Britannica Student Encyclopedia - 2010

Bach was born on March 21, 1685, in

Eisenach (now in central Germany). His

eldest brother, who was an organist,

probably gave him his first keyboard

lessons. Bach attended school in Luneburg,

where he sang in a boys’ choir. By

the time he left, he was a skilled organist

and composer.

Career

Bach worked as a musician and composer

in churches and in the service of

German noblemen in various cities. His

first major position was as the official

organist for a duke atWeimar. Later he

also became director of the duke’s

orchestra. His duties included composing

a sacred cantata—a type of music for

use during church services—every

month.

In 1723 Bach became the director of

church music for the city of Leipzig.

During his early years in this job, he

composed many cantatas, sometimes up

to one per week. At Leipzig he also

directed an orchestra off and on from

1729 into the early 1740s. Bach died in

Leipzig on July 28, 1750.

During his lifetime Bach was known

mainly for his skill as a musician. After

his death his compositions were mostly

forgotten until the early 1800s. Then

people began to rediscover his works.

Today the music of Bach is highly

acclaimed and is performed frequently.

#More to explore

Classical Music • Musical Instruments

• Orchestra

A painting from 1720 shows Johann

Sebastian Bach.

4 Bach, Johann Sebastian BRITANNICA STUDENT ENCYCLOPEDIA

 

Bacteria

Bacteria are small organisms, or living

things, that can be found in all natural

environments. They are made of a single

cell. Most bacteria can be seen only with

a microscope.

Bacteria do not have most of the structures

found in the cells of other organisms.

They are much simpler and

smaller than all other cells of living

things.

Bacteria take in food and send out waste

through their cell walls. Most bacteria

reproduce by dividing down the middle

to form two separate cells. These each

divide again to form a total of four cells.

Through this process, billions of bacteria

may form from a single bacterium in

only 24 hours.

Bacteria that cause diseases can get into

the human body through the nose, the

mouth, and cuts in the skin. Once

inside, these bacteria quickly reproduce

and cause illness, called an infection.

The infection may result from the bacteria

themselves or from their poisonous

waste products, called toxins. Luckily,

the immune system of the human body

can fight these threats.

Sometimes the immune system needs

help in fighting off bacteria. Doctors

may inject dead or weakened bacteria

into the human body. This is called a

vaccine. A vaccine prepares the body to

fight off the same bacteria in the future.

Doctors may also use medicines called

antibiotics to kill bacteria in the body.

#More to explore

Antibiotic • Cell • Immune System

• Vaccine

Badger

Badgers are mammals known for their

powerful digging. They are related to

weasels, skunks, otters, and mink.

Badgers live in many habitats, including

grasslands and forests. There are eight

species, or types, of badger. The American

badger lives in the western part of

North America. The Eurasian badger

can be found in Europe and Asia. The

other types live in Southeast Asia. They

include hog badgers, ferret badgers, and

stink badgers.

Badgers are heavily built animals with

short legs. The different species range

from 13 to 32 inches (33 to 81 centimeters)

long, not including the tail. They

Most bacteria are so small that they can be

seen only by using a microscope. This bacteria

sample has been magnified 2,000

times.

Scientists have

found remains

of bacteria

that are more

than 360 million

years old.

BRITANNICA STUDENT ENCYCLOPEDIA Badger 5

 

are about 9 to 12 inches (23 to 30 centimeters)

high. The American badger

sometimes looks wider than it is high.

Most badgers have gray or brown fur.

Many types have black-and-white marks

on the face and back.

Badgers have strong front feet with

heavy claws that are excellent for digging.

Badgers dig to make underground

homes called burrows. They may also

dig to find small animals such as squirrels,

mice, and rabbits to eat. Many

kinds eat insects, lizards, birds, and

plants, too. Badgers feed mainly at

night.

Badgers are strong for their size. They

can fight fiercely when threatened. All

badgers have scent glands near the tail.

Like skunks, stink badgers shoot a foulsmelling

liquid from these glands at

their enemies.

..More to explore

Mammal • Mink • Otter • Skunk

•Weasel

Baghdad

Population

(2007

estimate), urban

area,

5,054,000

Baghdad is the capital of the Middle

Eastern country of Iraq. It is also Iraq’s

largest city. Baghdad lies on both banks

of the Tigris River.

Most of Iraq’s industries are located in

and around Baghdad. At one time the

city produced a wide variety of goods,

including cloth, furniture, chemicals,

and electrical equipment. The economy

of the city was disrupted by wars in the

late 20th and early 21st centuries.

People have lived on the site of Baghdad

for some 4,000 years. In AD 762 an Arab

Muslim ruler moved the capital of his

large empire there. Baghdad reached its

greatest power in the late 700s and early

800s. It also became a center of learning.

In 1258 the Mongols captured Baghdad.