Respiration and Gas Transport

Hemoglobin in red blood cells binds to oxygen in the lungs and transports it throughout the body to deliver oxygen to tissues. Nitrogen is mostly inert and is not transported by hemoglobin. Helium is a noble gas with no biological transport role. Hydrogen is not a physiological gas transported in blood.

This is the correct option. During respiration, the digested food is broken down by the reaction with oxygen in the body cells to produce carbon dioxide, water and heat energy.

The respiratory quotient (RQ = CO2 produced/O2 consumed) indicates substrate type. Carbohydrates have RQ = 1, fats have RQ ≈ 0.7, proteins have RQ ≈ 0.8. Organic acids have RQ > 1 because they are already partially oxidized and release more CO2 than oxygen consumed during their complete metabolism.

Yes, it is correct as here, CO₂ is evolved, but O₂ is not consumed. RQ = 2CO₂              0O₂ RQ = infinity

Exhaled air contains all the components of inhaled air, but in different proportions: nitrogen remains the largest component, oxygen decreases (some used in respiration), carbon dioxide increases (produced by respiration), and water vapor is added. Therefore all four - N2, CO2, O2, and water vapour - are present.

Respiration is the process where living organisms use oxygen to break down food, releasing carbon dioxide, water vapor, and energy. Option C incorrectly reverses this - claiming respiration uses CO2 and produces O2, which describes photosynthesis, not respiration. The statement 'uses carbon dioxide and produce oxygen' is the opposite of actual respiration.

Yes, it is correct. Carbohydrates (Sugars and starches) are a component of our food, which are the main source of energy.

Yes, it is the correct answer. Platelets are responsible for clotting or coagulation of blood. In case of an injury, the blood clots after some time. This prevents excess loss of blood.

Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration. Oxygen and carbon dioxide move across the plasma membrane by diffusion - O₂ enters the cell (high outside, low inside) and CO₂ leaves the cell (high inside, low outside). This is the primary mechanism for gaseous exchange.

Aerobic respiration produces approximately 36-38 ATP molecules per glucose molecule, whereas anaerobic respiration yields only 2 ATP. This 18-fold difference in energy yield makes aerobic respiration far more advantageous for organisms. Option C is incorrect because both processes cause complete breakdown - anaerobic also fully breaks down glucose (to lactate/ethanol).

Increased CO2 concentration in blood is detected by chemoreceptors in the medulla and carotid bodies, which signal the respiratory center to increase breathing rate. This enhanced ventilation helps eliminate excess CO2 and restore normal blood pH. This is a negative feedback mechanism - elevated CO2 triggers increased breathing to reduce it back to normal levels.

Carbon dioxide is the gas that we breathe out during the respiration process. It is one of the major waste products of our body which get removed through this process.

  Haemoglobin facilitates metabolism among living organisms as it helps the constituent body cells to absorb more of oxygen.

Its affinity is about 200 times greater than oxygen for the iron of hemoglobin.

This option is correct because deoxy- and oxyhemoglobin have different colours.