A Box In The Zoo A zebra and a fox found a box with a zipper in the zoo. An ox took an ax and ran into the zoo. The ox zigzagged and wigwagged. The zebra and the fox dropped the box.

## Fill in the Blank Fill in the blank with the correct words: 1. Work is the use of _____________ to move an object. _____________ 2. Only the part of the applied force that acts in the same _____________ as motion does work. _____________ 3. Work transfers _____________ from one form to another. _____________ 4. The unit of work is the _____________ (J). _____________ 5. The formula for work is _____________ . _____________ [Word Bank]: force, direction, energy, joule, $W = F \times d$ ## Multiple Choice Questions Choose the correct answer from the choices for each question: 1. Which statement best describes when work is done on an object? * A. A force acts on the object while it moves in the same direction as the force. * B. A force acts on the object while it does not move. * C. The object moves but no force is applied. * D. A force acts opposite to the motion and the object does not move. 2. If a force of 10 N moves an object 3 m in the same direction as the force, how much work is done? * A. 3 J * B. 10 J * C. 30 J * D. 13 J 3. Which unit correctly measures work? * A. Newton (N) * B. Meter (m) * C. Joule (J) * D. Watt (W) 4. If a force acts perpendicular to the motion of an object, how much work does that component do? * A. Maximum work * B. Zero work * C. Negative work * D. Equal to force times distance 5. Using the example from the passage, the work done lifting a 30 N dog 2 m is: * A. 15 J * B. 60 J * C. 32 J * D. 90 J ## Open-Ended Questions Answer the following questions in complete sentences: 1. Explain in your own words why only the component of force in the direction of motion does work. 2. A student pushes a box with a 25 N horizontal force and the box moves 4 m horizontally. Calculate the work done and show your steps using the formula from the passage. 3. Describe one real-life example (not in the passage) where work transfers energy from one form to another. Identify the force, the distance, and the energy transfer.

Create questions based on the following text Not long ago, I grabbed breakfast at a hotel in southern Spain. The only cereal available was a local version of frosted corn flakes, so I readied myself to enjoy a bowl of my childhood favorite. But my sweet indulgence wasn't what I'd expected: The cereal milk was heated — apparently standard in this part of Spain — and my poor frosted flakes immediately turned to mush. Not so grrrrrrreat. Soggy flakes or not, I find breakfast to be a fun part of my travel day, especially because the experience varies so much from one country's breakfast table to the next. The farther north you go in Europe, the heartier the breakfasts. The heaviest is the traditional British "fry." Also known as a "Plate of Cardiac Arrest," the fry is a fundamental part of the bed-and-breakfast experience, and is generally included in your room price. A standard fry comes with cereal or porridge, a fried egg, Canadian-style bacon or sausage (and sometimes mackerel or haggis), a grilled tomato, sautéed mushrooms, baked beans, and fried bread or toast. This protein-stuffed meal can tide me over until dinner. You'll quickly figure out which parts of the fry you like. Your host will likely ask you up front which breakfast items you actually like, rather than serve you the whole shebang and risk having to throw out uneaten food. The Scandinavian breakfasts buffet is the perennial favorite for the "most food on the table" award. It pays to take advantage of breakfast smorgasbords when you can. For about $20 (a cheap meal in these parts), you can dig into an all-you-can-eat extravaganza of fresh bread, cheeses, yogurt, cereal, boiled eggs, herring, cold cuts, and coffee or tea. In place of cereal and milk, Scandinavians like to pour thick yogurt over their granola. Throughout the Netherlands, Belgium, Germany, Austria, Switzerland, and most points east of there, expect a more modest buffet — but still plenty of options (rolls, bread, jam, cold cuts, cheeses, fruit, yogurt, and cereal). In these countries, there's a good chance of finding hard-boiled eggs, but scrambled or fried eggs are relatively rare. In Poland, track down jajecznica, the local wake-up call of eggs scrambled with kielbasa sausage, served with a side of potato pancakes. The breakfast of choice in Russia is oladi, pancakes perfectly fried to be crisp on the outside but soft in the middle, then topped with sour cream, honey, or berries. Germans have an endearing habit of greeting others in the breakfast room with a slow and dour "Morgen" ("Morning" — short for "good morning"), though they have plenty to be happy about. Breakfast is usually included, and offers hearty fuel for the day: ham, eggs, cheese, bread, rolls, and pots of coffee. In Switzerland, don't miss an opportunity to try Bircher Muesli, a healthful mix of oats, nuts, yogurt, and fruit that tastes far more delicious than it looks. If breakfast is optional, take a walk to the nearest bakery — every German, Austrian, and Swiss town has at least a few bakeries offering a world of enticing varieties of bread and pastries, baked fresh every morning. As you move south and west (France, Italy, Spain, and Portugal), skimpier "continental" breakfasts are the norm. You'll mostly likely get a roll with marmalade or jam, occasionally a slice of ham or cheese, and coffee or tea. The good news? These little breakfasts compel you to sample regional favorites: In Spain, look for chocolate con churros (fritters served with a thick, warm chocolate drink), pan con tomate (a toasted baguette rubbed with fresh garlic and ripe tomato), or a tortilla española (a hearty slice of potato omelet). Italian breakfasts are particularly tiny, but the delicious red orange juice you get is made from Sicilian blood oranges. And you can buy a delightful toasted sandwich from a corner bar anywhere, anytime in Italy to make up for the minuscule breakfast. In France, locals just grab a warm croissant and coffee on the way to work. Queue up with the French and consider the yummy options: croissants studded with raisins, packed with crushed almonds, or filled with chocolate or cream. If you expect breakfast to be too sparse, plan ahead to supplement it with a piece of fruit and a wrapped chunk of cheese from a local market. Being a juice man, I keep a liter box of OJ in my room for a morning eye-opener. Coffee drinkers know that breakfast is the only cheap time to caffeinate yourself. Some hotels will serve you a bottomless cup of a rich brew only with breakfast. After that, the cups acquire bottoms and refills will cost you. Juice is generally available at breakfast, but in Mediterranean countries, you have to ask…and you'll probably be charged. In many countries, breakfast is included in your hotel bill, though if you make prior arrangements with the hotelier, you may be able to skip breakfast and pay a lower price for the room. If breakfast costs extra, it's often optional, and you can usually save money and gain atmosphere by buying coffee and a roll or croissant at the café down the street or by brunching picnic-style in the park. When deciding whether to request breakfast, consider your timing; if you need to get an early start, skip the breakfast — few hotel breakfasts are worth waiting around for. Come to the European breakfast table with an adventurous spirit. I'm a big-breakfast traditionalist at home, but when I feel the urge for an American breakfast in Europe, I beat it to death with a hard roll.

Not long ago, I grabbed breakfast at a hotel in southern Spain. The only cereal available was a local version of frosted corn flakes, so I readied myself to enjoy a bowl of my childhood favorite. But my sweet indulgence wasn't what I'd expected: The cereal milk was heated — apparently standard in this part of Spain — and my poor frosted flakes immediately turned to mush. Not so grrrrrrreat. Soggy flakes or not, I find breakfast to be a fun part of my travel day, especially because the experience varies so much from one country's breakfast table to the next. The farther north you go in Europe, the heartier the breakfasts. The heaviest is the traditional British "fry." Also known as a "Plate of Cardiac Arrest," the fry is a fundamental part of the bed-and-breakfast experience, and is generally included in your room price. A standard fry comes with cereal or porridge, a fried egg, Canadian-style bacon or sausage (and sometimes mackerel or haggis), a grilled tomato, sautéed mushrooms, baked beans, and fried bread or toast. This protein-stuffed meal can tide me over until dinner. You'll quickly figure out which parts of the fry you like. Your host will likely ask you up front which breakfast items you actually like, rather than serve you the whole shebang and risk having to throw out uneaten food. The Scandinavian breakfasts buffet is the perennial favorite for the "most food on the table" award. It pays to take advantage of breakfast smorgasbords when you can. For about $20 (a cheap meal in these parts), you can dig into an all-you-can-eat extravaganza of fresh bread, cheeses, yogurt, cereal, boiled eggs, herring, cold cuts, and coffee or tea. In place of cereal and milk, Scandinavians like to pour thick yogurt over their granola. Throughout