1.4 requirements for human life

When you open a bottle of sparkling water, the carbon dioxide gas in the bottle form bubbles. If the bottle is left open, the water will eventually "go flat." Explain these phenomena in terms of atmospheric pressure.

In a sealed bottle of sparkling water, carbon dioxide gas is kept dissolved in the water under a very high pressure. When you open the bottle, the pressure of the gas above the liquid changes from artificially high to normal atmospheric pressure. The dissolved carbon dioxide gas expands, and rises in bubbles to the surface. When a bottle of sparkling water is left open, it eventually goes flat because its gases continue to move out of solution until the pressure in the water is approximately equal to atmospheric pressure.

On his midsummer trek through the desert, Josh ran out of water. Why is this particularly dangerous?

The primary way that the body responds to high environmental heat is by sweating; however, sweating requires water, which comes from body fluids, including blood plasma. If Josh becomes dehydrated, he will be unable to sweat adequately to cool his body, and he will be at risk for heat stroke as his blood pressure drops too much from the loss of water from the blood plasma.

pressure

force exerted by a substance in contact with another substance

Humans have the most urgent need for a continuous supply of ________.

oxygen

Which of the following statements about nutrients is true?

All classes of nutrients are essential to human survival.

C.J. is stuck in her car during a bitterly cold blizzard. Her body responds to the cold by ________.

breaking down stored energy

nutrient

chemical obtained from foods and beverages that is critical to human survival