Week 10 - Cells

3. Cellular Organization

Lesson 7

Science in Action 8
Pages 120-125

ScienceFocus 8
Pages 138-145

Lesson 7: Cellular Organization

Background Information

Living things are organized in special ways. Some living things, such as the paramecium are made up of only one cell (unicellular) . That one cell carries out all of the activities necessary for life. The unicellular organism responds to the environment, reproduces, and uses energy. You are likely more familiar with living things that are made up of many cells (multicellular) . An earthworm is an example of a multicellular organism. The cells of an earthworm are organized into groups. The cells of each group do special jobs. For example, cells that line the small intestine absorb nutrients that have been digested in other section of the worm's gut.

Groups of cells, such as those in the intestine, are called tissues . A tissue is a group of cells that work together to carry out a special job. Bone, muscles, blood, and nerves are examples of tissues found in animals. Bark, the outer surface of leaves, and water conducting vessels are examples of tissues found in some types of plants. Like cells, tissues can be organized into groups. An organ is a group of tissues that work together to do a job. For example, in the pharynx is an organ found in an earthworm. The job of the pharynx is to suck food into the earthworm's gut. In earthworms, the pharynx, esophagus, crop, and intestine are organs that are involved with the digestion of food.

A group of organs that work together to do a certain job form an organ system . In earthworms, the organs of the digestive system work together to process the food that the worm eats. The organs of the circulatory system are responsible for the movement of blood and the transportation of nutrients of waste to and from every cell. In multicellular organisms, all the organ systems working together make up an organism. An organism is a living thing. Earthworms are organisms with several organ systems. They have digestive system and a circulatory system, to name only two systems. Note: For more information on earthworms or if you are interested in getting involved with the National Earthworm Survey, go to the Worm Watch website ( http://www.wormwatch.ca )

Exercise 2.3: Cellular Organization

Check Your Understanding

Do the Check and Reflect questions found on page 124.

1. Answer the questions as stated.
2. Answer the question as stated!
3. Answer the question as stated!
4. Answer the question as stated!	a) b) c)

Do the Assess your Learning questions found on page 125.

1. Answer the questions as stated.
2. Answer the question as stated!	a) b) c)
3. Answer the question as stated!
4. Answer the question as stated!
5. Answer the question as stated! You could look for some of the images on the Internet. I went to the Internet and searched google for images. I typed in the phrases: microscope images of salt, microscope images of a hair, microscope images of pepper, and microscope images of dandruff. The only one I didn't get pictures for was dandruff.	Only one of the four is to be done!
6. Answer the question as stated!