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Jason Murphy Science Mid Term Chapter 1: 1-1 The goal of science is to investigate and understand nature, to explain events in nature, and to use those explanations to make useful predictions Science: an organized way of using evidence to learn about the natural world. Also refers to the body of knowledge that scientists have built up over years of using this process. Evidence Based on Observation: Observation: using 1 or more of the senses to gather information. Data: evidence, the information gathered from observation. Quantitative Observations: involve numbers, counting or measuring objects. Qualitative Observations: involve characteristics that cannot be easily measured or counted, Ex: color or texture. Inference: a logical interpretation based on prior knowledge and experience. Hypothesis: a possible explanation for a set of observations or an answer to a scientific question. A skeptical person continues to ask questions and looks for alternative explanations. 1-2 The factors in an experiment that can change are called variables. Whenever possible, a hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or controlled. Independent/manipulated variable: variable deliberately changed. Dependent/responding variable: changes in response to the independent variable. Theory: a hypothesis that is so well supported from evidence in numerous investigations. In science, the word theory applies to a well tested explanation that unifies a broad range of observations. 1-3 Biology: study of life Living things share several characteristics. These characteristics include the following:
Living things obtain and use materials and energy
Living things respond to their environment
Living things maintain a stable internal environment
Living things, taken as a group, change over time
Cell: small, self contained units that make up all life. Sexual reproduction: two cells from different parents unite to produce the first cell of the new organism. Asexual reproduction: the new organism has a single parent. Metabolism: the combination of chemical reactions through which an organism builds up or breaks down materials as it carries out it’s life processes. Homeostasis: the process by which organisms keep their internal conditions relatively stable. Evolve: change over time. The many levels at which life can be studied include molecules, cells, organisms, populations of a single organism, communities of populations living in the same area, and the biosphere. 1-4 Most scientists use the metric system when collecting data and performing experiments. The metric system is a decimal system of measurement. Microscopes are devices that produce magnified images of structures that are too small to see with the unaided eye. Light microscopes produce magnified images by focusing visible light rays. Electron microscopes produce magnified images by focusing beams of electrons. Compound light microscopes allow light to pass through the specimen and use two lenses to form an image. Electron microscopes focus beams of electrons on specimens. Cell culture: a group of cells, often isolated for experimentation. Cell fractionation: process to separate cell parts. Chapter 2: 2-1 The Nature of Matter Atom: basic, smallest unit of matter The subatomic particles that make up atoms are protons, neutrons, and electrons. Nucleus: center of the cell, formed by protons and neutrons. Contains DNA, the blueprint for the cell. Electron: negatively charged particles located on orbitals. Proton: positively charged sub-atomic particle located in the nucleus of cells. Element: a pure substance that can’t be broken down into a more simpler substance, consists entirely of one type of atom. Isotopes: Atoms of the same element with a different atomic mass number. Because they have the same number of electrons, all isotopes of an element have the same checmical properties. Compound: A chemical compound is a substance formed by the combination of two or more elements in definite proportions. The main types of bonds are ionic bonds and covalent bonds: Ionic bonds: An ionic bond is formed when 1 or more electrons are transferred from one atom to another. Ions: positively or negatively charged atoms Covalent bonds: A covalent bond forms when electrons are shared between atoms. Bonds are only dealing with the giving or sharing of electrons. Molecule: The molecule is the smallest unit of most compounds. Ex: water molecule-2 hydrogen atoms, 1 oxygen atom. When molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules. Chemists call such intermolecular forces of attraction, van der Waals forces. 2-2 A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. Cohesion: an attraction between molecules of the same substance. Ex: water Adhesion: an attraction between molecules of different substances. A mixture is a material composed of two or more elements or compounds that are physically mixed together but not chemically combined. Solution: type of mixture Solute: The substance that is dissolved. Solvent: The substance in which the solute dissolves. An acid is any compound that forms H+ ions in solution. Acidic solutions contain higher concentrations of H+ ions than pure water and have pH values below 7. A base is a compound that produces hydroxide ions in solution. Basic, or alkaline, solutions contain lower concentrations of H+ ions than pure water and have pH values above 7. Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH. 2-3 Monomers: smaller units of macromolecules. Polymers: chains or joined monomers. Four groups of organic compounds found in living things are carbohydrates, lipids, nucleic acids, and proteins. Living things use carbohydrates as their main source of energy. Plants and some animals also use carbohydrates for structural purposes. Monosaccharides: single sugar molecules, carbs. Polysaccharides: large macromolecules formed from monosaccharides. Lipids can be used to store energy. Some lipids are important parts of biological membranes and waterproof coverings. Nucleic acids store and transmit hereditary, or genetic, information. Two kinds: RNA and DNA. Nucleotides: Individual monomers Proteins are polymers or molecules called amino acids (20 kinds) Some proteins control the rate of reactions and regulate cell processes. Some are used to form bones and muscles. Others transport substances into or out of cells or help to fight disease. 2-4 A chemical reaction is a process that changes one set of chemicals into another set of chemicals. Reactants are compounds entering the reaction, the compounds produced are called products. Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products. Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy. Activation energy: energy needed to get a reaction started. Catalyst: a substance that speeds up the rate of a chemical reaction. Enzymes are proteins that act as biological catalysts. Cells use enzymes to speed up chemical reactions that take place in cells. Substrates: the reactants of enzyme-catalyzed reactions are known a substrates. Chapter 7 7-1 Cells: the basic units of all forms of life. Cell theory:
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells.
