Question

question 1
2.5 points
nondisjunction or failure of chromosomes to separate can occur.
a during mitosis of sex cells.
b during meiosis i or ii of sperm or egg cells.
c during meiosis i only of sperm or egg cells.
d during meiosis ii of sperm or egg cells.
e during meiosis i or ii in egg cells only.
question 2
2.5 points
a black guinea pig crossed with an albino guinea pig produced 12 black offspring. when the albino was crossed with a second black one, 7 blacks and 5 albinos were obtained. what is the best explanation for this genetic situation?
a albino phenotype is recessive
b uv radiation causes albinos
c albinism is a codominance phenotype
d genetic heterogeneity

Explanation:

For Question 1: Nondisjunction can occur during meiosis I or II in sperm or egg cells. It is not limited to just meiosis I or II or to egg - cells only, and sex cells undergo meiosis not mitosis.
For Question 2: When a black guinea - pig and an albino guinea - pig cross and in one case all offspring are black and in another case there is a mix of black and albino offspring, it indicates that the albino phenotype is recessive. If it were codominance, both traits would be expressed simultaneously in the heterozygous state. UV radiation is not relevant here as it is a genetic cross situation, and genetic heterogeneity is not the best explanation for this simple dominant - recessive pattern.

Answer:

Question 1: B. during meiosis I or II of sperm or egg cells.
Question 2: A. albino phenotype is recessive