Heredity and Human Inheritance Flashcards
Gregor Mendel concluded that each pea has two units for each trait, and each gamete contains one unit. Mendel’s “units” are now celled
genes.
What is the ratio of phenotypes in the offspring produced by the cross Aa x Aa? Assume complete dominance for the trait.
75% dominant: 25% recessive
According to the law of segregation
pairs of alleles separate during the formation of gametes
If we cross two pea plants, each heterozygous for yellow seed color genes, the expected ratio of yellow; green among the offspring will be
75% yellow; 25% green
What is the genotype of a dominant individual if some of its offspring show the recessive phenotype?
Dd
Albinism results from a recessive allele. Which of the following describes the expected offspring from a normally pigmented male with an albino father and an albino wife
50% normal 50% albino
All of the following combinations are possible in the gametes of an organism that is AaBb EXCEPT:
aa
In pea plants, tall plants are dominant over short, and green pods are dominant over yellow. If you crossed true-breeding tall, green-podded plants with true-breeding short, yellow-podded plants, and then crossed the F1 individuals among themselves, what proportion of the F2 offspring would you expect to be tall and yellow-podded?
3/16
In humans, the sex of the offspring is determined by the
sex chromosome carried by the sperm cell
A recessive allele on the X chromosome causes color deficiency. A noncolor-deficient woman (whose father is color deficient)marries a color-deficient man. What is the chance that their son will be color deficient?
50%
A man who carries a harmful sex-linked (on the X chromosome)gene will pass the gene on to
all of his daughters
Two parents with normal vision have two sons, one color deficient and one with normal vision. If this couple then has six daughters, can you predict what percentage of the daughter will have normal color vision
100%
Blood typing is often used as evidences in paternity cases in court. In one case, the mother had blood type B and the child had blood type O. Which of the following blood types could the water NOT have?
AB
Codominance occurs when
both of the alleles in a heterozygote are expressed phenotypically in an individual
In Mendel’s experiments, if the gene for tall (T) plants was incompletely dominant over the gene for short (t) plants, what would be the result of crossing two Tt plants?
25% tall, 50% intermediate, and 25% short
