Question 1

Genotypes are the outward expression of an allele combination.

Accepted Answer

The outward expression of an allele combination is the phenotype.

Question 2

In the section "Investigating Life: Heredity and the Hungry Hordes",what did the researchers conclude from the data in the figure?

Accepted Answer

The researchers concluded that resistance to Bt toxin is recessive because the data showed that only larvae with two copies of the resistance allele survived in the presence of the toxin.

Question 3

Place the following events in the correct order in which they occur: fertilization,haploid gametes produced,meiosis of diploid cell,and new diploid organism formed.

Accepted Answer

The independent assortment of alleles into gametes leads to fertilization by such gametes. This, in turn, leads to a wide range of diploid genotypes.

Question 4

A recessive allele is one whose effect is masked if a dominant allele is also present.

Accepted Answer

This is the definition of a recessive allele, meaning it can only be expressed in the absence of a dominant allele.

Question 5

The most common allele for any trait is always the dominant allele.

Accepted Answer

The most common allele for any trait is not always the dominant allele. The frequency of an allele in a population depends on a variety of factors, including selective pressure and genetic drift, and may not necessarily be related to whether it is dominant or recessive.

Question 6

The environment only rarely affects gene expression.

Accepted Answer

The environment can have a significant impact on gene expression, especially during critical periods of development. Factors such as diet, stress, exposure to toxins, and social experiences can all influence gene expression. This is known as epigenetics, which refers to changes in gene function that result from modifications to DNA or chromatin that do not involve changes to the underlying DNA sequence.

Question 7

The wide variation in skin color in humans is best explained by

Accepted Answer

Skin color is determined by multiple genes, each contributing a small effect to the overall variation in skin color. Therefore, skin color is a polygenic trait. Other factors, such as exposure to sunlight, can also contribute to variations in skin color but do not explain the full range of human skin tones.

Question 8

Sexual reproduction passes on hereditary information through

Accepted Answer

Gametes are produced through meiosis, which reduces the amount of genetic material in each cell by half. This allows for genetic variation to occur in offspring, as each parent contributes a unique set of chromosomes to their offspring. Autosomes and sex chromosomes both play a role in passing on hereditary information, but it is only through the combination of both sets of chromosomes in a fertilized egg that the full genetic information of an individual is passed on. Linked genes do not play a direct role in sexual reproduction.

Question 9

Place the following terms in order from smallest to largest: cell,chromosome,DNA nucleotides,and gene.

Accepted Answer

DNA nucleotides are the smallest units, forming genes. Genes are segments of DNA on chromosomes, which are structures within cells.

Question 10

Each gamete arises from a diploid cell containing two sets of homologous chromosomes.

Accepted Answer

Gametes are haploid cells that are formed through meiosis from a diploid parent cell. During meiosis, the parent cell undergoes two rounds of cell division, resulting in four haploid daughter cells. Each daughter cell contains only one set of chromosomes, unlike the parent cell which had two sets of homologous chromosomes.

Question 11

Mendel's law of segregation states that the two alleles of each gene are packaged into separate gametes.

Accepted Answer

This is the correct statement of Mendel's law of segregation. It means that during gamete formation, the two copies of a gene (one from each parent), which may be different alleles, separate from each other so that each gamete receives only one allele.

Question 12

The individual sometimes referred to as the "father of genetics" because he influenced the science of genetics more than anyone else is Gregor Mendel.

Accepted Answer

Gregor Mendel is widely regarded as the "father of genetics" because of his groundbreaking work on the inheritance of traits in pea plants in the mid-19th century, which laid the foundation for understanding the principles of genetic inheritance.

Question 13

A male expresses an X-linked recessive disorder only if he inherits these alleles from both parents.

Accepted Answer

The answer of A male expresses an X-linked recessive disorder...

Question 14

Any dihybrid cross should theoretically yield a 3:1 phenotypic ratio.

Accepted Answer

A dihybrid cross involves two traits, each with two alleles, resulting in four possible gamete combinations. If the alleles assort independently (meaning they are on different chromosomes), then the expected phenotypic ratio would be 9:3:3:1, not 3:1. The 3:1 ratio only applies to a monohybrid cross involving one trait with two alleles.

Question 15

For the traits Mendel studied one allele is completely dominant and the other is completely recessive.

Accepted Answer

Mendel's laws of inheritance are based on the concept of dominance and recessiveness of alleles. According to his experiments, one allele is completely dominant over the other, and hence it expresses its trait in the offspring, while the other allele remains hidden in the background.

Question 16

What structure holds the inheritance information of a living organism?

Accepted Answer

Chromosomes hold the genetic information of an organism, including information about inheritance. These structures contain genes, which are passed on from parents to offspring during reproduction. Monohybrid and dihybrid crosses are experimental methods used to study inheritance patterns, while phenotype refers to the observable physical characteristics of an organism. Mitosis and meiosis are cellular processes involved in cell division and reproduction, but they do not specifically hold inheritance information.

Question 17

In the ABO blood type system,there are six possible genotypes,but only two possible phenotypes.

Accepted Answer

In the ABO blood type system, there are three possible alleles (A, B, and O) resulting in 6 possible genotypes (AA, AB, AO, BB, BO, OO) and four possible phenotypes (A, B, AB, and O). Therefore, there are more than two possible phenotypes.

Question 18

In the section "Investigating Life: Heredity and the Hungry Hordes",adult female bollworm moths lay eggs on cotton bolls.These eggs then hatch and grow into caterpillars that eat the seeds of the boll.Eggs and sperm produce by

Accepted Answer

Meiosis is the process that produces eggs and sperm, which are the gametes necessary for sexual reproduction.

Question 19

Crossing over is used to create a chromosome map of linked genes to determine the

Accepted Answer

Crossing over occurs during meiosis, when homologous chromosomes exchange genetic material, including linked genes. By analyzing the frequency of crossing over events, scientists can create a chromosome map of the relative locations of these linked genes on the chromosome. This information can be used to determine the locus, or specific location, of each gene.

Question 20

X-linked recessive disorders affect more females than males.

Accepted Answer

X-linked recessive disorders are more likely to affect males than females. This is because males only have one X chromosome, so if that X chromosome carries a disease-causing gene, they will develop the disorder. Females, on the other hand, have two X chromosomes, so even if one X chromosome carries the gene, the other X chromosome may carry a normal gene that can compensate for it. In rare cases, females can also develop X-linked recessive disorders if both of their X chromosomes carry the disease-causing gene.

Quiz 10: Patterns of Inheritance