Cell Membrane: a thin, flexible barrier around the cell. Cell Wall (plants only): strong layer around cell. Cell walls and cell membranes protect and support cells, while allowing them to interact with their surroundings. Nucleus: a large structure that contains all genetic material and controls cell activities. Cytoplasm: material inside the cell membrane. Biologists divide cells into two categories: eukaryotes and prokaryotes. The cells of eukaryotes have a nucleus, but the cells of prokaryotes do not. Organelles: specialized structures that perform important cellular functions. 7-2 The main function of the cell wall is to provide support and protection for the cell. Nucleolus: assembly of ribosomes Nuclear envelope: double-membrane layer surrounding the nucleus. Cytoskeleton: helps support the cell. The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape. The cytoskeleton is also involved with many forms of cell movement. Microtubules: hollow tubes of protein that maintain cell shape and serve as “tracks” along which organelles are moved. Microfilaments: long, thin fibers that function in the movement and support of the cell. Proteins are assembled on ribosomes, small particles of RNA and protein. Ribosomes: produce proteins following coded instructions that come from the nucleus. Endoplasmic Reticulum (ER): smooth-no ribosomes, rough-ribosomes. The ER is the organelle in which components of the cell membrane are assembled and some proteins are modified. Golgi Apparatus: Enzymes in the Golgi Apparatus attach carbohydrates and lipids to proteins. Lysosomes: Small organelles filled with enzymes that break down lipids, carbohydrates, and proteins from food into particles that can be used by the rest of the cell. Also break down old organelles to not clutter up the cell. Vacuoles: Saclike structures used to store water, salts, proteins, and carbohydrates. Plant cells have a single large vacuole. Makes it possible for plants to support heavy structures. Chloroplasts: Found in plants. Chloroplasts use the energy from sunlight to make energy-rich food molecules in a process known as photosynthesis. Mitochandria: Organelles that release energy from stored food molecules. Mitochandria use energy from food to make high-energy compounds that the cell can use to power growth, development, and movement. 7-3 The cell membrane regulates what enters and leaves the cell and also provides protection and support. Lipid bilayer: The core of nearly all cell membranes is a double-layered sheet called the lipid bilayer. The concentration of a solution is the mass of solute in a given volume of solution, or mass/volume. Diffusion: The process by which molecules move from an area where there is a higher concentration of molecules to an area of less concentration. When concentration is equal, it is at an equilibrium. Diffusion causes many substances to move across a cell membrane but does not require the cell to use energy. Selectively permeable: Most membranes are selectively permeable, meaning that some substances can pass through them and others cannot. A process called osmosis allows water molecules to pass easily through most biological membranes. Osmosis is the diffusion of water through a selectively permeable membrane. Isotonic: concentrations equal inside and outside of membrane Hypotonic: more concentration on outside of membrane. Hypertonic: more concentration inside of membrane. Facilitated diffusion: helps diffusion of molecules across the membrane. Active transport: The material moves from an area of lower concentration to an area of greater concentration in a process called active transport. Endocytosis: taking material into the cell through infoldings, or pockets of the cell membrane. Phagocytosis: engulfing of large particles located on the outside of the membrane. Exocytosis: removal of large amounts of material. 7-4 Cells are the basic units of all organisms A single-celled organism is also called a unicellular organism. They grow, respond to the environment, and reproduce. Colonial organisms live in groups of individuals of the same species that are attached to one another but have few specialized structures. Organisms made up of many cells that work together are called multi-cellular organisms. Multi-cellular organisms have cell specialization, or separate roles for each type of cell. Cells in multicellular organisms are specialized to perform particular functions within the organisms. Levels of organization: The levels of organization in a multicellular organism are individual cells, tissues, organs, and organ systems. Tissue: a tissue is a group of similar cells that perform a particular function. Four main types:
Muscle, epithelial, nervous, and connective.
