Chapter 14
A heterozygous Pea Plant for flower color is crosses with another heterozygous. What is the probability that the offspring will have the recessive genotype?
25%.
A man with blood type AB and a woman blood type 0 have children.
What's the chances their children will have o type?
what blood types are possible among their children?
0%
Type A and Type B only.
What does the chromosomal theory of inheritance state?
Genes are located on chromosomes, and chromosome behavior during Meiosis explains inheritance patterns.
What syndrome will a person whose genotype shows XXY have?
Klinefelter syndrome.
If DNA sample contains 30% adenine, what percentage of cytosine does it have?
20%
In Guinea pigs, black fur B is dominant over white fur. Two heterozygous are crossed. how many of the offspring will be white? how many of the offspring will be heterozygous?And how many offspring will be black but not homozygous?
25% white. 50% heterozygous. 50 black but not homozygous.
Whats the difference between gene and allele?
A gene is a segment of DNA that controls a trait. An allele is a different version of that gene.
Colorblindness is an X-linked recessive trait. A colorblind man and a woman who is heterozygous for normal vision have children. What is the probability that a son will be colorblind.
50%
A person whose genotype is XXY will be...?
biologically a male.
Why does adenine always pair with thymine instead of cytosine?
Adenine pairs with thymine because of hydrogen bonding patterns, and because they fit correctly within the double helix.
You have a plant with genotype RrYy and you crossed it with another RrYy plant.
If round seeds (R) are dominant over wrinkled, and yellow seeds Y are dominant over green (y), what fraction of offspring will be wrinkled and Green?
1/16.
Why can a recessive trait appear in the F2 generation after disappearing in the F1 generation?
Because recessive alleles can be hidden in heterozygous individuals and reappear when two recessive alleles come together.
Because males only have one X chromosome, so a single recessive allele is expressed.
Why is Turner syndrome considered unusual among monosomies?
Because it's the only known viable human monosomy.
why are okazaki fragments formed on the lagging strand but not the leading strand?
DNA polymerase synthesize DNA in the 5' to 3' direction.
What is the probability that a couple who had 4 boys will have another boy?
50%
two alleles for a trait separate during gamete formation, so each gamete receives only one allele.
Why do linked genes violate Mendel's law of independent assortment?
because genes located close together tend to be inherited together.
Achondroplasia is caused by a dominant allele that is lethal when homozygous. Two affected heterozygous parents have children. What fraction of their living children are expected to have achondroplasia?
2/3 of offspring.
A mutation prevents helicase from functioning. What's going to happen?
DNA strands will be unable to unwind and separate.
Two unaffected parents have a child with a recessive genetic disorder.
What must be the parents' genotypes?
Both parents must be heterozygous.
A scientist claims that dominant traits are always the most common traits in a population. Why is this incorrect?
Dominant does not mean common. A dominant allele can be rare, while a recessive can be very common in a population.
What Meiotic error causes aneploidy?
Nondisjunction.
Why can female tortoishell cats have both orange and black fur patches?
because of X-inactivation randomly turning off one X-chromosome in different cells producing patches expressing different fur-color alleles.
A DNA molecule contains 20% guanine.
1. What percentage is cytosine? What percentage is adenine? if the molecule contains 10k nucleotides total, how many adenines are present?
30% Adenine.
Approx 3k adenines.