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Questions and Answers
Which of the following accurately describes observational science?
Which of the following accurately describes observational science?
What is the basic unit of life according to biological studies?
What is the basic unit of life according to biological studies?
What type of microscope offers the highest level of detail?
What type of microscope offers the highest level of detail?
Which statement correctly defines a compound?
Which statement correctly defines a compound?
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What percentage of the matter in living organisms is made up of just four elements?
What percentage of the matter in living organisms is made up of just four elements?
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What determines the reactivity of an atom?
What determines the reactivity of an atom?
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What type of bond is formed when electrons are transferred from one atom to another?
What type of bond is formed when electrons are transferred from one atom to another?
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Which of the following elements are generally considered inert?
Which of the following elements are generally considered inert?
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What is a defining feature of a hypothesis in scientific research?
What is a defining feature of a hypothesis in scientific research?
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In a controlled experiment, what is the role of the independent variable?
In a controlled experiment, what is the role of the independent variable?
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What aspect of a scientific theory enhances its credibility?
What aspect of a scientific theory enhances its credibility?
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What is the importance of a large sample size in experimentation?
What is the importance of a large sample size in experimentation?
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Which statement best describes the relationship between a hypothesis and its predictions?
Which statement best describes the relationship between a hypothesis and its predictions?
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What does failure to falsify a hypothesis imply?
What does failure to falsify a hypothesis imply?
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Which of the following is NOT an essential component of a controlled experiment?
Which of the following is NOT an essential component of a controlled experiment?
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What is the primary purpose of peer-reviewed scientific research papers?
What is the primary purpose of peer-reviewed scientific research papers?
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What reaction is involved in the synthesis of a polymer?
What reaction is involved in the synthesis of a polymer?
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Which of the following functional groups is primarily involved in protein structure?
Which of the following functional groups is primarily involved in protein structure?
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Which type of isomer differs in the position of the carbonyl group?
Which type of isomer differs in the position of the carbonyl group?
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What type of bond is formed between two monosaccharides to create a disaccharide?
What type of bond is formed between two monosaccharides to create a disaccharide?
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How are polysaccharides characterized in terms of structure?
How are polysaccharides characterized in terms of structure?
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What defines the primary structure of a protein?
What defines the primary structure of a protein?
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Which of the following is NOT a function of proteins?
Which of the following is NOT a function of proteins?
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What occurs during a hydrolysis reaction?
What occurs during a hydrolysis reaction?
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What type of secondary protein structure is formed mainly by hydrogen bonds between the backbone of amino acids?
What type of secondary protein structure is formed mainly by hydrogen bonds between the backbone of amino acids?
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What characterizes the tertiary structure of a protein?
What characterizes the tertiary structure of a protein?
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Which component is required for the function of proteins but is not considered part of their amino acid sequence?
Which component is required for the function of proteins but is not considered part of their amino acid sequence?
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What is the primary function of mRNA in the cell?
What is the primary function of mRNA in the cell?
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Which category of lipids is known for containing a glycerol backbone and fatty acid chains?
Which category of lipids is known for containing a glycerol backbone and fatty acid chains?
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What distinguishes saturated fats from unsaturated fats?
What distinguishes saturated fats from unsaturated fats?
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What is a characteristic feature of phospholipids?
What is a characteristic feature of phospholipids?
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What is the relationship between DNA strands in the double helix?
What is the relationship between DNA strands in the double helix?
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What term describes the unequal sharing of electrons in a covalent bond?
What term describes the unequal sharing of electrons in a covalent bond?
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Which type of molecule results from the partial positive and negative charges created by polar covalent bonds?
Which type of molecule results from the partial positive and negative charges created by polar covalent bonds?
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What is the primary reason water can exist as a liquid at temperatures between 0 - 100ºC?
What is the primary reason water can exist as a liquid at temperatures between 0 - 100ºC?
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How many covalent bonds can a carbon atom typically form?
How many covalent bonds can a carbon atom typically form?
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What is the role of buffers in a biological system?
What is the role of buffers in a biological system?
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Which type of bonding is typically weaker than both covalent and ionic bonds?
Which type of bonding is typically weaker than both covalent and ionic bonds?
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What does the separation of water into H+ and OH- indicate?
What does the separation of water into H+ and OH- indicate?
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What characteristic property of water is primarily due to its hydrogen bonding?
What characteristic property of water is primarily due to its hydrogen bonding?
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Study Notes
The Scientific Method
- Investigative approach to acquiring knowledge through observation, explanation, and testing.
- Hypotheses are testable, falsifiable, tentative explanations.
- Controlled experiments compare experimental and control groups, identifying independent, dependent, and controlled variables.
- Statistical analysis of large sample sizes is crucial for interpreting results.
- Failure to falsify a hypothesis doesn't prove it true; further research is needed.
- Peer-reviewed scientific papers are integral to disseminating findings.
- Scientific theories are well-substantiated explanations supported by extensive experimentation. They are unlikely to be contradicted by future research.
- Observational science uses statistical techniques to infer patterns and causes in situations where controlled experiments are difficult (e.g., astronomy, ecology).
Biology and the Scale of Life
- Biology is the study of living things.
- The cell is the basic unit of life.
- Microscopy (light and electron) allows visualization at various scales.
Matter, Elements, and Compounds
- Matter occupies space and has mass; it consists of pure elements.
- Elements cannot be broken down chemically into other substances.
- Compounds are substances with two or more elements in a fixed ratio.
