Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce_____.
A) all sharp-spined progeny
B) 50% sharp-spined, 50% dull-spined progeny
C) 25% sharp-spined, 50% dull-spined, 25% spineless progeny
D) all spineless progeny
E) It is impossible to determine the phenotypes of the progeny.
Answer: A
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A man who has normal hearing and has a recessive deafness allele on chromosome 17 marries a woman who also has normal hearing and also has a recessive deafness allele, but this allele is on chromosome 3. The probability that their children will be deaf due to either of these mutated genes is closest to
A) 100%. B) 50%. C) 25%. D) 0%.
What would be the physiological effect of an increase in the venous return to the heart?
A. increased stroke volume B. decreased cardiac output C. increased sympathetic stimulation of the heart D. increased secretion of ADH (vasopressin) E. decreased secretion of atrial natriuretic hormone Clarify Question What is the key concept addressed by the question? What type of thinking is required? Gather Content What do you already know about blood return to the heart? What other information is related to the question? Choose Answer Given what you now know, what information 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?
Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant allele. The
couple has a son with normal hands and feet, but the couple's second child has extra digits. What is the probability that their next child will have polydactyly? A) 1/32 B) 1/2 C) 3/4 D) 1/8 E) 7/16
Water molecules are uncharged and ________
Fill in the blank(s) with correct word