BIO Exam 2 Homeworks 5, 6, 7, 8 PDF

Homework 5 - Chemistry in Biology What results from the unequal sharing of electrons between atoms? - A polar covalent bond What gives rise to the cohesive property of water? - Hydrogen bonds An example of a hydrogen bond is the bond between... - The H of one water molecule and the...

Homework 5 - Chemistry in Biology What results from the unequal sharing of electrons between atoms? - A polar covalent bond What gives rise to the cohesive property of water? - Hydrogen bonds An example of a hydrogen bond is the bond between... - The H of one water molecule and the O of another water molecule A molecule of carbon dioxide (CO2) is formed when one atom of carbon (atomic number 6) is covalently bonded to two atoms of oxygen (atomic number of 8). What is the total number of electrons that must be shared between the carbon atom and the two oxygen atoms in order to complete the outer electron shell of all three atoms? - 4 electrons Van der Waals interactions result when... - Electrons are not symmetrically distributed in a molecule. Electrons exist only at fixed levels of potential energy around a nucleus. However, if an atom absorbs sufficient energy, a possible result is that... - An electron may move to an electron shell farther out from the nucleus. Sometimes atoms form molecules by sharing two pairs of valence electrons. When this occurs, the atoms are said to be joined by... - A double covalent bond In a single molecule of water (H2O), two hydrogen atoms are bonded to a single oxygen atom by... - Polar covalent bonds What type of bond must be broken for water to vaporize? - Hydrogen bonds In ammonium chloride salt (NH4Cl) the anion is a single chloride ion (Cl-) with a charge of -1. What is the cation of NH4Cl? - NH4, with a charge of +1 What is the difference between covalent bonds and ionic bonds? - Covalent bonds involve the sharing of electrons between atoms, and ionic bonds involve the electrical attraction between oppositely charged atoms. Which of the following molecules contains the strongest polar covalent bond? - H2O A Van der Waals interaction is the weak attraction between… - The nuclei of one molecule and the electrons of a nearby molecule. Which of the following most completely explains the attraction of water molecules to one another? - Hydrogen bonds Why does ice float in liquid water? - Hydrogen bonds stabilize and keep the water molecules in ice farther apart than those in liquid water. Which of the following results from the transfer of electron(s) between atoms? - Ionic bond The high specific heat of water is mainly due to... - The absorption and release of heat when hydrogen bonds break and form. A covalent bond is likely to be polar when… - One of the sharing atoms is much more electronegative The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called? - A hydrogen bond The ionic bond of sodium chloride (NaCl) is formed when... - Chlorine gains an electron from sodium. Which of the following effects is due to the high surface tension of water? - A water strider can walk across the surface of a small pond. When two atoms are equally electronegative, they will interact to form... - Nonpolar covalent bonds Homework 6 - Macromolecules Which of the following is true of both starch and cellulose? - Both starch and cellulose are polymers of glucose, There are 20 different biologically important amino acids on Earth. What makes one amino acid different from another? - The unique structure of its "side chain" or "R-group," which is attached to the central carbon atom of the amino acid Which of the following statements regarding lipids is false? - They are soluble in water The images below are of testosterone and estradiol, the respective male and female sex hormones in many vertebrates. In what way(s) do these molecules differ from each other? - Testosterone and estradiol have different functional groups attached to the same carbon skeleton What is the maximum number of covalent bonds that carbon can form? - 4 What mainly maintains the secondary structure of a protein? - Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart Which of the following is not a polymer? - Glucose Which is the best description of a carbonyl functional group? - A double covalent bond joins a carbon atom to an oxygen atom. Research indicates that ibuprofen, a drug that is used to relieve inflammation and pain, is a mixture of two enantiomers. This means that ibuprofen is/has…  - Two mirror-image molecules with the same chemical formula but different 3D structures Which of the following statements correctly describes geometric isomers? - Molecules that have the same types and number of atoms but differ in their covalent bond arrangement What would be an unexpected consequence of changing one amino acid in a protein consisting of 325 amino acids? - The primary structure of the protein would be changed. - The tertiary structure of the protein might be changed. - The biological activity of the protein might be altered. Which two functional groups are always found in amino acids? - Carboxl and amino The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the alpha form. Which of the following could amylase break down? - Glycogen Organic chemistry is defined as… - The study of carbon-based compounds. Which bonds are created during the formation of the primary structure of a protein? - A peptide bond What is the chemical mechanism by which cells make polymers from monomers? - Dehydration synthesis Which of the following stores and transmits hereditary information? - Nucleic acids The bonding of two amino acid molecules to form a larger molecule requires... - The release of a water molecule On food packages, what does the term "insoluble fiber" refer to? - Cellulose (carbohydrate) Which of the following statements best describes the carbon atoms present in all organic molecules? - They were incorporated into organic molecules by plants. - They were processed into sugars through photosynthesis. - They were ultimately derived from carbon dioxide. Research indicates that albuterol, a drug used to relax bronchial muscles, improving airflow and thus offering relief from asthma, consists of only one enantiomer, the R-albuterol. Why is it important for this drug to consist of only one enantiomeric form, rather than a mixture of enantiomers? - Different enantiomers may have different or opposite physiological