Chapter 8 - Microscope

Chapter 8 A. LIGHT SOURCE a bulb or reflection from a mirror sends light up through the object being viewed B. DIAPHRAGM controls the amount of light reaching the object C. STAGE: supports the microscope slide D. STAGE CLIPS: hold the slide in place E. OBJECTIVE LENS: magnifies the image F. TU...

Chapter 8 A. LIGHT SOURCE a bulb or reflection from a mirror sends light up through the object being viewed B. DIAPHRAGM controls the amount of light reaching the object C. STAGE: supports the microscope slide D. STAGE CLIPS: hold the slide in place E. OBJECTIVE LENS: magnifies the image F. TUBE: holds the eyepiece and the objective lens at the correct working distance from each other G. EYEPIECE: has a lens that enlarges the image from the objective lens H. COARSE-ADJUSTMENT KNOB: brings the image into focus; used only with the low-power objective lens I. FINE-ADJUSTMENT KNOB: brings the image into clearer focus; used with the medium-power and high-power objective lenses J. ARM AND BASE: supports the microscope K. Nosepiece: The rotating part that holds the objective lenses and allows switching between them. L. Condenser: Focuses the light from the light source onto the specimen compound microscopes - have a stronger magnification than earlier devices and use light to illuminate objects being viewed. -Magnifies objects 400 to 1000 times their actual size electron microscopes -that magnify more than 600 000 times by relying on a beam of electrons rather than light -Object or specimen must be dead and covered in chemicals to observe using a transmission electron microscope (TEM) -living organisms are examined with a scanning electron microscope (SEM) where electrons pass over the specimen to produce a 3D image Contrast and Staining -Scientists learned that staining cells improved the contrast between internal cell parts. -Unstained cells are virtually colorless with little contrast between parts. -Manipulating the light source (diaphragm) allows you to alter the contrast of different structures in a cell. Properly Handling a Microscope - Be Careful!! - Carry it with 2 HANDS: one on the arm and the other on the base - Clean only with a soft cloth/tissue - Make sure it’s on a flat surface - Don’t bump it Using a Microscope -Start on the lowest magnification and use the coarse adjustment knob to focus. - Never use the coarse adjustment knob on high magnification you’ll break the slide!! - Increase the magnification and only use the fine adjustment to focus on medium and high power. What scientists learned from their observations, and the questions they continued to ask about cells, have led to many technological advances that depend on knowledge from microscopy. The development of the microscope was a great boost for science. It allowed scientists who studied cells (referred to as cytologists) to observe details in plant and animal cells. These observations allowed them to develop greater understanding of the living world. Such advances include: -blood work to identify disease mechanisms - urine analyses to detect various substances (Example: sugar) that are indicators of disease (Example: diabetes) - the development of hybrid plants that have defenses against certain plant diseases and parasites - genetic developments, such as cloning hand lens -curved glass for magnifying dissecting scopes - microscope consisting of two eye pieces, a low power lens, and a medium power lens Anton Van Leeuwenhoek- The one who played a leading role in the development of microscopes. Organization of Life (cell hierarchy) Atom – smallest unit of matter for both living and non living Molecules – atoms grouped together form molecules Organelle – part of a cell that carries out a specific function or role Cell – smallest unit of life; the building block of all living organisms from the Latin word cella, meaning small room Tissue –cells combined to perform a specific task or function Organ – two or more tissues combined work together to do a specialized role System – any group of organs working together to perform a specialized role Organism – any living thing that carries out all 7 activities necessary to survive Cell theory 1. Cells are responsible for function and structure in all organisms. 2. All living things are made up of cells. 3. All cells reproduce from other living things. Plant and animal cell structure A) Cell Membrane separates inner cell from surrounding environment semi-permeable (allows some materials in and keeps harmful materials out) B) Cytoplasm jellylike fluid holds organelles in place C) Nucleus “brain” or control centre directs overall cell activity contains DNA D) Vacuole stores food, water, and waste materials looks like an empty sac E) Endoplasmic Reticulum (ER) transports food, water, and waste materials F) Mitochondrion “powerhouse” releases energy in the cell uses oxygen and digested food for energy G) Golgi Apparatus holds waste products until cell removes it packages and transports proteins specialized part of the ER H) Cell Wall (only in plant cells) protection and strength for