Biology 101: Cells /Chapters 5, 6a/ Pearson Mastering Biology

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified? A. as a pentose B. as a disaccharide C. as a monosaccharide D. as a hexose E. as a polysaccharide

as a disaccharide

What are the primary functions of carbohydrates in cells? A. energy storage, information storage, polymerization, and raw material source for synthesis B. catalysis, energy storage, metabolism, and structure C. cell identity, energy storage, raw material source for synthesis, and structure D. catalysis, digestion, energy storage, and information storage

cell identity, energy storage, raw material source for synthesis, and structure

Which of these is a polysaccharide? A. cellulose B. sucrose C. lactose D. glucose E. galactose

cellulose

You isolate an organic molecule that contains C, H, O, N, and S. This molecule _____. A. could be cellulose or glycogen B. must be a polymer C. is a disaccharide D. could be a glycoprotein

could be a glycoprotein

Which of the following statements correctly summarizes the roots of several key terms in the map?

macro = big; poly = many; mono = one; saccharide = sugar

This figure is an example of a(n) _____. A. protein B. saturated fat C. nucleic acid D. steroid E. unsaturated fat

saturated fat

Peptidoglycan forms sheets that stiffen the cell walls of bacteria. How is the formation of sheets possible?

Individual strands are joined by peptide bonds, a type of covalent bond.

Which molecule is NOT a carbohydrate? A. Cellulose B. Starch C. Glycogen D. Lipid

Lipid

Which of the following statements about monosaccharide structure is true? A. All monosaccharides contain carbon, hydrogen, oxygen, and nitrogen atoms. B. Aldoses and ketoses differ in the position of their hydroxyl groups. C. Monosaccharides can be classified according to the spatial arrangement of their atoms. D. A six-carbon sugar is called a pentose.

Monosaccharides can be classified according to the spatial arrangement of their atoms.

Which of the following classes of macromolecules always contains a carbohydrate portion? A. Proteins B. Water C. Lipids D. Nucleic acids

Nucleic acids

Which of the following additions to the map would be correct?

Nucleotides in DNA include adenine (A), thymine (T), guanine (G), and cytosine (C).

Which polysaccharide contains a modified monosaccharide? A. Cellulose B. Peptidoglycan C. Starch D. Glycogen

Peptidoglycan

Which of these is a phospholipid?

Phospholipids are composed of a phosphate group, a glycerol, and fatty acids.

Which of these is NOT a lipid? A. wax B. cholesterol C. RNA D. phospholipid E. steroids

RNA

Starch and cellulose ________. A. can be digested by humans B. are polymers of glucose C. are structural components of the plant cell wall D. are interchangeable E. are used for energy storage in plants

are polymers of glucose

A function of cholesterol that does not harm health is its role _____. A. in calcium and phosphate metabolism B. as the primary female sex hormone C. as a component of animal cell membranes D. All of cholesterol's effects cause the body harm. E. the most abundant male sex hormone

as a component of animal cell membranes

Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane?

C and D only

_____ is the most abundant organic compound on Earth. A. Starch B. Glucose C. Glycogen D. Lactose E. Cellulose

Cellulose

A food company hydrogenated a barrel of fat. The treatment ... A. (a) made the fat less fluid. B. (b) made the fat less saturated. C. (c) lengthened the fat tails. D. (d) put more bends (kinks) in the fat tails. D. Both (a) and (d).

(a) made the fat less fluid.

Polymers that contain sugars ... A. (a) may store hereditary information. B. (b) may store energy. C. (c) may protect cells. D. Both (b) and (c). E. (a), (b), and (c).

(a), (b), and (c).

What do fats, steroids, and waxes have in common? A. (a) Moderate polarity. B. (b) Low solubility in water. C. (c) They occur in membranes. D. Both (a) and (c). E. Both (b) and (c).

(b) Low solubility in water.

What are three ways monosaccharides differ from one another?

- the location of their carbonyl group - the number of carbon atoms they contain - the orientations of their hydroxyl groups

What is the energetic efficiency of corn bioethanol production? To determine the energetic efficiency of corn bioethanol, you have to not only consider the energy available in the ethanol end product, but also all the energy that goes into growing the corn and processing it into ethanol. Corn has to be grown on a farm, which requires energy in the form of fertilizers and pesticides, fuel for tractors and other farm machinery, harvesting and separation of the corn kernel from the rest of the plant, and cleaning and drying of the corn. Then the corn must be transported to the ethanol production facility, and the resulting fuel must be transported to the gas stations where it is sold to the consumer. The following graph shows the energy inputs required for agricultural production, processing, and transportation compared to the energy outputs from the bioethanol itself, as well as the energy savings from use of corn byproducts. The heat of combustion is expressed in megajoules (MJ), which stands for millions of joules, a unit of energy. Based on the information in the graph, answer the questions below. Round your answers to the nearest whole number.

