Chapter I PDF

Exploring BLOOD AND GUTS One of the first people to observe internal body structures and devise a scheme of how they worked was a Roman called Galen. He...

Exploring BLOOD AND GUTS One of the first people to observe internal body structures and devise a scheme of how they worked was a Roman called Galen. He was a keen observer, which is an important quality for someone interested in studying the natural world. Galen wanted to find out how the human body worked, but at the time, there were strict laws against opening up dead human bodies. Luckily, Galen’s job allowed him to view the inner workings of the human body. He was the doctor to the gladiators! Roman gladiators had to fight each other to the death. As a result of these combats, the survivors were often injured badly. While he was trying to heal their gaping wounds, he could observe their internal organs. And because these wounds bled so much, he was able to observe how blood flowed in the body. Through his observations and experiments, he did make some Galen lived from A.D. 129 to 216. important discoveries. But his ideas about how body parts worked He eventually became the seem quite bizarre today. He mapped the major nerves of the body, emperor’s doctor. but he thought they were hollow tubes through which flowed a “life force.” He also thought that the liver was the most important structure in the body because it was so big and had lots of tubes coming out of it. He decided that its purpose was to heat the body. 82 Unit B: Cells and Systems  Though these ideas might seem odd today, doctors accepted Galen’s theories on how the body worked right up until the sixteenth century. G i v e i t a TRY A C T I V I T Y PIECING TOGETHER THE BODY You may think Galen’s theories were absurd, but what do you know about the body’s internal and external parts and how they work together? In this activity, you will have a chance to put your knowledge to the test. Work with one or two of your classmates. Make a list of all the body parts that you can think of, both internal and external. Write each one on a small piece of paper. Try to figure out how they work together to keep you alive. Once your group has decided that there is a pattern, create a concept map showing how these body parts are linked. How many body parts could you name? Did you know the functions of the parts you named? Did you know how each part related to another? Focus THE NATURE OF SCIENCE On As you work through this unit, you will be reading and doing activities about cells and systems. You will encounter three major themes that are important to the study of life science: systems, cells, and structures and functions. You will need an understanding of these themes to do the project about investigating single-celled organisms. Use the following questions to guide your reading as you learn about cells and systems. 1. What do all living things have in common? 2. What types of systems do living things have, and how are they organized? 3. What are the functions of various structures found in living things? Exploring 83  Living things share certain 1.0 characteristics and have structures to perform functions. Key Concepts In this section, you will learn about the following key concepts: organisms cells organs structure and function systems response to stimuli Learning Outcomes When you have completed this section, you will be able to: describe the characteristics of living things Giant sequoia Amoeba analyze the general structure and function of living things explain how living things There are about 1.75 million different types of living things on have different structures for Earth. They come in many different forms—from a single-celled similar functions bacteria that can be seen only with a microscope to a giant blue show how the body is whale over 30 m long, to a giant sequoia tree that’s over 100 m organized into systems tall. Despite the differences among all the different life forms on this planet, there are similarities between them. All living things have features in common that distinguish them from non-living things. Living things have an amazing variety of functioning parts. For example, some have leaves, some have wings. One way of making sense of this variety is to think about the function of the parts, or what they are used for. What do cats use their claws for? What does a tree use its roots for? Does the structure of these parts tell you something about how they work? Any single living thing is made up of different structures. These structures work together to keep you, or any other plant or animal, alive. These parts work together as a single unit to keep a plant or animal running smoothly. 84 For Web links relating to 1.0, visit www.pearsoned.ca/scienceinaction 1.1 The Characteristics of Living Things Before you can make sense of the millions of different living things on Earth, you have to be able to know what is alive and what is not. When trying to decide what is living and what is non-living, you have to find common characteristics for all forms of life. Although they are still debating, most scientists agree on these six characteristics of living things: are made of cells need energy grow and develop respond to the environment reproduce have adaptations for their environment All living things, or organisms, have all of these characteristics. Non-living things may have some of these characteristics (for example, clouds may grow in size), but they will not have all of them. Figure 1.1 What is the energy source for the animal? What is the energy source for the plant? G i v e i t a TRY A C T I V I T Y DEAD OR ALIVE? Draw a table with