cell. non-living. I.) Chloroplast (only in plant cells) contains chlorophyll (green color) helps collect sunlight for photosynthesis. Chapter 9 Life function common to living things 1. Transportation- moving parts or internal materials 2. Nutrition - produce or obtain food 3. Growth & Repair- build and repair body parts 4. Reproduction- making new cells or organisms 5. Regulation - responding to changes 6. Metabolism - breath, digest, eliminate waste 7. Synthesis - create needed substances Four organism things that adapt to each environment 1. Philippine Eagle (Pithecophaga jefferyi) Habitat: Rainforests of Mindanao, Luzon, Leyte, and Samar Adaptations: Strong talons and beak: Allows it to hunt large prey such as monkeys and flying lemurs. Keen eyesight: Essential for spotting prey in dense forests. Large wingspan: Helps maneuver through the canopy of trees. 2. Tarsier (Carlito syrichta) Habitat: Forests in Bohol, Leyte, Samar, and Mindanao Adaptations: Large eyes: Excellent night vision for hunting insects at night. Long, powerful hind legs: Enable them to leap between trees to catch prey. Rotatable head: Can turn nearly 180 degrees to detect predators or prey. 3. Bangus (Milkfish) (Chanos chanos) Habitat: Coastal areas, estuaries, and freshwater ponds Adaptations: Flexible diet: Can feed on plankton, algae, and small organisms, allowing them to thrive in varying habitats. Tolerant to salinity changes: Can adapt between freshwater and saltwater environments. Streamlined body: Enhances swimming efficiency to escape predators. 4. Rafflesia (Rafflesia philippensis) Habitat: Forest floors in Luzon and other regions Adaptations: Parasitic nature: Attaches to a host vine (Tetrastigma) to extract nutrients. Large, foul-smelling flowers: Attracts carrion flies for pollination. Camouflage: Blends into the forest floor, reducing visibility to herbivores. All plants and animals need a continual supply of energy in order to grow and function. Plants make their own food in the chloroplast by the process of photosynthesis and stores the energy produced. Animals obtain their energy from the food they eat. Food obtained by plants and animals undergoes a chemical change and releases the stored chemical energy through the process of cellular respiration in the mitochondria. The process of photosynthesis (carbon dioxide + water + energy glucose + oxygen) 1. Plants take in sunlight through their leaves using a green pigment called chlorophyll. 2. They absorb water from the soil through their roots. 3. They take in carbon dioxide from the air through tiny holes in their leaves. 4. Using sunlight as energy, they combine water and carbon dioxide to make sugar (food) for themselves. 5. In the process, they release oxygen into the air. The process of cellular respiratory (energy glucose + oxygen > carbon dioxide + water) 1. Glucose + Oxygen = Energy The process starts when organisms eat food (like sugar or starch) and breathe in oxygen. 2. Breaking Down Glucose The food is broken down step by step to release energy. 3. Energy for Cells The energy released is stored as ATP, which powers all activities in cells. The organ of the digestive system 1. From the Body to the Heart Deoxygenated blood (low in oxygen, high in carbon dioxide) from the body enters the right atrium of the heart through two large veins: Superior vena cava: From the upper body (head, arms, chest). Inferior vena cava: From the lower body. --- 2. To the Lungs for Oxygenation The blood flows from the right atrium to the right ventricle. The right ventricle pumps the blood to the lungs via the pulmonary arteries. In the lungs, the blood releases carbon dioxide and picks up oxygen. --- 3. Back to the Heart Oxygen-rich blood returns from the lungs to the left atrium through the pulmonary veins. The blood then flows from the left atrium to the left ventricle. --- 4. To the Body The left ventricle pumps the oxygen-rich blood into the aorta, the largest artery in the body. The blood travels through arteries, then smaller arterioles, and finally to tiny capillaries, delivering oxygen and nutrients to all body cells. --- 5. Returning to the Heart After delivering oxygen, the blood collects waste products (like carbon dioxide) and becomes deoxygenated. It travels back to the heart through veins and returns to the right atrium to start the process again. The Digestive System: Breaks down and digests food into simple chemicals (nutrients) that enter cells. Body uses these nutrients for energy, growth and repair. Nutrients: Carbohydrates, protein, fat, vitamins, minerals, and water Rids body of solid wastes. Pathway of food: esophagus – push food to stomach stomach – muscles contract to mix food, releases acids that activate enzymes to digest food, this dissolves food to liquid form small intestine – neutralizes stomach acid, absorbs 80-90% of nutrients, releases digestive juices to digest food. large intestine – absorbs vitamins, minerals and water anus – discharges solid undigested food (feces). The Circulatory System: A closed system, no holes or escape for the fluid (blood). move blood through body, transporting food molecules, oxygen, carbon dioxide, and wastes heart – muscle pumps blood through body arteries – vessels bring oxygenated blood from heart to body veins – bring deoxygenated blood back to heart from body capillaries – smallest blood vessels, connecting veins and arteries, where gas exchange occurs The Digestive and Circulatory Systems work together: 1. Nutrients enter blood from the digestive system through capillaries. 