Epithelial tissues, such as skin cover or line body surfaces. Connective tissues include bone, blood, cartilage, and lymph. Many groups of tissues work together as an organ. A group of organs that work together to perform a specific function is called an organ system. 8-1 Energy and Life: Plants and some other types of organisms are able to use light energy from the sun to produce food. Organisms such as plants, which can make their own food, are called autotrophs. Other organisms, such as animals, cannot use the sun’s energy directly. These organisms, known as heterotrophs, obtain energy from the foods they consume. ATP=Adenosine triphosphate ADP=Adenine diphosphate The characteristics of ATP make it an exceptionally useful molecule that is used by all types of cells as their basic energy source. 8-2 Photosynthesis: CO2 + H20 + energy (sunlight)=C6H12O6(glucose) + O2. Jan van Helmont discovered water was a reactant through his plant and water experiment. Priestly discovered oxygen as a product through his candle experiment with the glass jar. Ingenhousz found sunlight as a reactant by performing Preistly’s experiment in the dark. The experiments performed by van Helmont, Priestly, Ingenhousz, and other scientists reveal that in the presence of light, plants transform carbon dioxide and water into carbohydrates and release oxygen. Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into oxygen and high energy sugars. In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts. Plants gather the sun’s energy with light-absorbing molecules called pigments. The plants’ principal pigment is chlorophyll. Two types, chlorophyll a, and chlorophyll b. 8-3 Photosynthesis takes place inside chloroplasts. Saclike photosynthetic membranes called thylakoids. Thylakoids are arranged in stacks known as grana. The Calvin cycle takes place in the stroma, the region outside the thylakoid membrane. A carrier molecule is a compound that can accept pair of high-energy electrons and transfer them along with most of their energy to another molecule. The light-dependent reactions produce oxygen gas to convert ADP and NADP+ into the energy carriers ATP and NADPH. The Calvin cycle uses ATP and NADPH from the light dependent reactions to produce high energy sugars. Factors Affecting Photosynthesis -shortage of water can slow or stop photosynthesis -temperature -intensity of light also affects the rate at which photosynthesis occurs. 9-1 A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degrees Celsius. Glycolysis releases a small amount of energy. Glycolysis, the Krebs cycle, and the electron transport chain make up a process called cellular respiration. Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound. TermDefinitionautotrophorganisms such as plants, which make their own foodheterotrophorganisms such as animals, which obtain energy from foods they consumeATPone of the main chemical compounds that living things use to store energyphotosynthesiswhen plants use sunlight to convert water and carbon dioxide into oxygen and high-energy carbsohydrateschlorophyllthe plants principal pigmentthylakoidthe saclike photosynthetic membranes in chloroplastsstromathe region outside the thylakoid membranesNADP+a carrier moleculelight dependent reactionthe recation in plants which require lightATP synthasea protien contained in the membrane of the electron transport chaincalvin cyclewhen plants use the energy that ATP and NADPH contain to build high-energy compounds that can be stored for a long timecaloriethe amount of energy needed to raise the temperature of 1 gram of water 1 celcuis degreeglycolysisa process that releases only a small amount of energycellular respirationthe process that releases energy by breaking down food molecules in the presence of oxygenNAD+an electron carrier that accepts 4 electronsfermentationthe process of a non-present oxygen pathway and glycolysisanaerobicmeans to not require oxygenaerobicthe pathways in cellular respiration, which require oxygemkrebs cyclepyruvic acid produced in glycolysis, which passes to the second stage of cellular respirationelectron transport chainthe electrons passed from the carriers