1. Agricultural production, processing, and transportation (all the inputs) require approximately how much energy for each liter of corn bioethanol produced? = 20 MJ 2. About how much energy does one liter of bioethanol produce when combusted (not counting byproducts)? = 21 MJ 3. What is the total output per liter of bioethanol when you count the energy in fuel plus the energy in the byproducts? = 26 MJ 4. What percentage of that total output is required for all the inputs (agricultural production, transport, and processing)? = 77%

High-fructose corn syrup is produced by converting starch from corn into a mixture of glucose and fructose monosaccharides. What two events must occur in this process in order to turn starch into these simple sugars? Match the terms in the left column to the appropriate blanks in the sentences on the right. Terms can be used once, more than once, or not at all.

1. First, the starch must be [hydrolyzed] by an enzyme such as [amylase]. 2. Since [fructose] is not in starch, the second event must be to convert some of the [glucose] sugars into [fructose].

Sucrose is cleaved in your saliva by the enzyme sucrase to release glucose and fructose. Use the structural formula of sucrose to describe fructose using the terms that define its carbon number and placement of the carbonyl group. Match the terms in the left column to the appropriate blanks in the sentences on the right. Not all terms will be used.

1. Fructose is [a hexose] based on having [six] carbons. 2. Fructose is [a ketose] because the carbonyl is [within] the carbon chain ([C-2]).

How do you get energy from fuel? Whether it is a fossil fuel or a biofuel, the fuel you put into your car must be burned to release energy that can power the car. This reaction is called combustion, and the engine in your car is an example of an internal combustion engine. Let's examine a simple combustion reaction so that you can see how energy is released. In the reaction below, methane (the fuel) is burned with oxygen to produce carbon dioxide and water. Use the reaction above to fill in the sentences below.

1. In the combustion reaction, [methane and oxygen] are the reactants, and [carbon dioxide and water] are the products. 2. Because [oxygen] is more electronegative than [carbon], the electrons in carbon dioxide are shared [unequally]. 3. Bonds with electrons shared [unequally] are lower energy than bonds with electrons shared [equally]. 4. In the combustion reaction, the [carbon] in methane is oxidized, and [oxygen] is reduced. 5. Heat is produced because [higher energy] bonds in the reactants have been replaced with [lower energy] bonds in the products.

What can you conclude from these results about learning retention in rats whose diet included fructose versus those without fructose? How did the presence or absence of dietary omega-3 fatty acids (an essential nutrient) affect memory in this test? Match the terms in the left column to the appropriate blanks in the sentences on the right. Not all terms will be used.

1. The escape times of fructose-fed rats were always [slower] than those of the rats not fed fructose. This result suggests that fructose [impaired] their ability to recall what they had learned about finding the escape chamber. 2. The rats that were fed a diet [enriched] in omega-3 fatty acids demonstrated a(n) [enhanced] memory because they were [faster]. Therefore, we can suggest that [omega-3 fatty acid] offset the effects of [fructose].

How might the results of this study influence your diet while studying biology? Match the terms in the left column to the appropriate blanks in the sentences on the right. Not all terms will be used.

1. The rats that were fed a diet [enriched] in [omega-3 fatty acid] demonstrated an enhanced memory. 2. The best diet for performance in your classes will be [rich] in omega-3 fatty acids and Blank in fructose.

Glucose (C₆H₁₂O₆) has a single carbonyl group (—C=O) in its linear form. Based on the number of oxygen atoms in glucose, how many hydroxyl groups (—OH) would you expect glucose to have?

5

Which of the following types of molecules would have the highest capacity to store chemical energy? A. A six-carbon molecule rich in C-H bonds, such as a lipid B. A six-carbon molecule rich in C-O bonds, such as a hexose C. A two-carbon molecule rich in C-O bonds, such as ethanol D. A two carbon molecule rich in C-H bonds, such as ethane

A six-carbon molecule rich in C-H bonds, such as a lipid

Which complex carbohydrate contains only a-1,4-glycosidic linkages? A. Glycogen B. Amylopectin C. Amylose D. Cellulose

Amylose

The presence of many C-C and C-H bonds causes fats to be ... A. (a) rich in energy. B. (b) insoluble in water. C. (c) low in energy. D. Both (a) and (b). E. Both (b) and (c)

Both (a) and (b).

