X chromosome inactivation in humans occurs ____
a. after fertilization but before cell division begins
b. just after cleavage begins
c. at implantation
d. gestational week 1
e. just after birth
ANSWER: b
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In humans, hemophilia is caused by a recessive allele on the X chromosome. Suppose a man with hemophilia has children with a healthy woman whose mother had hemophilia. If an ultrasound test shows that their first child is a girl, what is the probability that she has hemophilia? (Enter the probability as a percent. Enter the number only without the percent sign. For example, enter 100% as 100 and enter 12.5% as 12.5 )
50 Clarify Question · What is the key concept addressed by the question? · What type of thinking is required? · What key words does the question contain? Gather Content · What do you already know about X-linked inheritance? Consider Possibilities · What other information is related to the question? Which information is most useful? Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? Reflect on Process · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
Lysosomes function best at a pH of ____
a. 7.4 b. 6.5 c. 3.2 d. 5.0 e. 8.2
As air moves down the trachea, where does it enter next?
a. esophagus b. larynx c. primary bronchi d. pharynx
Which organisms lack nuclei?
a. protists b. fungi c. ctenophores d. amoebae e. bacteria