Glucose Breakdown in Yeast:
When glucose breaks down anaerobically in yeast, the following reaction occurs:
C6H12O6 (glucose) → 2C2H5OH (ethanol) + 2CO2 (carbon dioxide) + energy
This process is known as alcoholic fermentation and is utilized by yeast to produce energy in the absence of oxygen.

Respiratory Pigment in Human Beings:

Hemoglobin:
Hemoglobin is the respiratory pigment found in human beings. It is a protein found in red blood cells and is responsible for transporting oxygen from the lungs to the body tissues and carbon dioxide from the tissues back to the lungs.

Role of Hemoglobin in Respiration:
- Oxygen Transport: Hemoglobin binds to oxygen in the lungs, forming oxyhemoglobin. This oxyhemoglobin is then transported to the body tissues where it releases oxygen for cellular respiration.
- Carbon Dioxide Transport: Hemoglobin also binds to carbon dioxide in the tissues, forming carbaminohemoglobin. This carbaminohemoglobin is then transported back to the lungs where it releases carbon dioxide for exhalation.
- Buffering pH: Hemoglobin acts as a buffer, helping to maintain the pH balance of the blood by binding to hydrogen ions and preventing a drastic change in blood pH.
- Regulation of Blood Pressure: Hemoglobin plays a role in the regulation of blood pressure by releasing nitric oxide, which helps dilate blood vessels and improve blood flow.
In conclusion, hemoglobin plays a crucial role in the respiratory system of human beings by facilitating the transport of oxygen and carbon dioxide, buffering pH, and regulating blood pressure.