Helpful Hints for the Living Environment Midterm

Transcription

1 Helpful Hints for the Living Environment Midterm Unit 1: Scientific Method and Graphing All experiments test a hypothesis A hypothesis is written as an if then statement Experiments have at least one experimental group and always have a control group The control group represents normal and is used as a comparison against the results of the experimental group(s) The independent variable is the idea that is being tested in an experiment (ex: effect of temperature on plant growth) The dependent variable what you are measuring during the experiment (Think: Dependent variable is my Data) (ex: effect of temperature on plant growth) Only one independent variable can be tested in an experiment (ex: if you were testing the effect of temperature on plant growth you would only change the temperature of the plants in the experimental groups. If you changed both the temperature and the amount of water each experimental group received you wouldn t know if plant growth was affected by the temperature or the water or both together) Controlled variables are conditions that are kept the same (constant) between all of the groups in an experiment (ex: if you were testing the effect of temperature on plant growth you would give each experimental group the same amount of water, light, soil, pot, time, etc.) Two ways to increase the validity of an experiment are to either repeat the experiment multiple times or use a larger testing group (ex: we always calculate and graph the class average in any experiment we ve conducted instead of your group s individual results. If I had averaged all 4 of my classes data that would have represented an even larger sample size and would have made the results more valid than the class average) The y-axis (vertical, left) is titled with the dependent variable The x-axis (horizontal, bottom) is titled with the independent variable. Increments used on either axis should go by 1 s, 5 s, 10 s, 20 s, 25 s, 50 s or 100 s. Do not use breaks like you do in math.

2 Unit 2: Characteristics of Life Homeostasis is a state of stable internal environment All organisms have structures and functions which maintain homeostasis (ex: maintaining blood sugar, maintaining body temperature, regulating water loss, fighting off infection, etc.) Metabolism is the term used to describe all chemical reactions that occur within cells to maintain homeostasis (ex: cellular respiration, digestion, excretion, protein synthesis, photosynthesis, etc.) Nutrition is how organisms take in materials from the environment and use them for energy. (ex: autotrophs take in abiotic materials to do photosynthesis and create their own food, heterotrophs take in other biotic organisms and digest them for energy) Transport is how organisms cycle nutrients and waste within their cells. Unicellular organisms exchange materials directly with the environment, multicellular organisms have systems to move materials within their bodies (ex: circulatory system) Respiration is the process by which organisms break down food (usually glucose/sugar) to release energy Growth occurs through the division of cells within multicellular organisms Excretion is the removal of waste from metabolic reactions that occur within cells (CO2, urea, heat, excess water, excess salt). Waste products must pass through the cell membrane into the blood and are transported to different organs for removal (lungs get rid of CO2 and water vapor; skin gets rid of excess heat, water and salt; kidneys get rid of urea and excess water) Regulation of homeostasis occurs through the interaction of the nervous and endocrine system (nerve impulses and hormones) Reproduction is how organisms create offspring. Reproduction is either asexual or sexual

3 Unit 3: Molecules of Life and Enzymes Molecules are either organic or inorganic Organic molecules contain carbon and hydrogen Inorganic molecules may contain carbon but do not contain hydrogen Carbohydrates, proteins, and lipids are organic Water, carbon dioxide, oxygen and salt or inorganic Dehydration synthesis is the process by which large biomolecules are created from small ones by removing an OH from one molecule and an H from another to create a water molecule. (ex: bonding glucose molecules together to make starch, bonding amino acid molecules together to make a protein) Hydrolysis is the process by which large biomolecules are broken down into smaller ones by adding water. (ex: digesting starch into glucose molecules, digesting protein into amino acid molecules) Carbohydrates are sugars All carbohydrates end in -ose Carbohydrates contain carbon, oxygen and hydrogen atoms Carbohydrates have hydrogen to oxygen ration of 2:1 (there are twice as many hydrogen as there are oxygen) Carbohydrates include monosaccharides, disaccharides and polysaccharides HONORS Monosaccharides are glucose, galactose and fructose (review structures) HONORS Disaccharides are lactose, sucrose and maltose (review structures) Polysaccharides are plant starch, cellulose (plant cell walls), animal starch (glycogen) and chitin (insect shells) Lipids are made of one glycerol and three fatty acid molecules Lipids contain carbon, hydrogen and oxygen atoms Lipids are used to store energy or make up cell membranes