two columns, one headed Living, the other Non-living. Place each of the following items under the appropriate heading: radio, tree, mushroom, hair, fish, rain, bicycle, moss, skirt, soil, television, carrot, baseball, rock, seeds, air. Do all the things that you placed in the Living category meet the six characteristics of living things? Were there any items that you had trouble placing in either category? Living Things Share Certain Characteristics and Have Structures to Perform Functions 85 info BIT CELLS The cell is the basic unit of life. A cell can perform all the processes Viruses that life depends on. All organisms are made up of at least one cell, Have you ever had a and every cell comes from another cell. cold? Colds (and many Cells are usually microscopic in size, so a other diseases) are caused by viruses. single-celled organism is almost always Viruses are extremely tiny. A large organism, such as a tree, can small and come in be made of trillions of microscopic cells. many different shapes. Non-living things are not made of There is an entire cells. However, there are exceptions. branch of biology Cells are found in non-living material if devoted to the study of that material was alive at one time. For viruses, even though example, if you looked at a piece of wood most scientists don’t under a microscope, you would see consider them to be evidence of cells. This is because the wood alive. This is because came from a tree that was once alive. Figure 1.2 Cells from a cork viruses can’t reproduce by themselves. They ENERGY depend on living cells of other living things to Everything an organism does requires energy. Think of all the things reproduce. you did in the last few hours: you slept, had breakfast, walked to school or ran to catch the bus, and started school. All of these things required energy. Energy is the ability to make things move or change. Organisms get energy from the environment. Plants and animals differ in how they get their energy. Plants use the energy from the sun to make their own food. Animals get their food from the environment around them. Plants and animals both obtain nutrients polio virus from their food and the environment. Nutrients are substances that provide the energy and materials that organisms need to grow, develop, and reproduce. Many different chemical processes happen inside cells. Some of these processes create energy, and some of them use energy. For an organism to stay alive, there has to be a balance between these flu virus energy-using processes and the energy-creating processes. The sum of all the different processes that happen in an organism is called the organism’s metabolism. RESPONDING TO THE ENVIRONMENT You step out onto the street and suddenly you see a moving car barrelling toward you. What do you do? You jump out of the way. The sight of the moving car is actually a stimulus. A stimulus is anything that causes a response in an organism. Jumping out of the way of the car is a reaction, or response, to a stimulus. 86 Unit B: Cells and Systems GROWTH AND DEVELOPMENT You may have grown a few centimetres taller in the past year. But growth is not just about getting bigger. It may also involve a change in structure. When you plant a seed, it grows roots and produces a stem and leaves. Once the plant gets to a certain size, it may not get any bigger, just as you will not grow beyond a certain height. But growth doesn’t end there. Parts of any living thing wear out or get damaged. Every year, trees produce new leaves. Your skin keeps replacing itself as it gets worn away. As some organisms grow, they change their body shape quite drastically. This is called development. Think of a frog. Adult frogs release eggs in the water. As each egg develops, it turns into a tadpole with a tail and gills. As the tadpole grows, it loses its gills and tail and develops lungs and limbs. Finally, it moves from the water onto the land. REPRODUCTION All living things come from other living things. This process is called reproduction. Reproduction is not actually necessary for an organism to survive. But since all individual organisms die, reproduction is necessary for the survival of each type of organism. G i v e i t a TRY A C T I V I T Y MISINTERPRETING THE EVIDENCE It seems pretty clear to us that living things come from living things, but time this wasn’t always so obvious. People noticed that mice often appeared from stacks of straw, and that flies and maggots appeared from rotting meat. People then assumed that the piles of straw and the rotting meat could create mice and flies. The idea that living things could come from non-living things was called spontaneous generation. But people had misinterpreted the evidence. time However, in the 1600s, an Italian doctor called Francisco Redi performed an experiment to test the idea of spontaneous generation. He put some meat into three jars. One he left open, another he sealed shut with a lid, and a third he covered with a mesh screen. He thought that if spontaneous time generation actually happened, maggots would appear on the spoiled meat in all the jars. Figure 1.3 shows the results of the experiment. Observe the results of the experiment. How did the experiment disprove spontaneous generation? Figure 1.3 Living Things Share Certain Characteristics and Have Structures to Perform Functions 87  ADAPTATIONS re SEARCH In the winter, snowshoe hares grow a white coat of fur. This allows Monarch Development them to blend in with their snowy surroundings and avoid being Monarch butterflies go noticed by predators. This coloration is an example of an through an amazing adaptation. An adaptation is a characteristic that allows an development in their organism to live in its environment. Animals and plants have many life cycle. What are the adaptations. A cactus has spines to stop animals from eating it. A stages of development mountain goat has tiny feet to allow it to perch on steep cliffs. of the butterfly? What happens at each stage? Figure 1.4 Snowshoe hare in winter CHECK AND REFLECT 1. List the characteristics of living things. Give an example of each characteristic. 