Respiration and Gas Exchange

In a sealed room, CO2 buildup would reach lethal levels before oxygen depletion becomes critical. Humans exhale CO2 continuously, and concentrations above 10% can be fatal while oxygen would still be present.

Fish breathe through gills, which are specialized organs that extract dissolved oxygen from water and release carbon dioxide, allowing them to survive underwater.

While sneezing violently can cause minor strains or rare injuries, the extreme claims about ribs fracturing easily, dying from suppressed sneezes, and eyes popping out from being kept open are medical myths. Sneezing with eyes open is physically possible and normal, and your eyes are securely held in place by muscles and nerves.

Lungs reside in the thoracic cavity, protected by the ribcage. The abdominal cavity contains digestive organs, pericardial cavity holds the heart, and buccal cavity is the mouth.

In a sealed room, CO2 poisoning occurs before oxygen deprivation because we exhale CO2 (about 4% of each breath). CO2 builds up to toxic levels while there's still oxygen remaining. The key mechanism is CO2 toxicity, not lack of O2.

While cough speeds can vary, measurements indicate that coughs typically exit the mouth at speeds between 50-80 mph (80-130 km/h), making 60 mph a reasonable average approximation within this range.

Humans cannot breathe in space because there is no atmosphere - space is a vacuum with essentially zero pressure and no oxygen. Without a pressurized spacesuit supplying oxygen, humans would lose consciousness within 15 seconds and die within minutes. The vacuum of space would also cause bodily fluids to boil. Therefore, the statement is false.

This is anatomically correct. The right lung has three lobes and is larger than the left lung (which has only two lobes and must accommodate the heart). The right lung's greater volume means it can take in more air. The left lung is smaller to leave space for the heart in the chest cavity.

Oxidative phosphorylation occurs in the inner mitochondrial membrane where the electron transport chain is located. The proton gradient across this membrane drives ATP synthesis via ATP synthase. The matrix contains TCA cycle enzymes, and chloroplast structures are involved in photosynthesis, not respiration. Note: 'mito-' in option C is an abbreviation for mitochondrion.

Perspiration (sweating) is the body's primary cooling mechanism. When sweat evaporates from the skin surface, it absorbs heat energy from the body, causing a cooling effect. This process is called evaporative cooling. Respiration is for gas exchange (oxygen/carbon dioxide), mastication is chewing, and urination is waste excretion - none of these primarily function in temperature regulation like perspiration does.

The right lung is actually LARGER than the left lung. The right lung has three lobes (upper, middle, lower) while the left lung has only two lobes (upper, lower) because the heart occupies space on the left side of the chest. The right lung's capacity is approximately 50% greater than the left.

In respiratory distress, babies show multiple visible signs: nasal flaring (nostrils widen), chest/abdominal retractions (stomach muscles visibly work harder), and changes in overall body posture/structure. These signs together indicate breathing difficulty.