Marbles is a calico cat with a Manx tail. She wants to have kittens with a male calico, but can't find one. Male calicos are rare; the only ones have the sex chromosome constitution XXY. Male calicos are therefore rare because
A) all male cats have a dominant gene on the Y chromosome that masks the calico gene on the X chromosome.
B) most male cats only have one Y chromosome, so it cannot be shut off.
C) most male cats have only one X chromosome, so it cannot be shut off.
D) male calico cats lack sex chromosomes.
C) most male cats have only one X chromosome, so it cannot be shut off.
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Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
A) The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP, i, and NADP+ to the light reactions. B) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. C) The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. D) The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split. E) There is no relationship between the light reactions and the Calvin cycle.
Which of the following is not a chief effect of progesterone?
A. reduced uterine motility B. low blood pressure C. increased uterine blood flow D. reduced maternal immune response to fetus E. relaxation of smooth muscle
The following (C6 ® 2 C3) best represents
A. glycolysis. B. Krebs cycle. C. electron transport system. D. All of these choices are correct.
The largest vessel in the body is the ____
a. carotid artery b. superior vena cava c. femoral artery d. ascending aorta e. coronary artery