Unit 1 Biology Exam

When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?

1 L of 1.0 MNaCl

Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a calcium atom must have

20 protons

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence

3'TAACGT5'

One mole (mol) of a substance is

A and D only

A given solution contains 0.0001(10-4) moles of hydrogen ions (H+) per liter. Which of the following best describes this solution?

Acidic: H+ donor

The R group or side chain of the amino acid serine is -CH2COOH. The R group or side chain of the amino acid alanine is -CH3. Where would you expect to find these amino acids in a globular protein in an aqueous solution?

Alanine would be in the interior, and serine would be on the exterior of the globular protein.

Technology can be described as...

All of the above

If the pH of a solution is decreased from 9 to 8, it means that the

Both B and D are correct

The molecular formula for glucose is C6H1206. What would be the molecular formula for a molecule made by linking three glucose molecules togther by dehydration reactions?

C18H32016

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

Dehydration reactions

The molecular mass of glucose (C6H12O6) is 180g. Which of the following procedures should you carry out to make a 0.5 M solution of glucose?

Dissolve 90g of glucose in a small volume of water, and then add more water until the total volume of the solutions is 1 L.

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

Each hydrogen atom has a partial positive charge.

Which of the following is reflective of the phrase "the whole is greater than the sum of its parts"?

Emergent properties

Which of the following is NOT a polymer?

Glucose

Sulfur is in the 3rd Period, 6 boxes over to the right. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

H2S

Why does ice float in liquid water?

Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water.

A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound?

It should dissolve in water

Which of the following sequences represents the hierarchy of biological organization from least to the most complex level?

Molecule, cell, organ system, population, ecosystem, biosphere

Which of the following statments concering prokaryotic and eukaryotic cells is NOT correct?

Prokaryotic cells contain small membrane-enclosed organelles.

Often, as scientists examine a very complex part of nature, they will begin with a ______ approach and then eventually, try a _______ approach.

Reductionist, systems

Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what ways do these molecules differ from each other?

Testosterone and estradiol are genetic have different functional groups attached to the same carbon skeleton.

Which of the following statements about the 5' end of a polynucleotide strand of DNA is correct?

The 5' end has a phosphate group attached to the number 5 carbon of ribose.

Why are hydrocarbons insoluble in water?

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

Which of the following is an example of hydrolysis?

The reaction of a fat, forming glycerol and fatty acids with the utilization of water.

All of the following statements concerning saturated fats are true EXCEPT?

They have multiple double bonds in the carbon chains of their fatty acids.

Which of the following statements is true about buffer solutions?

They maintain a relatively constant pH when either acids or bases are added to them.

An element "X" on the left side of the Periodic Table is known to give electrons to other atoms that are more electronegative. Which of the following statements is true?

This element would form a type of cation.

Three or four of the following statements are true and correct. Which one, if any, is false? If all the statements are true, choose answer E.

Virtually all organisms require the same elements in the same quantities.

Which is the best description of a carbonyl group?

a carbon atom joined to an oxygen by a double covalent bond

Which of the following descriptions best fits the class of the molecules known as nucleotides?

a nitrogenous base, a phosphate group, and a pentose sugar

Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement?

a steroid

Which of the following contains nitrogen in addition to carbon, oxygen, and hydrogen?

an amino acide such as glycine

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

as a disaccharide

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

carbon, hydrogen, nitrogen, oxygen

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

different side chains (R groups) attached to an alpha carbon

Which of the following explains most specifically the attraction of water molecules to one another?

hydrogen bond

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

nonpolar covalent bonds

Hydrophobic substances such as vegetable oil are

nonpolar substances that repel water molecules

How do isotopes of the same element differ from each other?

number of neutrons

A covalent chemical bond is one in which

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

Which bonds are created during the formation of the primary structure of a protein?

peptide bonds

The mass number of an element can be easily approximated by adding togther the number of__________ in an atom of that element.

protons and neutrons

The alpha helix and the beta pleated sheet are both common polypeptide forms found in which levels of protein structure?

secondary

The illustration above represents a map of a network of protein interactions within a eukaryotic cell. This type of analysis would be best be described as which scientific approach listed below?

systems

An example of a hydrogen bond is the bond between

the H of one water molecule and the O of another water molecule

Organic chemistry is currently defined as

the study of carbon compounds