the Netherlands, Belgium, Germany, Austria, Switzerland, and most points east of there, expect a more modest buffet — but still plenty of options (rolls, bread, jam, cold cuts, cheeses, fruit, yogurt, and cereal). In these countries, there's a good chance of finding hard-boiled eggs, but scrambled or fried eggs are relatively rare. In Poland, track down jajecznica, the local wake-up call of eggs scrambled with kielbasa sausage, served with a side of potato pancakes. The breakfast of choice in Russia is oladi, pancakes perfectly fried to be crisp on the outside but soft in the middle, then topped with sour cream, honey, or berries. Germans have an endearing habit of greeting others in the breakfast room with a slow and dour "Morgen" ("Morning" — short for "good morning"), though they have plenty to be happy about. Breakfast is usually included, and offers hearty fuel for the day: ham, eggs, cheese, bread, rolls, and pots of coffee. In Switzerland, don't miss an opportunity to try Bircher Muesli, a healthful mix of oats, nuts, yogurt, and fruit that tastes far more delicious than it looks. If breakfast is optional, take a walk to the nearest bakery — every German, Austrian, and Swiss town has at least a few bakeries offering a world of enticing varieties of bread and pastries, baked fresh every morning. As you move south and west (France, Italy, Spain, and Portugal), skimpier "continental" breakfasts are the norm. You'll mostly likely get a roll with marmalade or jam, occasionally a slice of ham or cheese, and coffee or tea. The good news? These little breakfasts compel you to sample regional favorites: In Spain, look for chocolate con churros (fritters served with a thick, warm chocolate drink), pan con tomate (a toasted baguette rubbed with fresh garlic and ripe tomato), or a tortilla española (a hearty slice of potato omelet). Italian breakfasts are particularly tiny, but the delicious red orange juice you get is made from Sicilian blood oranges. And you can buy a delightful toasted sandwich from a corner bar anywhere, anytime in Italy to make up for the minuscule breakfast. In France, locals just grab a warm croissant and coffee on the way to work. Queue up with the French and consider the yummy options: croissants studded with raisins, packed with crushed almonds, or filled with chocolate or cream. If you expect breakfast to be too sparse, plan ahead to supplement it with a piece of fruit and a wrapped chunk of cheese from a local market. Being a juice man, I keep a liter box of OJ in my room for a morning eye-opener. Coffee drinkers know that breakfast is the only cheap time to caffeinate yourself. Some hotels will serve you a bottomless cup of a rich brew only with breakfast. After that, the cups acquire bottoms and refills will cost you. Juice is generally available at breakfast, but in Mediterranean countries, you have to ask…and you'll probably be charged. In many countries, breakfast is included in your hotel bill, though if you make prior arrangements with the hotelier, you may be able to skip breakfast and pay a lower price for the room. If breakfast costs extra, it's often optional, and you can usually save money and gain atmosphere by buying coffee and a roll or croissant at the café down the street or by brunching picnic-style in the park. When deciding whether to request breakfast, consider your timing; if you need to get an early start, skip the breakfast — few hotel breakfasts are worth waiting around for. Come to the European breakfast table with an adventurous spirit. I'm a big-breakfast traditionalist at home, but when I feel the urge for an American breakfast in Europe, I beat it to death with a hard roll. Can you make 5 questions based on the text

Long ago, people from different cultures had stories about how the world began and how humans came to be. These stories are called creation stories. Even though these cultures were different, their creation stories often had similar ideas. Two creation stories that we will explore are one from Native Americans in North America and one from ancient Greece. Both stories talk about bringing light and fire to people. They also have something called archetypes, which are important in creation stories. Archetypes are things that show up a lot in different stories from different times and places. They can be symbols, patterns, or types of characters. Archetypes help us understand that even though cultures are different, they have some things in common. In these creation stories, there are two archetypal figures - the Raven and Prometheus. They represent things like wanting to learn, make progress, and find enlightenment. Both stories show how these figures go