Test 1- Biochemistry Flashcards
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?
Carbon, hydrogen, nitrogen, and oxygen
Why is each element unique and different from other elements with respect to its chemical properties?
Each element has a unique number of protons
Knowing just atomic mass of an element allows inferences about which of the following?
The number of protons plus neutrons in the element
In what way are elements in the same column of the periodic table the same?
They have the same number of electrons in their valance shell
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?
Molybdenum atoms can have between 50 and 50 neutrons
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?
Some carbon atoms in nature have more neutrons
An atom has six electrons in its outer shell. How many unpaired electrons does it have?
2
The atomic number of neon is 10. Therefore, which the following is most correct about an atom of neon?
It has 8 electrons in its outer electron shell and it is inert
If a salamander relied on hydrogen bonds to cling to surfaces, what type of surfaces would cause the most problems for this animal?
A surface made with carbon and hydrogen atoms covalently bonded together
A covalent chemical bond is one in which
Outershell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms
Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms ammonia (NH3)?
Each hydrogen atom has a partial positive charge, the nitrogen atom has a partial negative charge
When two atoms are equally electronegative, they will interact to form
Nonpolar covalent bonds
What results from an unequal sharing of electrons between atoms?
A polar covalent bond
A single molecule of water, two hydrogen atoms are bonded to a single oxygen and by
Polar covalent bonds
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?
A hydrogen bond
The partial negative charge in a molecule of water occurs because
The Electrons shared between oxygen and hydrogen atoms spend more time around the oxygen atoms nucleus then around the hydrogen atoms nucleus
Water molecules are able to form hydrogen bonds with
Compounds that have polar covalent bonds
Which of the following effects is produced by the high surface tension of water?
A water Strider can walk across the surface of a small pond
Which type of bond must be broken for water to vaporize?
Hydrogen bonds
A strong acid like HCl
Ionizers completely in a aqueous solution
Which of the following ionizes completely in solution and is considered to be a strong base (alkali)?
NaOH
One L of a solution of pH 9 has how many more hydroxyl ions (OH-) than 1 L of a solution of pH 4?
100,000 times more
Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely
Positively charged
The element present in all organic molecules is
Carbon
The complexity and variety of organic molecules is due to
The chemical versatility of carbon atoms
The Carbon atom is most likely to form what kind of bond(s) with other atoms?
Covalent
Which of the following statements best describes the carbon atoms present in a seed-eating bird
They were incorporated into organic molecules by plants, they were processed into sugars through photosynthesis, and they are ultimately derived from carbon dioxide
Why are hydrocarbons insoluble in water?
The majority of their bonds are nonpolar covalent carbon hydrogen linkages
Which two functional groups are always found in amino acids?
Carboxyl and Amino
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 C
c-c=c-c
I I
c c
O
R-C
O-H
What is the name of the functional group shown in the figure above?
Carboxyl
Humans and mice differ because
their cells have some differences in the sequence of nucleotides in their nucleic acids
Which of these classes of biological molecules consist of both small molecules and macromolecular polymers?
Carbohydrates
Which of the following is not a polymer?
Glucose
What is the chemical reaction mechanism by which the cells make polymers from monomers?
Dehydration reactions
How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?
10
Which of the following polymers contain nitrogen?
Chitin
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?
C18H32O16
A molecule with the chemical formula C6H1204 is probably a
Carbohydrate
All the following are polysaccharides except
Lactose
Which of the following is true of both starch and cellulose?
They areboth polymers of glucose
The bonding of two amino acid molecules to form a larger molecule requires
The release of a water molecule
There are 20 different amino acids. What makes one amino acid different from another?
Different sidechains (R groups) attached to an a carbon
Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein?
99
What aspects of protein structure are stabilized or assisted by hydrogen bonds?
Secondary, tertiary, and quaternary structures, but not primary structure
Which level of protein structure do the a helix and the B pleated sheet represent?
Secondary
Which class of biological polymer has the greatest functional variety?
Proteins
Which of the following categories includes all others in the list?
Carbohydrate
The structural level of a protein least affected by a disruption on hydrogen bonding is the
Primary level
