2

In hydrolysis reactions, which of the following occurs?

A polymer is broken down by the addition of water: water is consumed.

Here is the chemical formula for glucose: C6H12O6. Maltose is a disaccharide formed when two glucose moleules combine via a dehydration reaction. Using this information, determine the chemical formula of maltose.

C12H22O11 bc (g*2)=C12H24O12 - H2O

The average American consumes approximately ____ times the amount of sugar recommended by the World Health Organization.

6

Which of the following statements about carbon skeletons is correct?

Carbon skeletons can be straight or in the shape of a ring. Carbon skeletons can be straight or in the shape of a ring. A carbon skeleton forms the"backbone" of most organic molecules. Carbon skeletons are not always straight, nor are they always unbranched. They can take the shape of a ring, as in a sugar, and can be branched, as in starch or glycogen. Carbon skeletons can be held together by single C-C bonds or by double C=C bonds. Carbon skeletons are not "usually short": polysaccharides consist of long chains of sugar units.

When comparing DNA and RNA, ...

DNA directs RNA in assembling proteins.

Which is the correct sequence of events in gene expression?

DNA→RNA→protein

The "building blocks" of the nucleic acids DNA and RNA are called ________. These building blocks are _________.

The "building blocks" of the nucleic acids DNA and RNA are called nucleotides These building blocks are monomers. Each nucleotide consists of a 5-carbon (ribose) sugar, a phosphate group, and a nitrogenous base. Polysaccharides are made up of a chain of monomers or simple sugars such as glucose. Polysaccharides are polymers. Amino acids are the monomers that make up proteins. Simple sugars are carbohydrates. A polymer of such sugars is a polysaccharide. Each nucleotide is a monomer, which is a building block of the polymers DNA or RNA.

Why are the two strands of DNA called "complementary"?

The base sequence of one strand exactly predicts the base sequence of the other. a-t c-g

Lactose intolerance appears to be the "norm" for humans, yet many Northern Europeans happily consume large quantities of milk and cheese. Which of the following probably led to the high prevalence of lactase in Northern Europeans?

The cold climate of Northern Europe forced people to rely on dairy products.

Which of the following statements is correct regarding double-layered cell membranes?

The phosphate-glycerol "heads" face the watery environment. In double-layered cell membranes, the phosphate-glycerol "heads" face the watery environment. This is because the phosphate "head" is negatively charged, making it hydrophilic. The fatty acid chain, by contrast, is held together by nonpolar C-H bonds and is hydrophobic. The phosphate-glycerol "heads" do not face the center of the membrane: they are hydrophilic and face the water environment. The fatty acid "tails" are hydrophobic. The phosphate-glycerol "heads" are hydrophilic. Cell membranes typically contain cholesterol.

The backbone of protein molecules coils or folds into local patterns. This gives the protein its ________ structure. A protein composed of more than one polypeptide chain has a __________ structure.

secondary: quaternary

The "R" groups of an amino acid consist of which of the following?

carbon atoms with different functional groups attached

Which of the following is an INCORRECT match between a type of protein and its function?

enzyme: speed up reactions contractile: muscle contraction antibody: chemical messaging* transport: move materials into and out of cells storage: provide nutrients The incorrect match between a type of protein and its function is antibody: chemical messaging. Antibodies are proteins of the immune system that help defend the body from infection. Chemical messengers are signal proteins such as hormones that coordinate activities throughout the body. Transport proteins move sugar and other molecules into and out of cells. Storage proteins such as those in seeds and embryos provide nutrients to developing organisms. Contractile proteins in muscle cells cause muscle shortening when they change their shapes. Enzymes are proteins that speed up chemical reactions and regulate cellular activity in the body.

Sucrose, the most common disaccharide, is made of a ________ molecule joined to a ________ molecule by means of a _________ reaction.

glucose: fructose: dehydration Sucrose, the most common disaccharide, is made of a glucose molecule joined to a fructose molecule by means of a dehydration reaction. Glucose and fructose are monosaccharides. All disaccharides are formed by dehydration, not hydrolysis, reactions. Glucose joined to glucose by means of a dehydration reaction results in maltose (malt sugar). Galactose is a monosaccharide. It joins with glucose in a dehydration reaction to form lactose.

When you eat a piece of cheese, which of the following occurs in your digestive tract?

hydrolysis, then dehydration When you eat a piece of cheese, hydrolysis reactions occur to break polymers into smaller molecules, then dehydration reactions re-form these molecules into larger molecules that the body needs. Dehydration, then hydrolysis is incorrect because larger molecules must first be broken down into smaller molecules, which requires hydrolytic reactions. A series of hydrolysis reactions only would result in smaller and smaller molecular fragments. These would not be usable by the body. A series of dehydration reactions only would result in ever-larger molecules being created. These would not be usable by the body. Although dehydration reactions generate water, the fluid needed for digestion is provided by ingested liquid and by the organs of the digestive system.

Fatty acids, unsaturated fats, saturated fats, and cholesterol are alike in which of the following ways?

Fatty acids, unsaturated fats, saturated fats, and cholesterol are alike in that they do not mix well with water. Lipids, in contrast to carbohydrates and most other biological molecules, are hydrophobic. For fats, this is mainly because of their nonpolar C-H bonds in their hydrocarbon tails. Lipids do not all contain glycerol. Glycerol is present in fats and phospholipids but not in steroids or cholesterol. All lipids do not contain fatty acid chains. Fatty acids and phospholipids contain such chains, but steroids and cholesterol do not. Saturated fatty acids are solids at room temperature, but unsaturated fatty acids and the cell membrane components phospholipids and cholesterol are not. Lipids store more than twice as much energy as an equivalent mass of polysaccharide.

