A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true?

A) The amount of available food may have increased.

B) The number of predators may have decreased.

C) The squirrels of subsequent generations should show greater levels of genetic variation than previous generations, because squirrels that would not have survived in the past will now survive.

Choose correct combination,

#Question id: 11941

#Unit 7. System Physiology – Animal

Under conditions of normal renal function, which of the following is true of the concentration of urea in tubular fluid at the end of the proximal tubule?

#Question id: 11942

#Unit 7. System Physiology – Animal

A patient’s urine is collected for 2 hr, and the total volume is 600 ml during this time. Her urine osmolarity is 150 mOsm/L, and her plasma osmolarity is 300 mOsm/L. What is her “free water clearance”?

#Question id: 11943

#Unit 7. System Physiology – Animal

Which of the following changes tends to increase GFR?

#Question id: 11944

#Unit 7. System Physiology – Animal

The maximum clearance rate possible for a substance that is totally cleared from the plasma is equal to which of the following?

#Question id: 11945

#Unit 7. System Physiology – Animal

A patient has the following laboratory values: arterial pH = 7.13, plasma HCO3− = 15 mEq/L, plasma chloride concentration = 118 mEq/L, arterial Pco2 = 28 mm Hg, and plasma Na+ concentration = 141 mEq/L. What is the most likely cause of his acidosis?

#Question id: 11946

#Unit 7. System Physiology – Animal

A 3-week-old infant is brought to the emergency room in a comatose condition. The history reveals that her parents have been feeding her concentrated, undiluted formula for 5 days. (Infant formula preparations are often sold in concentrated forms that must be properly diluted with water before feeding.) The infant’s plasma osmolality is 352 mOsm/L (normal is 280 to 300 mOsm/L), and the osmolality of the urine is 497 mOsm/L. What is the explanation for the hyperosmotic condition of the plasma?