Scientific Process

AHSGE Review for ScienceFrom Passing the Alabama Graduation Exam in Science from The American Book Company

Scientific Process • Analysis - separation of parts or facts to determine their relationship to each other • Assimilation - process of gathering facts and information about an event or phenomenon for the purpose of understanding it • Conclusion - judgement or inference made based on observation and experimentation • Control Group - situation maintained in an experiment in which no variable conditions are introduced • Data - collection of observed and measurable results • Deductive reasoning - using a generalization that can test a hypothesis or theory to deduce or predict a specific event or phenomenon

Scientific Process cont. • Experiment - process designed to yield measurable results about a hypothesis under carefully controlled conditions • Experimental Group - selected variable conditions for experimentation to support or reject a hypothesis • Hypothesis - possible explanation or educated guess given as a solution to a problem • Inductive reasoning - using specific observations and measurements to enable a scientist to arrive at a generalized explanation of a scientific problem which can be expressed as a hypothesis or theory • Observation - noticing an event or phenomenon and gathering facts about it without manipulation of the evidence • Prediction - to forecast an event or to anticipate the results of an experiment

Scientific Process cont. • Results - the end product of an investigation or experiment • Science - an exact study by which we acquire knowledge of the universe • Scientific Process - method of investigation which follows logical steps in problem solving • Theory - complete explanation of how or why something happens based on research and testing • Tables are good ways to organize data • Line graph are best used to show how one variable changes with respect to another • Bar graphs are used to show easy-to-read, unconnected, bars which represent a quantity of information • Circle graphs are used to show parts of a whole

Steps to the Scientific Method • 1. Define or state a problem • 2. State a hypothesis • 3. Perform an experiment • 4. Collect data from experiment • 5. Draw a conclusion for results • 6. Make predictions about similar situations in the future

Atoms and Elements • Atom - smallest part of an element composed of electrons (e-), neutrons (no), and protons (p+) • Electron shell - energy level where electrons are found in concentration as they move around the nucleus • Element - atoms that have the same number of protons in the nucleus • Ion - electrically charged atoms (loses or gains e-) • Metalloids - elements that have properties of both metals and nonmetals (touching zigzag line) • Molecules - chemically bonded group of atoms (act as unit) • Metals - have luster, good conductors of heat and electricity, and have one to three electron is outer shell (left of zigzag)

Atoms and Elements cont. • Noble gases - elements in the last column of the periodic chart that are stable and unreactive (gases at room temp) • Nonmetals - outer energy shell contains more than four electrons and they are dull in appearance and do not conduct heat well (right of the zigzag line) • Nucleus - central portion of an atom containing no and p+ • Radiation - transfer of energy by waves as particles are released from a decaying nucleus

Structure of the Atom • Atomic Theory - states that all matter is made up of tiny particles called atoms • Octet rule - states that the outer shell of electrons cannot hold more that eight electrons • Valence electrons - number of electrons in outer shell of an atom (1, 2, 3, 4, 5, 6, 7, 8) • Oxidation number - tells how many electrons an atom gives or takes when it reacts (+1, +2, +3, +/-4, -3, -2, -1, 0)

Elements • The number of p+ in an atom gives the atom its identity • If the number of protons changes, the element changes • Elements on the periodic chart are arranged according to their atomic number (# of p+) • When you add p+ plus no, it is equal to the atomic mass or mass number • Atoms of the same element do not always have the same number of neutrons (isotopes) • In metals, reactivity increase the further left and down you go in the chart (most reactive metal if francium) • In nonmetals, reactivity increases the further right and up you go (most reactive nonmetal is fluorine)

Elements cont. • The first column of elements are the Alkali Metals • The second column are the Alkaline Earth Metals • The next to last column are the Halogens • The small columns in the middle are the transition metals • The two bottom rows are the Actinide and Lanthanide Series (rare earth elements)

Radioactive Elements • Alpha particles - 2 p+ and 2 no; have a positive charge; low in energy; can be stopped by a piece of paper • Beta particles - 1 e-; negative charge; medium energy; 1cm of lead can stop • Gamma rays - wave of energy; no charge, high energy, thick lead or thicker concrete can stop

Bonding of Atoms • Ionic bond - results from transfer of electrons from one atom to another; very strong bonds; high melting and boiling points; usually solids at room temp.; usually between a metal and nonmetal • Covalent bond - formed when two or more elements share electrons to create a more stable outer electron structure; weaker bonds; low melting and boiling points; between two or more nonmetals; diatomic molecules form these

