BIOL 105 General Biology – Cell Structure, Genetics, Chemistry of Life, Exam Questions with 100% Correct Answers

This document provides BIOL 105 exam 1 questions and answers with verified accuracy. It covers cell biology, prokaryotic and eukaryotic differences, genetics, taxonomy, and the chemistry of life. An essential study aid for students reviewing the foundations of biology. Why study biology? - answerWe study biology to help us understand how we and our environment function separately and jointly. If we can better understand how everything functions, it can help improve not only our lives, but preserve the life of our environment. What questions about the natural world have biologists answered? - answerBiologists have been able to answer how our genes work, from how our cells translate our genetic code to an actual map of how our genetics are laid out. They've been able to answer how we get sick and the differences between bacterial and viral illnesses. Along with bringing to light how we get sick, they've answered how we can best avoid it as well as how to develop better treatment options. What questions or problems are current biologists working to solve? - answerOne of the problems that biologists are trying to solve today is how to cure the illnesses we suffer from, such as viruses (HIV), or diseases where the body is killing itself (cancer, ALS). Other problems that biologists take care of include how to create crops that produce more and are able to live in harsher conditions. How would you describe the difference between something that is alive and something that is nonliving? Be able to explain each characteristic. - answerAll living things contain cells, they grow, - 2 -: respond to stimuli, can adapt to change, consume some form of energy, and reproduce. How does a prokaryotic cell compare to a eukaryotic cell; similarities and differences? - answerA eukaryotic cell has a nucleus as well as organelles that are contained by a membrane, while a prokaryotic cell doesn't have either. There are also two types of prokaryotic cells, domain Bacteria and domain Archaea, where eukaryotic cells only have one type. Prokaryotic and Eukaryotic cells are similar in that they both have protective plasma membranes to keep things from it's environment out and they both contain DNA (it's just where the DNA is stored that's different). What is spontaneous generation? Is spontaneous generation possible? - answerSpontaneous generation is the idea of living organisms can come from nonliving matter. Spontaneous generation is not considered possible today. Who originally developed our taxonomic system? - answerCarl Linnaeus is seen as the original creator of the taxonomic system. How are organisms named and how are they written? - answerOrganisms are named based on their genus and epithet. The genus is always put in front as well as capitalized, while the epithet is placed last and not capitalized. What does it mean to have a hierarchical system? - answerIt means it's a system that groups broader species together and slowly groups them into more specific pairings. How are organisms classified now? What was Woese's contribution? - answerOrganisms are classified into a three-domain system. Woese discovered the third domain, the archaea. How are protists different from bacteria and archaea? - answerArchaea are all of the single cell organisms that are classified as prokaryotic while protists are all of the single cell organisms that are classified as eukaryotic. Hypotheses: Prior to the scientific method, what hypotheses were used to - 3 -: explain the following questions? What causes disease? (ex. Flu, whooping cough, smallpox, leprosy, TB, etc...) - answerPrior to the scientific method, people used to believe that evil spirits cause diseases as well as curses. What is a hypothesis? - answerA hypothesis is a question that can be proven true or false by gathering data. What is an element? - answerAn element is a substance that cannot be broken down into simpler substances by typical chemical reactions. Which elements make up most of life? - answerFour elements make up about 96% of the mass of most organisms. These elements are hydrogen (H), oxygen (O), carbon (C), and nitrogen (N). Why is the concept of elements that make up most of life important to recognize? - answerChemical similarities among organisms on Earth provide strong evidence for the evolution of organisms from a common ancestry. This can also help biologists apply information learned about bacteria and other animals to many organisms, including humans. What is the relationship between an atom and an element? - answerAtoms are the smallest portion of an element that still retains its chemical properties. Atoms make up elements. What components make up an atom? What are their properties? - answerAtoms are made up of subatomic particles. Protons are positively charged particles that reside in the nucleus of an atom. Their individual mass is about 1 amu (atomic mass unit/Dalton). Neutrons also reside in the nucleus, although they have a neutral charge. Neutrons also have a mass of 1 amu. Electrons are much lighter with a mass of about 1/1800 amu. They hold a negative charge and move around rapidly in electron orbitals. How is an atom identified? - answerAn atom is identified as belonging to a certain element by its number of - 4 -: protons in the nucleus. The number of protons is also represented as the atomic number. The number is represented in subscript (lower) to the left of the chemical symbol. What is atomic mass? - answerAtomic mass indicated how much matter is contained in the atom. This can be used to compare atoms sizes. Atomic mass is calculated by adding the number of protons and neutrons in an atom's nucleus. The symbol for atomic mass is amu or daltons. Electrons mass is not included as the mass is much to small to make a noticeable difference. The atomic mass number is located to the left of the chemical symbol as a superscript (upper). How does the Bohr model represent the structure of an atom? - answerBohr models show electrons arranged in concentric circles around the atom's nucleus. The models are inaccurate because the space compared to the nucleus is much larger and electrons do not move in concentric circles. Although, the models are convenient, simple, and accurately show the number of electrons for an