Which of the following atoms make up a protein's polypeptide "backbone"?

N and C bonded to each other, plus the attached H and O, make up a protein's polypeptide "backbone." This is formed by the linkages between adjacent carboxyl and amino groups as a result of dehydration reactions. R groups are variable chemical groups that are attached to the backbone. They are not part of the backbone, however. The sequence of amino acids in the polypeptide is its primary structure, but not its backbone. Each amino acid includes an R group, which is not part of the backbone.

Which component of the core structure of an amino acid makes the molecule acidic?

carboxyl group carboxyl group of an amino acid makes the molecule acidic. An amino acid consists of a central carbon atom, to which an amino group, a carboxyl group, a hydrogen atom, and an R group are bonded. The carboxyl group consists of a carbon bonded to a hydroxyl group as well as to an oxygen atom. In solution, the H+ from the OH group is given up, ionizing the carboxyl group and making it acidic. Amino acids do not have carbonyl, hydroxyl or phosphate groups as part of their core structure. Amino groups make the molecule more basic, not acidic.

Which functional group can transfer energy among organic molecules?

phosphate A phosphate group transfers energy among organic molecules. This group consists of a phosphorus atom bonded to four oxygen atoms. It is rich in energy and usually ionized. A hydroxyl group consists of a hydrogen atom bonded to an oxygen atom. An amino group consists of a nitrogen atom bonded to two hydrogen atoms. It can act as a base by picking up an H+ from a solution, thereby becoming ionized. A carboxyl group consists of a carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group. It can act as an acid by contributing an H+ to a solution, thereby becoming ionized. A carbonyl group consists of a carbon atom is linked by a double bond to an oxygen atom. It can be located at the end, or anywhere along the chain, of a carbon skeleton. One way to remember the difference between a carbonyl and a carboxyl group: the carboxyl group has an "xtra" group whose name contains an "x"—a hydroxyl group.

Here is a partial list of substances found in living cells. Which, if any, of these substances is not a macromolecule?

proteins nucleic acids LIPIDS carbohydrates

In chemistry, an "organic" compound is a compound with which of the following characteristics?

It always contains carbon atoms. An "organic" compound is a compound that contains carbon atoms. These atoms are usually arranged in chains. The molecules of an organic compound usually also contain hydrogen bonded to the carbons. The term "organic" as used in chemistry is unrelated to the presence of toxic chemicals or to FDA approval. The term is sometimes used in a commercial, non-chemistry context to describe such chemicals or approvals. Organic compounds may contain oxygen. They always contain carbon. Organic compounds do not contain all the macromolecules of life. For example, starch is an organic polymer that does not contain fat, and ethane is an organic molecule that contains neither protein, fat, carbohydrate, or nucleic acids.

Your apartment has a cockroach problem. When you walk across your kitchen floor late at night, you hear "CRUNCH, CRUNCH," as you trample on an army of cockroaches. What substance in the insects' bodies produces that sound, and of what is it made?

chitin: structural polysaccharide Chitin in the cockroaches' bodies produces the "crunch" sound. It is a structural polysaccharide present in insects' exoskeletons and the cell walls of fungi. The term "globular" does not apply to polysaccharides. Some proteins, such as enzymes, have a globular structure. Starch is a storage polysaccharide, and cellulose is a tough structural polysaccharide, but they are found in plants, not in insect exoskeletons.

Cellulose is a _____ made of many _____ linked together with _______ bonds.

polymer: glucose molecules: hydrogen Cellulose is a polymer made of many glucose molecules linked together with hydrogen bonds. Cellulose is a polysaccharide, which is a polymer formed of hundreds to thousands of glucose monomers linked together by hydrogen bonds. Animals do not have the enzymes necessary to break these bonds, which is why they cannot digest cellulose without the help of resident microorganisms (in some species such as cows). A polypeptide is a polymer of amino acids, not sugars, each of which is a monomer. Such a polymer makes up a protein. Covalent bonds are present in many molecules and their presence does not characterize cellulose in particular. Cellulose is a polymer of glucose and therefore is a carbohydrate. It is not, however, composed of fatty acids. Double bonds are present in many molecules and their presence does not characterize cellulose in particular. Cellulose is not a protein; it is a carbohydrate. Proteins consist of long chains of amino acids linked together by peptide bonds. Polar bonds are present in many molecules and their presence does not characterize cellulose in particular. Cellulose is a polymer made of many glucose, not fructose, molecules linked together by hydrogen bonds.

According to the long-term Nurses' Health Study, which of the following foods is associated with the lowest relative risk of heart disease?

polyunsaturated fats Polyunsaturated fats are associated with the lowest relative risk of heart disease in the Nurses' Health Study. The relative risk of these fats was 0.62, on a scale where 1.0 indicates no relative risk for the substance. Such fats have more than one C=C double bond and are found in some types of fish and in oils. Monounsaturated fats, which have one C=C double bond, had a relative risk of 0.81. Saturated fats, which have no C=C double bonds, had a relative risk of 1.17. Trans fats had a relative risk of 1.93. These partially hydrogenated oils were labeled "not generally recognized as safe" by the FDA in 2015. Fatty acids are components of saturated, unsaturated, monounsaturated, and polyunsaturated fats. Fatty acids are molecules composed of an acidic carboxyl group linked to a long, nonpolar hydrocarbon chain.

Which of the following side effects is NOT linked to anabolic steroid use?

reduction in bone growth infertility cancer improvement in mood * increased cholesterol levels