Biology ch 9.7-9.15

heterozygous for the trait and able

A carrier of a genetic disorder who does not show symptoms is most likely to be ________ to transmit it to offspring.

karyotyping; biochemical testing Submit

Amniocentesis and chorionic villus sampling allow for ________ and ________ of the fetus so that it can be tested for abnormalities.

25%

Assuming that the probability of having a female child is 50% and the probability of having a male child is also 50%, what is the probability that a couple's first-born child will be female and that their second-born child will be male?

pleiotropy

Blood samples are taken from the heel of newborn babies to test for a mutation in the PKU gene, which, if left untreated and in severe cases, can lead to mental retardation, reduced skin pigmentation, and seizures. Which concept is being illustrated by this example?

PKU can be completely treated with dietary management of the amino acid phenylalanine, preventing any negative outcomes in the child, but the diet needs to be started immediately.

Blood samples are taken from the heel of newborn babies to test for a mutation in the PKU gene. Why is this so important?

Dd and Dd Submit

Dr. Smith's parents have normal hearing. However, Dr. Smith has an inherited form of deafness. Deafness is a recessive trait that is associated with the abnormal allele d. The normal allele at this locus, associated with normal hearing, is D. Dr. Smith's parents could have which of the following genotypes?

Her genotype cannot be determined. Submit

Imagine that a deaf male has a child with a hearing female. You know that the male must have the genotype dd, but the female could be either Dd or DD. If the couple's first child has hearing, can you determine the mother's genotype? (Hint: Draw Punnett squares for the two possible crosses.)

recessive alleles.

Most genetic disorders of humans are caused by

not affected at all by the disease.

Most people afflicted with recessive disorders are born to parents who were

pleiotropy.

Sickle-cell disease is an example of

both the interaction between genetics and the environment.

The individual features of all organisms are the result of

-If a deaf child is born to hearing parents, both parents must be Dd. -The child of a deaf man and a DD hearing woman will definitely have hearing. -If a deaf man and a hearing woman have a deaf child, the mother's genotype must be Dd.

Use the Punnett square from the introduction and the ones you drew for Part A to select the three statements that are true about the inheritance of this form of deafness.

1/6 + 1/6 = 1/3

Using a six-sided die, what is the probability of rolling either a 5 or a 6?

Most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce.

Which statement best explains why dominant alleles that cause lethal disorders are less common than recessive alleles that cause lethal disorders?

Height is determined by variations in more than a hundred genes as well as environmental conditions.

Which statement is true of the determination of height in humans?

Chorionic villus sampling is typically performed later in the pregnancy than amniocentesis.

Which statement regarding prenatal testing is false?

Sickle-cell disease causes white blood cells to be sickle-shaped. Submit

Which statement regarding sickle-cell disease is false?

polygenic inheritance

Which term refers to a situation where a single phenotypic character is determined by the additive effects of two or more genes?