Following statement regarding to acrosome reaction in sea urchin.

A. Activation of the acrosome reaction serves as a barrier to intraspecies fertilizations.

B. The acrosome reaction is initiated by sulfate-containing polysaccharides in the egg jelly that bind to specific receptors located directly above the acrosomal vesicle on the sperm cell membrane.

C. These polysaccharides are often highly species specific, but egg jelly factors from one species of sea urchin generally activate the acrosome reaction in closely related species.

D. The elevated Ca2+ level in a relatively basic cytoplasm triggers the fusion of the acrosomal membrane with the adjacent sperm cell membrane, releasing enzymes that can lyse a path through the egg jelly to the vitelline envelope.

Which of the following statements are correct?

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#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?

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#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?

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#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?