How many countries are there?

There are about 195 countries in the world today. But because the political world is constantly changing, that number never stays the same for very long. The number 195 includes Taiwan. Although Taiwan operates as an independent country, many countries (including the United States) do not officially recognize it as one. Of these countries, 192 belong to the United Nations (UN), an international organization that aims to get countries to cooperate with one another. The exceptions are Taiwan (in 1971, the UN disqualified Taiwan and replaced it with the People’s Republic of China), Vatican City, and Kosovo. The newest UN members are Switzerland (2002) and Montenegro (2006).

How can a microwave oven cook food so fast?

Unlike other ovens, which cook food with heat waves made from burning gas or electric currents, microwave ovens use special bands of electromagnetic energy called microwaves (similar to light waves) to cook food. While heat waves gradually work their way inside food to cook it, microwaves can travel right through food in an instant. In a microwave oven a device called a magnetron produces a beam of microwaves that pass through a spinning fan, which sends the waves bouncing in all directions. As they travel through food their energy is absorbed by molecules of water. The water molecules vibrate at the same high speed as the microwaves (2.45 billion times per second!) and rub against other molecules. All this movement and friction causes a great deal of heat, cooking the food inside and out. Microwaved food is cooked through a process similar to steaming, which explains why it doesn’t turn brown. But some microwave ovens have traditional heating elements to make food look more appealing—giving it the outer color that we expect in cooked food. Certain materials allow microwaves to pass through (meaning they are not heated by the waves) while other materials absorb the waves and still others reflect them, or bounce them back. For this reason it is important to be careful about the containers and coverings we use in microwave ovens. Microwaves pass through glass and plastic wrap, for example, which are safe to use, as are paper products and most sturdy plastics. But metal containers and coverings like aluminum foil are reflective. Such surfaces keep food from absorbing microwaves, allowing the waves to bounce around so much inside an oven that it may break.

What types of government are there in the world?

There are three general forms of government, based upon who rules: (1) those governments in which the authority is placed in one single person, (2) those dominated by several people, and (3) those controlled by many. In some nations, governing is done by a single individual, such as a king, queen, or dictator. This form of government is known as an autocracy. An autocratic government is called an oligarchy if a small group, such as landowners, military officers, or wealthy merchants, make up the government. If the country’s people make up the government and contribute to its decision-making process, that nation’s government is known as a democracy. There are also several ways in which governments do their governing. Limited governments, such as the United States and most countries in Western Europe, are known as constitutional governments, since these governments are limited as to What they are permitted to control. In other words, they have limited power, and this limited power is enforced by a separation of powers.

Most of these nations have constitutions that define the scope of governmental power. In contrast to a constitutional government, a government is called authoritarian when it has no formal limits; the government is limited by other political and social institutions in the land—such as churches, labor unions, and political parties. While these governments are sometimes responsive to these sources of limitation, there is no formal obligation for the government to represent its citizens. Examples of recent authoritarian governments include Spain from 1936 to 1975 under General Francisco Franco. Totalitarian governments attempt to control every area of political, economic, and social life and are usually associated with dictators who seek to end other social institutions that might challenge the government’s complete, or total, power. Some examples of totalitarian governments include Nazi Germany from 1933 to 1945 under dictator Adolf Hitler, the Soviet Union from 1928 to 1953 under dictator Joseph Stalin, and Cuba from 1959 to 2008 under Fidel Castro.

Can an eagle see a mouse from two miles away?

Yes! The expression “eagle eyes” is taken from the golden eagle, whose incredible eyesight allows it to see a rabbit or mouse from 2 miles (3.2 kilometers) away. For comparison purposes, a human being could not see the same rabbit from one-quarter of a mile (0.40 kilometers) away. As a bird of prey, an eagle has eyes that are designed for clear vision in daylight, from early morning light to early evening. Its pupil is not big enough for night vision. The bony ridge above the eagle’s eyes helps protect them from sunlight and assist in effective hunting.

What is the most common household pet in the United States?

According to a national survey conducted by the American Pet Products Manufaturers Association in 2008, Americans owned about 75 million dogs and 88 million cats. Approximately 39 percent of U.S. households own at least one dog, and 34 percent own at least one cat.

According to the American Kennel Club, Labrador retrievers are the most popular dog breed, followed by Yorkshire terriers, German shepherds, and golden retrievers. Persian cats are the most popular feline breed, followed by the Maine coon and the Siamese. Combined reptiles are the next popular type of pet, followed by birds and horses.

Why does the body need vitamins and minerals?

Vitamins are chemicals that the body needs to function well; minerals are metals and salts that the body also needs in tiny amounts to run properly. Both help the human body grow. Different foods, like vegetables, contain different amounts of vitamins and minerals, so it is important to have variety in your diet so you can get a good balance. When it comes to vitamins, each one works differently in your body. Vitamin D in milk helps your bones grow; vitamin A in carrots helps you see at night; vitamin C in oranges helps boost your immune system and helps your body heal if you get a wound; and the B vitamins in leafy green vegetables help your body make protein and energy.

And although some vitamins like A (which helps your eyesight) and D are stored in your body (for several days or up to several months), others, like C and the B vitamins, quickly pass through your bloodstream. So it’s important to replace your vitamins every day.

Do all plants have leaves?

Most plants have leaves, even if they do not look like leaves. For example, blades of grass are really leaves. Mushrooms and other fungi do not have leaves, and seaweeds and lichens do not have leaves. Seaweed, a type of algae, also does not have flowers or roots. As an underwater plant, it usually clings to stones, shells, and rocks with its holdfast, a part of the plant that looks like roots. Unlike other plants that feed through their roots, seaweed takes its nutrients from the water in which it grows.