Scott Foresman Science - Grade 4 | Week 1 Day 3 (Teacher's Edition)

★ Science Objective: The student knows that similar cells form different kinds of structures.

2 Teach (continued)

Quick SUMMARY

All plant and animal cells have a cell membrane, cytoplasm, and a nucleus.
Cells are organized into tissues, organs, and organ systems.
A living thing in its entirety is called an organism.

Student Book • p. 8

The Parts of a Cell

Beetles, eagles, and elephants look nothing alike. But the cells that make up these animals have many similar parts. All cells have a nucleus and a cell membrane. All cells have a gel-like liquid called cytoplasm. The different parts of a cell have special jobs.

Each part of a cell helps it carry out its life processes. The nucleus is the control center for the cell. The instructions for the cell's activities are stored in the nucleus. The cell membrane is the cell's outer border. It separates the cell from its environment. It also controls what substances move into or out of the cell. The cytoplasm contains the things that the cell needs to carry out its life processes.

The size and shape of a cell are related to the cell's job.

Cells Working Together

If cells are the building blocks of life, what can they build? In a many-celled plant or animal, cells are organized to work together. Different types of cells do different kinds of work. Groups of the same type of cell form a tissue. Groups of tissues that work together form an organ. Groups of organs that work together form systems.

An organism is the highest level of cell organization. It is a complete living thing that is made from all parts in all of the systems working together.

Tissue: A group of one type of cell is a tissue. Each kind of tissue does a certain job.

Organ: A group of tissues that work together is an organ. The heart is one of many organs.

Organ System: Organs and tissues that work together form an organ system. The heart, blood, and blood vessels are some parts of one system.

Transmission electron micrograph of virus

Viruses

A virus is a very tiny particle that has characteristics of both nonliving and living things. Viruses are not made of cells. Viruses do not make or use food. A virus can reproduce only by using plant, animal, or other cells to make more viruses. Many scientists do not think a virus is a true living thing.

Cellular Organization Flow

cells

work together in↓

tissues

work together in↓

organs

work together in↓

organ systems

work together in↓

organisms

ELL Leveled Support: Cell Parts

Beginning: Provide drawings of an animal cell and a plant cell with lines leading to cell parts. Have students label and say each vocabulary word aloud.

Intermediate: Have students develop question cards for each cell part (e.g., "What thin layer separates the cell from the environment?").

Advanced: Ask students to write a "What Am I?" riddle about a cell part and trade riddles to solve.

Use Every Student Learns Teacher's Guide, p. 2.

Student Book • p. 9

Like animal cells, plant cells have a cell membrane, cytoplasm, and a nucleus. But plant cells also have parts that animal cells do not have.

Plants make their own food. They need special parts to do this. Chloroplasts are the special parts in plant cells that trap the Sun's energy. The plant needs this energy to make food. Animal cells do not have chloroplasts.

The cell wall is another part of a plant cell that animal cells do not have. The cell wall is outside the cell membrane. It helps support and protect the cell.

A Plant Cell

✓ Lesson Checkpoint

1. Describe the difference between a cell, a tissue, and an organ.

2. Can a single-celled organism contain tissues? Explain.

3. 🎯 Compare and Contrast Make a graphic organizer to compare and contrast animal and plant cells.

Science Background: Special Roles of Cells

Certain cell parts are common among all kinds of cells. For example, all cells have a thin cell membrane that separates the inside of the cell from the environment. However, one cell may look different from another kind of cell due to the specialized role each cell plays in the organism.
For example, the role of the red blood cell is to carry oxygen and other molecules to body cells and then carry carbon dioxide and other wastes away from body cells. The flattened disk shape provides a large surface area for efficient exchange of molecules.

🎯 Guide Comprehension Scaffolded Strategy

Ask students the following scaffolded questions to assess understanding.

1. Define

What is a tissue?

A tissue is a group of similar cells that work together to perform a special function.

2. Infer

What characteristic of a virus leads some scientists to argue that a virus is a living thing?

A virus can reproduce, but it must use other plant or animal cells to do so.

3. Develop Strategy

Suppose you discovered a new organism. How would you determine if the organism is a plant or an animal?

Look at the cells under a microscope. Compare parts of cells in the organism to features found in plant and animal cells.

📖 Extend Vocabulary Greek Roots

The term chloroplast comes from the Greek chloro- meaning "green" and -plast meaning "able to be molded." Challenge students to find the origins for the word cytoplasm (Greek kytos meaning "cell"). Cytoplasm is the moldable material found outside the nucleus. You may connect with the word plastic.

3 Assess

Lesson Checkpoint Answers:

1. A cell is the smallest unit of a living thing. A tissue is a group of similar cells working together. An organ is a group of tissues working together.

2. No; a tissue is a group of cells.

3. Compare and Contrast: Answers will vary. Organizers should indicate that plant and animal cells both have a nucleus, cell membrane, and cytoplasm. Animal cells do not have chloroplasts or a cell wall.

Unit A • Life Science | Chapter 1 • Lesson 1

The Parts of a Cell

Cells Working Together

Chapter 1 • Lesson 1

A Plant Cell

Science Background: Special Roles of Cells