Please help Crossing over occurs during which stage of meiosis? a. Prophase I b.
ID: 253044 • Letter: P
Question
Please help
Crossing over occurs during which stage of meiosis? a. Prophase I b. Prophase II c. Anaphase I d. Anaphase II e. Metaphase I and II Use the following description to answer questions 18-20. A dihybrid cross of two strictly Mendelian inherited traits is carried out by a husband and wife that want to have children. The man is homozvgous for a widow's peak (W) and attached earlobes (al while the woman has no widow's peak (w) but free-hanging earlobes. But, the woman's father has attached earlobes! 18. What are the genotypes of the man? c. WwAa wwaa 19. What are the genotypes of the woman? C. WwAa e. wWAa What is the probability that this man and woman have a child with a widow's peak and attached earlobes? a. 0% b. 25% c. 50% d. 75% e. 100% 21. There are 2 stages of meiosis where non-disjunction may occur. They areand_ a. Prophase I and anaphase I b. Anaphase I and prophase II c. Prophase II and anaphase lI d. Anaphase I and anaphase II e. Prophase I and prophase II 22. Griffith was a scientist who injected 4 separate groups of mice with deadly or friendly bacteria. The mice in group 1 were injected with living deadly bacteria and they died. The mice in group 2 were injected with living friendly bacteria and lived. Mice in group 3 were injected with heat-killed deadly bacteria and they also died. There was an unusual feature of the mice in group 4, however. What did Griffiths find in his group 4 mice? a. Those mice lived when they were injected with more friendly than deadly bacteria. b. Those mice lived because they were protected by early antibiotics. c. Those mice died when they should have lived since they were injected with living friendly bacteria and dead deadly bacteria Those mice died because they were poisoned by a toxin released by heat-killed deadly bacteria at their death d.Explanation / Answer
17 - The correct answer is option A that is prophase I as this is the phase where crossing over occurs.
18 - The genotype of man is WWaa.
19 - The genotype of woman is wwAa.
20 - The correct answer is option C that is 50% because the probability of getting widow's peak is 1 because man is homozygous and probability of getting attached earlobes is 1/2. So, 1/2*1 is 0.50 that is 50%.