AAMC Bio QPack 1-done Flashcards
The sodium pump would be most active in cells of which of the following structures?
loop of henle
Of the structures listed, Na+ reabsorption is of utmost importance to the function of the loop of Henle (B), where Na+ is reabsorbed from the filtrate moving through the nephron. This is ultimately the mechanism whereby the kidneys concentrate urine. While cells of the other structures may express Na+ pumps to help maintain ion gradients across their cell membranes, those cells are not nearly as dependent on the Na+ pump for their primary function as is the loop of Henle.
All somatic cells undergo _____, whereas only germ cells undergo ______.
mitosis, meiosis
H. pylori infection may cause increased proliferation of mucosal cells in the stomach. This may lead to gastric cancer if:
If H. pylori infection causes increased proliferation of mucosal cells in the stomach, this could lead to gastric cancer if genetic mutations occur in proliferating somatic cells that line the stomach.
Which of the following statements explains most plausibly why host antibodies are ineffective against H. pylori?
H. pylori infections in the stomach. Without treatment by antibiotics, such infections can be persistent. The most plausible explanation for why host antibodies are ineffective against H. pylori is that antibody proteins may be denatured (destroyed) in the harsh (acidic) environment of the stomach. If the antibody proteins are denatured, they will not function properly.
Which of the following recombinant processes depends on the F factor plasmid?
conjugation
Bacteria can exchange genes by three processes: conjugation, transformation and transduction. The process of conjugation involves production of a special conjugation pilus (sex pilus) by one bacterium and transfer through it of DNA to another bacterium. It requires special genes for the pilus and these are usually present on a plasmid, a separate extragenomic strand of DNA not incorporated into the bacterium’s own DNA. This plasmid is referred to as the fertility or F factor. Conjugation is a feature of Gram-negative bacteria. It confers the advantages of sexual reproduction on the bacterium. The plasmid benefits by being able to move from one host bacterium to another through the conjugation pilus. Conjugation is the process described in the stem, so choice C is correct. Choice A and B are the other two processes that do not require a plasmid. In transformation bacteria take up DNA from their surroundings, the media in which they are immersed. Transduction is the process whereby genes are transferred by a virus. Choice D is also incorrect; translocation, is a general term used in biology to describe movement from one place to another (genes on a chromosome, proteins in a cell, sap in a tree).
If some but not all of the offspring from repeated matings of the same pair of fruit flies show the recessive traits of vestigial wings (vv) and ebony color (ee), which of the following could have been the genotypes of the individuals mated?
both VvEe
The question asks the examinee to identify the genotypes of fruit flies that, when mated, produce some offspring that display the recessive phenotypes of vestigial wings (vv) and ebony color (ee) and some offspring that display the dominant phenotypes for those traits. To display both recessive phenotypes, the offspring must have inherited a recessive allele for each gene from both parents. This implies that each parent must have at least one copy of a recessive allele for both genes. However, some of the offspring did not display the recessive phenotypes for these traits. This implies that at least one parent has a dominant allele for the vestigial gene and at least one parent has a dominant allele for the ebony gene. Of the options listed, only B, both parental genotypes VvEe, satisfies these requirements.
Inflation of the lungs in mammals is accomplished by:
negative pressure pumping action
Inflation of lungs in mammals is accomplished by negative pressure pumping action. Because the lung stays in contact with the thoracic wall as it enlarges due to contraction of the diaphragm and the external intercostal muscles, a pressure that is lower than atmospheric pressure (negative pressure) is generated within the alveolar sacs. Although diffusion of gases is important in the movement of oxygen into the blood from the alveoli and the movement of carbon dioxide out of the blood into the alveoli, it does not explain the inflation of the lung alveoli at inspiration. Active transport describes a situation in which the net movement of a substance occurs against the energy gradient.
After Sarah’s accident, her attending physician detected the protein myoglobin in her urine. What type of injury is consistent with this observation?
Broken bone
Damaged muscle
Damaged kidney
2 and 3
After Sarah’s accident, the physician detected myoglobin in Sarah’s urine. Myoglobin is the substance that holds oxygen in the muscles and organs. The physician’s observation is consistent with an injury to muscle or organs, but not bone.
Aldosterone causes Na+ ____
reabsorption by kidney tubules
Aldosterone causes Na+ ____
reabsorption by kidney tubules
The liver is different from many other organs in that it can at least partially regenerate following illness or damage. This regeneration is accomplished primarily through:
mitosis
The liver is different from many other organs in that it can at least partially regenerate following illness or damage. This regeneration is accomplished primarily through:
mitosis
Aldosterone stimulates Na+ reabsorption by the kidneys. What changes in blood volume and pressure would be expected as a result of aldosterone deficiency?
decrease both
An aldosterone deficiency would result in lower Na+ reabsorption into the bloodstream. Because H2O passively follows Na+ during reabsorption in the kidney, less Na+ reabsorption would result in less H2O reabsorption into the bloodstream. This would result in decreased blood volume. Blood volume would also be affected by lower blood Na+ levels because there would be less of this ion to osmotically hold water in the extracellular fluid.
Aldosterone stimulates Na+ reabsorption by the kidneys. What changes in blood volume and pressure would be expected as a result of aldosterone deficiency?
decrease both
An aldosterone deficiency would result in lower Na+ reabsorption into the bloodstream. Because H2O passively follows Na+ during reabsorption in the kidney, less Na+ reabsorption would result in less H2O reabsorption into the bloodstream. This would result in decreased blood volume. Blood volume would also be affected by lower blood Na+ levels because there would be less of this ion to osmotically hold water in the extracellular fluid.
The sequence of events in the human menstrual cycle involves close interaction among which organs?
hypothalamus, pituitary, ovary
