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Midterm

Midterm Test Review-Week 1 Questions

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Department
Biology
Course
BIOL 1500
Professor
Tanya Da Sylva
Semester
Fall

Description
Midterm Test Review-Intro to Biology  Distinguish between quantitative and qualitative data. o Quantitative Data is a measurable observation, usually to do with numbers. o Qualitative data is data that can be observed that can be described but not measured.  Example: primatologist Alison Jolly has spent over 40 years making observations of lemur behavior during field research in Madagascar, amassing data that is mostly qualitative.  Distinguish between a scientific theory and a hypothesis. o Hypothesis is a proposed explanation for a set of observations. A good hypothesis leads to predictions that scientists can test. o Scientific theory is much broader in scope than a hypothesis.  Scientific theory has supported evidence  Scientific theory describes a great diversity of observations that are supported by evidence.  Describe seven properties common to all life. o Order  A highly ordered structure that typified life.  Living cells are the basis of this organization because they are the smallest units of life. o Reproduction  Organisms reproduce their own kind o Growth and Development  Inherited information in the form of DNA controls the pattern of growth and development of all organisms. o Energy Processing  When a predators eats its prey, the predator will use the chemical energy in its prey to power its own activities and chemical reactions. o Response to the environment  All organisms respond to environmental stimuli o Regulation  Many types of mechanisms regulate an organisms internal environment, keeping it within limits that sustain life. o Evolutionary Adaptation  Adaptations evolve over many generations, as individual traits with traits best suited for their environment have greater reproductive success and pass on their traits to their offspring.  Describe the levels of biological organization from molecules to the biosphere, noting the interrelationships between levels and discuss how hierarchical organization and evolution tie together all major themes in biology. o 1) Biosphere  All of the environments on earth that support life.  Includes: Regions of land, bodies of water and the lower atmosphere. o 2) Ecosystem  All the organisms living in a particular area, as well as the physical component with which the organisms interact with (such as air, soil, water and sunlight) o 3) Community  The entire array of organisms. So all the species inhabiting in a certain area. o 4) Population  All the individuals of a particular species, living in an area. o 5) Organism  An individual living thing o 6) Organ System  Several organs that co-operate in a specific function. Such as circulatory system or nervous system. o 7) Organ  An organ is made up of several different tissues  Ex. Our brain o 8) Tissue  Is made up of a group of similar cells that perform a specific function.  Ex. Nervous System o 9) Cell  A fundamental unit of life.  Ex. Nerve cell o 10) Organelle  A membrane-enclosed structure that performs a specific function in a cell  Ex. Nucleus o 11) Molecule  Is a cluster of small chemical units called atoms held together by chemical bonds.  Ex. DNA  Discuss how Hierarchial organization and evolution tie together all major themes in biology. o At each new property, there are novel properties that arise, properties that were not present at the preceding level o Emergent properties is an important theme in biology because everything is always developing and coming together.  Explain why cells are a special level in biological organization. o Cells are the fundamental unit of life o Cells are the smallest unit of life  Chemistry and Macromolecules  Describe the importance of chemical elements to living organisms and relate major principles of chemistry to the study of biology. o All types of matter (anything that occupies space) are composed of elements. Elements are substances that cannot be broken down to other substances by ordinary chemical means. o About 25 elements are essential to life, the 4 most common are oxygen, carbon, hydrogen, and nitrogen.  These 4 elements are the main ingredients for biological molecules such as proteins, sugars, and fats. (these 4 elements make up 96% of human weight) o Calcium and phosphorous are responsible for bone formation. o Potassium, sodium, calcium, and chlorine are essential for nerve signalling (4% of human body weight) o Trace elements are needed for all forms of life  Iron is vital for energy processing and for transporting oxygen in your blood.  