Triglycerides vary with respect to the number of ... A. (a) hydrocarbon tails. B. (b) C atoms in the tails. C. (c) double bonds in the tails. D. Both (b) and (c). E. All of the above.

Both (b) and (c).

Which of the following complex carbohydrates is listed with its correct function? A. Cellulose: structural component of plant cell walls B. Chitin: constituent of bacterial cell walls C. Starch: primary energy-storage molecule in animals D. Amylose: main component of plant starch

Cellulose: structural component of plant cell walls

The molecular formula for glucose is C₆H₁₂O₆. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions? A. C₁₈H₃₀O₁₅ B. C₃H₆O₃ C. C₁₈H₃₂O₁₆ D. C₁₈H₃₆O₁₈ E. C₆H₁₀O₅

C₁₈H₃₂O₁₆

Dairy cattle were unknown in Thai culture until recently, and 97 percent of Thai people are lactose intolerant as adults. Which explanation for such widespread lactose intolerance is most likely correct? A. Allergies are becoming more common in humans as more chemicals are being encountered during longer lifetimes. B. The ability to digest sugar in milk is determined by environment, and most humans are not exposed to milk as a food source beyond childhood years. C. There is no good explanation for this situation in humans. D. Evolutionarily, producing an enzyme to break down a sugar that will never be encountered is wasteful.

Evolutionarily, producing an enzyme to break down a sugar that will never be encountered is wasteful.

Use the following paragraph to answer the corresponding question. Masatomo Kawakubo et al. reported in Science in August 2004 that the human stomach contains a natural, carbohydrate-based antibiotic that probably protects a large portion of the population from various diseases caused by the bacterium Helicobacter pylori. This bacterium has been linked to peptic ulcers, gastritis, and stomach cancer. This naturally occurring antibiotic is described by Kawakubo as having a terminal α-1,4-linked N-acetylglucosamine (NAG), and it acts by inhibiting the biosynthesis of a major component of the cell wall in H. pylori. [SOURCE: M. Kawakubo et al., Science 305 (2004): 1003.] Refer to the paragraph about Kawakubo's group. Kawakubo's group created a glycoprotein with a terminal NAG (i.e., a protein with NAG attached to its end). Their hypothesis is that the terminal NAG, and not the protein component, is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis?

Grow H. pylori in a test tube with a glycoprotein that has its terminal NAG removed.

What do DNA, proteins, and fats have in common? A. They contain phosphorus. B. They contain nitrogen. C. They are polymers. D. They contain carbonyl groups. E. They are polar.

They contain carbonyl groups.

True or false? All four types of macromolecules always contain carbon (C), hydrogen (H), and oxygen (O), but NOT all of them contain nitrogen (N).

True

True or false? Peptidoglycan is a polysaccharide found only in bacteria.

True

Dr. Haxton told one of his students, "To move in the bloodstream, fats need the help of phospholipids." What would a good student say?

Yes. Nonpolar molecules aren't compatible with water.

The bond that joins two monosaccharides into a disaccharide is _____. A. a hydrogen bond B. an ionic bond C. a glycosidic bond D. a van der Waals bond

a glycosidic bond

The molecule shown in the accompanying figure is ________. A. a pentose B. a phosphate C. a maltose D. a hexose E. a fructose

a hexose

A sugar that has the chemical formula C₅H₁₀O₅ would be characterized as _____. A. a hexose B. a polysaccharide C. an oligosaccharide D. a triose E. a pentose

a pentose

Glycogen is _____. A. a polysaccharide found in plant cell walls B. the form in which plants store sugars C. a source of saturated fat D. a transport protein that carries oxygen E. a polysaccharide found in animals

a polysaccharide found in animals

Which of the following building blocks are not used to build very large polymers? A. amino acids B. nucleotides C. fatty acids D. monosaccharides

fatty acids

Which of the following is NOT a polymer? A. glucose B. DNA C. cellulose D. chitin E. starch

glucose

Which of these best reflects the following relationship: monosaccharide versus polysaccharide? A. 1,4-glycosidic linkage versus 1,6-glycosidic linkage B. α-linkage versus β-linkage C. glucose versus fructose D. glucose versus glycogen

glucose versus glycogen

The highlighted part of this molecule is derived from ... A. guaiacol. B. cholesterol. C. aniline. D. fatty acid. E. glycerol.

glycerol.

