Chemical Basis of Life

Use the illustration below to answer question 1.

Water Strider

1. Which of the following is a property of water that allows a water strider to walk on the surface of water?

A. solubility

B. cohesion

C. high specific heat

D. low freezing point

2. Which statement describes the formation of a protein molecule?

A. Amino acids combine to form a protein chain.

B. Fatty acid monomers dissolve to form a protein chain.

C. Fatty acid monomers combine to form a protein chain.

D. Amino acids dissolve monomers to form a protein chain.

Use the table below to answer question 3.

Students’ Descriptions of Four Organic Compounds

3. Which two students correctly described organic compounds?

A. students 1 and 2

B. students 2 and 3

C. students 3 and 4

D. students 2 and 4

4. Carbonic anhydrase is an enzyme involved in the reaction of carbon dioxide with water to form a molecule that dissolves well in the liquid part of blood. How does carbonic anhydrase affect this reaction?

A. by making the reaction reversible

B. by changing chemical products of the reaction

C. by increasing the time needed for the reaction to occur

D. by decreasing the amount of energy needed to complete the reaction

Student Organic Compounds Description

1 carbohydrates complex compounds made of purines and pyrimidines that

function as data-storage molecules

2 lipids use the relatively high energy contained in

carbon-hydrogen bonds to perform their primary function

3 proteins chains of amino acids that can function as enzymes,

hormones, or antibodies

4 nucleic acids compounds, produced by photosynthetic plants, that

contain only carbon, hydrogen, and oxygen

5. Which graph best shows how enzyme activity changes as the temperature is adjusted above and below the enzyme’s optimum temperature?

A. B.

Optimum Optimum

Temperature Temperature

C. D.

Enzy

me

Act

ivit

y

Enzy

me

Act

ivit

y

Enzy

me

Act

ivit

y

Enzy

me

Act

ivit

y

6. The opening of the stomata allows water to evaporate from inside the leaf in a process known as transpiration. As this occurs, water molecules cling to one another and pull water in a continuous stream up the stem of the plant from the roots to the leaves. Which property of water makes this movement possible?

A. cohesion

B. freezing point

C. high specific heat

D. temperature-dependent density

7. Cells are largely made of organic compounds that contain carbon. Which property of the carbon atom makes it an essential component of organic compounds?

A. Carbon is a nonmetal.

B. Carbon oxidizes to carbon dioxide.

C. Carbon is solid at room temperature.

D. Carbon can form four covalent bonds.

Use the diagram below to answer question 8.

Biological Reaction

Peptide BondPeptide Bond

Tyrosine + Valine + Proline

8. Which statement best describes the event shown in the diagram?

A. Glucose is being synthesized in the chloroplast using nitrogen from plants.

B. Amino acid monomers are joining together to form a protein macromolecule.

C. A polymer in the nucleus is being broken into its individual monomer subunits.

D. Lipid molecules are forming fatty acid chains in a dehydration synthesis reaction.

tyrosine

valine

proline

9. Which characteristic allows carbon atoms to form chains and rings with other carbon atoms?

A . Carbon has several forms .

B . Carbon can form four covalent bonds .

C . Carbon is the fourth most abundant element in the universe .

D . Carbon is a structural part of lipids, carbohydrates, proteins, and nucleic acids .

10. Cellulose is a carbohydrate and a polymer of glucose . Which statement

best describes how cellulose is formed within living organisms?

A . It is assembled by bonding individual atoms .

B . It is constructed by connecting smaller monomer subunits .

C . It is the product of the decomposition of a much larger molecule .

D . It is the result of a physical change that alters the shape of a compound .

11. Many plants have a waxy coating on their leaves . Which statement describes the

most likely structure and function of the waxy coating?

A .The waxy coating is a protein that can help attract other organisms for pollination .

B .The waxy coating is a protein that can help release waste molecules during transpiration .

C .The waxy coating is a lipid that can help absorb more sunlight in hot environments .

D .The waxy coating is a lipid that can help prevent excess water loss in dry environments

12. The enzyme pepsin is found in the stomach . Which medicine is most likely to directly interfere with pepsin’s function?

A .a medicine that affects pH

B .a medicine that prevents clotting

C .a medicine that blocks neural impulses

D .a medicine that lowers cholesterol levels

13. Carbon can combine with many different elements but frequently combines with oxygen, hydrogen, and nitrogen to form organic molecules. Which statement best explains why carbon is able to form a large number of different molecules?