2. Circulatory system carries digested food to cells of the body. 3. Nutrients travel through all cells in the body. 4. Waste molecules pass from cells back to blood through capillaries. 5. Circulatory system disposes of waste and toxins (like salt). The digestive system mouth — where food enters body; contains teeth and salivary glands teeth — chew food into smaller pieces for swallowing salivary glands — moisten food with enzymes that begin chemical breakdown esophagus — pushes food to stomach through wave-like muscle spasms stomach — muscles contract to mix food; releases acids that activate chemicals to digest food; dissolves food into liquid form small intestine — has chemicals to digest food; neutralizes stomach acid; absorbs 80 to 90 percent of nutrients large intestine — absorbs vitamins, minerals, and water gallbladder — stores bile pancreas — provides most digestive enzymes; produces insulin to extract nutrients from food rectum — stores solid waste (undigested food) anus — discharges solid mass of undigested food called feces Technology device that you might see in the emergence clinic X-ray - it is use to show any damage to the bone EKG- it is use to diagnose disorder in the heart EEG- It is use to study brain activity Chapter 10 Nutrition branch of science studying foods and how bodies use them Nutritionist study the food needs of humans and other organisms - develop daily nutrient requirements. Nutrients substances found in foods which provide the body with nourishment - Health is maintained in an organism when a mixture of foods and drinks are taken and have enough nourishment and energy in them for the body to maintain its cells, tissues, organs, as well as supporting growth and development. Malnutrition essential nutrients are missing from a diet. - Malnourished people suffer high levels of sickness and disability, have shorter life spans, and may not grow properly or suffer brain damage. Essential Nutrients Carbohydrates → in form of sugar and starch. The primary energy source of the body. Proteins → build tissue, regulate chemical activity, and supply energy when carbs or fat are missing Fats → stored in body as an energy source when carbs are low or missing Vitamins → organized according to whether absorbed in fat or water. -Vitamins A, D, and E in foods containing fats - Vitamins B and C are soluble in water Minerals → help carry out life functions -Example: Calcium, phosphorus, magnesium, iron, and iodine Water → essential for life because it’s used in all life functions - water balance is key: in = out  The things you can find in a food label are: Serving Size Energy(calories) Protein Fat Carbohydrate Vitamins Mineral Analyzing Diets Diet refers to the amount and type of food eaten daily. Mixed Diets (contains a wide variety of foods) are the best way to get all the nutrients the body needs. The Canadian Food Guide is a good example of this. - Canada’s Food Guide recommends how many Food Guide Servings people should eat from each of the four food groups, plus a small amount of added oils and fats. It has five guidelines: 1. Eat a variety of foods 2. Eat a lot of whole grain cereals, breads, fruits and veggies. 3. Choose low fat dairy products, lean meats, and foods prepared with little to not fat. 4. Be active. 5. Limit salt, sugar, alcohol, and caffeine. Food Labeling – the only way to tell what nutrients are in packaged foods. We need to read labels to be educated as to what we are eating.  Vegetarian Diets – a vegetarian is someone who chooses not to eat animal products. A vegan (strict vegetarian) eats no animal products (including cheese and eggs). Because of the lack of meat in their diets, vegetarians need to eat a variety of plants that provide protein. This kind of diet has the added benefits of high fiber and low harmful fats. The down side is low iron, calcium and vitamin B (which can be taken in vitamin supplements). Fad Diets – are current diet ideas about how or what people should eat, mostly to lose weight. An example is the Atkins Diet. This diet is high protein and low carb. Many athletes believe this is good, but they are lacking the energy that carbohydrates provide them. Too much protein is also dehydrating because it takes more water to eliminate the waste products from excess protein in the body. The Role of Diet Your body depends on you to fuel it with a good balance of nutrients at regular intervals. Choosing too many fats causes several problems - your body has to work harder to digest fats - excess fats in your digestive system may cause you to throw up - high fats diets can cause fatigue and lack of energy - cholesterol from fatty foods blocks arteries - over time, fats cause weight gain Skipping meals also causes problems. - Low blood sugar levels when you haven’t eaten for a long period of time - Body metabolism slows down to conserve energy - Results in feeling drowsy and be unable to concentrate Digestive system: Mining the nutrient It would not matter how many nutrients you ate if your body did not absorb them. The job of your digestive system is to break up the food you eat and obtain the necessary nutrients. This work involves three processes. 