bio exam 2 study guide
Humans have ________ pairs of homologous chromosomes.
23
Suppose Dwere dominant and dwere recessive, and you could label the Dallele in the P generation with a radioactive substance that could be inherited over several generations. You create hybrids by mating your radioactive DDindividuals to ddindividuals. Finally, you cross two F1 individuals (with the Ddgenotype). In 1,000 offspring, how many would you predict would be radioactive?
750
Which of the following statements is NOT true?
A genotype is always expressed in the phenotype.
A person is genetically XX and develops as a male. How can this be explained?
A piece of a Y chromosome has become attached to one of the X chromosomes.
The leaf color of a certain plant is controlled by one gene. For that gene, the allele G= orange and g= green. You have a plant with orange leaves, but do not know whether that plant's genotype is GGor Gg. Which of the following would help you determine the plant's genotype?
Cross the plant to a plant with green leaves.
Which of the following represents all of the possible gametes that can be formed by an individual with the genetic makeup FfGgHH?
FGH, FgH, fGH, fgH
Both members of a couple are carriers for a recessive disease allele. If the couple has four children, which of the following statements must be true?
Fifty percent of the children could be carriers of the disease.
During cell division a piece of a chromosome breaks off and reattaches to the same chromosome, but the piece is now in reverse order. How would this abnormality affect the chromosome?
Genes in the section that was inverted could lose normal function.
A karyotype of an individual with mild mental retardation shows three copies of the X chromosome. If this individual decides to have children, how is her chromosomal abnormality likely to affect her offspring?
Half of her eggs will contain an extra copy of the X chromosome.
Which of the following statements regarding genes is NOT true?
In sexually reproducing species, each cell contains a single copy of every gene.
Which of the following is true for mutations?
Mutations will affect the genotype, which may affect the phenotype.
Because an individual with an XX genotype is a female, is an individual with an XO (no second sex chromosome) a male?
No, because the Y chromosome contains the gene that makes an embryo male.
In a particular plant, two genes control leaf shape and color. Round leaves (R) are dominant to jagged leaves (r). Yellow fruits (Y) are dominant to white fruits (y). A true-breeding round-leaved, yellow-fruited plant is mated with a jagged-leaved, white-fruited plant. What are the genotypes of the plants involved in this cross?
RRYY × rryy
Which of the following did Gregor Mendel notice in garden peas?
Some plants always produced offspring with flowers that were the same color as the parent plant's flowers.
In which of the following situations would it become nearly impossible to predict the phenotype of an individual with a known genotype?
The environment affects the phenotype.
Two organisms that are true-breeding for a certain genetic characteristic are mated and their offspring analyzed. Which of the following statements about this situation is true?
The offspring are either 100 percent homozygotes or 100 percent heterozygotes.
Which of the following statements is a basic summary of one of Mendel's laws?
The separation of alleles for one gene does not affect the separation of alleles for other genes.
If you compare a sperm cell in a human to a skin cell from the same individual, which of the followingdifferences would you expect to find?
The sperm cell would contain only one allele for a given gene; the skin cell wouldcontain two alleles.
Which of the following statements about homologous chromosomes is true?
They contain the same genes in the same locations.
The figure shown indicates two Labrador retrievers that are both homozygous recessive for fur color. Why is one dog brown and the other is yellow?
This is an example of epistasis.
Which of the following expresses Mendel's law of segregation?
Two alleles of a gene separate during meiosis and end up in different gametes.
Which of the following statements is NOT true?
Two organisms with the same genotype are homozygous.
BbCCdd
Which of the following choices represents the genotype of an individual diploid organism?
Which of the following genotypes represents a human male?
XY
A karyotype from an adult male indicates a chromosomal abnormality, which does not affect his health. Which of the following abnormalities is most likely seen?
a translocation between chromosome 14 and chromosome 15
allele
a version of a gene.
Chromosomes that are NOT involved in determining gender are known as
autosomes
Two genes control fur color in Labrador retrievers. The first gene determines whether the pigment to be deposited in the hairs will be black or brown. The second gene determines whether the pigments are put into the dog's hairs at all. A dog homozygous for the recessive allele of this second gene will be yellow because no pigment is deposited in its hairs. This is an example of
epistasis.
The X chromosome in humans is
found as a pair in females.
In the Punnett square shown below, the lettered circles on the top and left of the square (indicated by the arrows) represent the
gametes that may be produced by each parent involved in the cross.
Mendel used ________ as his research organism to study patterns of genetic inheritance.
garden peas
In the pedigree shown, the individual indicated represents a(n)
healthy female.
A chestnut-colored horse is mated with a cremello (cream-colored) horse. Over a 10-year period, all of their offspring are palominos. This pattern of inheritance is best explained by
incomplete dominance.
When Mendel proposed the law of segregation, which of the following pieces of information did he NOT have?
knowledge of the location of the alleles for flower color
In humans, the "master sex switch" that determines whether an embryo will become a male is the
locus
Mendel's laws of segregation and independent assortment both have their biological basis in events that take place during
meiosis.
In a genetic cross of Ggwith Ggguinea pigs, none of the four offspring were gg. This
neither supports nor disproves Mendel's law of independent assortment.
A ________ is a chart that shows genetic relationships within a family over several generations.
pedigree
One of the first medical tests a newborn receives determines if the child has phenylketonuria (PKU). PKU is the result of a mutation in a single gene that causes mental retardation and a host of other phenotypes (light hair and skin color, eczema, and a "mousy" smell). By detecting PKU early, doctors are able to reduce the effect of this condition with a modified diet. PKU is an example of
pleiotropy.
A Punnett square is used to
predict the outcome of a genetic cross.
Most inherited human genetic disorders are inherited as ________ alleles.
recessive
An allele that appears more frequently in males is most likely
sex-linked.
In Mendel's controlled mating experiments the individuals produced by crossing two true-breeding parents are referred to as
the F1 generation.
One chromosomal abnormality that is usually fatal is
the addition of an extra autosomal chromosome.
Which of the following does NOT represent a phenotype?
the alleles in a mouse that control hair color
In a karyotype of a male, which of the following would indicate an abnormality?
three copies of chromosome 22
Mendel's manuscript discussing his pea-breeding results is considered one of the two most important scientific papers of the nineteenth century because he was the first to explain how
traits are passed from one generation to the next.
What is the smallest number of traits that are needed to test Mendel's law of independent assortment?
two
On chromosomes within an individual, there are ________ alleles for a given gene found on ________ chromosomes.
two; homologous
What information is NOT visible in a karyotype?
whether the individual carries genetic mutations