against higher powers to give people something good. The Raven and Prometheus are smart, resourceful, and want to make life better for humans. Understanding archetypes helps us see that cultures have things in common. The Raven and Prometheus are symbols that show what it means to be human. By studying and comparing these symbols, we can learn more about what people believe and want, no matter where they come from. The Raven and Prometheus remind us that people always want to learn, make progress, and find enlightenment. In the Native American creation story, the Raven brings light to the world. Long ago, the world was very dark and people had a hard time finding their way. But then, a clever bird called the Raven decided to help. The Raven stole a box that held the sun, moon, and stars from a powerful being. As the Raven flew across the sky, the box opened and filled the world with light. This light helped guide and teach humans. The Raven is seen as smart, resourceful, and a symbol of light. In the ancient Greek story, Prometheus steals fire from the gods on Mount Olympus. Prometheus cared a lot about humans and wanted to help them. Fire was something special that only the gods had, and it represented knowledge, creativity, and civilization. Prometheus brought fire down to Earth secretly because he knew it would make life better for humans. With fire, they could stay warm, cook food, and protect themselves. Prometheus was brave and kind, and he wanted to help humanity. Both the Raven and Prometheus stories have similarities. They are both about giving humans something important that helps them learn and progress. The Raven gave light, while Prometheus gave fire. The Raven and Prometheus are both very smart and clever. They wanted to make life better for people. These stories show us that no matter where people come from, they all have a desire to learn, make progress, and find enlightenment.

Plant cells have three kinds of structures that are not found in animal cells and that are extremely important to plant survival: plastids, central vacuoles, and cell walls. PLANT CELLS Most of the organelles and other parts of the cell just described are common to all eukaryotic cells. However, plant cells have three additional kinds of structures that are extremely important to plant function: cell walls, large central vacuoles, and plastids. To understand why plant cells have structures not found in ani- mal cells, consider how a plant’s lifestyle differs from an animal’s. Plants make their own carbon-containing molecules directly from carbon taken in from the environment. Plant cells take carbon diox- ide gas from the air, and in a process called photosynthesis, they convert carbon dioxide and water into sugars. The organelles and structures in plant cells are shown in Figure 4-21. SECTION 4 OBJECTIVES ● List three structures that are present in plant cells but not in animal cells. ● Compare the plasma membrane, the primary cell wall, and the secondary cell wall. ● Explain the role of the central vacuole. ● Describe the roles of plastids in the life of a plant. ● Identify features that distinguish prokaryotes, eukaryotes, plant cells, and animal cells. VOCABULARY cell wall central vacuole plastid chloroplast thylakoid chlorophyll Chloroplast Golgi apparatus Mitochondrion Cell membrane Nucleolus Nucleus Cytoskeleton Rough endoplasmic reticulum Pore Smooth endoplasmic reticulum Central vacuole Ribosome Cell wall In addition to containing almost all of the types of organelles that animal cells contain, plant cells contain three unique features. Those features are the cell wall, the central vacuole, and plastids, such as chloroplasts. FIGURE 4-21 Copyright © by Holt, Rinehart and Winston. All rights reserved. 88 CHAPTER 4 CELL WALL The cell wall is a rigid layer that lies outside the cell’s plasma membrane. Plant cell walls contain a carbohydrate called cellulose. Cellulose is embedded in a matrix of proteins and other carbohy- drates that form a stiff box around each cell. Pores in the cell wall allow water, ions, and some molecules to enter and exit the cell. Primary and Secondary Cell Walls The main component of the cell wall, cellulose, is made directly on the surface of the plasma membrane by enzymes that travel along the membrane. These enzymes are guided by microtubules inside the plasma membrane. Growth of the primary cell wall occurs in one direction, based on the orientation of the microtubules. Other components of the cell wall are made in the ER. These materials move in vesicles to the Golgi and then to the cell surface. Some plants also produce a secondary cell wall. When the cell stops growing, it secretes the secondary cell