1. Mechanical digestion - teeth and stomach break food into small pieces 2. Chemical digestion - chemicals known as enzymes break food down into smaller particles 3. Absorption - molecule-sized products of chemical digestion move into the bloodstream Mouth The teeth are the most important role in mechanical digestion. They reduce the size of food and mix it with liquids in the mouth called saliva. Enzymes found within saliva chemically break down starch into smaller fragments. Stomach As Dr. Beaumont found in his research on Alexis St. Martin, the stomach breaks down food and mixes it with gastric juices to form a pasty fluid. Acids in the gastric juices activate enzymes that digest food and turn it into liquid form. Special enzymes begin the process of chemical digestion by breaking down proteins. Once the food is partially digested, the stomach releases it into the small intestine. Small Intestine Most of the chemical digestion and nearly all of the absorption of nutrients occurs in the small intestine. As food materials arrive from the stomach, enzymes secreted by glands such as the liver and pancreas neutralize the gastric juices. Carbohydrates - Enzymes further break down carbohydrates into sugars. These sugars are in a form that can be absorbed into the bloodstream. Protein -Enzymes split the absorption. proteins into simpler components ready for Fat - Bile, a fluid produced by the liver, breaks fat into smaller particles Enzymes produced in the pancreas can then digest these smaller particles Once this is complete, fats are ready to be absorbed Large Intestine Absorption continues in the large intestine. It is here that water, minerals, and vitamins are absorbed into the bloodstream. The large intestine also stores waste materials in the form of feces. Feces are made up mostly of dead bacteria and undigested food. They are temporarily stored in the colon and discharged through the anus. Chapter 11 The environment around you is always changing. The environment inside your body is constantly changing as well. For example, during stressful situations your body reacts by producing some hormones that supply you with energy right away and others that cause your heart to speed up. This reaction to stress helps you perform well during competitions, tests, and emergencies. Like a teeter-totter, your body can go in and out of balance. A hinge in the out- side environment generates a response from your body's internal environment. Your body has to maintain the proper internal conditions while responding to changes in the outside environment. When a teeter-totter is in balance, we say that it is in equilibrium. The ability of your body to maintain an internal balance is called homeostasis (hoh mee o STAY sis). Enzyme Levels Enzymes help regulate the functions of the cells within the body. They control the release of energy from food molecules in the mitochondria. Waste Product Levels Every time you exhale, your respiratory system eliminates waste carbon dioxide. Your body gets rid of toxic materials by filtering the blood through the kidneys. Concentration of Substances in Blood The concentration of sub- stances in your blood is constantly changing. The organs and systems have a role to play in distributing and disposing the various materials that circulate in the blood throughout the day. These include oxygen and carbon dioxide, glucose, minerals, vitamins, and wastes. Heart Rate During times of stress or high activity, your heart rate increases to help circulate more blood to deliver the necessary nutrients and oxygen to the cells. Blood Sugar Level After you eat a meal high in sugar, the concentration of glucose in the blood vessels rises. In response, the pancreas releases a hormone called insulin. Insulin moves glucose from the blood to body tissues. This returns glucose concentrations to an optimal level. Water Balance Special hormones influence mineral and water balance in the body. Human bodies are made up of 65-70% water. This balance is necessary for cell activity. That is because most of a cell's cytoplasm consists of water. Technology that maintain homeostasis A.Doctors diagnose artery disease by inserting a hollow tube into an artery in the groin or elbow. An angiogram provides an X-ray picture of blood vessels. This X ray shows any irregularities in blood flow. B. A procedure called angioplasty clears a blocked artery. A balloon is threaded into a hollow tube. When it reaches the blocked area, it is inflated. This enlarges the artery and restores normal blood flow. C.A pacemaker is an electrical