Iodine is essential for hormone produced by thyroid gland  Iodine deficiency= goitre or retardation o Fluoride reduces tooth decay  Describe the structure of an atom and be able to sketch a representative structure when given key information about an element. o An atom is the smallest unit of matter that retains properties of an element. o The structure of an atom consists of 3 kinds of particles  Proton: a subatomic particle with a single positive electrical charge (+)  Electron: a subatomic particle with a single negative charge (-)  Neuron: a subatomic particle with a neutral charge (no charge)  Electrons move around the nucleus  The attraction between the electrons and the protons hold the electrons near the nucleus o Atomic Number: all atoms of a particular element have a unique number of protons (# of protons = # of electrons, making the net electrical charge = 0) o Mass Number: The sum of protons and neutrons in the nucleus in daltons.  Proton=1 Dalton, Neutron= 1 Dalton  Electron = 1/2000 dalton  Compare and contrast between ionic, hydrogen, and covalent bonds. o Ionic Bonds:  Attraction between ions of opposite charges, when the attraction holds them together it is called an ionic bond  The transfer of an electron between two atoms  An ion is an atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons.  Loose electron= electrical charge of +1  Gain of electron= electrical charge of -1  The environment affects the strength of an ionic bond o Hydrogen Bonds:  The weakest kind of bond  Most large molecules are held in their 3-dimentional shape by weak hydrogen bonds  A hydrogen atom that has formed a polar covalent bond with an electronegative atom (ex: oxygen or nitrogen). The hydrogen atom then has a partially positive charge which allows it to be attracted to partially negative atoms (usually oxygen or nitrogen atom).  Hydrogen bonds help create a proteins shape (and thus its function) and hold two strands of DNA molecules together.. o Covalent Bonds:  Is the strongest kind of chemical bond  Where two atoms share one or more pairs of outer shell electrons  Two or more atoms held together by covalent bonds form a molecule  An atoms attraction for shared electron is called its electronegativity.  The more electronegative an atom = the more strongly it pulls shared electrons towards to nucleus. o Non-polar covalent bonds: o When electrons are shared between atoms. o When two or more atoms exert an equal pull on the electrons.  Ex. Molecules of only 1 atom  H2o or O2 (water or oxygen)  Oxygen O2 is the most electronegative atom o Polar Covalent Bonds: o Unequal sharing of electrons o It is the pulling of shared, negatively charged electrons closer to the more electronegative atom.  This makes the atom partially negative and the other atom partially positive.  Ex. H2O=Oxygen is slightly negative and the hydrogens are slightly positive  Ex. Polar molecules: an unequal distribution of charges.  Describe chemical reactions in terms of atomic structure and bonding and explain how they change the composition of matter. o Basic theme of chemistry:  The structure of atoms and molecules determine the way they behave. o The chemical behaviour of an atom is determined by the number and arrangements of its subatomic particles, particularly its electrons. o Chemical reactions is the breaking and making of chemical bonds leading to changes in composition of matter. o Chemical reactions do not create nor destroy matter; they only rearrange it in various ways. o Properties emerge when atoms combine to form molecules and when molecules interact. o In chemical reactions, they rearrange matter in various ways, which changes the shape and therefore the function of the molecule.  List and define the life-supporting properties of water and relate them to the structure of water. o We can trace waters life-supporting properties through their structure, interactions, of its molecules, their polarity, and their hydrogen bonds between molecules. o Hydrogen bonds make liquid more cohesive  Cohesion: the tendency of molecules of the same kind to stick together.  The cohesion for water is much stronger than it is for other liquids.  Adhesion: the clinging of one substance to another  Surface Tension: a measure of how difficult it is to stretch or break the surface of a liquid  Hydrogen bonds give water a high surface tension. o Water has a stronger resistance to temperature change then most other substances  Heat is absorbed in order to break hydrogen bond  Heat is released in order to make hydrogen bonds  Waters resistance to temperature change stabilizes ocean temperatures  Water is 60% of body weight, the water helps moderate your temperature. o When a water evaporates, the surface of liquid remains behind cools down, while the molecules with the greatest energy (the hottest ones) leave.  Evaporative cooling prevents land-dwelling organisms form overheating. o As water freezes, each molecule makes stable hydrogen bonds.  The ice has fewer molecules than an equal volume of liquid water. Hence ice is less dense then liquid water so the ice floats on top.  