Question

1) Analysis of a blood sample from a fasting individual who had not eaten for 24 hours would be expected to reveal high levels of

A) insulin. B) secretin. C) oxytocin. D) glucagon. E) glucose.

2) Most of the carbon dioxide produced by humans is

A) bound to hemoglobin.
B) transported in the erythrocytes as carbonic acid.

C) simply dissolved in the plasma.

D) bicarbonate ions bound to hemoglobin.
E) converted to bicarbonate ions in red blood cells.

3) An anthropologist discovers the fossilized heart of an extinct animal. The evidence indicates that the organism's heart was large, well-formed, and had four chambers, with no connection between the right and left sides. A reasonable conclusion supported by these observations is that the animal was

A) most closely related to mammals.
B) most closely related to fish.
C) most closely related to reptiles.
D) most closely realted to athropods and molluscs. E) most closely related to amphibians.

4) The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that

A) urea can be exchanged for Na+.

B) urea is less toxic than ammonia.

C) urea requires more water for excretion than ammonia.

D) urea does not affect the osmolar gradient.

E) less nitrogen is removed from the body.

Answer 1

1. D) Glucagon.

Fasting state is the postabsorptive state, during this state glucose levels drop in the blood, in response to this the alpha cells of pancreas release glucagon, which acts on liver to convert stored form of glucose, glycogen to glucose.

2) E) Converted to bicarbonate ions in red blood cells.

Some amount of carbon di oxide binds to hemoglobin and transported, but most of CO2 are transported as bicarbonate ions. carbonic anhydrase is an enzyme in the blood which converts CO2 and water into bicarbonate and hydrogen ion, this bicarbonate ion is transported to lungs where it it is reconverted to CO2 to be eliminated.

3) A) most closely related to mammal

Birds and mammals have fully separated ventricles and are four chambered, endothermic animals include all birds and mammals, while amphibans have three chambered heart, most of the reptiles other than crocdile have three chambered heart. Fishes are known to have two chambered heart.

4) B) urea is less toxic than ammonia

Ammonia is more volatile and smaller molecule than urea, if it accumulates in body it can increase the blood pH to toxic levels, which can be very fatal, so the liver immediately converts it into urea.