2. What adaptations does a fish have for living in water? 3. Is skin a living thing? 4. Is the following statement true or false? Explain your answer and provide an example. Each individual organism must reproduce in order to survive. 88 Unit B: Cells and Systems 1.2 Structure and Function As well as having certain characteristics, living things have to do certain things to keep themselves alive. Some of the things animals do are to exchange gases, move, and gather food. Plants don’t move like animals do, but they do exchange gases and gather nutrients. Organisms have developed many different ways of doing these tasks and have developed different body parts, or structures, to do them. Each structure is used for a specific function, which means it carries out a specific task. G i v e i t a TRY A C T I V I T Y WHICH STRUCTURE FOR WHAT FUNCTION? List a number of functions an organism must perform in order to survive. Your list might include movement, food gathering, breathing, and so on. Make a table and place these functions in the first column, and place the organisms pictured in Figure 1.5 in the top row, as illustrated below. Look at the organisms in Figure 1.5 and decide what structure each organism uses to perform each function. Then, fill in the table. When you are finished, compare your table with those of your classmates. Did they list important functions that you did not? Which function was listed by the most people? Did all the organisms have structures for all the functions you listed? Dolphin Tree Beetle Tiger movement food gathering Figure 1.5 info BIT Spiracles Some animals have unusual ways of breathing! Insects have small holes in the sides of their abdomens called spiracles. Insects adjust the amount of air that enters their bodies by adjusting the size of their spiracles. Spiracles are the dark spots on the side of the abdomen. Living Things Share Certain Characteristics and Have Structures to Perform Functions 89 Figure 1.6 Gibbon using its arms to move DIFFERENT STRUCTURES FOR SIMILAR FUNCTIONS All organisms have to perform certain tasks or functions to stay alive, but different plants and animals have developed different structures for doing similar functions. For example, most animals have to move about in order to find food. But animals have very different structures for performing this function. Birds have wings to fly through the air, and whales have tail flukes and flippers to FIGURE XX. Gibbon using its arms to move. swim through the water. We humans mostly use our legs to move around, but gibbons mostly use their arms. Can you think of other structures animals have for moving around? Organisms have an amazing variety of food-gathering structures. Barnacles have tentacles that rake the seawater for tiny bits of food. Birds have bills. Insects have very complicated mouth parts. Mammals have different types of teeth to help them chew the food they eat. Teeth can vary from the sharp teeth of a lion to no teeth at all. An anteater has no teeth, just a long, sticky tongue that allows it to gather ants. Figure 1.7 Feeding structures of barnacles and an anteater 90 Unit B: Cells and Systems  Gills, lungs, spiracles, skin—all of these are breathing structures used by different animals. Plants use their leaves to exchange gases with the surrounding air. Leaves can vary widely in shape, from the tiny needles of spruce trees to enormous flat leaves up to 2 m wide! Conifers, like the spruce, have tiny needles to reduce the amount of water lost in their dry environment. Figure 1.8 Leaves come in many shapes and sizes. VARIATIONS IN STRUCTURE As you have seen, structures used for a certain function can be very different. But they aren’t always wildly different. Similar organisms often have slight variations in their structures. These variations are often very easy to see in animals living on islands. The Galapagos islands are located off the west coast of South America. On the islands, there are 13 closely related species of birds, commonly known as finches. They were discovered by the famous biologist Charles Darwin over 100 years ago. These finches, known as Darwin’s finches, as well as many other birds, have different bill structures to perform the function of food gathering. Living Things Share Certain Characteristics and Have Structures to Perform Functions 91 re SEARCH VARIATIONS IN BILL SHAPE Three of Darwin’s 13 species of finches are pictured in Figure 1.9. Marine Iguanas Finches are usually seed-eating birds with large bills adapted for There are other crushing hard seeds. However, typical of island organisms, Darwin’s species living on the Galapagos islands finches have different structures for the function of feeding. that have unique Study the different bird bills in Figure 1.9 and decide what kind features. What of food-gathering functions each bill structure would be best suited structures does the for. One bird is a warbler-like finch that eats insects hiding within marine iguana have the bark of trees. Another is a ground-dwelling finch that eats seeds to help it gather and nuts. The third type is a parrot-like finch that eats tree fruit. food? How is it different from other species of iguana? Figure 1.9 Three of Darwin’s finches CHECK AND REFLECT 1. Name as many functions as you can think of that an organism must carry out in order to survive. 