device implanted under the collarbone. It releases electrical charges to stimulate a steady heartbeat. The heart continues to beat normally after its natural pace- maker no longer works properly D.The Jarvik-7 is an artificial heart.Artificial hearts are used because there are not enough human heart donors and it is difficult for humans to stay alive on hearts from other species. Researchers continue to improve artificial hearts. E. A technician inserts an endoscope into the rectum and large intestine. This provides a view of the lower digestive tract. Colonoscopy is used to check for abnormalities, cancer, inflammation, and rectal bleeding. F. Kidney dialysis is used when the kidneys no longer function. A system of tubing allows blood to flow into a machine that removes waste products. Purified blood is then cycled back into the body. Chapter 12 What is energy? Energy is not a substance (no mass and doesn’t take up space) o Energy is a property or quality that provides ability to move or do work causes change cannot be created nor destroyed, only converted (Law of Conservation) Food contains chemical potential energy, which fuels life processes All energy ultimately comes from the Sun o Green plants capture light energy from the Sun during photosynthesis where it is converted to chemical energy by making a sugar called glucose  Plants use energy from glucose for life activities If more sugar is produced than they need, plants store excess glucose as starch -Starch is stored in the leaves, stems, seeds, and roots - Other living organisms consume starch when they each carbohydrate foods - Starch is broken down into glucose during digestion Glucose is subsequently used for cellular respiration in the mitochondria of the cells to release the stored chemical energy needed to support life Functions Ecosystems- communities of living things and the environment they live in. -They contains: 1. living things (plants, animals, bacteria, etc.) 2. non-living things (rocks, weather, water, etc.) All things in an ecosystem are interrelated - if one thing is changed it is all changed Energy flows from one level in it to the next. - The first level gets energy from the sun -producers -Example: green plants -Create glucose with photosynthesis -energy is passed to other organisms in the ecosystem - plants are eaten by herbivore animals primary consumers Example: deer - primary consumers are then eaten by carnivores (meat eaters) secondary consumer Example: wolves The transfer of energy form one level to the next is called the food chain. - The food chain is a step by step sequence of who eats whom, -begins with a producer -Each organism gets energy from the one before it in the chain. Arrows are drawn to show the direction of energy flow. The arrow points from the organism being eaten to the organism doing the eating.  Food webs are series of interlocking food chains, showing the transfer of energy through various levels of an ecosystem. o It is more complex and realistic than a food chain because most organisms are consumed by several other types of organisms, not just one. o In a food web, a change in one thing will affect almost everything else because they are all connected in some way (all interconnected) Decomposers consume the waste materials, like dead/decaying animals. pyramid of energy - shows the total amount of chemical energy that flows through each feeding level in an ecosystem As you move up the chain, each organism uses up energy for its own growth and life processes. Some energy is also lost as heat. Only about 10% of the total energy originally consumed at each level is available to the organism that eats it in the next level - the other 90% is NOT available (lost to an unusable form of energy) -That is why there are fewer organisms in the top level of the energy pyramid Cycle of matter The Sun is the driving force behind all cycles of matter - Each year, producers convert more than 10% of the total carbon dioxide in the atmosphere into sugars Matter recycles in nature The Water Cycle Water evaporates constantly from streams, lakes, and the bodies of organisms This cycle maintains fresh-water environments and supplies the vast quantities of water necessary for life on land The Carbon and Oxygen Cycle These gases cycle during the processes of photosynthesis and cellular respiration Decomposers use oxygen to break down dead organisms and animal waste - They return carbon dioxide to the atmosphere The Nitrogen Cycle Nitrogen is an important nutrient that all organisms need for growth  Certain bacteria, and even lightning, convert nitrogen gas to nitrate forms that are useful for plants Plants and animals die and decay - The compounds in their bodies that contain nitrogen are converted by other bacteria to make nitrates - The nitrates are used again by plants or returned to the atmosphere as nitrogen gas It is estimated that about 50% of all household waste could be composted! Decomposing plant and animal waste contain nitrates and other nutrients - One hundred years ago, farms spread these on the soil to help plants