Test 1- Biochemistry

Question 1

About 25 of the 92 natural elements are known to be essential to life. Which of the 25 elements make up approximately 96% of living matter?

Answer 1

Carbon, hydrogen, nitrogen, and oxygen

Question 2

Why is each element unique and different from other elements with respect to its chemical properties?

Answer 2

Each element has a unique number of protons

Question 3

Knowing just atomic mass of an element allows inferences about which of the following?

Answer 3

The number of protons plus neutrons in the element

Question 4

In what way are elements in the same column of the periodic table the same?

Answer 4

They have the same number of electrons in their valance shell

Question 5

Molybdenum has an atomic number 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, what to the following can be true?

Answer 5

Molybdenum atoms can have between 50 and 50 neutrons

Question 6

Carbon 12 is the most common isotope of carbon, and has a mass number of 12. However, the atomic mass of carbon is slightly more than 12 Daltons. Why?

Answer 6

Some carbon atoms in nature have more neutrons

Question 7

An atom has six electrons in its outer shell. How many unpaired electrons does it have?

Answer 7

2

Question 8

The atomic number of neon is 10. Therefore, which the following is most correct about an atom of neon?

Answer 8

It has 8 electrons in its outer electron shell and it is inert

Question 9

If a salamander relied on hydrogen bonds to cling to surfaces, what type of surfaces would cause the most problems for this animal?

Answer 9

A surface made with carbon and hydrogen atoms covalently bonded together

Question 10

A covalent chemical bond is one in which

Answer 10

Outershell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms

Question 11

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms ammonia (NH3)?

Answer 11

Each hydrogen atom has a partial positive charge, the nitrogen atom has a partial negative charge

Question 12

When two atoms are equally electronegative, they will interact to form

Answer 12

Nonpolar covalent bonds

Question 13

What results from an unequal sharing of electrons between atoms?

Answer 13

A polar covalent bond

Question 14

A single molecule of water, two hydrogen atoms are bonded to a single oxygen and by

Answer 14

Polar covalent bonds

Question 15

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?

Answer 15

A hydrogen bond

Question 16

The partial negative charge in a molecule of water occurs because

Answer 16

The Electrons shared between oxygen and hydrogen atoms spend more time around the oxygen atoms nucleus then around the hydrogen atoms nucleus

Question 17

Water molecules are able to form hydrogen bonds with

Answer 17

Compounds that have polar covalent bonds

Question 18

Which of the following effects is produced by the high surface tension of water?

Answer 18

A water Strider can walk across the surface of a small pond

Question 19

Which type of bond must be broken for water to vaporize?

Answer 19

Hydrogen bonds

Question 20

A strong acid like HCl

Answer 20

Ionizers completely in a aqueous solution

Question 21

Which of the following ionizes completely in solution and is considered to be a strong base (alkali)?

Answer 21

NaOH

Question 22

One L of a solution of pH 9 has how many more hydroxyl ions (OH-) than 1 L of a solution of pH 4?

Answer 22

100,000 times more

Question 23

Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely

Answer 23

Positively charged

Question 24

The element present in all organic molecules is

Answer 24

Carbon

Question 25

The complexity and variety of organic molecules is due to

Answer 25

The chemical versatility of carbon atoms

Question 26

The Carbon atom is most likely to form what kind of bond(s) with other atoms?

Answer 26

Covalent

Question 27

Which of the following statements best describes the carbon atoms present in a seed-eating bird

Answer 27

They were incorporated into organic molecules by plants, they were processed into sugars through photosynthesis, and they are ultimately derived from carbon dioxide

Question 28

Why are hydrocarbons insoluble in water?

Answer 28

The majority of their bonds are nonpolar covalent carbon hydrogen linkages

Question 29

Which two functional groups are always found in amino acids?

Answer 29

Carboxyl and Amino

Question 30

Three or four of the following illustrations depict different structural isomers of the organic compounds with molecular formula C6H14. For clarity, only the carbon skeletons are shown; hydrogen atoms that would be attached carbons have been omitted. Which one, if any, is not a structural isomer of this compound?

Answer 30

Answer C c-c=c-c I I c c

Question 31

O R-C O-H What is the name of the functional group shown in the figure above?

Answer 31

Carboxyl

Question 32

Humans and mice differ because

Answer 32

their cells have some differences in the sequence of nucleotides in their nucleic acids

Question 33

Which of these classes of biological molecules consist of both small molecules and macromolecular polymers?

Answer 33

Carbohydrates

Question 34

Which of the following is not a polymer?

Answer 34

Glucose

Question 35

What is the chemical reaction mechanism by which the cells make polymers from monomers?

Answer 35

Dehydration reactions

Question 36

How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?

Answer 36

10

Question 37

Which of the following polymers contain nitrogen?

Answer 37

Chitin

Question 38

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?

Answer 38

C18H32O16

Question 39

A molecule with the chemical formula C6H1204 is probably a

Answer 39

Carbohydrate

Question 40

All the following are polysaccharides except

Answer 40

Lactose

Question 41

Which of the following is true of both starch and cellulose?

Answer 41

They areboth polymers of glucose

Question 42

The bonding of two amino acid molecules to form a larger molecule requires

Answer 42

The release of a water molecule

Question 43

There are 20 different amino acids. What makes one amino acid different from another?

Answer 43

Different sidechains (R groups) attached to an a carbon

Question 44

Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein?

Answer 44

99

Question 45

What aspects of protein structure are stabilized or assisted by hydrogen bonds?

Answer 45

Secondary, tertiary, and quaternary structures, but not primary structure

Question 46

Which level of protein structure do the a helix and the B pleated sheet represent?

Answer 46

Secondary

Question 47

Which class of biological polymer has the greatest functional variety?

Answer 47

Proteins

Question 48

Which of the following categories includes all others in the list?

Answer 48

Carbohydrate

Question 49

The structural level of a protein least affected by a disruption on hydrogen bonding is the

Answer 49

Primary level