- 96% of living matter comprises carbon, hydrogen, oxygen, and nitrogen.
Atomic Structure and Isotopes
- Atomic number equals the number of protons.
- Atomic mass equals the sum of protons and neutrons.
- Isotopes are atoms with the same number of protons but different numbers of neutrons (same atomic number, different atomic mass).
- Radioisotopes are unstable isotopes that decay, releasing energy; their decay rate defines their half-life.
- Radioisotopes are used as radioactive tracers to measure chemical processes and substance movement.
Electrons and Chemical Bonds
- The number of electrons usually equals the number of protons in a neutral atom.
- Electrons occupy orbitals within shells. Stable orbitals have paired electrons.
- Valence electrons (outermost shell) determine an atom's reactivity; full valence shells generally indicate inertness.
- Reactive elements form molecules through chemical bonds.
Types of Chemical Bonds
- Ionic bonds: Electron transfer creates ions (cations and anions) with opposite charges.
- Covalent bonds: Atoms share valence electrons, resulting in distinct 3D molecular shapes; the structure relates to function.
- Electronegativity: Measures an atom's electron attraction in a covalent bond; unequal sharing creates polar covalent bonds.
- Polar molecules: Possess partial positive and negative charges due to unequal electron sharing.
- Hydrogen bonds: Occur between a partially positive hydrogen atom and a partially negative atom (e.g., in water). Weaker than covalent and ionic bonds.
- van der Waals forces: Weak attractions between nonpolar molecules due to temporary electron distribution imbalances.
Water and Hydrogen Bonds
- Water's unique properties (high specific heat, density changes with temperature) arise from hydrogen bonding.
- Water is an excellent solvent, dissolving polar molecules and ions through hydration shells.
- Water ionization produces H+ and OH- ions.
pH and Buffers
- pH measures the concentration of H+ ions; acids donate H+, bases accept H+.
- Buffers resist pH changes by absorbing or releasing H+, typically weak acids or bases. The carbonic acid–bicarbonate system buffers blood pH.
Carbon Compounds
- Carbon's tetravalence (four bonds) allows diverse and large molecule formation.
- Hydrocarbon chains vary in length and shape; those with carbon atoms bonded only to hydrogen atoms are called hydrocarbons.
- Functional groups (hydroxyl, carbonyl, carboxyl, amino, phosphate, sulfhydryl) affect molecule reactivity and properties. Structure is related to function.
Dehydration and Hydrolysis Reactions
- Dehydration reactions synthesize polymers by removing water and forming bonds.
- Hydrolysis reactions break down polymers by adding water and breaking bonds.
Carbohydrates
- Sugars and their polymers; function as fuel and building materials.
- Monosaccharides are multiples of CH2O (e.g., glucose, fructose, galactose); isomers have the same formula but different structures and functions (structural isomers, enantiomers).
- Disaccharides are two monosaccharides linked by a glycosidic bond (e.g., sucrose, lactose, maltose).
- Polysaccharides are polymers of monosaccharides; they may be branched or unbranched, and their linkage type influences their properties.
Proteins
- Proteins have diverse structures and functions (structural support, storage, transport, catalysis, communication, movement).
- Proteins are composed of one or more polypeptide chains.
- Polypeptides are polymers of amino acids. There are 20 different amino acids, categorized by their side chains (nonpolar, uncharged polar, charged).
- Peptide bonds (covalent) link amino acids; they are formed via dehydration reactions. Amino acids are added only to the carboxyl end.
Protein Structure
- Primary structure: The linear sequence of amino acids.
- Secondary structure: H-bonds between backbone atoms create α-helices or β-pleated sheets.
- Tertiary structure: All types of bonds between R groups determine the 3D shape and function.
- Quaternary structure: Two or more polypeptides assemble.
- Prosthetic groups are non-protein components necessary for protein function.
Nucleic Acids
- Nucleic acids (DNA and RNA) are polymers of nucleotides. They store and transmit genetic information. RNA also has functional roles (mRNA, tRNA, rRNA).
- Nucleotides consist of a nitrogenous base, a pentose sugar, and one to three phosphate groups.
- DNA uses deoxyribose; RNA uses ribose. Uracil is only in RNA; thymine is only in DNA. ATP and GTP store energy.
- DNA is a double helix; two polynucleotide chains are antiparallel, connected by hydrogen bonds between bases adenine (A), guanine (G), cytosine (C), and thymine (T) or uracil (U).
Lipids
- Nonpolar; not true macromolecules because they lack a defined monomer subunit.
- Have a hydrocarbon backbone. Biological examples include fats, phospholipids, and steroids.
- Fatty acids: Saturated fats have maximal hydrogen atoms and no double bonds. Unsaturated fats have at least one double bond causing bending in the molecule.
- Fats: Formed via dehydration reactions between glycerol and fatty acids. 1g of fat has more energy than 1g of starch.
- Phospholipids: Amphipathic (both hydrophilic and hydrophobic regions) found in cell membranes.
- Steroids: Have four carbon rings; many have dual solubility (polar and nonpolar regions).
Putting it Together
- Living things are made of carbon compounds – carbohydrates, proteins, lipids, and nucleic acids.
- Water is essential due to its solvent properties and hydrogen bonds.
- Interactions between molecules govern cell structure and function.
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Description
Explore the key concepts of the scientific method and its application in biology. Understand how hypotheses are formed, tested, and validated through controlled experiments. This quiz also covers the foundational aspects of biology, emphasizing the importance of cells in the scale of life.
