Genetics

Sickle cell is a recessive trait, only individuals with two copies of the mutated allele end up with sickle cell disease. A father who is homozygous recessive has sickle cell disease, the mother is heterozygous for this same trait and does not have sickle cell disease. The same father is heterozygous for the widows peak hairline, while the mother is homozygous recessive and expresses a straight hairline. These parents then have an offspring who has sickle cell and a straight hair line. Which of the following statements gives the best explanation for why the offspring has inherited the sickle cell trait and the straight hair line trait?

• The law of dominance states that only dominant traits can be inherited together by the offspring

• The law of independent assortment states that alleles for each trait are passed to offspring independently.

• The law of segregation states that traits must be inherited separately and can never be inherited by one offspring.

• The law of inheritance states that all traits must come from either the mother or the father and all traits are inherited together.

The theory of evolution can help scientists better understand certain inherited diseases. For example, natural selection explains why many African populations have high frequency of the allele that causes sickle cell disease. Individuals with just one copy of the allele are resistant to the disease malaria, which is common in Africa.

Why would sickle cell disease become common in African populations?

• Individuals with the allele were able to resist malaria and survive and reproduce.

• Malaria forced the African populations to mutate a new allele to survive.

• Having sickle cell disease is beneficial to the human populations and just started in Africa.

• There is no advantage to having a sickle cell allele in African populations.

Which of these choices best describes a pedigree?

• an illustration that shows the genetic diversity among different species

• a hypothesis that explains why genes are recessive or dominant

• a diagram of family relationships that includes several generations

• a diagram that lists alleles of two parents and shows the possible allele combinations of their offspring

Carrie is studying the genes of two fruit flies in her lab. She knows what alleles they have. She wants to know the potential combinations of alleles their offspring could inherit. Which of these choices would help Carrie identify the potential combinations?

• an allele

• a carrier

• a pedigree

• a Punnett Square

Pea plants produce green or yellow peas. The gene for yellow peas is dominant and the gene for green peas is recessive. Say two yellow pea plants are crossed and produce three yellow pea plants and one green pea plant. What are most likely the genotypes of the yellow pea plants?

• Both are homozygous yellow pea plants.

• One is homozygous yellow and the other is homozygous green.

• One is heterozygous yellow and the other is homozygous yellow.

• Both are heterozygous yellow pea plants.

Raylene inherited certain physical characteristics from her parents. Which of these follow is not an inherited characteristic?

• blue eyes

• wavy, red hair

• dimpled cheeks

• long fingernails

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

In humans, brown eyes (B) are dominant over blue (b)*. A brown-eyed man marries a blue-eyed woman and they have three children, two of whom are brown-eyed and one of whom is blue-eyed. Draw the Punnett square that illustrates this marriage. What is the man’s genotype?

• BB

• Brown Eyes

• Bb

• Impossible to determine with the information provided

In his laboratory, Jin is studying the genetics of mice. For a particular trait, an adult female mouse has the alleles AA, and an adult male mouse has the alleles Aa. Which of these questions could Jin answer by using a Punnett square?

• Do these two adult mice have any other alleles in common?

• Are AA and Aa the only alleles present in these two adult mice?

• Is this gene associated with an inherited trait or an acquired trait?

• What possible combinations of alleles could the offspring of these adults inherit?

predicts the outcomes for the children

• Phenotype:100% of the offspring will be straight hair

• Phenotype: 50% of the offspring will be straight hair and 50% curly hair

• Genotype: 0 % of the offspring will be Cc

• Genotype: 50% of the offsprings will be CC

What are the parents alleles

• BB and BB

• BB and Bb

• Bb and Bb

• Bb and bb