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8 From Cells to Organisms Understanding Life Systems Enduring Understandings • • • • All living things are made of cells. Processes witnessed on the cellular level are also witnessed in more complex multicellular organisms. For every function or need, specific structures are present at both the unicellular level and the multicellular level to complete the function or meet the need. Understanding the structures, functions, and interdependence of human organ systems can result in improvements in human health. Essential Guiding Questions for Unit Design • • • • • • What advancements in medicine have led to improvements in human health? What is the advantage of being made of one cell instead of many? What is the advantage of being made of many cells instead of just one? How can a microorganism or a tree be as “alive” as a human being? Why do we breathe (eat, etc.)? My car is alive! Prove me wrong? Important for Students to Know • • • • • • • that living things can be unicellular or multicellular; the differences/similarities between plant and animal cell; the main parts of the plant and animal cell which can be identified under a microscope (e.g., nucleus, cell membrane, cell wall, cytoplasm, vacuole); that specialization exists on a cellular level and a systems level; the hierarchical organization in multicellular organisms; the processes of diffusion and osmosis; and how water and nutrients are moved through a plant. Important for Students to Do.. • • use the microscope to identify plant and animal cells and some of the key structures; investigate the properties of cells and/or the functioning of plants through experimentation. Life Systems-Grade 8-Cells, Tissues, Organs, and Systems Students focus on the structure and function of cells in plants and animals and on the organization of cells into tissues, organs, and organ systems. Teacher Background Student Vocabulary Ion - charged atom or molecule. unicellular amoebae Cell - the microscopic units sometimes called building blocks, that make up all living things including the human body. A typical cell consists of a cell membrane surrounding numerous organelles suspended in a fluid substance called cytoplasm. multicellular organelles vacuole nucleus chloroplast tissue organ system Unicellular - an organism consisting of a single cell, they include protists and bacteria (amoebae, paramecia, euglena and some fungi (e.g.,yeast). diffusion osmosis selectivity permeable membranes Multicellular - having more than one cell, some fungi (mushrooms, plants and animals). How The Body Works From Body To Atom Bacteria cells - prokaryotic containing no nuclear membrane or no membrane bound organelles. It is the smallest type of organism. System Cell membrane - 2 layers of oily molecules with proteins and carbohydrates attached. It allows the passage of food and structural materials to enter and wastes to pass out. Found in all cells. Organ Cell wall - found only in plants; thicker dead covering around the cell membrane; supports the cells so the plant can stand upright. Tissue Organelle - a tiny structure inside a cell. • Nucleus - the control centre or brain of the cell. It contains the cell’s genetic information in the form of DNA packaged into chromosomes. • Chloroplast - contains chlorophyll (green pigment) which traps the sun’s energy and uses it to make glucose through photosynthesis. • Mitochondria - organelle where (ATP) energy is produced by cellular respiration. The powerhouse of the cell. It releases energy from glucose and sugar. • Ribosome - organelle where proteins are made. • Vacuole - clear fluid filled sacs that store water and other materials giving shape and support in plants and in animals. Cell Organelle Molecule White Blood Cells - blood cells that have no hemoglobin and migrate into the tissue to fight off infection and digest cell debris. Atom Red Blood Cells - a hemoglobin (red pigment) containing cell with no nucleus, that carries oxygen from the lungs to body tissue. continued… JK-8 Science & Technology 1-20 Basic Concepts Life Systems-Grade 8-Cells, Tissues, Organs, and Systems Continued 2. . . . . Teacher Background Cells in Animals - in multi cellular organisms cells are organized into tissues, tissues into organs and organs into organ systems. Each tissue is composed of a group of cells that work together to perform a specific function. Cells and Tissues in Plants • Guard cells - control the entry and exit of gasses in the underside of leaves. • Epidermis cells - outer layer on the upper and lower surface. In some species they may be covered by a waxy cuticle which functions to prevent water loss. • Palisade mesophyll cells - long, thin cells that contain chlorophyll and perform photosynthesis. • Spongy mesophyll - cells that contain chlorophyll and perform photosynthesis. • Xylem - tubes that carry raw materials such as water and minerals throughout the plant • Phloem - tubes that carry food throughout the plant • Cortex - stores food; photosynthesis can also occur here. Diffusion– molecules or ions moving from a region of