Why are massive main-sequence stars not likely to have planets that contain life?
a. The life zones around these stars is too small.
b. These stars would sweep away all of the material from which planets could form.
c. These stars are too hot to allow water to exist as a liquid on any planets that might form.
d. These stars are on the main sequence for too short a time to allow life to evolve.
e. These stars are almost always binaries and planetary orbits are unstable around binaries.
d
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The array of potential antibodies to the variety of possible antigens is amazing. Which statement explains this development?
A. Recombination of genes coding for the variable regions of immunoglobulins occurs during the developmental stage of lymphocyte production. B. The existing antibody molecules change their shapes, allowing them to fit with a large number of antigens. C. There is a shuffling of genes that code for self markers as well as nonself markers, mixing them together and producing reactive lymphocytes to those markers. D. Mutations in the antibody gene occur within the activated B cells, since they meet the antigen.
In diabetes mellitus, the problems associated
with this disorder arise because
a. fat breakdown produces harmful waste products. b. protein breakdown produces harmful waste products. c. excess glucose results in harmful substances. d. all of these (a through c) occur. e. fat breakdown and protein breakdown produce harmful waste products
An increase in total peripheral resistance, in the absence of any change in cardiac output, would
A) reduce the stretch on the aorta. B) elevate mean arterial pressure. C) decrease pulmonary venous pressure. D) reduce mean arterial pressure. E) decrease central venous pressu
Common end products of fermentation include ________ and ________.
What will be an ideal response?