Britannica Student Encyclopedia - 2010

use slaves to run them. They often disagreed

with the slaveholders in eastern

Virginia. In 1863, more than 50 counties

in northwest Virginia decided to

become the separate state ofWest Virginia.

Virginia was the site of Bull Run and

many other bloody battles during the

CivilWar. By April 1865, Confederate

leaders realized that the South could not

win. Confederate general Robert E. Lee

surrendered to Union commander

Ulysses S. Grant at Appomattox, Virginia.

This surrender ended the war.

Virginia rejoined the Union in 1870. It

took a long time for the state to rebuild

all the structures that had been damaged

during the war. It also took many years

for African Americans in the state to

gain the same rights as whites.

In the 20th century Virginia began to

show characteristics of both the North

and the South. Virginia’s northern

counties reflected the worldly city character

of the nearby national capital,

Washington, D.C. Other areas of the

state remained more rural. In rural Virginia

the history and culture of the Deep

South could still be felt.

In the late 20th century some cities

began to spread into the countryside.

Some people in the state were unhappy

with this growth. They complained that

important American CivilWar battlefields

were sometimes threatened by

people wanting to take over the land to

build more houses.

#More to explore

American Revolution • Richmond

96 Virginia BRITANNICA STUDENT ENCYCLOPEDIA

 

Virunga

Mountains

The Virunga Mountains are a mountain

range, or group of mountains, in eastcentral

Africa. They span parts of

Uganda, Rwanda, and the Democratic

Republic of the Congo. There are eight

major peaks. All are volcanoes.

Six of the major peaks in the Virunga

Mountains are extinct volcanoes, meaning

that they no longer erupt. The

extinct volcanoes are named Mikeno,

Sabinio, Visoke, Mgahinga, Muhavura,

and Karisimbi. Karisimbi is the highest

peak in the Virunga Mountains. It is

14,787 feet (4,507 meters) high. It is on

the border between Rwanda and the

Democratic Republic of the Congo.

The other two major peaks are active

volcanoes. This means that eruptions

still take place there. The active volcanoes

are named Nyiragongo and Nyamulagira.

In 2002 a flow of lava, or

melted rock, from Nyiragongo destroyed

much of the city of Goma in the Democratic

Republic of the Congo.

Forests on the slopes of the Virunga

Mountains are home to the mountain

gorilla. The mountain gorilla is very rare

and in danger of dying out. All three

countries in the region have set aside

areas as national parks. In a national

park, wild animals and their habitat are

protected by law.

#More to explore

Africa • Gorilla • Volcano

Virus

Viruses are tiny particles that cause disease

in people, other animals, and

plants. Different viruses cause the common

cold, influenza (flu), chicken pox,

measles, AIDS, and many other diseases.

Viruses are so tiny that people can see

them only with powerful microscopes.

Some viruses have a spherical, or round,

shape. Others are shaped like rods.

Viruses are made up mostly of a substance

called nucleic acid surrounded by

protein.

On its own, a virus is lifeless. However,

it becomes active when it infects, or

enters, a cell of an animal or a plant.

Once inside a cell, a virus can reproduce

itself, like living things can. The copies

that a virus makes of itself are called

virions. These virions can leave the origi-

Antibiotic

drugs kill

bacteria but

have no effect

on viruses.

Drugs that

work against

viruses are

called antiviral

drugs.

Muhavura is one of the main peaks of the

Virunga Mountains.

BRITANNICA STUDENT ENCYCLOPEDIA Virus 97

 

nal cell and infect other cells. Viruses

also can live in bacteria, which are living

things made up of only one cell.

Humans and other animals have natural

defenses against viruses. Fever is one

important way that the human body

fights viruses. A fever is when a body’s

temperature rises. A fever causes some

viruses to become inactive. The body’s

immune system also fights viruses. It

produces white blood cells and substances

called antibodies to attack

viruses. After these cells and antibodies

have attacked a virus, they stay in the

body. This prevents future infection by

the same virus.

Doctors use vaccines to prevent many

diseases caused by viruses. Vaccines are

substances made from dead or weakened

viruses. They prepare the immune system

to fight off active forms of these

viruses.

#More to explore

Cell • Disease, Animal • Disease,

Human • Immune System • Vaccine

Vitamins

Vitamins are nutrients that humans

need in order to grow, reproduce, and be

healthy. Only two vitamins are made in

the human body. People get most of the

vitamins they need from food or vitamin

pills.

Scientists have identified 13 vitamins: A,

eight B vitamins, C, D, E, and K. These

vitamins can be obtained through a

healthy diet filled with a variety of

A virus reproduces itself by taking over a

living cell and making it into a virus factory.

98 Vitamins BRITANNICA STUDENT ENCYCLOPEDIA

 

foods, including plenty of fruits and

vegetables.

Vitamins D and K are both found in

foods and produced by the human body.

The body makes vitamin D when the