Physical and Chemical Changes in Matter • Catalyst - substance which speed up a chemical reaction without being used up in process • Chemical change - rearrangement of the atoms within substances to form a product totally different from the original substance(energy is taken in or given off) • Physical change - change in form or state of matter in which the molecular structure of a substance remains unchanged while the appearance may be altered (most common is phase changes of matter) • Products - substances produced at the end of a chemical reaction • Reactants - starting substances in a chemical reaction

Physical and Chemical Changes in Matter • Surface area - the exposed area of a substance involved in a chemical change • Temperature - the degree of average kinetic energy within a substance which is measured as heat • The Law of Conservation of Matter - states that in a physical or chemical change, matter is neither created or destroyed

Chemical Changes • Combustion - a chemical process in which light and heat are produced • Fermentation - a chemical change in which a partial breakdown of substances occurs without the presence of oxygen • Electrolysis - the decomposition of a compound into simpler substances by passing an electric current through the compound

Rates of Chemical Reactions • The addition of a catalyst to a reaction will cause the reaction to speed up (in the end, the catalyst can be recovered without having been changed) • The greater the surface area of the reactant substances, the faster the reaction between two substances will take place

States of Matter • Physical Characteristics of Matter are identifying characteristics of matter such as: color, odor, feel, shape, solubility, hardness, mass, weight, and taste • Chemical Characteristics of Matter are identifying characteristics of matter such as: atomic structure, density of atoms within matter, and molecular bonds

States of Matter cont. • Gas - has no definite shape and no definite volume (fills any container) • Liquid - has definite volume and no definite shape (takes shape of container) • Solid - has a definite shape and volume • Matter - a substance existing alone or in some combination

Characteristics of Liquids • Viscosity - resistance of a liquid to flow • Surface tension - tendency of a liquid to form a “skin” on the surface • Cohesion - attraction between particles of the same substance • Adhesion - attraction between particles of different substances

Characteristics of Solids • Malleable - can be hammered into thin sheets • Ductile - can be drawn into a wire • Elasticity - can be stretched or bent and returned to its original shape • Brittleness - the ease with which a solid breaks when hammered • Hardness - is the ability of a solid to resist being scratched • Tensile strength - is the resistance of a solid to break under tension

Transfer of Matter and Energy Through Biological Systems • Autotrophs/producers - produce their own food through photosynthesis • Heterotrophs/consumers - depend on others for food • Biotic - living things in an ecosystem • Abiotic - nonliving things in an ecosystem • Biological Systems - living organisms which interact with their environment and perform functions necessary for life • Cellular Respiration - series of chemical changes within a cell in which sugar is broken down, oxygen is used, energy is released, and water and carbon dioxide are produced

Transfer of Matter and Energy Through Biological Systems • Decomposers - help to break down and decompose dead organisms and the wastes of living organisms (fungi & bacteria) • Energy - inner cellular power within an organism to carry on activities necessary to live • Energy Pyramid - the transfer through feeding levels of a food chain from producers to various numbers of consumers • Food Chain - flow of energy and organic material in which the lowest organisms become food for the next highest organisms • Food Web - all the interconnecting food chains in an ecosystem

Transfer of Matter and Energy Through Biological Systems • Matter - anything that takes up space • Nutrients - materials needed by the cell to live and grow • Photosynthesis - the process in which a plant makes food from water and carbon dioxide using energy from the sun • Herbivores - animals that eat only plants • Omnivores - animals that eat both plants and other animals • Carnivores - animals that eat only other animals • Photosynthesis: 6CO2 + 6H2O C6H12O6 + 6O2 • Respiration: C6H12O6 + 6O2 6CO2 + 6H2O + energy

Diversity of Life • Aerobes - organisms that use oxygen to break down food and release energy • Anaerobes - organisms that do not use oxygen to break down food and release energy • Binomial Nomenclature - a system developed by Linnaeus for naming living things (Homo sapien or Homosapien) • Parasites - organisms that live on or in another organism and are harmful to that organism • Plankton - organisms that float on or near the surface of the ocean • Saprophytes - organisms that feed on dead matter • Taxonomy - the science of classifying living things

Taxonomy • Living things are classified according to their evolutionary relationships (structure, chemistry, similarities, development, behavior, nutritional needs, methods of obtaining food, and DNA) • Kingdom is the most inclusive classification and species is the least inclusive Ex. • King Kingdom Animalia • Phillip Phylum Chordata • Came Class Mammalia • Over Order Primates • For Family Hominidae • Good Genus Homo • Sport Species sapien

Monera Kingdom • Single prokaryotic cell with a cell membrane and a cell wall like plants • Have no membrane-bound organelles or nucleus • Some contain chlorophyll • Live in damp places or in water and reproduce by asexual fission • Two phylum of monerans: bacteria and cyanobacteria • Viruses are often included in this kingdom

