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TLS Online TPP Program

#Question id: 163

Which of the following statements about cystine is correct?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. Cystine forms when the —CH2—SH R group is oxidized to form a —CH2—S—S—CH2— disulfide bridge between two cysteines.

  2. Cystine is an example of a nonstandard amino acid, derived by linking two standard amino acids.

  3. Cystine is formed by the oxidation of the carboxylic acid group on cysteine.

  4. Cystine is formed through a peptide linkage between two cysteines.

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TLS Online TPP Program

#Question id: 12218

#Unit 7. System Physiology – Animal

The control of gastric acid secretion in response to a meal involves several events that take place over a 4- or 5-hr period following the meal. These events include
(1) a decrease in the pH of the gastric contents,
(2) an increase in the rate of acid secretion,
(3) a decrease in the rate of acid secretion, and
(4) an increase in the pH of the gastric contents. Which of the following best describes
the correct temporal order of events over a 4- or 5-hr period following a meal?
TLS Online TPP Program

#Question id: 12219

#Unit 7. System Physiology – Animal

When the dietary intake of K+ increases, body K+ balance is maintained by an increase in K+ excretion primarily by which of the following?
TLS Online TPP Program

#Question id: 12220

#Unit 7. System Physiology – Animal

A female patient has unexplained severe hypernatremia (plasma Na+ = 167 mmol/L) and complains of frequent urination and large urine volumes. A urine specimen reveals that the Na+ concentration is 15mmol/L (very low) and the osmolarity is 155 mOsm/L (very low). Laboratory tests reveal: plasma renin activity = 3 ng angiotensin I/ml/hr (normal = 1.0), plasma antidiuretic hormone (ADH) = 30 pg/ml (normal = 3 pg/ml), and plasma aldosterone = 20 ng/dL (normal = 6 ng/dL). Which of the following is the most likely reason for her hypernatremia?
TLS Online TPP Program

#Question id: 12221

#Unit 7. System Physiology – Animal

Juvenile (type I) diabetes mellitus is often diagnosed because of polyuria (high urine flow) and polydipsia (frequent drinking) that occur because of which of the following?
TLS Online TPP Program

#Question id: 12222

#Unit 7. System Physiology – Animal

In acidosis, most of the hydrogen ions secreted by the proximal tubule are associated with which of the following processes?
TLS Online TPP Program

#Question id: 12223

#Unit 10. Ecological Principles

Evidence shows  that some grasses benefit from being  grazed. Which of the following  terms would  best describe this plant-herbivore interaction?