A. Carbon forms only ionic bonds.

B. Carbon can form only ring structures.

C. Carbon can form four covalent bonds.

D. Carbon forms small, simple structures.

14. Which statement correctly describes how a protein is formed?

A. A monosaccharide bonded to a side chain is broken apart.

B. Amino acids are bonded together in a long chain to form a new molecule.

C. A molecule containing glycerol bonded to three fatty acids is broken apart.

D. A nitrogenous base, a sugar, and a phosphate group combine to form a new molecule

Use the chart below to answer the question.

Biological Molecule Information

Molecule Structure Cellular Use

1

a molecule made mostly of carbon with two nonpolar chains and a polar head

is a component of plasma membranes

2

a polar molecule made of repeating units of sugar bonded to a phosphate and a nitrogenous base

stores genetic information

15. Which biological molecules are most likely represented by molecules 1 and 2?

A. molecule 1: lipid molecule 2: nucleic acid

B. molecule 1: lipid molecule 2: protein

C. molecule 1: carbohydrate molecule 2: nucleic acid

D. molecule 1: carbohydrate molecule 2: protein

16. Which action must occur for an enzyme to catalyze a chemical reaction?

A. A competitive inhibitor must first bind to an active site.

B. A substrate must bind to an active site of the enzyme.

C. A substrate must bind to an allosteric site of the enzyme.

D. A noncompetitive inhibitor must first bind to an active site.

17. Lipase is an enzyme that breaks down lipids in the digestive system of humans. It functions best at a pH range of 4.0 to 5.0. When a person takes an antacid tablet to relieve heartburn, the antacid increases the pH to around 7 in certain areas of the digestive system. Which initial effect would most likely be caused by a change in pH?

A. More lipids would be digested.

B. Fewer lipids would be digested.

C. The production of lipase molecules would increase.

D. The production of lipase molecules would decrease.

18. . Trees are typically able to transport water from their roots to their stems and leaves. Which statement describes the property of water that most supports the transportation of water to all parts of a tree?

A. Water forms a crystalline structure when it freezes.

B. Water dissolves fewer substances than any other liquid.

C. Water has strong attractions to itself and many other molecules.

D. Water can absorb large amounts of energy with minimal temperature changes.

19. Which process best describes the assembly of proteins from amino acids?

A. Atoms are linked to form a compound.

B. Monomers are linked to form a polymer.

C. Atoms are added to a monomer until it becomes a polymer.

D. Molecules are added to a compound until it becomes a monomer

20. Which statement best describes a relationship between enzymes and a simple biological reaction?

A. Enzymes will increase the amount of substrate formed during a biological reaction.

B. Enzymes will decrease the amount of substrate formed during a biological reaction.

C. A reaction rate can be increased when the specific enzyme for a

biological reaction is present.

D. A reaction rate can be decreased when multiple enzymes for a

biological reaction are present.

1. Continued. Please refer to the previous page for task explanation.

Part A: Describe two similarities in the structure of the organic molecules shown.

Similarity 1:

Similarity 2:

Part B: “Structure determines function” is an important concept to biology. Select one of the organic molecules shown and explain how its structure is related to its function.

CONSTRUCTED-RESPONSE ITEM

Use the graph and diagram below to answer question 2.

Effects of Enzyme A

Reaction Progress

Enzyme A

substrates

active sites

2.

without

Enzyme A

with Enzyme A Free

En

ergy

Part A: Explain how Enzyme A acts as a catalyst in the reaction.

Be sure to include energy and time in your answer.

Part B: Conditions around an enzyme change and affect the shape of the enzyme’s active sites. Predict how this would affect the enzyme’s ability to catalyze the reaction.

Lipids are compounds that consist mainly of carbon and hydrogen atoms bonded

by nonpolar bonds that make them hydrophobic. Therefore, lipids will not mix

with water. Another property of lipids is that they contain high energy bonds. A

gram of fat, a large lipid, stores more than twice as much energy as a gram of

starch, a carbohydrate. There are two categories of lipids, saturated and

unsaturated. Saturated fats are solids at room temperature and unsaturated fats are

liquids. Diets rich in saturated fats can contribute to cardiovascular disease when

lipid deposits called plaques build up on the blood vessels reducing blood flow.

Question:

3. Describe the structural differences between saturated and unsaturated fats.