Punnett Squares
What are the genotypes of two parents who have a 25% chance of producing offspring with a recessive phenotype?
heterozygous
The physical expression of a trait is known as this
Phenotype
what shapes indicate male and female in a pedigree?
square = male
circle = female
A population has 16% of individuals expressing a recessive trait. What is q2?
.16
This type of cell division produces gametes
meiosis
If black fur (B) is dominant over brown (b), what is the chance of brown offspring from BB × bb?
0%
Humans have this many chromosomes in a typical diploid body cell
46
what does a shaded in shape on a pedigree indicate?
affected organism
A woman with genotype BO and a man with genotype OO have children. Which blood types are possible?
B and O
If two genes are located close together on a chromosome, how does that affect inheritance?
They are likely inherited together (linked)
Short tails on lemurs are recessive, while long tails are dominant. Two long tailed lemurs had a baby. What are the odds that their baby will also have a long tail?
We don't know, we need to no if they are homozygous dominant or heterozygous
A carrier female for an X-linked disorder has children with an affected male. What percentage of daughters are affected?
50%
In a pedigree, a trait appears only in males and never in females. What is the most likely inheritance?
Y linked recessive
If p2 is .16 and q2 is .34, what is 2pq?
.5
A karyotype shows three copies of chromosome 21. What likely caused this?
Nondisjunction during meiosis
In a codominant cross, how many phenotypes can appear in offspring?
3
A male with an X-linked recessive disorder passes the allele to which offspring?
all daughters
A carrier female has children with an affected male (X-linked recessive). What fraction of all children are expected to be affected?
50%
A trait is passed from father to son repeatedly. What inheritance pattern does this indicate?
The term for when neither trait if fully expressed in a heterozygote
incomplete dominance
Red flowers crossed with white flowers produce all pink offspring. What are the parent genotypes?
RR × WW
What is the expected percent outcomes of a cross between two carriers of an autosomal recessive disorder?
25% affected, 50% carriers, 25% unaffected
A pedigree shows unaffected parents with an affected daughter. Why does this rule out X-linked recessive inheritance?
An affected daughter would require an affected father, which is not the case
In a population, q² = 0.09. What percentage of the population is heterozygous?
42%
Why are triploid organisms often sterile/infertile?
Chromosomes cannot pair properly during meiosis