Protist Kingdom • Protists can be single-celled or multicellular • All protists have a nucleus (eukaryotic) • Some have chlorophyll • They can be plantlike (euglenas, diatoms, dioflagellates, and algae), animal-like (ciliates, flagellates, sarcodinas, and sporozoa), and fungus-like (molds, mildews, and rusts)

Fungi Kingdom • Fungi are saprophytes (parasites) • Have cell walls • Multicellular organisms that are heterotrophic • The body of a fungus, the mycelium, is a mass of thread-like tubes called hyphae that grow underground • Reproduce by spores or by budding • Like warm, moist places • Include zygote fungi, sac fungi, club fungi, imperfect fungi, and lichens

Plant Kingdom • Angiosperm - flowering plants which develop their seeds in a fruit or protective structure • Chlorophyll - green pigment in plants necessary for the process of photosynthesis • Deciduous - a broad-leafed plant which loses its leaves in late autumn • Evergreen - plant which sheds its leaves and grows new ones continuously throughout the year • Gymnosperm - cone-bearing plants which develop their seeds without a protective covering • Herbaceous - plant with a soft green stem • Nonvascular - lacking connective or supporting tissue • Vascular - network of connected conducting tubes within some plants • Woody - hard fibrous stem which supports the structure of plants

Plant Kingdom cont. • Multicellular organisms with specialized tissues • Have an organized structure consisting of roots, stems, and leaves • Autotropic • Contain chlorophyll • Have a cell wall • Need water, carbon dioxide, and sunlight to produce sugar and release oxygen • Bryophytes: Non-vascular spore producing plants • Tracheophytes: Vascular plants

Basic Parts of a Flower • Stamen - the male structure of the flower • Pistil - the female structure of the flower • Anther - produces pollen • Ovary - produces the ovule • Stigma - traps the pollen • Style - the tube from the stigma to the ovary

Animal Kingdom • Invertebrates - animals without a backbone or internal skeleton; account for 90% of all animals (porifera, cnidarians, worms, mollusks, echinoderms, anthropods) • Vertebrates - more highly developed with small flexible bones along their dorsal side encasing the nerve cord (chordata) • External features - outside appearance • Internal features - specialized parts of each phylum are more highly developed than the previous phylum

Animal Kingdom cont. • All are multicellular (cells form tissues and tissues form organs and organs make up organ systems) • All are heterotrophic • They grow, reproduce, and develop from larva or embryos • They are free moving at some stage of their development • Respond to their environments and are capable of complex reactions to environmental stimuli • As animal systems become more complex, the organ systems are more highly developed and specialized

Systems Found in Organisms • Digestive System - take food into the body and break it down (mouth, esophagus, stomach, intestines, anus) • Circulatory System - carry food and oxygen to all the cells of the organism (heart, arteries, veins, capillaries) • Respiratory System - supply the body cells with O2 and eliminate CO2 (trachea, bronchi, lungs, alveoli) • Excretory System - remove excess H2O and waste products from the organism (cells, veins, kidneys, skin) • Nervous System - detect and respond to stimuli in the environment, controls and coordinates body movement and body processes (brain, spinal cord, nerve cells, ganglia, sense organs)

Systems Found in Organisms cont. • Muscular System - responsible for body movement (muscle tissues or cells) • Reproductive System - produce eggs and sperm and contain developing embryo (testes, ovary, uterus) • Skeletal System - work together to provide support for the body (bones, cartilage, ligaments, chitin)

Cells • Active transport - movement of substances through a membrane with the use of energy • Cell - the unit of structure, function, and development • Chromatin - the substance of which chromosomes are made: proteins, DNA, and RNA • Endocytosis - a type of active transport that imports particles or small cells into a cell • Eukaryotic cells - having a true nucleus with a nuclear membrane and organelles • Exocytosis - a form of active transport by which cells move molecules, particles, or other cells contained in vesicles across the plasma membrane to the cell’s environment

Cells cont. • Gametes - a reproductive cell that contains half the normal number of chromosomes; a sperm or egg cell • Homologous chromosomes - pair of chromosomes that resemble each other in length, shape, and the genes they carry (one from mother and other from father) • Meiosis - type of cell division that results in two daughter cells, each with half the number of chromosomes of the parent • Mitosis - type of cell division that results in two daughter cells that have the same number and kind of chromosomes as the mother cell

Cells cont. • Multicellular - an organism that is composed of more than one cell with each cell having a particular function unique to the well-being of the organism • Organelles - parts of the cell whose function are to contribute to the nourishment, function, and development of the entire cell • Passive transport - movement of substances into and out of a cell without the use of energy • Plasma membrane - selective permeable, molecular boundary that separates the cytoplasm of a cell from the external environment • Prokaryotic cells - have no organized membrane between DNA and cytoplasm and no true organelles

