Final Exam Study Guide Biology I Unit 1 1 What are the characteristics of living things organisms What are cells Organized cellular reproduce response to stimuli acquire convert energy growth and development regulate internal conditions evolve Cells are the lowest level of organization that can preform all activities required for life 2 What is the alternative definition of life The alternative definition to life is anything that can evolve heritable characteristics that can be passed on to progeny cellular regulation metabolism not required virus 3 What is the relationship between structure and function Structure reflects function and vice versa 4 What is evolution What is a gene What is an allele Evolution is the change in an allele frequency in a population A gene is a sequence of DNA that codes for a trait An allele is a form of a particular gene 5 Describe how evolution by natural selection occurs What three conditions are required for natural selection to occur Natural selection is the differential reproductive success among individuals because of environmental influences THREE requirements are variation among the population differences in success and inheritance of important traits 6 What are the different levels of biological organization Different levels of biological organization are the biosphere ecosystem community population organism system organ tissue blood cell organelle nucleus DNA molecule atom 7 What is the difference between a prokaryotic and eukaryotic cell The difference between a prokaryotic and eukaryotic cell is that eukaryotic cells have a nucleus with membrane bound organelles Prokaryotic cells have neither Prokaryotic cells are usually much smaller as well 8 What is an atom What are the subatomic particles How are they charged An atom is the smallest particle that retains properties of the chemical elements and cannot be broken down by chemical reactions The subatomic particles that make it up are neutrons neutral charge protons positive charge and electrons negative charge 9 What is a molecule A compound An ion An isotope A molecule is two or more atoms held together by covalent bonds An ion is a charged atom A compound is a substance consisting of two or more different elements combined in a fixed ratio An isotope is a different form of an element with a different number of neutrons they behave the same in chemical reactions 10 What is the difference between ionic and covalent bonds What does it mean to say a covalent bond is polar or non polar In ionic bonds an atom donates an electron to another element In a covalent bond they share electrons When a covalent bond is polar or non polar we are talking about the electronegativity and how strong the bond is 11 What is electronegativity How does it affect whether covalent bonds are polar or non polar Electronegativity is an atoms attraction of the shared electrons in a covalent bond In a polar bond atoms have different electronegativities so electrons aren t shared equally In a nonpolar bond atoms have a similar electronegativity Nitrogen and Oxygen the most are very electronegative and Carbon and Hydrogen are somewhat electronegative 12 Explain hydrogen bonding How do hydrogen bonds occur How do hydrogen bonds affect DNA Hydrogen bonds are formed when a partial positive charge on a hydrogen atom that is covalently bonded to an electronegative atom allows the hydrogen to be attracted to a different electronegative atom nearby Hydrogen bonds hold together the two strands in a double helix of DNA stable attachment but weak enough to break with little energy wasted Hydrogen bonds are weaker than covalent bonds and are formed by electronegative charges 13 How do ionic bonds form How do covalent bonds form Ionic bonds form when cations and anions attract each other A covalent bond is the sharing of a pair of valence electrons by two atoms 14 What are hydrogen bonds How do they form in water A hydrogen bond is a type of weak bond that forms when the positive part of a hydrogen atom is attracted the partially negative part of a different atom 15 Describe and explain the properties of cohesion adhesion and surface tension How do cohesion and adhesion allow large drops of water to stand on a penny Large drops of water can stand on a penny because of the cohesion and adhesion The cohesiveness of the water allows for a strong surface tension The adhesion is when the water droplets stick to the surface of the penny 16 Explain how ice insulates water Is ice more or less dense than liquid water Why Ice is LESS DENSE than liquid water because of the structure of the atoms when they slow down Since ice floats on top of water it acts as a layer of insulation 17 What makes water a powerful solvent What is a hydration shell Water is a powerful solvent because of its polarity When a solute is being dissolved in an aqueous water solution the partially positive H atoms surround the solute forming a shell and attach to make bonds with the atoms of the solute breaking them apart and making them part of the solution hydration shells A hydration shell is the sphere of water molecules around each dissolved ion a What is meant by hydrophilic and hydrophobic and what kinds of substances exhibit such properties Any substance that has an affinity for water is said to be hydrophilic cotton A substance that repels water is said to be hydrophobic vegetable oil 18 What is specific heat What results from the high specific heat of water Specific heat is the amount of energy required to increase the temperature of a substance High specific heat allows water to absorb and give off a lot of heat without changing temperature 19 What are buffers and how do they work A buffer is a substance that minimizes the changes in the concentration of H and OH in a solution It does this by accepting hydrogen ions from the solution when there is excess and donating hydrogen ions when they have been depleted 20 What makes a solution acidic or basic How does the pH scale measure this A solution is acidic or basic depending on the amount of H and OH The more H the more acidic the more OH the more basic We measure this in scientific notation 21 What is meant by organic compounds What element is present in all organic molecules Compounds containing carbon are said to be organic Carbon is present in all of these molecules and most contain hydrogen in addition to carbon 22 What are hydrocarbons Are they polar or non polar Hydrocarbons are organic molecules that
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