effects. A carbon atom is most likely to form what kind of bond(s) with other atoms? - Covalent bonds Which of the following polymers contain nitrogen? - Chitin Organic chemistry is a science that is based on mainly studying... - Carbon-containing compounds Which of the following statements concerning saturated fats is false? - They have multiple double bonds in the carbon chains of their fatty acids. The two molecules shown in this image are glucose and fructose. These two molecules differ in the… - arrangement of their functional groups Polysaccharides, lipids, and proteins are similar in that they... - are synthesized from monomers by dehydration reactions. Homework 7 - Tour of Cells A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. This cell could be… - A plant cell Which of the following structure-function pairs is incorrect? - Golgi apparatus; ATP production. Which of the following is a major cause of the size limits for certain types of cells? - There is a need for a surface area of sufficient size to allow for all the cell's functions. Which is one of the main energy transformers of cells? - The Mitochondria In animal cells, hydrolytic enzymes are packaged to prevent general destruction of cellular components. Which of the following organelles functions in this compartmentalization? - The Lysosome Which type of organelle is primarily involved in the synthesis of oils, phospholipids, and steroids? - The smooth endoplasmic reticulum The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements correctly describes this polarity? - Transport vesicles fuse with one side of the Golgi and leave from the opposite side. - Proteins in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other side. - Lipids in the Golgi membrane may be sorted and modified as they move from one side to the other. - Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as they move from one side to the other. Which of the following contains its own DNA and ribosomes? - Mitochondria All of the following are part of a prokaryotic cell except… - An endoplasmic reticulum Which of the following is the site of synthesis of proteins that may be exported from the cell? - Rough endoplasmic reticulum Under which of the following conditions would you expect to find a cell with lots of free ribosomes? - A cell that is making a lot of cytoplasmic enzymes. Which structure is not part of the endomembrane system? - Chloroplasts The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by... - The function of the Golgi apparatus is to sort membrane components. Which structure is common to plant and animal cells? - Mitochondria Which of the following are capable of converting light energy into chemical energy? - Chloroplasts Why are the mitochondria not considered part of the endomembrane system? - Its structure is not derived from the endoplasmic reticulum. The liver is involved in the detoxification of many poisons and drugs. Which structures are primarily involved in this process and, therefore, abundant in liver cells? - Smooth endoplasmic reticulum Which of the following is present in prokaryotic cells? - Ribosomes Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules? - Proteins In addition to the nucleus, where else can one find DNA inside a eukaryotic cell? - Chloroplast Which statement correctly characterizes bound ribosomes? - Bound ribosomes generally synthesize cytoplasmic proteins Homework 8 - Cell Membranes Which of the following is true of integral membrane proteins? - They are usually transmembrane proteins and pass through layers of the membrane Which of the following types of molecules are the major structural components of the cell membrane? - Phospholipids and proteins Which of the following would move most easily through a lipid bilayer of the plasma membrane? - CO2 In order for a protein to be considered a transmembrane membrane protein, which of the following would have to be used? - Amphipathic Glucose is a large polar molecule that diffuses very slowly across the cell membrane. The cells lining the small intestine, however, very rapidly take up large amounts of glucose from glucose-rich food into glucose-poor cytoplasms. Which of the following might offer an explanation for how small intestine cells accomplish this task? - Facilitated diffusion targets glucose for transport across the cell membrane Water passes through cell membranes more quickly than expected because… - It passes through dedicated aquaporins in the cell membrane. Which of the following statements about diffusion is correct? - It is a process where molecules move from a region of high concentration to a region of low concentration. According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? - They can move laterally along the plane of the membrane You are working with a team that is designing a new drug. In order for this drug to work, it must enter the cytoplasm of target cells. Which of the following would be a factor that determines whether the molecule enters the cell? - The similarity of this new drug to a molecule that would normally be transported into target cells Which of the following might be true regarding the evolution of membranes? - As populations evolve, different properties of their cell membranes are selected for or against In what ways can the membranes of a eukaryotic cell vary? - Certain proteins are unique to certain membranes What kind of molecules pass through a cell membrane easily? - Small and hydrophobic molecules Which of the following is a feature of a membrane carrier protein? - They are specific to the type of molecules they transport across a membrane Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures? - The double bonds form kinks in the fatty acid tails, pushing adjacent lipids further apart. The membranes of winter wheat are able to remain fluid when it is very cold outside because... - They can increase the levels of unsaturated phospholipids in their membranes. Why are lipids and proteins free to move laterally in the cell membrane? - The individual membrane components are not covalently attached to each other. Which of the following is not embedded in the lipid bilayer at all?  - Peripheral proteins The presence of cholesterol in the plasma membrane of some animals… - Enables the membrane to stay fluid more easily when temperatures drop. Which of the following would be involved in active transport? - Integral membrane proteins