grow A mixture of decomposing plants and soil is called compost - Today may people add this to their house plants, lawns, or gardens - Composting is one way to recycle yard and kitchen wastes and reduce the volume of garbage sent to landfills for disposal Chapter 14 Ecosystem Biodiversity - is a variety of all living things in the area Organisms depend on a variety of factors that are part of the non-living, physical environment such as temperature, amount of precipitation, and type of soil. Both living organisms and non-living factors in an environment make up an Ecosystem The biotic community is made up of all the biotic factors or living components in an ecosystem while all the abiotic factors or non-living components in an ecosystem are called the abiotic environment. In any ecosystem, the biotic community interacts with the abiotic environment -Abiotic factors dictate the kinds of organisms able to live in a certain area - Subsequently, these organisms affect the local environment Ecosystems can be any size, large or small as long as the following interactions occur: - Living things interact with one another -Living things interact with other species - Living things interact with the abiotic factors that make up their environment Example: pond, forest, underside of a leaf Climate and Land Ecosystems  The climate of an area is its average weather conditions based on long-term records -Certain temperature range in each season for each type of climate - Average annual precipitation varies between each type of climate Climate affects living things in many ways, such as regulating reproductive cycles Example: Sheep in the Rocky Mountains have their young in the spring when there is lots of food. If they had their babies in the winter, many would starve Three factors help determine climate - Topography – physical features of an area, such as bodies of water - Latitude – distance north or south from the equator affects sunlight - Altitude – height of an area above sea level (elevation) Location and Soil Topography, latitude, and altitude also influence the type of soil in an area, which in turn affects the number and types of plants (producers) Soil is the thin layer of rock fragments that covers the land o Composed of rock particles of different sizes -the smallest particles are called clay -the next largest are called silt, then sand -gravel is the largest particle size found in soil NOTE: not all soil contains every type of rock particle Good soil also contains plant nutrients, like nitrogen, traps water, and gives plants a firm base in which to grow Soil also contains animal wastes and decaying remains of organisms - Decomposers live in the soil and consume this matter to help it decay - Earthworms drag the debris underground - The material gradually become humus, which consists of fibres, soil particles, and a black, sticky liquid that is really the decayed remains of organisms as well as living organisms, like bacteria and fungi, and trapped moisture Humus binds particles of various size together to make soil crumbs, which are good for several reasons: -Space between crumbs allow plant roots to grow and spread out - Space between crumbs allow air to get into the soil - Crumbs help keep soil moist, but spaces also allow excess water to drain away - Crumbs are less likely to be blown away by wind than small soil particles Humus also helps prevent leaching of minerals from the soil -Leaching is soil material being washed out by the rain  Eventually humus is completely broken down by bacteria, leaving behind only its valuable minerals in the soil Biomes There are two large ecosystems in Alberta: the northern boreal forest and the grassland Ecologist have divided Alberta into four main climatic and soil zones, each with different communities of plants and animals - Boreal Forest - Mountain and Foothill - Parklands - Grasslands A large geographic area with distinct plants and animals is called a biome Biodiversity describes the number and variety of living things in an area - Climate greatly affects the diversity in a biome Boreal Forest Biome -Very large, located in the northern latitudes around the world - Climate is colder than the grassland biome, but receives enough precipitation to support trees - Soil thaws completely during the spring and summer - Some summer days are surprisingly hot - Earthworms are rare because it’s cold, wet, and the soil is acidic - Action of bacteria slowed down in the cold, therefore dead organisms decompose slowly Grassland Biome - Alberta’s grasslands extend from the great western pains in the United States - Few trees grow because of low precipitation, drying winds, extremely cold winters, fierce snowstorms in late spring, and drought in the summer. - Before being ploughed by settlers, the grasslands had a large biodiversity, covered with mixed grasses and communities of animals, plants, fungi and Decomposers What Threatens Biodiversity Today only small parts of Alberta are true grasslands or boreal forests Some of the organisms that lived here 100 years ago are now extinct Extinction is