This ice ―blanket‖ prevents water below from freezing allowing aquatic mammals to survive. o In many cases water is a solvent (the dissolving agent) and other substances are the solute (what gets dissolved, ex. like salt)  Water is a solvent because of the polarity of its molecules o Water and ions are attracted to each other due to their opposite charges  The hydrogen end of a water molecule has a positive charge so it attracts negatively charged ions.  The oxygen end of a water molecule has a negative charge so it attracts to positively charged ions.  Water surrounds and separates all ions. o Water dissolves other ionic compounds as well. o Water dissolves non-ionic compounds as well o Water dissolves large molecules, with ionic or polar regions as well.  Solvent inside all blood cells.  Water dissolves an enormous variety of solutes necessary for life.  What is the difference between heat and temperature? o Heat is the amount of energy associated with the movement of atoms and molecules in a body of matter. So the total amount of heat energy o Temperature is the intensity of heat, so the average speed of molecules.  Explain the pH scale and the formation of acid and base solutions. o pH stands for potential of hydrogen o Use pH scale to describe how acidic or basic a solution is o The pH of 1 is very acidic o The pH of 14 is very basic o The pH of 7 is neutral, neither an acidic or basic (H+) = (OH-)  The pH of most living things is close to 7. A slight change can be very harmful because the proteins and other complex molecules in the cell are very sensitive to the concentration of (H+) and (OH-) o Each level down the pH scale has 10 times more hydrogen ions (H+), hence ten times more acidic o Each pH unit represents a 10-fold change in the concentration of H+  Ex. For example, lemon juice at pH 2 has 10 times more H than an equal of a cola at amount pH 3 and 100 times more H than tomato juice at pH 4. o A compound that donates hydrogen ions (H+) to solutes is called an acid  An acidic solution has a higher concentration of hydrogen ions (H+) then hydroxide ions (OH-) o A base is a compound that accepts hydrogen ions and removes them from a solution.  Base donate OH- , this OH- combines with H+ to form H2O, therefore reducing the H+ concentration  Basic solutions are called alkaline solutions o What is a buffer?  Biological fluids contain buffers  Buffers are substances that minimize changes in pH, they do this by accepting H+ when it is an excess and donating H+ when it is depleted.  Add small amount of acid to water, pH goes from 7 to 2  Add same amount to acid of blood (with buffers) pH goes from 7.4 to 7.3  Describe the importance of caron to life’s molecular diversity (NOT ON LEARNING OBJECTIVES BUT DID IT ANYWAYS) o Almost all molecules a cell makes are composed of carbon atoms bounded to one another and atoms of other elements. o Carbon has the ability to form large and complex molecules, which built the structures and carry out the functions required for life. o Carbon-based molecules are called organic compounds o Carbon is considered the lead player in chemistry because it only has 4 electrons in its valence shell, and it is able to hold another 4 bonds.  The number of electrons in the outermost shell of its atoms determines an element’s chemical properties. A carbon atom has 4 electrons in a valence shell that holds 8. Carbon completes its outer shell by sharing electrons with other atoms in four covalent bonds ( see Module 2.6). Thus, each carbon atom is a connecting point from which a molecule can branch in up to four directions.  Each carbon can branch off in 4 different directions o Hydrocarbons-  Compounds composed of only carbon and hydrogen are called hydrocarbons. Methane and propane are examples of hydrocarbon fuels. As components of fats, longer hydrocarbons provide fuel to your body cells.  The chain of carbon atoms in an organic molecule is called a carbon skeleton ( shaded in gray in the figure). o Compounds with the same formula but different structural formulas are called isomers  Isomers can result from different spatial arrangements of the 4 partners bonded to a carbon atom.  The different shapes of isomers result in unique properties and add to the diversity of organic molecules. o Six Chemical Groups important to life  The first 5 are functional groups. These groups are polar because oxygen and nitrogen atoms exert a strong pull on shared electrons. This polarity tends to make these groups hydrophilic (water loving) and therefore soluble in water.  The sixth group is a methyl group, this group is non-polar and not reactive, but it affects molecular shape and therefore its function. o HYDROXYL GROUP- A hydroxyl group consists of a hydrogen atom bonded to an oxygen atom, which in turn is bonded to the carbon skeleton. Ethanol, shown in the table, and other organic compounds containing hydroxyl groups are called alcohols. o CARBONYL GROUP- In a carbonyl group, a carbon atom is linked by a double bond to an oxygen atom. If the carbonyl group is at t
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