BIOL 1408 SAPLING CH 2 HW
Organisms use carbohydrates to build large molecules. Some carbohydrates act as energy stores, and others give structural support. Carbohydrates are also broken down to generate metabolic energy. Match the three specific examples of carbohydrate use below to general function.
- A plant cell synthesizes starch from glucose: energy storage - A plant cell synthesizes cellulose from glucose: structural support - A brain cell uses the energy to synthesize ATP: metabolism for energy
Which of the following statements describe hydrogen bonding between water molecules or describe properties of water that lead to hydrogen bonding between water molecules?
- A water molecule is polar because it has a bent structure and its shared electrons are more attracted to the oxygen atom than the hydrogen atoms. - The slightly negative oxygen atom of one water molecule is attracted to the slightly positive hydrogen atom of another water molecule.
Select the description of the ways hydrocarbon skeleton structures may vary.
- Branching of the carbon chain - Presence of carbon-carbon double bonds - Length of the carbon chain - Presence of enclosed carbon atom rings
Why is carbon so prevalent in biological molecules, such as nucleic acids?
- Carbon-based molecules can take on a number of different shapes. - Carbon can form up to four covalent bonds with other atoms. - Carbon can share electrons with hydrogen to form hydrocarbons.
Choose all of the items in the list that are composed of matter.
- Ice cubes in a glass - Clouds in the sky - Air inside a balloon
Which of the following examples illustrate how the property of ice floating on water supports life on Earth?
- Ice provides a habitat for land-dwelling arctic and antarctic animals. - Aquatic animals can survive when the surface of water freezes.
Which of the following describe a chemical bond?
- Interaction between ions with opposite charges - Sharing of electrons between atoms
Determine whether each carbohydrate is best described as a monosaccharide, a disaccharide, or a polysaccharide.
- Monosaccharides: fuctose / glucose - Disaccharides: sucrose - Polysaccharides: starch / cellulose
How many protons, neutrons, and electrons does a neutrally charged Carbon atom have?
- Number of protons: 6 - Number of neutrons: 6 - Number of electrons: 6
Match the subatomic particles with each statement that describes them. Some answer choices more than once, and some descriptions require multiples answers.
- Positively charged: protons - Negatively charged: electrons - No charge: neutrons - Outside the nucleus: electrons - Components of the nucleus: protons/neutrons - Have significant mass: protons/neutrons
Match each description to the appropriate type of isomer.
- Structural isomers: compounds with the same molecular formula that vary in how the atoms are connected - Cis-trans isomers: compounds with the same molecular formula that vary in their arrangement around a double bond - Enantiomers: compounds with the same molecular formula that vary in their spatial arrangement around a chiral, or asymmetric, carbon atom
An atom of nitrogen has 7 protons, 7 electrons, and 7 neutrons. What is the atomic mass of the nitrogen atom?
14 because the nitrogen atom has 7 protons and 7 neutrons
How many electrons are in the first and second electron shells of carbon?
2, 4
How many protons does an ion with 10 electrons and a charge of -3 contain?
7
What is the typical pH of biological fluids in humans, such as blood and extracellular fluid?
7.4
How does the specific heat of water influence biological systems?
A high specific heat enables organisms to resist temperature fluctuations.
The strength of an acid o base is indicated by pH, a measurement of the concentration of hydrogen atoms in the solution. Sort the common substances below based on whether they are acidic, neutral, or basic using the provided pH scale.
Acid: - gastric fluid - coffee Neutral: - pure water Basic: - drain cleaner - baking soda
What is the difference between an anion and a cation?
An anion has a negative charge whereas a cation has a positive charge.
Which of the following statements about organic compounds is true?
An organic compound typically has at least one carbon - hydrogen or carbon - carbon bond.
Which of the following is unique, defining property of atoms of a particular element?
Atomic number
How does 14C (carbon-14) differ from 12C (carbon-12)?
Carbon-14 has 2 more neutrons than carbon-12 does.
