to have brown eyes. A blue-eyed child from brown-eyed parents means each parent must carry a recessive blue-eyed allele, which the child inherits from both.

Question 18

One trait that illustrates the principle of codominance is

Accepted Answer

AB blood type is an example of codominance because both alleles are expressed equally, resulting in a phenotype that displays features of both alleles. In this case, individuals with AB blood type have both A and B antigens on their red blood cells, due to the codominant expression of both the A and B alleles. This is in contrast to incomplete dominance, where the heterozygote shows an intermediate phenotype between the two homozygotes, or complete dominance, where one allele completely masks the expression of the other.

Question 19

For traits that are determined by single pairs of genes, recessive traits occur on population phenotypes ____ than those of dominant traits.

Accepted Answer

Recessive traits are only expressed when an individual has two copies of the recessive allele. Therefore, they occur less often than dominant traits which only need one copy of the dominant allele to be expressed.

Question 20

The specific pairs of genes that control a characteristic are

Accepted Answer

The specific pairs of genes that control a characteristic are called alleles. Phenotypes refer to the physical and observable traits resulting from the interaction of genes and the environment. Ranges of reaction refer to the idea that the expression of a trait can vary depending on the environment. Autosomes are any chromosomes that are not involved in sex determination, whereas alleles are specific variations of a gene.

Quiz 2: Hereditary Influences on Development