In fat synthesis, ________and fatty acids combine to make fats plus ________.

glycerol; water

The _____ functional group can always be found in a carbohydrate molecule. A. amino B. hydroxyl C. water D. The molecular formula of many carbohydrates is (CH₂O)n. While hydrogen and oxygens are found in carbohydrates, water is not a functional group. E. phosphate

hydroxyl

In the reaction that builds a fat,________ groups react with ________ groups.

hydroxyl; carboxyl

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet? A. lactose B. maltose C. starch D. mannose

lactose

glucose + glucose —> _____ by _____. A. starch + water ... dehydration synthesis B. sucrose + water ... dehydration synthesis C. cellulose + water ... hydrolysis D. maltose + water ... dehydration synthesis E. lactose + water ... hydrolysis

maltose + water ... dehydration synthesis

A primary function of carbohydrates attached to the glycoproteins and glycolipids of animal cell membranes is to ________. A. maintain membrane fluidity at low temperatures B. facilitate diffusion of molecules down their concentration gradients C. mediate cell—cell recognition D. actively transport molecules against their concentration gradients E. maintain the integrity of a fluid mosaic membrane

mediate cell—cell recognition

Which of these is a source of lactose? A. milk B. starch C. sugar cane D. sugar beets E. potatoes

milk

A molecule with the chemical formula C₆H₁₂O₆ is probably a _____. A. polysaccharide B. nucleic acid C. phospholipid D. fatty acid E. monosaccharide

monosaccharide

Which of these is rich in unsaturated fats? A. butter B. olive oil C. a fat that is solid at room temperature D. beef fat E. lard

olive oil

Which of the following molecules contains at least one peptide bond? A. chitin B. glycogen C. cellulose D. peptidoglycan

peptidoglycan

Concept Map: What are the macromolecules of life?** Launch the Concept Map by clicking the button below. Read the instructions that appear on the new screen. Drag the terms and phrases to build a Concept Map. Click "Submit" in the Concept Map when finished.

the four major macromolecules of life include → 1. proteins → [are polymers of] → amino acids →2. nucleic acids → [are polymers of] → nucleotides →3. lipids →4. carbohydrates → [are polymers of] → monosaccharides

The most unsaturated fats have ... A. the most double bonds. B. the shortest hydrocarbon tails. C. the fewest double bonds. D. the highest ratio of H to C. E. the longest hydrocarbon tails.

the most double bonds.

Which of the following can vary among monosaccharides? A. the presence of hydroxyl groups B. the number of carbon atoms C. the presence of sulfur groups D. the presence of a carbonyl group

the number of carbon atoms

What is the difference between an aldose sugar and a ketose sugar? A. the position of the hydroxyl groups B. the position of the carbonyl group C. One is a ring form; the other is a linear chain. D. the number of carbons

the position of the carbonyl group

Structure A in the figure is a(n) _____.

transport protein

What molecules supply the energy in biofuels? Biofuels take advantage of high-energy molecules naturally produced by plants in photosynthesis (the solar-powered process by which glucose is produced from carbon dioxide). During photosynthesis, the carbon atom in carbon dioxide is reduced (it gains electrons), making the resulting carbohydrate (glucose) a potent source of energy. (Note all the carbon-to-carbon and carbon-to-hydrogen bonds in glucose.) In addition to providing energy to the plant itself, glucose from photosynthesis provides the fundamental starting material for building more complex biomolecules: carbohydrates, nucleic acids, proteins, and lipids. Some of these carbohydrates and lipids are the key energy sources in biofuels. First, let's examine the main energy storage molecule in corn: starch. A starch molecule is composed of glucose monomers in the alpha formation. These alpha bonds allow the polymer to be quite flexible, resulting in an overall helical (spiral) shape. A helical starch molecule is shown below. But corn starch can't be burned directly in conventional gasoline vehicles because it is not easily soluble and therefore it cannot be easily made into a liquid fue

→ extraction (red box) 2. starch (blue box) → digestion using alpha-amylase (red box) 3. alpha-glucose (blue box) → fermentation (red box) 4. ethanol (blue box)