the total elimination of a species from existence - Sometimes this is a normal process of the natural world Sometimes species cannot adapt to a natural climate change Example: many species became extinct during the ice ages - Catastrophic events, such as a volcanic eruption or a floor, may also cause extinction, like 250 million years ago when two thirds of all marine species nearly half of all land organisms died out very suddenly About 65 million years ago, most species of dinosaurs became extinct, possibly because of a large meteorite crashing into Earth Human activity over the last hundred years has increased the rate of extinction - The main reason is loss of habitat Habitat includes an organism’s shelter and food - Wetlands are filled in, loggers clear-cut forests, farmers plough grasslands and put up fences, dams divert rivers All of these activities destroy habitat for plants and animals Species at risk refers to plants and animals that are close to becoming extinct Some of these species are common in some areas, but rare or missing in others Chapter 15 Producing More Food biodegradable -any material that can be broken down by organisms in the environment Include any organic matter from organisms that were once living Example: paper, food waste, etc. non-biodegradable -materials that break down very slowly or not at all Example: plastics, glass, metal, etc. As the human population increase, more and more food is needed Farmers grow as much food as they can each year o Earth has a limited amount of suitable (and available) land for agriculture o Farmers use technology to help them grow more food o There are consequences that go with the benefit of producing more food Scientists have developed two major chemicals to help increase food production, which include pesticides and synthetic (man-made) fertilizers. Pesticides -chemicals that kill or control organisms that humans consider to be pests (unwanted organisms) - Insecticides kill insects - Herbicide kill weeds (unwanted plants) Resistance – sometimes organisms have natural resistance to herbicides and pesticides  i.e. the chemical doesn’t kill them This genetic characteristic is passed on to their offspring, eventually creating an entire population of resistant pests (inherited immunity) Producing More Food Biological Magnification - The toxic effect of pesticide chemicals increases in organisms as you move further along a food chain and the concentrations magnify - i.e. individuals at the top of a food pyramid (tertiary consumers) can be indirectly affected by chemicals through the foods they eat Synthetic Fertilizer contains nutrients, such as nitrates, that plants need - Increase crop yields (grow more food on the same amount of land) - The natural nitrogen cycle is balanced between the producers, consumers, and soil, however, it can be disrupted by human activity Algae growth increases due to nitrates from fertilizers that are washed into waterways from farms, golf course, and lawns Eutrophication buildup of nutrients in an aquatic ecosystem Energy demands increase as the human population increase -Vehicles, electricity, heat, etc. - In Alberta, most of the energy we need is produced from fossil fuels includes coal, oil, and natural gas formed from the remains of organisms that lived millions of years ago greenhouse effect is caused from heat being trapped by carbon dioxide and other atmospheric gases -excess CO2(g) makes this “blanket” thicker and prevents more heat from escaping into space without carbon dioxide in the atmosphere, Earth’s average surface temperature would be –18°C Global Warming is a theory that over time the increase it greenhouse gases (excess from burning fossil fuels, etc.) will cause the Earth’s average temperature to increase, which could have serious consequences! -Melting polar ice caps -Drastic changes to weather system -Cause droughts on agricultural lands Global Climate Change is another commonly accepted theory related to the effect of increased greenhouse gases from human activity  A lot of the food luxuries we enjoy today, like ice cream and fresh fruit, depend on the technology of refrigeration The refrigerator was invented in 1803 but was not used as a household appliance until the twentieth century Before refrigeration food was salted, dried, canned, or kept in cold cellars, well, or streams to be preserved - This process did not work well on all foods and did not always prevent bacteria from growing - Food spoilage was common and many people died from food poisoning - a compressor and a motor is used to move the liquid refrigerant that removes heat from the appliance - CFC’s (chlorofluorocarbons) is a type of refrigerant discovered in the 1920s that is safer for household use because it is stable and non-combustible scientists later discover that CFCs have a negative effect on the atmosphere’s ozone layer organisms, including humans, can be seriously harmed by the thinning of the ozone layer - more people develop skin cancer due to increased exposure to UV rays - high levels of UV radiation slows growth of major crops