Carbon dioxide levels in the blood and cerebrospinal fluid affect pH. This enables the organism to sense a disturbance in gas levels as _____
A) the brain directly measures and monitors oxygen levels and causes breathing changes accordingly
B) the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing
C) the brain alters the pH of the cerebrospinal fluid to force the animal to retain more or less carbon dioxide
D) stretch receptors in the lungs cause the medulla oblongata to speed up or slow breathing
B
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It has been determined from several human disease samples that bacteria exist that are 16S rRNA sequenced to be Gram-positive, but morphologically double-membraned like Gram-negatives, therefore requiring a new class.
Answer the following statement true (T) or false (F)
Since viruses have no active methods of entering plant cells, they must rely upon mechanically caused wounds, vegetative propagation of plants, grafting, seed, pollen, and being carried on the mouth parts of chewing insects. Tobacco mosaic virus is most commonly introduced into plants through small wounds caused by handling and by insects chewing on plant parts. What would prevent viruses from easily entering plant cells?
a. The cell wall on the virus b. The plasma membrane on the plant c. The cell wall on the plant d. The plasma membrane on the virus e. The protein coat on the virus
A child is born with a lethal dominant allele. This would seem to be impossible since either parent,
had they possessed this allele, would have suffered its lethal effects. What is a possible explanation? A. The child's allele is a spontaneous mutation that neither parent had to deal with. B. The allele could have varying expressivity and not always be lethal. C. The allele could have delayed onset. D. All of these are possible. E. None of these is possible.
Population density is determined by the number of:
a. individual organisms in a given area. b. individuals of a species in an ecosystem. c. species in a given area. d. individuals of a species in a given area.