The condition in which the blood has a lower than normal number of red blood cells or hemoglobin is: MCQ with Answer and Explanation

Explanation:
Rhizobium is a symbiotic bacterium found in legume root nodules that fixes atmospheric nitrogen into ammonia. Yeast (Saccharomyces cerevisiae) undergoes anaerobic respiration, producing CO2 that leavens bread dough. The vast majority of bacteria are harmless or beneficial (e.g., gut flora, decomposers); only a small fraction are pathogenic to humans. Thus, statements 1 and 2 are correct.

Explanation:
Trypsinogen, secreted by the pancreas, is activated to trypsin by enterokinase (intestinal enzyme). Trypsin then activates other zymogens. Pepsin is active in the stomach, rennin in infants, amylase digests starch. This cascade prevents premature protein digestion in the pancreas.

Explanation:
Mature mammalian red blood cells (erythrocytes) are enucleated to maximize space for hemoglobin. Platelets (thrombocytes) are cell fragments crucial for the blood coagulation cascade. Blood plasma, the liquid component, constitutes about 55% of total blood volume, while the formed elements (RBCs, WBCs, platelets) make up the remaining 45%. Thus, statements 1 and 2 are correct.