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Semester 1 Final ReviewAnswers What is the goal of science? The goal of science is to investigate and explain the natural world. Put the following terms in size order: Earth, molecule, atom, individual, population, galaxy, proton Largest to smallest Galaxy, Earth, population, individual, molecule, atom, proton List the eight characteristics of life a. made of cells b. able to reproduce c. based on genetic code (DNA or RNA) d. growth and development e. need for materials and energy f. respond to stimuli g. keep internal environment constant (called homeostasis) h. evolve (populations, not individuals) What element is the basis of all organic molecules? Why is this element so versatile? Carbon is the basis of all organic molecules. It is so versatile because it has four valence electrons, so it can bond to four other atoms. This means it can form double and triple bonds with itself. Also, it allows carbon to form many shapes, like rings and chains. What is the main function of carbohydrates? Carbohydrates are the main source of energy for living things, being converted to ATP inside of cells Carbohydrates can be stored for later use; they are stored as glycogen in the livers of animals, and as starch in plant roots. Carbohydrates help with body structure; they are found in plant cell walls and the exoskeletons of insects. What are two example of and two functions of lipids? Lipids like fats and oils are used for energy storage; they can be converted when the body runs out of carbohydrates. Lipids like phospholipids make all of your cell membranes (outer covering of cells) What trait do all lipids share in common? All lipids are hydrophobic, meaning they are repelled by water. What is the function of nucleic acids? DNA and RNA- they serve as the blueprint for making new cells and overall living things. What are two main functions of proteins that you have seen so far this year? a. transport of substances into and out of cells b. cell structure c. cell movement d. immune system response (antibodies) e. help with chemical reactions (enzymes) Explain how enzymes work. Enzymes are proteins that are made to help a specific chemical reaction take place inside of a cell. Enzymes have an active site that fits the substrate it wants to work on. The substrate is the reactants of a chemical reaction. When the substrate binds to the active site, the enzyme changes shape, transferring its kinetic energy to the molecules to help the reaction along. This is called ‘lowering the activation energy, which is the energy needed to make a reaction happen. The molecules are either broken down or linked together, forming the desired product. What monomers make up carbs, nucleic acids, and proteins? Monomer Amino Acid Polymer/ Macromolecule Protein Simple Sugars/ Starches Carbohydrates Nucleotides Nucleic Acids (DNA/RNA) What are two differences between prokaryotes and eukaryotes? prokaryotes do not have compartments in their cells; eukaryotes do eukaryotes can be multi-cellular; prokaryotes are only unicellular Main source of energy for ecosystems. The Sun Draw a food web and label producer, first, second, and third level consumers • See demo on board Define: autotroph, heterotroph, decomposer Autotroph: an organisms that makes it own food via sunlight or chemicals in its environment (plants) Heterotroph: an organism that gets its food/energy from another organism (deer, human) Decomposer: an organism that gets energy by releasing enzymes and absorbing nutrients from dead organisms (bacteria, fungi) Energy- how much gets passed on between trophic levels; where most is located in a ecological pyramid 10% is passed Most is located in the producers Biomass- definition; where most is located in an ecological biomass: the mass of all living things at the given trophic level Most biomass is contained within the producers (plants) Importance of water, carbon, nitrogen to living things. Water transports key molecules like proteins and sugars, and maintains an internal balance in cells. Carbon is the basis of all organic molecules, like DNA, proteins, carbohydrates, and fats Nitrogen is a major component of amino acids and proteins Difference between energy, matter cycle through ecosystems. Energy moves in one direction, from the sun to producer, to consumer and into the atmosphere. Matter, like carbon, nitrogen, and water, is recycled between solid, gas, and liquid forms. Explain: greenhouse effect, greenhouse gases, global warming • The greenhouse effect is the trapping of heat energy from the sun by greenhouse gases. • These gases are carbon dioxide, methane (CH4), and water vapor. • Too many gases/ heat trapped can lead to global warming, when the gases are not able to leave the atmosphere, trapping heat inside. Define: Niche and Competative Exclusion Principle • A niche is the role that an organism plays in an ecosystem. Part of this role is the food and shelter sources an organism uses. • The competitive exclusion principle explains that no two species can occupy exactly the same niche. One will outcompete the other, and the other will either evolve or go extinct. (Think of musical chairs) Draw a graph for logistic and exponential population growth • Logistic- birth rate= death when carrying capacity is reached, net pop growth = 0 • Exponential- high birth, low death, net pop growth is positive, unlimited resources Define: carrying capacity and what causes populations to reach it • Carrying capacity is the maximum amount of organisms an environment can support over time. • Populations can reach this when there is a limit on resources, causing the birth and death rate to be equal. Biotic vs. Abiotic factors • Biotic: predators, disease • Abiotic: natural disasters, habitat destruction • Biotic factors depend on density, while abiotic factors are density-independent Define: renewable vs. nonrenewable resources and give an example of each • Renewable resources will regenerate themselves if used wisely. Ex: fish, trees • Non-renewable resources will not regenerate themselves; when gone, they’re gone! Ex: fossil fuels Define: sustainable development • Using the earth’s renewable resources wisely, allowing them to regenerate for use of future generations