Cell Organelles • Nucleus - control center of cell; storage of hereditary information • Endoplasmic reticulum - system of folded membrane in cytoplasm; protein synthesis and distribution of materials throughout the cell • Ribosomes - round-shaped structures in the cytoplasm; sites of protein synthesis • Mitochondria - powerhouse of the cell, rod-shaped; chemical energy conversions for cell metabolism • Plastids (plants only) - structures that contain chloroplasts; conversion of light energy into chemical energy, store food • Golgi complex - flattened membrane sacs; synthesis, packaging, and distribution of materials in the cell

Cell Organelles cont. • Lysosomes - type of storage vesicle; digestion, waste removal • Microbodies - membranes containing enzymes; chemical conversions of fats to carbohydrates, discharge of wastes • Vacuoles - spherical vesicle; digestion, storage, and elimination • Microfilaments and Microtubules - fibers and tubes of protein; movement of internal cell parts • Cilia and Flagella - short and long extensions of microtubes from the surface of the cell; locomotion and production of currents that draw in food • Centrioles - short tubes near the Golgi bodies; necessary for cell reproduction within cells

Passive Transport • Diffusion - move from areas of high concentration to areas of low concentration • Facilitated diffusion - special diffusion that occurs when carrier-proteins in the plasma membrane assist in the passage of materials into or out of the cell • Osmosis - movement of water through a semi-permeable membrane from an area of high water concentration to an area of low water concentration • Hypotonic solution - when a cell is surrounded by a solution that has smaller concentrations of dissolved substances (swell and burst) • Hypertonic solution - solution on the outside of the cell is higher concentration than inside the cell (shrivel and die) • Isotonic solution - equal concentration inside and outside

Active Transport • Exocytosis - a form of active transport in which a cell discharges materials out of the cell • Endocytosis - a form of active transport in which a cell imports substances into the cell

Mitosis • Type of cell division which generates two daughter cells with the identical components of the mother cell • The daughter cells are identical to each other as well as the parent cell • The daughter cells have the same diploid (2n) number of chromosomes as the parent • Diploid number is 23 pairs or 46 chromosomes • Diploid cells are known as somatic cells

Stages of Mitosis • Prophase - the nucleus of the cell organizes the chromatin material into thread-like structures called chromosomes; spindles form between the centrioles • Metaphase - the chromosomes attached at the center or centromeres line up on the spindle at the center of the cell • Anaphase - chromosomes separate at the center, and the spindles pull them toward either end of the cell; a nuclear membrane forms around the chromosomes as they disorganize • Telophase - chromatin again forms from the chromosomes, and a cell membrane grows across the center between the two nuclei

Meiosis • Type of cell division necessary for sexual reproduction • Produces four reproductive cells with half the number (haploid) of chromosomes of the mother cell • Haploid number is 23 single chromosomes • There are two cell divisions, meiosis I and meiosis II • Haploid cells are known as reproductive cells

Heredity and Genetics • Allele - alternate forms of a gene carried by an individual • Chromosome - a strand of DNA in the nucleus of a cell along which genes are located • DNA - deoxyribonucleic acid, coiled double-stranded molecules that carry the genetic code • Dominant - one genetic trait that expresses itself over a recessive trait • Gene - the basic unit for heredity found encoded on the DNA of a chromosome • Genetics - the study of the passage of biological information from one generation to the next

Heredity and Genetics cont. • Heredity - the passing on of characteristic traits from parent to offspring • Meiosis - the process of cell division in which cells are produced that contain only half the number (n) of chromosomes present in the parent cell • Mutation - a sudden change in the DNA pattern passed on to offspring • Protein synthesis - the process within the cell which combines amino acids • RNA - ribonucleic acid, a single-stranded molecule involved in the manufacture of proteins by a cell • Recessive - a genetic trait that is suppressed in the presence of a dominant allele

Genetic Expression • Alternate forms of a gene are called alleles • Genes can be dominant or recessive • Dominant traits show up over recessive ones • The combination of alleles is the genotype (RR or Rr or rr) • The appearance of the trait is the phenotype (round or wrinkled) • If you have two like alleles then homozygous • If two different alleles then heterozygous

Punnett Square • Used to express the possible combinations for a certain trait an offspring may inherit from the parents (shows genotypes) • T t • T TT Tt 1:2:1 Ratio • t Tt tt 25% homozygous tall • 50% heterozygous tall • 25% short

DNA • The longs strands of DNA are made up of sugars and phosphates • Short strands are nitrogen-containing structures called bases (adenine, thymine, guanine, and cytosine) • Adenine and thymine always pair up • Guanine and cytosine always pair up

Scientific Process