Biology Chapter 20 Homework + Module

Sickle cell trait is an example of incomplete dominance. What is the percentage of each phenotype if a person with normal blood has a child with a person with sickle cell anemia?

100% sickle cell trait

Two people are carriers for the cystic fibrosis gene. What is the probability of having a child that does NOT have cystic fibrosis? What would be the genotype(s) of that child?

75%, FF or Ff

An albino child was born to two parents with normal skin. What are the likely genotypes of the parents?

Both parents are heterozygous

Theoretically, which of the following diseases should be the easiest to treat through gene therapy, considering the targeted organs and tissues where the corrected gene must be delivered?

Diabetes, since the target cells are found only in the pancreas

MODULE

KMS

Which of the following is the best definition for a gene?

A specific segment of a chromosome that encodes a protein

Which of the following chromosomes do you focus on to work on a treatment for BRCA2?

13

What can you say about the genotype of the offspring from one parent who is homozygous dominant for a trait with someone who is homozygous recessive for the same trait?

All offspring will be heterozygous for the trait.

Which of these gametes contains one or more recombinant chromosomes?

B and C

How is phenylketonuria normally tested?

Blood Samples

What do cystic fibrosis and albinism share in common?

Both are observed only in the recessive homozygous condition

The allele that causes cystic fibrosis is recessive. An individual who is heterozygous for cystic fibrosis

Is a carrier

While waiting in line for the school pictures, Alicia noticed that there was a lot of variation in height among her classmates. From this observation, what do you know about the inheritance pattern of height?

It is Polygenic

Which of the following genes is most similar to BRCA2?

RB gene, a tumor-suppressing gene linked to retinoblastoma.

When will the recessive trait show its phenotype?

Recessive homozygous individual

When does a dominant allele express its phenotype?

both in the homozygous and heterozygous conditions

If Sophie conceives a child, and the father neither has cystic fibrosis nor is a carrier, what are the chances that the child would have cystic fibrosis?

0%, because the child must receive the bad gene from both parents

If Sophie has a brother or sister from the same parents, what are the chances that sibling would have cystic fibrosis?

25%

A person with type A blood, one of whose parents is type O, has a child with a person with type B blood, one of whose parents is type O. What are the percentages of the different possible blood types?

25% A, 25% B, 25%AB, and 25% O

A woman named Julie is a carrier for color blindness. Julie marries David, who is color blind. What possible phenotypes can their children have?

25% color blind female, 25% carrier female, 25% color blind male, 25% normal male.

Peter is a normal male and has a child with Ann, who is a carrier for hemophilia. What possible phenotypes can their children have?

25% normal female, 25% carrier female, 25% normal male, 25% hemophiliac male

Sleeping in class is recessive. Two nonsleepers who each had one parent that were a sleeper had children. What percent of their children will be sleepers and what will be the genotypes of the sleeping children?

25%, ss

Huntington's disease is a dominant disorder. John lacks Huntington's and marries Jennifer, who has the disease. One of Jennifer's parents did not have Huntington's disease. What are the chances of Jennifer and John having a child with the disorder?

50%

Wavy hair is an example of incomplete dominance. WW = curly hair, Ww = wavy hair, and ww = straight hair. What is the percentage of each phenotype if a person with wavy hair has a child with a person with straight hair?

50% wavy hair and 50% straight hair

Which of the following is most obvious when you look at someone?

A dominant phenotype

Which of the following is the most accurate definition of phenotype?

A description of a person's appearance

A 9 : 3 : 3 : 1 ratio indicates _______.

A dihybrid cross

Which blood type cross will NOT yield type O blood?

AB x AB

Which of the following crosses could produce offspring with the recessive phenotype?

Aa x Aa

Which one is an example of a phenotype?

Ability to have x-ray vision

Which processes lead to most genetic variation in sexually reproducing organisms? SELECT ALL THAT APPLY

Crossing over Random Fertilization Independent Orientation of chromosomes in meiosis

Fragile X syndrome and cri-du-chat share what in common?

Both involve changes in the length of chromosomes

A man tests positive for BRCA2. Which of the following should he be monitored for?

Breast and Prostate Cancer

Which of the following do you think contributed the most to the success of Rhys' gene therapy?

Doctors were replacing only one gene, and they only had to insert that gene into bone marrow cells.

The genotype of a person with two copies of the same allele is __________ and the genotype of a person with two different alleles for a trait is __________.

Homozygous, Heterozygous

Most X-linked traits affect males and are passed down from their fathers.

False

Which of the following is LEAST likely to be a health problem for someone with cystic fibrosis?

Obesity

What is the term for a chart showing the genetic connections between individuals in a family?

Pedigree

The __________ of an individual is the physical expression of one or more genes of interest, and the __________ is the set of alleles the person possesses for the gene or genes of interest.

Phenotype, Genotype

A trait controlled by many genes is described as being __________.

Polygenic

Skin color is an example of _______.

Polygenic inheritance

You are a physician. A female patient tests positive for the BRCA2 gene. Which of the following would be best to tell her?

She has in increased risk of getting breast and ovarian cancer and should be monitored as such.

A woman tests positive for the BRCA2 mutation. Which of the following is true?

She inherited the gene from her mother or her father

Which of the following is an example of pleiotropy?

Sickle cell anemia

What is the best way to determine whether a genotype is heterozygous or homozygous dominant?

Study the person's pedigree

Which crosses are impossible for the grandparents if three out of six grandchildren have a particular trait and one parent of each of those children has the same trait?

TT x TT is impossible.

What does the law of segregation ensure?

That each gamete has only one allele for a given gene

Phenylketonuria (PKU) is a recessive disorder. John lacks PKU, and he has a child with Mary, who also lacks PKU. What are the chances of having a child with PKU?

There is not enough information to determine the chances of having a child with PKU.

What is TRUE about alleles?

There is one allele for a given gene when dealing with gametes.

A carrier is someone who displays the dominant phenotype but is heterozygous for a trait.

True

Alleles are alternative forms of a trait that can be inherited

True

The phenotype refers to the observable expression of the trait or traits.

True

Which cross is possible for the grandparents if three out of six grandchildren have a particular trait and none of grandparent's children have the same trait? The grandparents also do not have the trait.

Tt x Tx

If someone is a carrier of a recessive genetic disorder, it means he or she has __________ of the allele, and __________ exhibit symptoms of the disorder.

one copy; does not

Blood shows what type of genetic pattern(s)?

only codominance, recessive alleles, and multiple alleles

X-ray vision and the ability to turn invisible are found on separate chromosomes. Each trait is dominant. Two heterozygous people for each trait have a child. What is the genotype for a child that has no special abilities? X = x-ray vision, while x = normal vision. I = invisible, while i = normal vision.

xxii