Question

body systems
lesson 1
levels of organization
before you read
what do you think? read the two statements below and decide whether you agree or disagree with them. place an a in the before column if you agree with the statement or a d if you disagree. after youve read this lesson, reread the statements to see if you have changed your mind.

before	statement	after
a	a human body has organ systems that carry out specific functions.	a

read to learn
how are cells organized in the body?
libraries have thousands of books grouped together by subject, which helps keep them organized and easier to find. similarly, the way your body is organized helps it function.
some organisms are unicellular. they are made of one cell. other organisms are multicellular. they are made of more than one cell. your body has trillions of cells! multicellular organisms have different types of cells. each type has a different job.
multicellular organisms’ cells divide, producing new cells. this is how organisms grow. as shown in the figure on the next page, the first cells made can become any type of cell, such as a muscle cell, a nerve cell, or a blood cell, through the process of cell differentiation. different types of cells are grouped.
tissues groups of similar cells that work together to carry out specific tasks are called tissues. humans and most other animals have four main types of tissue. muscle tissue causes movement. connective tissue provides structure and support. often, it connects other types of tissues. nervous tissue carries messages to and from the brain. epithelial (eh puh thee lee ul) tissue lines the interior of organs and internal body cavities and forms the outer layer of skin.
key concept

• how are cells in living things organized?

cells in living things are organized, cells in living organisms are organized.
study coach
preview headings before you read the lesson, preview all the headings. make a chart and write a question for each heading beginning with what or how. as you read, write the answers to your questions.
academic vocabulary
organize
(verb) to arrange things in a particular order or pattern
science use v. common use
tissue
science use group of similar cells that work together to carry out specific tasks
common use a soft, thin paper

Explanation:

The content is about the levels of organization in the human body, specifically focusing on cells, tissues, and how the body is structured. This falls under Biology, a subfield of Natural Science, as it deals with living organisms' structure and function.

Answer:

Natural Science - Biology