Recognizes or recalls specific terminology, such as: rocks, igneous, molten rock, sedimentary, fossilized organisms, metamorphic, heat, pressure, formed, physical properties, minerals, hardness, color, luster, cleavage, streak color, quartz, feldspar, mica, calcite, talc, pyrite, graphite, resources, Earth, renewable, nonrenewable, physical weathering, wind, water, ice, temperature change, plants, erosion, gravity, wind, water, ice, technology, tools, phosphate, oil, limestone, silicon, solar energy Performs basic skills:  Identify the three categories of rocks: igneous (formed from molten rock); sedimentary (pieces of other rocks and fossilized organisms); and metamorphic (formed from heat and pressure). (SC.4.E.6.1)  Identify the physical properties of common earth-forming minerals, including hardness, color, luster, cleavage, and streak color. (SC.4.E.6.2)  Recognize the role of minerals in the formation of rocks. Recognize that humans need resources found on Earth and that these are either renewable or nonrenewable. Identify resources available in Florida (water, phosphate, oil, limestone, silicon, wind, and solar energy). Describe the basic differences between physical weathering (breaking down of rock by wind, water, ice, temperature change, and plants) and erosion (movement of rock by gravity, wind, water, and ice). Identify and describe the processes of physical weathering and erosion. Investigate how technology and tools help to extend the ability of humans to observe very small things and very large things.

The plasma membrane (also called the cell membrane) has several functions. For example, it allows only certain molecules to enter or leave the cell. It separates internal metabolic reactions from the external environment. In addition, the plasma membrane allows the cell to excrete wastes and to interact with its environment. Membrane Lipids The plasma membrane, as well as the membranes of cell organelles, is made primarily of phospholipids. Phospholipids have a polar, hydrophilic (“water-loving”) phosphate head and two nonpolar, hydrophobic (“water-fearing”) fatty acid tails. Water molecules sur- round the plasma membrane. The phospholipids line up so that their heads point outward toward the water and their tails point inward, away from water. The result is a double layer called a phospholipid bilayer, as shown in Figure 4-10. The cell membranes of eukaryotes also contain lipids, called sterols, between the tails of the phospho- lipids. The major membrane sterol in animal cells is cholesterol. Sterols in the plasma membrane make the membrane more firm and prevent the membrane from freezing at low temperatures. SECTION 3 OBJECTIVES ● Describe the structure and function of a cell’s plasma membrane. ● Summarize the role of the nucleus. ● List the major organelles found in the cytosol, and describe their roles. ● Identify the characteristics of mitochondria. ● Describe the structure and function of the cytoskeleton. VOCABULARY phospholipid bilayer chromosome nuclear envelope nucleolus ribosome mitochondrion endoplasmic reticulum Golgi apparatus lysosome cytoskeleton microtubule microfilament cilium flagellum centriole Cell membranes are made of a phospholipid bilayer. Each phospholipid molecule has a polar “head” and a two-part nonpolar “tail.” FIGURE 4-10 Copyright © by Holt, Rinehart and Winston. All rights reserved. 78 CHAPTER 4 OUTSIDE OF CELL INSIDE OF CELL 1. Cell-surface marker: Glycoprotein that identifies cell type 3. Enzyme: Assists chemical reactions inside the cell 2. Receptor protein: Recognizes and binds to substances outside the cell 4. Transport protein: Helps substances move across cell membrane Carbohydrate portion Protein portion Phospholipid heads Phospholipid tails Phospholipid Cholesterol bilayer Membrane Proteins Plasma membranes often contain specific proteins embedded within the lipid bilayer. These proteins are called integral proteins. Figure 4-11 shows that some integral proteins, such as cell surface markers, emerge from only one side of the membrane. Others, such as receptor proteins and transport proteins, extend across the plasma membrane and are exposed to both the cell’s interior and exterior environments. Proteins that extend across the plasma membrane are able to detect environmental signals and transmit them to the inside of the cell. Peripheral proteins, such as the enzyme shown in Figure 4-11, lie on only one side of the membrane and are not embedded in it. As Figure 4-11 shows, integral proteins exposed to the cell’s external environment often have carbohydrates attached. These carbohydrates can act as labels on cell surfaces. Some labels help cells recognize each other and stick together. Viruses can use these labels as docks for entering and infecting cells. Integral proteins play important roles in actively transporting molecules into the cell. Some act as channels or pores that allow certain substances to pass. Other integral proteins bind to a mol- ecule on the outside of the cell and then transport it through the membrane. Still others act as sites where chemical messengers such as hormones can attach. Fluid Mosaic Model A cell’s plasma membrane is surprisingly dynamic. Scientists describe the cell membrane as a fluid mosaic. The fluid mosaic model states that the phospholipid bilayer behaves like a fluid more than it behaves like a solid. The membrane’s lipids and pro- teins can move laterally within the bilayer, like a boat on the ocean. As a result of such lateral movement, the pattern, or “mosaic,” of lipids and proteins in the cell membrane constantly changes.

A Prairie Guard Dog I am on a journey. My trip is to a prairie. It is in the outdoor world called nature. Many animals live in a prairie habitat. This place has what prairie dogs need to survive. A prairie has a lot of grasses but few trees. Without places to hide, a prairie can be dangerous for some animals. Good Morning! It is early in the morning. First, I see a prairie dog. I name him Pete. He peeks his head out of his burrow underground. He looks around. Then Pete calls loudly to his family, "Yip!" He lets them know it is safe to come out. Soon four prairie dogs come out. Pete is the guard and he is restless. He cannot rest because he is always looking around for danger. This allows the other prairie dogs to safely munch on grasses and seeds. They can also groom each other or work on their burrow. A Scare Oh no! Pete spies a large badger! When he sees it, he gives a loud bark, "Yap! Yap!" His family recognizes the warning. Some hide in tall grasses, and some jump into the burrow. The badger runs at Pete, but the watchful guard is able to escape into the burrow. I am glad he is able to get away from danger. After a few minutes, Pete peeks his head out again and he is back on the job. Break Time The sun gets higher, and it is hot now. The prairie dogs slip into their deep burrow where it is cooler. Even Pete goes in. Tunnels, like hallways, lead to different areas. There is a sleeping room. There is a room used like a bathroom. The prairie dogs cover up roots and seeds in one room. Later, they eat the buried food there. Second Shift I keep watching the burrow. Finally, the sun begins to set and a different prairie dog peeks its head out. I name him Gary. Pete must be off duty. "Yip," Gary calls. The other prairie dogs come back out. The prairie dogs eat and play until the moon is high in the sky. Then they go to sleep in their burrows. I wonder if Pete will be back on duty. I will see in the morning.

Recognize common materials seen and used at home or in school as solid, liquid or gas.

5.12.B Recognize Exaggerated, Contradictory Or Misleading Statements In Text

SC.7.P.11.1 Recognize that adding heat to or removing heat from a system may result in a temperature change and possibly a change of state.

. recognize fact, opinion, and assertion; 2. distinguish opinion and commonplace assertion from fact; and 3. formulate statements of skim for major or central ideas.

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