BIOS 1404 test 4 - –Answer recessive 2. When two individuals who...

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BIOS 1404 test 4

• An allele masked or hidden by the presence of another is referred to as

–Answer recessive

• When two individuals who are heterozygous for a trait mate, what is the probability that

their offspring will exhibit the dominant trait?–Answer 75%

• When Mendel crossed two "true-breeding" pea plants with contrasting traits (e.g., tall versus

short), why did all the plants from the first (F1) generation only show one of the traits?–Answer All of the F1 generation was heterozygous for the trait.

• Mendel showed that only one of two factors (genes) associated with a trait is present in

gametes. This is known as the –Answer

–Answer law of segregation

• Mendel's Law of Segregation has which of the following relationships to the concept of

homologous chromosomes?–Answer One set of homologous contain one version of all the genes.

• The two forms of genes found in the same location on the homologous chromosomes are

called

–Answer alleles

• Explain the observation that recessive diseases often "skip a generation"?-
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–Answer Recessive alleles are not expressed in heterozygotes.

• Which enzyme is responsible for new DNA synthesis?

–Answer DNA polymerase

• Which of the following happens first in DNA replication?

–Answer The strands un- wind.

• Which of the following strands of DNA is(are) copied during DNA replica- tion

–Answer both the 5' to 3' and the 3' to 5' strands

• In which direction does DNA polymerase add new nucleotides?

–Answer 5' to 3'

• How would you determine if a human cell came from a genetic female?

–Answer - Look for the presence of a Barr body.

• The phenotype of women with more than one X chromosome is relatively normal

compared to other trisomies? Why?–Answer They can simply form two Barr bodies, leaving them with one active X chromosome.

• Which of the following proteins ensures that separated DNA strands don't anneal back

together?–Answer single-stranded binding proteins

• What is the area of DNA where DNA replication begins called?

–Answer origin of replication

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