wall between the plasma membrane and the primary cell wall. The secondary cell wall is very strong but can no longer expand. The wood in desks and tabletops is made of billions of secondary cell walls. The cells inside the walls have died and disintegrated. CENTRAL VACUOLE Plant cells may contain a reservoir that stores large amounts of water. The central vacuole is a large, fluid-filled organelle that stores not only water but also enzymes, metabolic wastes, and other materials. The central vacuole, shown in Figure 4-22, forms as other smaller vacuoles fuse together. Central vacuoles can make up 90 percent of the plant cell’s volume and can push all of the other organelles into a thin layer against the plasma membrane. When water is plentiful, it fills a plant’s vacuoles. The cells expand and the plant stands upright. In a dry period, the vacuoles lose water, the cells shrink, and the plant wilts. Other Vacuoles Some vacuoles store toxic materials. The vacuoles of acacia trees, for example, store poisons that provide a defense against plant-eating ani- mals. Tobacco plant cells store the toxin nicotine in a storage vacuole. Other vacuoles store plant pigments, such as the colorful pigments found in rose petals. The central vacuole occupies up to 90 percent of the volume of some plant cells. The central vacuole stores water and helps keep plant tissue firm. FIGURE 4-22 Central vacuole Nucleus Chloroplast Copyright © by Holt, Rinehart and Winston. All rights reserved. CELL STRUCTURE AND FUNCTION 89 PLASTIDS Plastids are another unique feature of plant cells. Plastids are organelles that, like mitochondria, are surrounded by a double mem- brane and contain their own DNA. There are several types of plastids, including chloroplasts, chromoplasts, and leucoplasts. Chloroplasts Chloroplasts use light energy to make carbohydrates from carbon dioxide and water. As Figure 4-23 shows, each chloroplast contains a system of flattened, membranous sacs called thylakoids. Thylakoids contain the green pigment chlorophyll, the main mole- cule that absorbs light and captures light energy for the cell. Chloroplasts can be found not only in plant cells but also in a wide variety of eukaryotic algae, such as seaweed. Chloroplast DNA is very similar to the DNA of certain photosyn- thetic bacteria. Plant cell chloroplasts can arise only by the divi- sion of preexisting chloroplasts. These facts may suggest that chloroplasts are descendants of ancient prokaryotic cells. Like mitochondria, chloroplasts are also thought to be the descendants of ancient prokaryotic cells that were incorporated into plant cells through a process called endosymbiosis. Chromoplasts Chromoplasts are plastids that contain colorful pigments and that may or may not take part in photosynthesis. Carrot root cells, for example, contain chromoplasts filled with the orange pigment carotene. Chromoplasts in flower petal cells contain red, purple, yellow, or white pigments. Other Plastids Several other types of plastids share the general features of chloro- plasts but differ in content. For example, amyloplasts store starch. Chloroplasts, chromoplasts, and amyloplasts arise from a common precursor, called a proplastid. Thylakoid Inner membrane Outer membrane chloroplast from the Greek chloros, meaning “pale green,” and plastos, meaning “formed” Word Roots and Origins A chloroplast captures energy from sunlight and uses that energy to convert carbon dioxide and water into sugar and other carbohydrates. FIGURE 4-23 Copyright © by Holt, Rinehart and Winston. All rights reserved. 90 CHAPTER 4 COMPARING CELLS All cells share common features, such as a cell membrane, cyto- plasm, ribosomes, and genetic material. But there is a high level of diversity among cells, as shown in Figure 4-24. There are signifi- cant differences between prokaryotes and eukaryotes. In addition, plant cells have features that are not found in animal cells. Prokaryotes Versus Eukaryotes Prokaryotes differ from eukaryotes in that prokaryotes lack a nucleus and membrane-bound organelles. Prokaryotes have a region, called a nucleoid, in which their genetic material is concen- trated. However, prokaryotes lack an internal membrane system. Plant Cells Versus Animal Cells Three unique features distinguish plant cells from animal cells. One is the production of a cell wall by plant cells. Plant cells contain a large central vacuole. Third, plant cells contain a variety of plastids, which are not found in animal cells. Cell walls, central vacuoles, and plastids are unique features that are important to plant function. 1. Identify three unique features of plant cells. 2. List the differences between the plasma mem- brane, the primary cell wall, and the secondary cell wall. 3. Identify three functions of plastids. 4. Name three things that may be stored in vacuoles. 5. Describe the features that distinguish prokary- otes from eukaryotes and plant cells from animal cells. CRITICAL THINKING