high concentration of the molecules or ions to a region of low concentration of the molecule. • Passive Transport - movement of solutes not requiring the cells energy (e.g., diffusion), also known as passive permeability. • Osmosis - diffusion involving moving water molecules across a membrane. • Facilitated Diffusion - involving larger ions or molecules as they move through protein channels in the cell membrane. Molecules move more quickly with help from protein molecules. Active Transport - movement of ions or molecules from a region of low concentration to a region of higher concentration. Requires energy from the cell. Insulin - produced in the pancreas; to maintain the proper level of glucose in the blood. Used in the control of diabetes. JK-8 Science & Technology 1-21 Basic Concepts 8 Systems at Work Understanding Structures and Mechanisms Enduring Understandings When designing, producing and testing mechanisms and systems, they should be efficient in their ease of use, energy demands and cost. • The needs of the consumer drive the design and manufacturing or products. • Essential Guiding Questions for Unit Design • • • • • • What makes a mountain bicycle “good”? What are the essential qualities of a good off-road vehicle? A good dishwasher? Through the use of machines (mechanical systems), how have humans made life easier? Have there been any social or environmental costs to mechanization? Are machines more efficient than humans? If so, how? What is “ergonomics” and what role does it play in your life? Important for Students to Know • • • • • that efficiency is a comparison of the useful work energy provided by a device or system to the work energy applied to the device or system; that the formula for efficiency is as follows: Efficiency = Energy output x 100% Energy input that the components chosen for a mechanical system and the ways in which they are connected effect the efficiency of the system; that the velocity ratio is a comparison of the distance a load moves to the distance traveled by the force (effort) required to move it; and that various forces, such as friction, affect the movement of an object. Important for Students to Do • • • • • measure forces that affect movement of objects; determine velocity ratios through direct observation of devices using pulleys and gears; investigate the mechanical efficiency of different mechanical systems through experimentation; research the kinds of information gathered from consumers prior to and during the design of a product; through technological design, investigate the concept of mechanical efficiency by designing a device that uses a mechanical system which is operated by hydraulics or pneumatics. Structures and Mechanisms-Grade 8 – Mechanical Efficiency Students develop their understanding of the efficient operation of mechanical systems. Special attention is given to the use of hydraulic and pneumatic power. Teacher Background Pneumatics- any machine that uses compressed air to transmit force from one place to another is called a pneumatic system. Compressed air leads to a lag in the time between the force being applied and the output or the resulting force. • Compressed Air - air that has been forced into a small space (such as blowing up a balloon or pumping up a bicycle tire). ergonomic design mechanical efficiency, velocity/velocity ratio hydraulic/pneumatic power. Hydraulics - any machine that uses a liquid to transmit force from one place to another is called a hydraulic system. To overcome the lag of a simple air filled system, fluids are incompressible and therefore, transmits a force immediately. • Pascal’s Law - pressure exerted on a contained fluid is transmitted in all directions throughout the fluid and perpendicular to the walls of the container. Syringe - a plastic tube with a plunger attached at the end. When the plunger is pulled out either air or water can fill the cavity of the tube. When the plunger is pushed in the air or water is forced out. Syringes can be attached to tubing and other syringes to produce either pneumatic or hydraulic systems. The size of the sending and receiving syringes will determine the amount of input and output movement. Ergonomics - designing products and structures to match human needs. Feedback - information coming back into a system about the way it is changing. One example is a thermostat, which shuts down the central heating system when the temperature rises above a certain level. continued… JK-8 Science & Technology 1-71 Basic Concepts Structures and Mechanisms-Grade 8 – Mechanical Efficiency Continued 2 . . . . Teacher Background Mechanical efficiency - the comparison of the useful work or energy provided by a machine or system with the actual work or energy supplied to the machine or system. Efficiency is usually stated as a percentage. The formula is as follows: • efficiency = energy output x 100% energy input Mechanical advantage - The advantage of the work done by a simple machine can be determined by comparing the load to the effort required to move or lift that load. The formula is as follows: • Mechanical Advantage = load