Question 1

A trait within an organism that is present but not expressed is called

Accepted Answer

A trait within an organism that is present but not expressed is called a recessive trait.

Question 2

An observable trait, the trait that is actually seen, is labeled

Accepted Answer

A phenotype is the observable trait that is actually seen, while a genotype is the genetic makeup that determines the phenotype. Dominant and recessive are terms used to describe how traits are inherited, rather than the observable trait itself. Therefore, the best choice is D.

Question 3

If the child has an XX pairing on the 23^rd chromosome, the child will be

Accepted Answer

XX is the typical genetic pairing for a female, indicating that the child is most likely female.

Question 4

The one trait that is expressed when two competing traits are present is called

Accepted Answer

Dominant traits are expressed in the phenotype even when a competing recessive allele is present, overshadowing the expression of recessive traits.

Question 5

When a child receives different forms of a certain gene from his/her parents, he or she is said to be

Accepted Answer

When a child receives different forms of a certain gene from his/her parents, it means that the child is heterozygous. Homozygous means that the child received the same form of the gene from both parents, while dominant and phenotype are related to the expression of the gene, not the variation.

Question 6

A child's sex is determined by which biological factor?

Accepted Answer

A child's sex is determined by the father's sperm, which can contribute either an X or a Y chromosome to the fertilized egg. If the sperm carries an X chromosome, the child will be female, while if it carries a Y chromosome, the child will be male.

Question 7

When a child inherits similar genes for a given trait from his/her parents, the child is said to be ________ for that trait.

Accepted Answer

When a child inherits similar genes for a given trait from both parents, the child is said to be homozygous for that trait. This means the alleles from both parents are the same, either both dominant or both recessive.

Question 8

The underlying combination of genetic material present (but not outwardly visible) in an organism is called

Accepted Answer

The term "genotype" refers to the combination of alleles (forms of genes) an organism has for a particular trait. This combination is not always immediately visible in the organism's physical appearance, but instead can be carried as hidden genetic information. Therefore, genotype refers to the underlying genetic material present in an organism.

Question 9

What is the term applied to studying the effects of heredity on psychological characteristics and behaviour?

Accepted Answer

Behavioural genetics is the field of study that examines the role of genetic and environmental influences on behaviors and psychological traits.

Question 10

The 23^rd pair of chromosomes in males contains the ___- shaped chromosome.

Accepted Answer

This pair of chromosomes in males contains one X-shaped chromosome and one Y-shaped chromosome, resulting in a XY pair.

Question 11

Evan and Evelyn are twins but are not genetically identical.They are ________ twins.

Accepted Answer

Dizygotic or fraternal twins form from two separate eggs fertilized by two separate sperm, resulting in two genetically unique embryos. This is in contrast to monozygotic or identical twins, which form from one fertilized egg that splits into two genetically identical embryos. Gamete and zygote do not accurately describe the type of twins that Evan and Evelyn are.

Question 12

Twins who are produced when two separate ova are fertilized by two separate sperm at roughly the same time are called ________ twins.

Accepted Answer

The answer of Twins who are produced when two separate...

Question 13

In ________ inheritance, a combination of multiple gene pairs is responsible for the production of a particular trait.

Accepted Answer

Polygenic inheritance refers to the inheritance of a trait that is controlled by multiple gene pairs. This means that the phenotype of the trait is determined by the interaction of several different genes, each of which contributes a small amount to the trait. Examples of polygenic traits include height, skin color, and intelligence.

Question 14

What percentage of genes are shared by all humans?

Accepted Answer

Humans share 99.9% of their genes with each other, meaning that the genetic difference between any two individuals is only 0.1%.

Question 15

What is the name of the inherited disorder in which a child is unable to make use of an essential amino acid present in proteins found in milk and other foods and that has the potential to cause brain damage and mental retardation?

Accepted Answer

Phenylketonuria (PKU) is an inherited disorder that increases the levels of a substance called phenylalanine in the blood. If untreated, high phenylalanine levels can lead to intellectual disability and other serious health problems.

Question 16

What type of gene is considered recessive and located only on the X chromosome?

Accepted Answer

A gene located only on the X chromosome is referred to as X-linked. Since males only have one X chromosome, they will express any allele present on that chromosome regardless of its dominance or recessiveness. This type of inheritance is referred to as hemizygous. Females, on the other hand, can be either homozygous or heterozygous for an X-linked gene. In order for a trait to be expressed in a female, she must either be homozygous for the recessive allele or heterozygous and have the dominant allele on her other X chromosome masked the recessive allele.

Question 17

Of the following, which are the least likely to have multiple births?

Accepted Answer

Younger women are generally less likely to have multiple births compared to older women, women who take fertility drugs, and those with a family history of multiple births. Older women and those using fertility treatments have a higher likelihood of releasing more than one egg per cycle, increasing the chance of multiples. Genetics also plays a role in the likelihood of having multiples.

Question 18

________ twins are no more genetically similar than two siblings born at different times.

Accepted Answer

Dizygotic twins, also known as fraternal twins, occur when two separate eggs are fertilized by two different sperm. Therefore, they are no more genetically similar than two siblings born at different times who share different sets of genetic material from their parents. Monozygotic twins, on the other hand, come from a single fertilized egg that splits into two embryos, making them genetically identical.

Question 19

Eric has blue eyes.Since the gene for blue eyes is recessive, Eric must be ______ for that trait.

Accepted Answer

Since blue eyes are recessive, Eric must have two copies of the recessive gene to express the trait. Therefore, he is homozygous for the blue eye gene.

Question 20

Multiple births have _________ in the last 30 years due to fertility drugs and the rising average age of mothers giving birth.

Accepted Answer

Multiple births have increased in the last 30 years due to the widespread use of fertility drugs and the increasing trend of women waiting until they are older to have children. Both of these factors increase the likelihood of multiple births.

Quiz 2: The Start of Life