What is an earthquake? Would you be surprised to learn that several million earthquakes happen every year? Seriously. Most are so small in magnitude or size that we cannot even feel them. In fact, only 20 earthquakes are efficiently reported each year in the United States Geological Survey. Wow! That is a huge difference! The Earth has four major layers. Inner core, outer core, mantle, and crust. Think of the crust and top of the mantle like the skin of the earth. This skin is made up of different pieces of rock called tectonic plates. There are about 15 major slabs that join together, kind of like a puzzle. The edges around the tectonic plates are called plate boundaries. These massive pieces of rock slide back and forth under the Earth's surface, bumping up against each other and creating a lot of tension. This tension and movement create faults, which are basically huge cracks in the rock. When the faults get stuck, they build up pressure. And when they get unstuck, you guessed it, an earthquake. So basically, an earthquake is caused by the shifting and sliding of tectonic plates on the Earth's upper mantle and crust. There are three ways that tectonic plates shift or slide. They are subduction, lateral sliding, and spreading. Subduction happens when plates crash into each other. This can cause one plate to slide under another and be destroyed. Or the edges of the plate may rise up and form mountains. Lateral sliding means that the plates slide alongside each other, which can create lots of friction. And like you might have guessed, spreading happens when plates move apart from each other. When they do, melted rock between the plates rises and cools, forming new crust. Here's an interesting fact. Nearly 90% of all earthquakes begin in the Pacific Ocean, in an area called the Ring of Fire. It's called the Ring of Fire because along with earthquakes, it's filled with many active volcanoes. More than 450! Earthquakes can be powerful enough to change the surface of the earth and can do a lot of damage. And sometimes earthquakes can even cause other natural disasters, like avalanches, landslides, and tsunamis. Pretty wild, right? The epicenter is the location of an earthquake on the Earth's surface. The closer you are to the epicenter, the more of the earthquake you will feel. Earthquakes lose intensity as they travel away from the epicenter. Scientists measure the intensity of an earthquake using a special device called a seismograph. Seismometers detect and measure the vibrations given off by an earthquake. Magnitude is the number given to record the size of an earthquake. For example, a magnitude 5.5 is considered moderate. Above 8.0 is considered a major earthquake and we see one every year or two. Earthquakes measured at 2.5 or less are usually not felt, but can be recorded. And believe it or not, there are millions that happen each year. You can make a model of a seismograph at home, and we are going to show you how. It's activity time! You can print off directions for this one on our website at learnbright.org. You'll need a cardboard box, string, a plastic cup, a marker, small heavy objects, a long strip of paper, and a friend because this is an activity for at least two people. Now comes the fun part. One friend shakes the box, alternating between hard and soft and slow and fast, while the other friend is pulling the strip of paper through the bottom. Watch the marker as it records the movement. This is exactly what a seismograph does during an earthquake. So, in a way, we have not only created our own seismograph, but our own earthquake as well. Now, we can analyze the data just like scientists. Can you tell how hard the box was shaking based on the line? Can you tell when it was barely shaking at all? You are on your way to becoming a seismologist. A seismologist is a person that studies earthquakes. It's pretty cool to watch the process, but it's even more exciting to do it yourself. You can head on over to our website to get detailed instructions for this activity. Just download the lesson plan and as always have fun! Hope you had fun learning with us! Visit us at learnbright.org for thousands of Hope you had fun learning with us! Visit us at learnbright.org for thousands of free resources and turnkey solutions for teachers and homeschoolers.

Complete the adjectives with a suffix in the box

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