effort (See page 108, Ontario Curriculum Science and Technology) fig. 1 Mechanical Advantage Less effort needed to lift load Velocity - rate of motion (speed) in a particular direction. Supports 1/2 the load Supports 1/2 the load Velocity ratio - The ratio between the distance moved by effort and the distance moved by the load. Whenever you gain in one movement you lose in the other. The formula is as follows: • Velocity Ratio = distance moved by effort distance moved by load JK-8 Science & Technology 1-72 Basic Concepts 8 Fluids Understanding Matter and Energy Enduring Understandings • • Fluids have specific properties (e.g., viscosity, density, buoyancy) that affect their behaviour and their use in natural (e.g., human body) and human-made (e.g., automobile engine) systems. Fluids under pressure exert forces that can be used to do work. Essential Guiding Questions for Unit Design • • • • How does an artificial heart function? How does it compare with a real heart? How do devices that you use in your daily life make use of the properties of fluids? How is a mechanic able to lift a car? If the viscosity of oil is so important to the protection of engine parts, why not make oil extremely viscous? Important for Students to Know • • • • • that fluids consist of both liquids and gases; that fluids can be compared according to their physical properties (e.g., viscosity, density and buoyancy); that some fluids (gases) can be compressed while others (liquid) cannot; that the particle theory can be used to describe the relationship between mass, volume and density; and that some properties of fluids (e.g., viscosity, density) are affected by changes in temperature. Important for Students to Do • • • use measuring devices correctly while investigating the properties of viscosity, density and buoyancy through experimentation; use the concepts of density and buoyancy to design and calibrate a hydrometer; apply the concepts of hydraulics and pneumatics through technological design. Matter & Materials-Grade 8 – Fluids Students are introduced to Fluid Mechanics. Fluids including air and water form the basis of hydraulic and pneumatic devices. Students will explore Archimedes’ principle by investigating and measuring buoyant forces on different objects. Teacher Background Student Vocabulary Matter - anything that has mass or takes up space (volume). Material - the parts or substances of which a thing is made. viscosity density pneumatic hydraulic particle theory flow rate compressibility Properties - (i) Physical - characteristics that can be described using the senses. (ii) Chemical - the way in which matter and materials behave under different conditions of light, heat, pressure, or chemical reaction. Fluid - anything that flows. It could be a gas or liquid (air and water). • Flow rate - the speed at which a liquid substance, moves from place to place. Viscosity - the property of fluid that describes how easily it flows. Force can decrease viscosity (e.g., margarine is affected by a knife as it is being spread). Law of Viscosity - Isaac Newton stated that the viscosity can be changed only by altering the fluid’s temperature. (e.g., honey as it is warmed flows more easily, therefore, it is less viscous). Density - the ratio of an object’s mass to its volume. The greater the viscosity the greater the density. Emulsion - the mixture of liquids that do not dissolve in each other .Tiny blobs of one liquid floating in another liquid, such as oil droplets floating in water. continued… JK-8 Science & Technology 1-35 Basic Concepts Matter & Materials-Grade 8 – Fluids Continued 2 . . . . Teacher Background Particle Theory - the fundamental theory that is used to explain matter. fig. 1, The theory states: • All substances are composed of tiny particles called atoms, molecules and ions and the tiny particles that have spaces between them. Spaces are very small in solids and very large in gasses (ions carry either positive or negative charges). Particle Nature of Solids, Liquids, and Gases fig. 1 Decreasing Temperature Solid Particles . . . . . . . . • The particles are in constant state of motion and the amount of motion increases from solid to liquid to gas. • The motion of particles is temperature dependent, that is, the higher the temperature the faster the particles in any state of matter will move. • There are forces of attraction between particles in solids liquids and gasses. These forces are strongest in solids, fairly strong in liquids, and very weak in gas. . . . . . . . . . . . . . . . . . . . . . . . . Liquid Particles Archamedies’ Principle - the buoyant force on an object in a fluid is equal to the weight of the fluid displaced by the object. fig. 2 fig. 2 . . . . . . . . . . . . . . . Gas Particles . . . . . . . . . . Increasing Temperature See The Way Things Work CD JK-8 Science & Technology . 