T/F
You genotype is a description of your combination of alleles for a given phenotype.
True
How many chromosomes are in a haploid human cell?
23
How many alleles exist for a given gene?
Each gene can have a different number of alleles.
If a person is homozygous for a particular trait this means ______.
the person has two identical alleles for the gene responsible for the trait.
A dominant allele is best defined as ______.
an allele that stops or hides the expression of the other allele.
A woman has blond hair and brown eyes. This statement is best described as indicating _______.
phenotype.
Recessive alleles are best defined as _______.
only expresses in present in a double dose.
What phenotype is associated with the genotype 47, XXY?
Klinefelter's syndrome
Why are both paternal and maternal chromosomes present in some gametes?
To increase variability of the offspring.
During what phase of meiosis do the tetrads align together in preparation for being separated?
Metaphase I
Chimpanzees have a diploid number of 48. How many total chromosomes should each of their diploid body cells have?
48
Which of the following is specifically associated with the formation and dissociation of chiasmata?
Genetic variability
During metaphase of meiosis I, homologous chromosomes and the alleles they possess are distributed to different gametes. What is this called?
Segregation.
Hair color and eye color are genes are located on the same chromosome. Since these genes are transmitted as a unit to daughter cells during mitosis, we describe these genes as...
linked.
Genes on the same chromosome are said to be _______.
linked.
What is the probability of a couple having three girls in a row?
1/8
A female infant is born with around one million oocytes, each one genetically unique. This is due to ______.
independent assortment & random cross over.
Using Tt and Tt, what is the probability of producing a homozygous dominant offspring?
25%
The ability to roll the tongue into a U shape may be assigned to a single dominant allele, T. Using Tt and Tt, what is the probability of producing an offspring who can roll his/her tongue?
75%
Using Tt and Tt, what is the genotype of a homozygous recessive offspring?
tt
At least three genes control skin color. How many possible combinations of skin color could result from those three genes with the mating of parents containing AABBCC (very dark) and aabbcc (very light)?
64
At how many weeks of pregnancy can chorionic villus sampling (CVS) be safely performed?
10 weeks
During amniocentesis, a need withdraws fluid from ______.
amniotic sac.
If two parents are heterozygous (Tt) for a trait, which is NOT a possibility for their offspring?
a) Half of the potential offspring would be genotypically different than the parents
b) Half of their offspring would be heterozygous
c) All of their offspring would be dominant for the trait
d) Most of the offspring would have the dominant phenotype
c) All of their offspring would be dominant for the trait.
Which of the following is an example of a disorder that exhibits incomplete dominance?
a) Tay-sachs disease
b) Cystic fibrosis
c) Sickle-cell anemia
d) Syndactyly
c) Sickle-cell anemia
The gene responsible for the condition known as sickle-cell anemia demonstrates ______.
incomplete dominance.
Given Cc and Cc, what is the phenotype ratio (assuming C is dominant and there is no incomplete dominance)?
3:1
Given Cc and Cc, if C were an incomplete dominant trait, what would the phenotype ratio be for the offspring?
1:2:1
Huntington's disease involves ______.
degeneration of the basal nuclei of the brain.
Which type of inheritance involves genes found on the non-autosomal chromosomes?
sex-linked inheritance
Inheritance of stature (height) in humans is probably due to ________.
sex-linked inheritance.
Best summarizes the difference between genotype and phenotype...
genotype refers to the gene alleles that one has, and phenotype refers to the trait that is expressed in response to those alleles.
Are enviromental factors more likely to affect genotype or phenotype?
Phenotype
A chromosomal aberration in which part of a chromosome is lost is known as _____.
deletion.
Sam has type A blood. Which of the following blood types are NOT at all possible for Sam's offspring?
a) type O
b) type B
c) type A
d) all of the listed blood types are possible.
d) all of the listed blood types are possible.
Nuclear DNA is NOT the only source of genetic information in the cell. Which of the following is another source of DNA in the cell?
Mitochondria
Pedigrees and blood test are both means of _______.
carrier recognition.
For which of the following are newborns infants not routinely screened at birth?
Color blindness
Which of the following is a noninvasive method for predicting genetic disease?
a) blood test
b) pedigree
c) amniocentesis
d) choronic-villus sampling
b) pedigree