2. Identify at least one type of structure that an organism would need to perform each of the above functions. 3. Why might similar organisms, such as birds, have different structures to perform the same function such as feeding? 4. What is the function of flowers? Why do you think they come in so many bright colours? 92 Unit B: Cells and Systems 1.3 Organs and Organ Systems So far, you have seen that you and other organisms have structures that allow you to survive and interact with your surroundings. But you have many other body structures that are constantly in use for other functions. These include your heart, lungs, brain, and kidneys. What other body parts can you think of? None of these body parts functions on its own. Each part is an organ. The organs that make up each organ system work together to perform a certain task or function. For example, the organs of your digestive system work together to break down food to supply your body with the energy and nutrients you need to survive. The following charts describe some of your body’s organ systems. G i v e i t a TRY A C T I V I T Y DRAWING SYSTEMS Notice that some of the organ systems mentioned in the text to follow do not have illustrations. That’s your job. On a piece of paper, draw a rough outline of the body. Study the list of structures of the circulatory system. Imagine what they look like and where in the body they are located. Draw these structures in your body outline. Repeat the process for the other organ systems. CIRCULATORY SYSTEM (see subsection 3.3) Structure Function of System heart transport oxygen, food, and arteries other substances throughout the veins body capillaries transport some wastes to other blood organs for elimination defend the body against diseases connect all other organ systems Figure 1.10 Red blood cells Living Things Share Certain Characteristics and Have Structures to Perform Functions 93 info BIT RESPIRATORY SYSTEM (see subsection 3.2) Only Skin Deep Structure Function of System The largest organ in the human body is nose transport oxygen from the the skin! It has a mouth outside air to the blood surface area of trachea transport carbon dioxide from almost 2 m2 and it diaphragm the blood to the outside air weighs almost 3 kg. bronchi lungs DIGESTIVE SYSTEM (see subsection 3.1) Structure Function of System salivary break down food pieces into glands much smaller pieces (particles) mouth so they can be absorbed and esophagus transported throughout the body stomach liver pancreas gall bladder small intestine Figure 1.11 The large intestine digestion of food begins in your mouth. NERVOUS SYSTEM (see subsection 3.5) Structure Function of System brain coordinate and control the spinal cord actions of all organs and organ nerves systems eyes, ears, detect, process, and respond to and other changes in external and internal sensing environments organs (hands, nose, etc.) Figure 1.12 The brain controls your nervous system. 94 Unit B: Cells and Systems EXCRETORY SYSTEM (see subsection 3.4) Structure Function of System kidneys remove chemical and gaseous bladder wastes from the blood lungs skin liver SKELETAL SYSTEM Structure Function of System bones provide a movable support Figure 1.13 You have 206 bones in cartilage frame for the body your body. protect soft-tissue organs such as the heart and lungs MUSCULAR SYSTEM Structure Function of System muscles move bones tendons move organs that contain muscle muscle tissue (such as the heart and stomach) Figure 1.14 Athletes learn how to control their muscles. Living Things Share Certain Characteristics and Have Structures to Perform Functions 95  INTEGUMENTARY SYSTEM Structure Function of System skin protects the body’s internal environment from the external environment senses pain, pressure, and temperature hair skin pore re SEARCH Glands An organ system that has not been sweat gland mentioned is the endocrine system. Find out what the endocrine system does. What is the role of each of its organs? Figure 1.15 Cross- blood vessel section of the skin CHECK AND REFLECT 1. Why are organs grouped together into organ systems? 2. Could you do without any of your organ systems? Why or why not? 3. How do you think the systems studied in this subsection might work together to provide the requirements for a living organism? 96 Unit B: Cells and Systems  SECTION REVIEW Assess Your Learning 1. How are living things different from non-living things? 2. As you dive into a pool, you hold your breath. What characteristic of living things are you showing and why? 3. Choose two organisms found in your area and compare the structures each one uses for the same function (e.g., food gathering, breathing). 4. Define structure and function. 5. Make a labelled sketch of the organs of the digestive system. 6. A doctor has a patient complaining of shortness of breath when climbing stairs. Describe what body systems may be causing this problem and why. Focus THE NATURE OF SCIENCE On Scientific knowledge develops through observation, experimentation, and the discovery of patterns and relationships. Think back over what you’ve learned in this section. 1. What observations have people made about living things? What new information was developed from these observations? 2. What relationship did Redi’s experiment establish? 3. Describe one relationship between human body systems that you discovered. Living Things Share Certain Characteristics and Have Structures to Perform Functions 97