4 Proteins are made of amino acids. Examples of proteins include enzymes, hormones, cell structures, receptors on cell membranes and protein channels in cell membranes for facilitated diffusion Proteins contain carbon, hydrogen, oxygen and nitrogen atoms Amino acids link together to form long chains which twist and fold into complex shapes. The final structure is called a protein The function of a protein depends on its structure Enzymes are proteins Enzymes act as catalysts. Catalysts are molecules which help chemical reactions happen easier. Enzymes lower the energy of activation for a chemical reaction so it can occur with the body temperature range of an organism Each type of enzyme only works for a specific substrate (molecule) All enzymes end in ase (ex: lipase breaks down lipids, sucrase breaks down sucrose, lactase breaks down lactose) Each type of enzyme can work within a certain temperature and ph range If an enzyme is heated it will denature (unravel) and become useless Two models of enzyme function are the lock and key model and the induced fit model Enzymes have an active site where it creates a temporary bond with the substrate to complete the chemical reaction it facilitates

5 Unit 4: Ecology Individual organisms of the same species make up a population Different populations make up a community The community interacting with abiotic factors make up an ecosystem All of the earth s ecosystems make up the biosphere Biotic factors are living organisms (bacteria, plants, fungus, animals) Abiotic factors are nonliving (soil, rocks, air, water, temperature, sunlight) Autotrophs are organisms that make their own food through photosynthesis (plants, algae) Heterotrophs are organisms that consume other organisms for energy (different types of consumers) Herbivores are heterotrophs that consume plants Carnivores are heterotrophs that consume animals Omnivores are heterotrophs that consume both plants and animals Scavengers are heterotrophs that consume the remains of animals that were killed by something else (vultures) Decomposers are a special type of organism that breaks down dead organisms into nutrients that are recycled back into the soil (bacteria and fungus) Symbiotic relationships are close associations between two organisms in an ecosystem in which at least one benefits Mutualism is a symbiotic relationship in which both organisms benefit Commensalism is a symbiotic relationship in which one organism benefits and the other is unaffected Parasitism is a symbiotic relationship in which one organism benefits (parasite) and one is harmed or sometimes killed (host)

6 The carrying capacity of an ecosystem is the maximum population size that can be supported Populations grow until they reach carrying capacity then the population levels off and reaches a state of dynamic equilibrium (fluctuations in population size from season to season or year to year based on changing factors in the ecosystem) Limiting factors to population growth include both biotic and abiotic factors (predators, disease, competition, amount of water, amount of plants, temperature) Where an organism lives is called its habitat An organism s role in the ecosystem is called its niche A food chain shows the movement of energy through organisms in an ecosystem. The arrows point in the direction the energy is moving. A food web is a complex overlapping of many food chains Energy pyramids show the relative amount of energy stored at each level of a food chain. The base of the pyramid always represent producers, the next level represents primary consumers (herbivores), the next level represents secondary consumers (carnivores) and the top represents tertiary consumers (top predator carnivores or omnivores) Only 10% of the energy at each level is passed on to the next level because organisms use 90% of the energy they consume to stay alive, reproduce and grow. Population size decreases are you go up the energy pyramid because there is less and less energy available for top predators

7 The nitrogen cycle is responsible for fixing atmospheric nitrogen into usable forms that plants can absorb to create amino acids. Plants called legumes have nitrogen fixing bacteria on their roots. HONORS - know the nitrogen cycle in detail The carbon cycle is responsible for moving carbon through the ecosystem. Plants take in CO2 and convert it into glucose through photosynthesis. Animals eat plants and break the sugar down into CO2 and release energy through the process of cellular respiration. Burning fossil fuels also releases a lot of CO2 into the ecosystem The water cycle moves water through the ecosystem. Evaporation, transpiration, condensation, precipitation, runoff and infiltration are all stages of the water cycle Ecological succession is the process by which a community is slowly replaced by another community in an ecosystem when a change has occurred (lava flow, forest fire, flood, etc) Primary succession occurs in areas where there is only barren rock, secondary succession occurs when there is already soil Pioneer species are the first to grow in an area (lichens and moss) The climax community is the final stable stage in ecological succession Terrestrial (land) biomes include the tropical rain forest, grasslands, desert, deciduous forest, coniferous forest (taiga), and tundra. Rain forests have the greatest amount of biodiversity, grasslands are great for farming, deserts have little rainfall and poor soil, deciduous forests have trees that lose their leaves every year, coniferous forests are evergreen forests and the tundra has permafrost Aquatic biomes include freshwater and marine biomes. Freshwater biome includes rivers, lakes, ponds and swamps. Marine biome includes all of the earth s oceans and seas (salt water habitats)

