1.Why do we need to breathe oxygen? Choose the most specific, correct answer. a.
ID: 55143 • Letter: 1
Question
1.Why do we need to breathe oxygen? Choose the most specific, correct answer.
a.to oxidize the carbon from the food we eat (glucose + O2 --> CO2 + H2O)
b.to accept electrons at the end of the electron transport chain in the inner mitochondrial membrane
c.to oxidize NADH
d.to break the ester bonds between carbons in glucose
e.because we don’t have chloroplasts to make it for us
QUESTION 6
What statement best explains why glucose transported across the apical membrane in intestinal epithelial cells is classified as indirect active transport?
a.Glucose is stored in the liver, but is initially absorbed by a different organ, the small intestine.
b.Most sugars must be digested in the mouth to generate glucose prior to absorption in the small intestine.
c.Glucose digestion leads to the generation of ATP, and this ATP is then used to transport additional glucose.
dGlucose is transported both into and out of intestinal epithelial cells without consuming ATP.
e.The formation of a glucose gradient requires a pre-existing sodium ion gradient
QUESTION 7
During photosynthesis and mitochondrial respiration, energy is temporarily stored as an “electrochemical gradient.” Which statement best describes this gradient?
a.It is a gradient of protons, which creates both a charge differential and chemical gradient across a membrane.
b.It is a gradient of electrons, which diffuse from one side of a membrane to other and thereby build a charge differential across a membrane.
c.It is a gradient of sodium ions, which creates both a charge differential and chemical gradient across a membrane.
d.It is a dual gradient of sodium and potassium, each of which is stored on a different side of a membrane.
e.It is a gradient of sodium ions across one membrane and gradient of chloride ions across a second membrane.
QUESTION 8
Gut epithelial cells cultured in a medium lacking high sodium concentrations (140 mM) quickly become sickly and die. Why?
a.Without extracellular sodium, they are unable to import glucose, so they starve to death.
b.Their Na+/K+ ATPase pumps run continuously, thereby using up all available ATP stores.
c.They cannot prevent extra water flowing across their plasma membrane, so they shrivel up.
d.They secrete bicarbonate ions and Ca+2 to replace the sodium in the extracellular fluid, and this inhibits all intracellular signaling.
e.Sodium is required for progression from G1 to S phase in the cell cycle.
QUESTION 9
Imagine that you discover a new cell surface transport protein, and that you deduce it is a channel protein. Which of the following properties would you expect this protein to have?
a.It will contain several hydrophobic regions that will cluster together to form a GPCR.
b.It will contain several hydrophobic regions that will form multiple alpha helices
c.It will bind to a mitochondrial translocation channel
d.It will contain a nuclear import sequence (signal sequence)
e.It will have a golgi complex signal sequence
Each question has only one answer.
Explanation / Answer
1)
We need to breathe oxygen, because to accept electrons at the end of the electron transport chain in the inner mitochondrial membrane. Thus, the correct option is (b).
6) The statement best explains why glucose transported across the apical membrane in intestinal epithelial cells is classified as indirect active transport is the formation glucose gradient requires, preexisting sodium ion gradient. Thus, the correct option is (e).
7) Option – A
8) Option –A
9) Option -B
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