Deck : 2 Chemistry Comes to Life

Question 1

Compare protons, neutrons, and electrons with respect to their charge, mass, and location within an atom.

Answer 1

Question 2

Water
a. is a nonpolar molecule and therefore an excellent solvent.
b. has a high heat capacity and therefore helps maintain a con- stant body temperature.
c. has a low heat of vaporization and therefore helps prevent overheating of the body.
d. makes up about 25% of the human body.

Answer 2

Water is a polar molecule. Because of unequal sharing of the electrons, the oxygen part of the molecule is slightly negative and the hydrogen parts of the molecule are slightly positive. Thus, answer choice a. is false. Water can absorb heat. It minimally reacts to slight changes in the temperature outside the body, maintaining the internal body temperature within a very small range of values. Thus, answer choice b. is true. It takes a lot of energy to raise the temperature of water; thus, it has a high heat of vaporization. Answer choice c. is false. Water makes up about two-thirds of the human body. Answer choice d. is false.

Question 3

For years your mother has been telling you to drink several large glasses of water each day. Having just read this chapter, you now understand the critical roles that water plays in your body. You vow to admit during your next phone call home that she has been right all along. Explain why dehydration might be dangerous.

Answer 3

Dehydration is dangerous because water is necessary for nearly every activity that takes place in the body. The body needs water to aid in digestion of food and excretion of wastes. It is needed for maintenance of body temperature. Drinking adequate water helps prevent many diseases, and it aids in weight loss. Water is necessary for maintaining the optimal pH level of our blood. It is also necessary for polymer formation and breakdown. Dehydration is the condition when there is inadequate water for normal body functioning, and when this happens, the kidneys can be damaged, digestion is impaired, the body can't fight disease and infection easily, and all the benefits of drinking water, which were enumerated above, are lost.

Question 4

Carbohydrates
a. consist of chains of amino acids.
b. supply our cells with energy.
c. contain glycerol.
d. function as enzymes.

Question 5

What is an isotope?

Question 6

Triglycerides
a. have one molecule of glycerol and three fatty acids.
b. are poor sources of energy.
c. are saturated when there are two or more double bonds link- ing carbon atoms.
d. are major components of plasma membranes.

Question 7

Dental x-rays are taken using small doses of radiation and are used to detect tooth decay, injuries to the roots of teeth, and problems with the bones supporting the teeth. A dental profes- sional covers the patient with a lead apron that runs from the neck to the abdomen and then leaves the room to take the x-ray. Why are such precautions necessary?

Question 8

Enzymes
a. speed up chemical reactions and are consumed in the process.
b. only function in decomposition reactions.
c. are usually nonspecific and therefore capable of binding to many different substrates.
d. have locations, known as active sites, to which the sub- strate binds.

Question 9

How is radiation used to diagnose or cure illness?

Question 10

Changes in temperature or pH can cause a protein to lose its three-dimensional shape and become nonfunctional. This process is called

Question 11

Describe covalent, ionic, and hydrogen bonds. Give an exam- ple of each.

Question 12

DNA and RNA are polymers of smaller units called

Question 13

What characteristics of water make it a critical component of the body?

Question 14

The structure of a protein is the precise sequence of amino acids.

Question 15

Define acids and bases according to what happens when they are added to water.

Question 16

are arranged in a double layer (bilayer) that forms the plasma membrane of cells.

Question 17

How are polymers formed and broken? Give three examples of polymers and their component monomers.

Question 18

In plants, the storage polysaccharide is and in animals it is

Question 19

Name two important energy-storage polysaccharides and one important structural polysaccharide.

Question 20

Buffers prevent dramatic changes in

Question 21

Describe the structure of a phospholipid. What important roles do phospholipids play in the human body?

Question 22

Describe the four levels of protein structure.

Question 23

Compare the structures of RNA and DNA.

Question 24

A friend eyes your lunch and begins to lecture you on the perils of high-fat foods. You decide to acknowledge the health risks of eating a high-fat diet but also to point out to her the important roles that lipids play in your body. What will you say?

Question 25

Describe the structure and function of ATP.

Question 26

What is an atom?

Question 27

Compare and contrast the ways in which proteins and nucleic acids are used in the body.

Question 28

Bill claims that eating fruits and vegetables is overrated because humans lack the enzyme needed to digest cellulose and thus cel- lulose passes unchanged through our digestive tract. Is Bill correct that we gain nothing from eating food that contains cellulose?

Question 29

Hydrogen bonds
a. are stronger than either ionic or covalent bonds.
b. form between a slightly positively charged hydrogen atom and a slightly negatively charged atom nearby.
c. maintain the shape of proteins and DNA.
d. b and c