8 Unit 5: Human Impact on the Environment Human population growth is the greatest threat to the ecosystem Utilizing nonrenewable resources (coal, oil, natural gas) for energy releases a lot of pollution into the ecosystem Utilizing renewable resources (solar, wind, geothermal) for energy has much less of an impact on the environment and we won t run out of them Invasive species are organisms that have been brought to new areas on purpose or by accident and may have a negative impact if they have no natural predators. Their population can grow and out compete native species causing them to die off As pollutants are released into the ecosystem they can accumulate in larger amount in organisms higher up the food chain and affect their populations. The is called biological magnification (biomagnification) Air pollution can cause acid rain which can slowly poison soil and freshwater lakes Use of aerosol cans release chemical that can break down the ozone layer which protects us from radiation from the sun that causes skin cancer Burning fossil fuels releases a lot of CO2 which is a greenhouse gas that traps excess heat from the sun. Slowly increasing global temperatures are responsible for melting the polar ice caps and creating climate change in some areas Recycling is a great way to conserve resources and save the environment for future generations Using biological controls (native species) to control pests is better than using pesticides Environmental laws can be passed which can protect a species habitat

9 Unit 6: Microscopes and Cells Review a diagram of a microscope. Know the names of its parts and functions Total magnification is found my multiplying the eyepiece X objective Everything you see through a microscope is reversed and upside down so if you need to move something to the right you need to move the slide to the left 1mm = 1000 micrometers Prokaryotic cells do not have a nucleus or organelles and are very small (bacteria), eukaryotic cells are complex, they have a nucleus, organelles and can be seen with a microscope (plant and animal cells) Nucleus contains the cell s genetic material (DNA) Cell wall protects plant cells (only in plant cells) Cell membrane regulates what enters and leaves the cell Cytoplasm fills the cell Mitochondria release energy in glucose through cellular respiration Ribosomes produce proteins Vacuoles store water, waste and nutrients Chloroplasts produce glucose through photosynthesis (only in plant cells) Plant cell and animal cells have many of the same organelles. Plant cells have cell walls and chloroplasts but animal cells do not Diffusion is the movement of particles from an area of high concentration to an area of low concentration Osmosis is the diffusion of water across a membrane Cell membranes are semipermeable (selectively permeable) they allow some particles to diffuse across but not others. Particles that do not diffuse across a membrane may be too big or are ions. Small molecules such as oxygen, carbon dioxide and water diffuse easily Facilitated diffusion is the diffusion of certain particles through protein channels embedded in the cell membrane. It s like diffusion with help Diffusion, osmosis and facilitated diffusion are examples of passive diffusion which do not require energy; particles move from high to low concentration Active transport is the movement of particles against the concentration gradient (from low to high concentration) with the use of energy

10 HONORS Cells may take in many particles at once through the process of endocytosis (pinocytosis is when a lot of liquid is taken in at once, phagocytosis is when a large particle is engulfed) HONORS Cells may remove a lot of waste all at once through the process of exocytosis A cell will shrink in a hypertonic solution A cell will swell in a hypotonic solution A cell will remain stable in an isotonic solution In the diffusion lab we placed glucose and starch inside a semipermeable membrane and placed it in an iodine solution The iodine diffused into the membrane and stained the starch black Starch molecules are too big to diffuse so they stayed inside of the cell Glucose particles diffused out of the cell. We tested the water outside of the cell with the glucose indicator and got a positive result. Glucose can diffuse through the membrane because it is a smaller molecule BASIC CHEMISTRY and INDICATORS: Iodine is an indicator for the presence of starch (turns black) BTB is an indicator for the presence of CO2 (turns yellow) Glucose indicator needs to be heated to work (turns puky orange) Acids are below 7 on the ph scale Bases are above 7 on the ph scale 7 is neutral on the ph scale Red litmus paper stays red in an acid, turns blue in a base Blue litmus paper stays blue in a base, turns red in an acid

11 Regents midterm will include the units listed above. Honors midterm will include everything above plus in depth questions on photosynthesis. HONORS ONLY: Unit 7: Photosynthesis Photosynthesis: CO2 + H2O + Light energy sugar (glucose) + O2 Photosynthesis takes place in the chloroplasts of plant cells Chlorophyll is the pigment that absorbs light energy Red/orange and blue/violet light is absorbed, green/yellow light is reflected The light dependent reactions take place in the thylakoid of the chloroplast Review the role of photosystems II and I, the ETC and ATP synthase The light independent reactions (Calvin cycle) take place in the stroma of the chloroplasts Review the steps of the Calvin cycle and what is produced Be able to describe the relationship between the light dependent and independent reactions