atom. What is an isotope? - answerIsotopes of the same element differ in their number of neutrons. The number of protons and electrons remain the same. Isotopes of a chemical element have the same chemical characteristics. What does an isotope do to atomic mass? - answerThe mass is expressed as an average mass of the isotopes, based on their abundance in nature. Heavier isotopes can increase the overall atomic mass of an element on the periodic table. The total difference depends on how abundant the isotopes are in nature compared to the ordinary element. How are these isotopes important in science and medicine? - answerMolecules containing radioisotopes, unstable isotopes that emit radiation as they decay, metabolize and/or localize in an organism in similar ways to other non radioactive isotopes. Scientists can use the decaying information as a research tool to - 5 -: date fossils, trace biochemical pathways, determine genetic information, and understand plant's sugar transport. Medically radioisotopes can be used to diagnosis or treat certain diseases. Radioisotopes can be used for labeling inside of the body. This is beneficial for showing blood flow. Radioisotopes also interfere with cell division so they can be used therapeutically for treating diseases characterized with rapid cell division. What is an electron orbital? How many electrons does an orbital hold? - answerAn electron orbital is a three-dimensional space outside of a nucleus where electrons rapidly move. Each orbital contains a maximum of two electrons. What is an electron shell? Why are there different electron shells? - answerAn electron shell consists of electrons in orbitals at the same principal energy level. Electron shells closer to the nucleus have a lower energy compared to the greater energy of electron shells distant to the nucleus. A few orbitals can be in each electron shell. How is an electron shell represented in the Bohr model? Is this accurate? Explain. - answerAn electron shell in the Bohr model is represented by a circle around the nucleus. This is inaccurate because electrons move in a three-dimensional area around the nucleus. Electrons also do not move in a particular pattern. The Bohr model also does not represent the orbitals in each electron shell. What is a valence electron? - answerValence electrons are the most energetic electrons and occupy the valence shell. They are the farthest away from the atom's nucleus. In the Bohr model the valence shell is represented by the outermost concentric circle. Why is more attention given to valence electrons than non-valence electrons? - answerValence electrons are key players in chemical reactions. Valence electrons can be transferred or shared between atoms during a chemical reaction. Non-valence electrons remain - 6 -: with the original atom, therefore they have a smaller and less dynamic role Can the periodic table be used to: Determine how many electrons each of the first three shells hold and arrangement of electrons around the nucleus? - answerYes, the periodic table can determine this. The second to last row on the periodic table provides a list of the number of electrons in each shell. Can the periodic table be used to predict atomic behavior? - answerThe periodic table cannot predict atomic decay because the table does not provide the number of neutrons for each atom. What is a covalent bond and why/how does it form? - answerCovalent bonds involve the sharing of electrons between atoms that results in each atom having a filled valence shell. The atoms will share the necessary number of electrons, keeping the atoms attracted simultaneously to each other. The electrons will whirl around both nuclei. Unlike atoms can also share covalent bonds forming molecules or covalent compounds. What is the difference between a single, double, and triple covalent bond? - answerA single covalent bond occurs when one pair of electrons is shared between two atoms by a covalent bond. A double covalent bond occurs when two pairs of electrons need to be shared for the atoms to achieve stability. A double covalent bond is represented in the structural formular by a set of parallel lines. Similarly, a triple covalent bond occurs when three pairs of electrons are shared between two atoms. A triple covalent bond is represented by three parallel lines in the structural formula. Be able to understand what the molecule formula means and be able to draw the Bohr model, Lewis Dot Structure, and Structural Formula. - answerThe subscripts in the molecular formula indicate the number of each type of atom per molecule. (H2O indicated molecule consists of to hydrogen atoms and one - 7 -: oxygen atom.) What is electronegativity? - answerElectronegativity is a measure of an atom's attraction for shared electrons in a chemical bond. How does electronegativity affect covalent bonding? - answerWhen covalently bonded atoms have similar electronegativities the electrons are shared equally (nonpolar covalent bond). Electrons are pulled closer to the atomic nucleus of the element with the greater electronegativity when the atoms differ in electronegativities (polar covalent bond). What is an ionic bond? - answerAn ionic bond is when one atoms gives up an electron (cation) to be received by another atom (anion). The donor becomes positively charged while the recipient becomes negatively charged. These opposite charges cause the atoms to form an ionic bond. When and how do ionic bonds tend to form? - answerThese bonds form when an atom cannot fill its valence shell due to too many or too few electrons in the shell. Cations are typically formed when an atom contains 1, 2, or 3 electrons in its valence. Anions are typically formed when an atoms has 5, 6, or 7 valence electrons. If an atom has only one electron its valence, the atom would become largely unbalanced if it had to receive 7 more electrons. The necessary valence electron is completely transferred to the anion. This causes the donating atom to become a positively charged ion and the accepting atom to become a negatively charged ion. How are ionic bonds and substances formed by them different from covalent bonds? - answerThe bonds formed in ionic bonds are strong in the absence of water but relatively weak in the presence of water. Ionic bonds are less stable than the strong covalent bonds. Covalent bonds form molecules