BIO Exam II

If you were to add olive oil to your food as part of a diet to lower your risk of atherosclerotic disease, you would use olive oil that

A liquid at room temperature.

When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This molecule rapidly enters the cell regardless of whether its concentration is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane?

Active Transport

Which of the following is a difference between active transport and facilitated diffusion?

Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.

The addition of a competitive inhibitor slows down a particular reaction. What could be done to increase the rate of the reaction, even in the presence of the inhibitor?

Add more substrate

Figure A. Changes in permeability of tubules in the kidney in response to the hormone vasopressin (AVP), which aids in osmoregulation. Figure B. Density of aquaporins in kidney tubule cells before, during, and after administration of vasopressin. Figure C. Permeability of tissues to water before, during, and after administration of vasopressin. The following question relate to these data indicating how the tubules in the kidney respond to the administration of the hormone vasopressin. Using the data from the graphs and what you know about membranes and metabolic pathways, predict which of the following is the likely reason why actions of aquaporins in a membrane can change so rapidly.

Aquaporins are inserted into the membrane as needed

Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____.

B ... the diffusion gradient there is steeper (As long as a metabolically active cell consumes oxygen as it enters, diffusion into the cell will continue because the concentration gradient favors movement in that direction. Provide Feedback)

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms?

Bacteria can't survive in a hypertonic solution because they lose water. (If a cell is placed in a hypertonic solution, it will lose water to its environment, shrivel, and probably die.)

Sulfa antibiotics damage bacteria by affecting a certain bacterial enzyme. The sulfa antibiotic looks similar to a substrate normally required by the bacterial cells to live. The sulfa antibiotic occupies the active site of the required enzyme and blocks entry of its normal substrate. This prevents the bacteria from making nucleotides that are required for their reproduction and survival. Based on this information, the action of sulfa antibiotics is an example of

Competitive Inhibition

Phagocytosis is to eating as pinocytosis is to

Drinking

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via _____.

Endocytosis

Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. This enzyme is a protein. Which of the following processes could be responsible for its secretion?

Exocytosis

The blood plasma of a man who drinks salt water will become ________ to his red blood cells, whereas the red blood cells will be ________ to the blood plasma.

Hypertonic, Hypotonic

Suppose you have two glucose solutions separated by a selectively permeable membrane. If there is a concentration gradient of glucose across the membrane, then one of the solutions cannot be

Isotonic

The process of a white blood cell engulfing a bacterium is

Phagocytosis

New drugs are being developed to lower levels of circulating cholesterol. A successful drug would be one that _____.

increases the rate of LDL receptor-mediated endocytosis (Because cholesterol levels in the blood reflect the balance of, addition to, and removal of cholesterol, anything that tips the balance in favor of removal will lower the concentration of circulating cholesterol. Increasing LDL receptor-mediated endocytosis will have exactly this effect.)

A diet high in animal products and hydrogenated vegetable margarine may increase the risk for atherosclerosis. This is because

most animal fats are saturated and many hydrogenated vegetable margarines contain high levels of trans fats.

Below are the structures of three fatty acids, palmitic acid, stearic acid, and oleic acid. What combination of these fatty acids could you use to make a fat that is liquid at room temperature?

one palmitic acid, one stearic acid, and one oleic acid

Define Endocytosis

the procedure that cells use to import large molecules across their membranes.