Classify each pair of atoms according to whether the pair forms a covalent bond or an ionic bond.
Covalent bond: - oxygen and oxygen - sulfur and oxygen - hydrogen and carbon Ionic bond: - calcium and selenium - sodium and bromine - lithium and flourine
What property of water molecules leads to the high surface tension of liquid water?
Formation of hydrogen bonds between water molecules.
Complete the table by entering the correct numbers of protons and neutrons for each of the isotopes.
Hydrogen-2: 1 proton / 1 neutron Carbon-12: 6 protons / 6 neutrons Carbon-14: 6 protons / 6 neutrons Nitrogen-14: 7 protons / 7 neutrons Oxygen-17: 8 protons / 9 neutrons
Classify each statement as applying to ionic bonds, covalent bonds, or both types of bonds.
Ionic: - Oppositely charged ions are attracted to each other - Form after one atom donates an electron to another atom - Com apart when mixed with polar water molecules Covalent: - Form when atoms share electrons - Stay together in water - Common in biomolecules, such as DNA and protein, in living organisms Both: - A strong interaction between atoms - Attraction based on the number of electrons in the outermost shells of the elements involved
Within atoms, there is an ongoing relationship between the nucleus and the electrons. Sort the characteristics by whether they describe the nucleus or the electrons.
Nucleus: - Positively charged - Attracts the negatively charged particles into the space surrounding it Electrons: - Negatively charged - Can gain or lose energy - Can move from one atom to another - Can bond two atoms into a molecule when shared between two atoms
Determine which molecules are organic and which molecules are inorganic.
Organic: Glycine / Methane Inorganic: Phosphate / Water
Determine whether each of the statements or molecules below refers to a polar bond or a nonpolar bond.
Polar bonds: - The bond between oxygen and hydrogen in water (H2O) - Electrons are not equally shared by the atoms in a covalent bond - One atom of a covalent bond has higher electronegativity than the other atom in the bond Nonpolar bonds: - The bond between hydrogen atoms in diatomic hydrogen (H2) - Electrons are equally shared between atoms in a covalent bond
Identify each item as describing a positive ion, negative ion, or neutral atom.
Positive ion: - 3p, 3n, 2e - 1p, 0n, 0e Negative ion: - 1p, 1n, 2e Neutral atom: - 2p, 2n, 2e - 1p, 0n, 1e - 3p, 4n, 3e
During cellular respiration, the cell forms CO2 (carbon dioxide) and H2O (water) by breaking down C6H12O6 (glucose) and O2 (oxygen). Classify the molecules as reactants or products in the chemical reaction.
Reactants: oxygen / glucose Products: water / carbon dioxide
Identify each item according to whether it describes an atom with a stable nucleus only, an atom with a neutral charge only, or an atom with a stable nucleus and a neutral charge.
Stable only: - 1p, 1n, 2e - 2p, 1n, 1e - 3p, 3n, 2e Neutral only: - 4p, 4n, 4e Stable and neutral: - 2p, 2n, 2e - 3p, 3n, 3e
Why do atoms form molecules?
To achieve a stable number of electrons
Why does water have a pH of seven?
Water dissociates to form an equal amount of ions H+ and OH-.
If the solid form of most molecules is heavier than the liquid form, why does ice float?
Water molecules are arranged farther apart when frozen than in liquid form.
Which of the following scenarios is due to the high heat of vaporization of water?
Your skin feels cold after emerging from a swimming pool.
Many elements are vital to biological life. The elements carbon, nitrogen, oxygen, and hydrogen are the building blocks for sugars and proteins. Classify the following molecules based on the number of oxygen atoms present in each molecule.
Zero oxygen atoms: C12H26 One oxygen atom: C10H12NO / C7H11N3O Two oxygen atoms: C11H12N2O2 Three oxygen atoms: C6H5NO3
A buffer is a substance that
accepts hydrogen ions when acid is added to a solution.
Which carbon chains are isomers?
molecules 1 and 2
Which of the following carbohydrates is a polysaccharide?
starch
