Question 1

Diseases carried by recessive genes are inherited when a child __________.

Accepted Answer

Diseases carried by recessive genes are only expressed when a child inherits two recessive genes, one from each parent. When a child inherits only one recessive gene and the other gene is dominant, they become a carrier of the disease but do not express the symptoms themselves.

Question 2

A trait controlled by a dominant gene will __________.

Accepted Answer

A trait controlled by a dominant gene will be expressed even when the corresponding gene in the other half of the pair is different. This is because dominant genes are able to express their trait even in the presence of a different gene on the other chromosome. The presence of a dominant allele will always lead to the expression of the trait it controls. Therefore, option A is the correct answer.

Question 3

A(n) __________ is a section of DNA containing a sequence of amines.

Accepted Answer

A gene is a section of DNA that contains a sequence of nucleotides, which code for a specific protein or characteristic. Amines are a type of organic molecule that contain one or more nitrogen atoms, and are not typically found in DNA.

Question 4

Eliza was born a female with only one X chromosome on the 23rd pair. As a result, she is very short, infertile, and sexually underdeveloped. Eliza is likely to be diagnosed with __________.

Accepted Answer

Turner syndrome is caused by a complete or partial absence of one X chromosome in females. This results in short stature, infertility, and underdeveloped sexual characteristics. PKU and Down syndrome are caused by genetic mutations unrelated to X chromosome abnormalities. Klinefelter syndrome is caused by an extra X chromosome in males.

Question 5

In __________ syndrome, the 23rd pair of chromosomes is missing an X, resulting in short, infertile females.

Accepted Answer

Turner syndrome is characterized by a missing X chromosome (45,X) in the 23rd pair, resulting in short stature, infertility, and other physical abnormalities. PKU (phenylketonuria) is a genetic disorder that affects metabolism, Down syndrome is caused by a trisomy of chromosome 21, and Klinefelter syndrome is characterized by an extra X chromosome in males (47,XXY).

Question 6

Aaron has cystic fibrosis. This means that his mother is a carrier for the cystic fibrosis gene, while his father __________.

Accepted Answer

Cystic fibrosis is an autosomal recessive disorder, meaning that for Aaron to have cystic fibrosis, he must have inherited one defective gene from each parent. Therefore, both his mother and his father must be carriers of the cystic fibrosis gene.

Question 7

A gene that only influences the expression of a trait when paired with another less active gene is called __________.

Accepted Answer

A gene that only influences the expression of a trait when paired with another less active gene is called recessive. This means that the trait will only be expressed if there are two copies of the recessive allele present. If there is at least one dominant allele present, the trait will be expressed regardless of whether a recessive allele is also present.

Question 8

A gene that actively controls the expression of a trait is called a __________ gene.

Accepted Answer

A dominant gene is one that actively controls the expression of a trait and is able to mask the effects of a recessive gene. This means that if an individual inherits a dominant gene from one or both parents, the trait associated with that gene will be expressed in their phenotype.

Question 9

At fertilization, the chromosomes from the father's sperm unite with the chromosomes from the mother's egg, creating a new cell called a(n) __________.

Accepted Answer

At fertilization, the sperm and egg unite to form a single cell known as a zygote. The zygote contains a complete set of chromosomes, half from the mother and half from the father, and it is the beginning of a new individual's life. Embryo, genome, and blastocyst refer to different stages in the development of the zygote, but they are not the immediate result of fertilization.

Question 10

A special molecule called __________ contains the genetic material of the organism.

Accepted Answer

DNA (deoxyribonucleic acid) is the special molecule that contains the genetic material of the organism. Genes are segments of DNA that code for a specific trait or characteristic. Chromosomes are structures made up of DNA that are organized into pairs and contain many genes. Amines are a class of organic compounds and are not related to genetic material.

Question 11

In __________ syndrome, the 21st pair of chromosomes contains an extra chromosome, resulting in symptoms such as wide-set, almond-shaped eyes and intellectual disability.

Accepted Answer

Down syndrome occurs when there is an extra copy of chromosome 21, resulting in physical and intellectual developmental delays. Symptoms often include almond-shaped eyes, a flat face, and a small head.

Question 12

What is the cause of Down syndrome?

Accepted Answer

Down syndrome is caused by the presence of an extra chromosome on the 21st pair, resulting in a total of 47 chromosomes instead of the typical 46. This extra genetic material can lead to developmental and intellectual delays, characteristic facial features, and other health problems.

Question 13

David was born a male with an extra X chromosome on the 23rd pair. As result, he has reduced masculine characteristics, enlarged breasts, and is obese and excessively tall. David is likely to be diagnosed with __________.

Accepted Answer

Klinefelter syndrome is a genetic disorder caused by the presence of an extra X chromosome in males. This leads to reduced masculine characteristics, enlarged breasts, obesity, and excessive height. PKU (phenylketonuria) is a metabolic disorder, Down syndrome is caused by an extra chromosome 21, and Turner syndrome is caused by a missing or incomplete X chromosome in females. None of these conditions match David's symptoms.

Question 14

Ovum is a term used to describe the __________.

Accepted Answer

Ovum specifically refers to the female sex cell or egg. The other choices refer to different stages of development after fertilization.

Question 15

Which of the following is defined as a gene that controls the expression of a certain trait?

Accepted Answer

A gene that controls the expression of a certain trait is known as a dominant gene. Dominant genes mask the expression of recessive genes and determine the physical appearance or characteristics of an organism. Mutated genes refer to genes that have undergone a change in their sequence or structure, while recombinant genes are created by combining genetic material from multiple sources.

Question 16

Rod-shaped structures in the cell nucleus that contain genes are referred to as __________.

Accepted Answer

Chromosomes are the structures in the cell nucleus that contain genes. DNA is the molecule that makes up the structure of chromosomes, but it is not the structure itself. Sex-linked traits are traits that are located on the sex chromosomes, but they are not the same as chromosomes themselves. Amines are a class of organic compounds and are not related to chromosomes.

Question 17

Which of the following is a special molecule that contains the genetic material of the organism?

Accepted Answer

DNA (Deoxyribonucleic acid) is the genetic material that carries the hereditary information of an organism. It is a special molecule made up of four nucleotide bases (adenine, guanine, cytosine, and thymine) that form the genetic code. Genes are segments of DNA that contain instructions for making specific proteins, and chromosomes are structures that contain long strands of DNA wrapped around proteins. Amines are organic compounds that contain nitrogen and are not directly related to genetic material.

Question 18

In normal developmental cases, humans have a total of __________ chromosomes.

Accepted Answer

Humans have 23 pairs of chromosomes, for a total of 46 chromosomes in normal developmental cases.

Question 19

How many pairs of chromosomes are normally in each cell of the human body?

Accepted Answer

Each cell in the human body normally contains 23 pairs of chromosomes, which is a total of 46 chromosomes. Half of these chromosomes are inherited from the mother and the other half from the father.

Question 20

Liv has blond hair, even though her mother and father each have brown hair. What do we know about Liv's parents?

Accepted Answer

Liv inherited one recessive gene for blond hair from each of her parents, which means both her parents must have at least one recessive gene for blond hair color.

Quiz 8: Development Across the Life Span