1-36 Basic Concepts 8 Water Systems Understanding Earth and Space Systems Enduring Understandings • • Water in all its forms shapes the environment (including climate) and is critical to the survival of plants and animals. The Amount of the earth’s water that is “drinkable” is a very small percentage; therefore, humans must use and manage water resources carefully. Essential guiding Questions for Unit Design • • • • Why did the Walkerton, Ontario water tragedy occur (summer of 2000)? How does construction (e.g., development of the Oak Ridges Moraine for a housing complex) affect water systems and resources? The search for landfill sites is a continuous problem as the amount of waste produced by our society increases. Why would you not want one in your backyard? Should Canada be involved in the bulk export of its water resources? Important for Students to Know • • • • • that water exists naturally in all three states on Earth (students should be able to give examples of conditions/locations for each state); that water is distributed unevenly about the world and circulates via the water cycle; that large bodies of water have an affect on global and regional climate and weather (e.g., moderation of temperature, changes in precipitation); that land formations affect water systems and water affects the creation of landforms, including waterways (e.g., Grand Canyon, Bay of Fundy); and that humans use, abuse and manage water resources in a variety of ways. Important for Students to Do • • investigate some of the physical properties of water (e.g., buoyancy in fresh and salt water) through experimentation; investigate needs of events relating to the earth’s water (e.g., changes in the world’s water distribution over time, ways in which humans use water and manage water resources) through research. Earth and Space Systems-Grade 8 – Water Systems Students learn the important role that water systems play in global ecosystems. They come to understand that large bodies of water influence climate and weather of the region in which they are located and that lakes and oceans interact with the atmosphere through a water cycle. They learn the importance of fresh and salt water to the sustainability of life on earth. Teacher Background Student Vocabulary States of Water fig. 1 • Solid - water exists as glaciers, snow mountains, and polar ice caps. sea mounts continental shelves sustainability trenches • Liquid - water exists as oceans, lakes, rivers, and groundwater. continental divide glacier ice caps salinity • Gaseous - water exists as part of the atmosphere currents basins • Evaporation - the change in state from a liquid to a gas. • Sublimation - the change in state from a solid directly to a gas or from a gas directly to a solid. • Condensation the change in state from a gas or vapor to a liquid. • Solidification (freezing) - the change in state from liquid to solid. fig. 1 Three States of Water Geological Features of the Ocean’s Floor • Ocean - large body of salt water. • Sea mounts - under water mountains. • Continental Shelves - areas near landforms where the ocean is relatively shallow (e.g. the Grand Banks of Newfoundland). Oceans tend to moderate climate since the water is warmer in the winter. • evaporation condensation Liquid melting freezing Solid Trenches - valleys where the ocean is deepest. Physical Characteristics of Salt Water: • Movement • Density - the amount of mass per unit volume • Buoyancy - the tendency to float or rise in a fluid. • Salinity - the amount of salt per unit volume. continued.... JK-8 Science & Technology 1-85 Basic Concepts take away heat to change state Water Cycle - the recycling of water. Water evaporates from the oceans and falls as precipitation becoming surface run-off, ground water, or part of a water table. If it is not evaporated from lakes or rivers, then it returns to the ocean to repeat the cycle again. add heat to change state Gas Earth and Space Systems-Grade 8 – Water Systems Continued 2 ... Teacher Background Formation of Lakes and Rivers • Basin - relatively shallow depression in the land that contains water. • Water Shed - Area from where all rivers flow to a certain place. The Great Lake’s Water shed refers to all the land where the rivers flow into the Great Lakes e.g., the Grand River water shed). • Continental Divide - the watershed boundary for North America e.g., the Rocky Mountains. Climate - the temperature, humidity, precipitation, winds, radiation, and other meteorological conditions characteristic of a locality or region over an extended period of time. Currents - the movement of water in the ocean caused by differences in temperature & the movement of the earth. Circulating currents are one way to cool off the planet. The sun warms water at the equator and water is transported to colder regions. As the water gets colder it sinks. Colder water then circulates back to regions where they can be warmed again. This pattern takes more than a 1000 years to complete. Desalination - the removal of salt from water through either reverse osmosis or distillation • Reverse Osmosis - pressure is applied to intake water, forcing water molecules through a semipermeable membrane which does not allow salt molecules through. • Distillation - the intake water is heated to produce steam and then condensed as drinkable water. JK-8 Science & Technology 1-86 Basic Concepts