All cells contains thousands of enzymes, and each of these enzymes is necessary for the cell. Check out this HowStuffWorks podcast to learn which enzymes cause apples and potatoes to turn brown upon exposure to oxygen.

In houses with a built-in sprinkler system, anti-siphon valves prevent pesticides, pet waste, and other contaminants from polluting the home's water source. Check out this HowStuffWorks podcast to learn more about anti-siphon valves.

A normal 120 volt outlet in the US has two vertical slots and a role hole centered below the slots -- the outlets with a pair of red and black 'test' and 'reset' buttons are known as GCFI outlets. Check out this HowStuffWorks podcast to learn more.

By using a computer to monitor the rotation of the car's wheels, an anti-lock braking system helps drivers avoid skids. Could this computer also monitor flat tires? Check out this HowStuffWorks podcast to learn more about brake systems.

The sound of gunfire is incredibly loud, and it is amazing that anything is able to silence a firearm. However, the principle behind a gun silencer is surprisingly simple. Check out our HowStuffWorks article to learn more about silencers.

Since the heart is a muscle, it relies on the oxygen and nutrients contained in blood. This blood is supplied by arteries on the exterior of the heart -- when these arteries are blocked, a heart attack results. Take a look at our HowStuffWorks article to

Jam, jelly, and preserves are all made from fruit mixed with sugar and pectin. Jell-O, on the other hand, is completely different. Take a look at our HowStuffWorks article to learn more.

Every person has a set of chromosomes, or coiled strands of DNA. Check out this HowStuffWorks podcast to learn how chromosomes combine to promote variation from one generation to the next.

There are three different technologies that fall into the catapult category: the ballista, the trebuchet and the catapult. Check out this HowStuffWorks podcast to learn more about the differences between catapult technologies.

All cars manufactured today contain at least one computer -- but what does it do? Check out this HowStuffWorks podcast to learn more about car computers.

The idea behind a water softener is simple: the calcium and magnesium ions in hard water are replaced with sodium ions. Learn more about the harmful effects of hard water -- and the benefits of soft water -- in this HowStuffWorks podcast.

Learn how the length of hydrocarbon atom chains have different properties, producing substances such as kerosene, methane and other forms of fossil fuel. Check out this HowStuffWorks podcast to learn more about fossil fuels.

The camel's hump is a giant deposit of fat that lets the camel survive up to 2 weeks without food. Learn more about camels in this HowStuffWorks podcast.

The fizzing you see when you drop an Alka-Seltzer tablet in water is the same sort of fizzing that you see from baking powder. This reaction is caused by an acid reacting with a base. Check out this HowStuffWorks podcast to learn more.

The problem of pipes banging on a wall is often called "water hammer." Check out this HowStuffWorks podcast to learn more about this phenomenon.

Catalytic convertors convert hydrocarbons, carbon monoxide, and nitrogen oxides into three harmless chemicals, making the exhaust of a vehicle much cleaner.

A 3-way bulb contains two filaments, and these filaments have differing wattages. Depending on the setting, the filaments operate separately or together to create the appropriate amount of light. Learn more about 3-way bulbs in this HowStuffWorks podcast.

For air in a submarine to remain usable, three things must happen: The oxygen must be replenished as it is consumed, the carbon dioxide must be removed from the air, and the moisture in human breath must also be removed.

In this podcast, learn what causes a fever and what actually happens to the body when a fever occurs.

Built before the invention of electric pumps, fountains in Rome were powered through an ingenious system of gravity, cisterns, and aqueducts. Learn more about fountains in Rome in this HowStuffWorks podcast.

One minute of arc on planet earth is equal to one nautical mile. Listen to this HowStuffWorks podcast and learn more about the measurement of nautical miles.

Today, most answering machines are digital, and use the same technology as a CD or MP3 player. Learn more about digital answering machines in this HowStuffWorks podcast.

The clear, thin sap of Maple trees must be boiled down to create maple syrup -- it takes about 30 to 40 gallons of sap to create one gallon of syrup. Check out this HowStuffWorks podcast to learn more about Maple syrup.

In many watches, phosphor is mixed with a radioactive element that continously charges the phosphor, powering glowing watch hands. Learn more about glowing watch hands in this HowStuffWorks podcast.

An uninterruptible power supply protects computers against surges, spikes, sags, and total power failure. Check out this HowStuffWorks podcast to learn more about uninterruptible power supplies.