Biology test 1

Thiol

-SH

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 liter of 1.0 M NaCl

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

10-4 M

How many electrons are present in a Phosphorus 3+ atom?

12

what can be attributed to water's high specific heat?

A lake heats up more slowly than the air around it.

correct order in terms of the hierarchy of the organization?

Biosphere → Ecosystem → Population → Community → Organism

Nitrogen (N) is more electronegative than hydrogen (H). What is a correct statement about the atoms in ammonia (NH3)?

Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.

Which of the following are qualities of any good scientific hypothesis? I.It is testable. II.It is falsifiable. III.It produces quantitative data. IV.It produces results that can be replicated.

I and II

What is true about proteins?

Some proteins form a complete 3-D structure only when they interact with their targets

What is true of unsaturated fats?

They have double bonds in their fatty acid chains.

what is true about buffer solutions?

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

For lipids to be fluid at room temperature, they should have ________.

a higher number of cis double bonds

When the atoms involved in a covalent bond have the same electronegativity, what type of bond results?

a nonpolar covalent bond

what factors will increase the rate of reaction in the forward direction?

addition of both nitrogen and hydrogen

What molecule is a part of ATP?

adenosine

In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits ________.

altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered

Atoms have no electric charge because they have ________.

an equal number of protons and electrons

Cohesion, surface tension, and adhesion are the properties of water molecules that ________.

are a result of hydrogen bonding

Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that ________

are mirror images of each other

The left to right order of elements in the periodic table is based on their ________.

atomic number

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

carbohydrate

Amino acids are acids because they always possess ________ as the functional group

carboxyl

Which polysaccharide is an important component in the structure of many animals and fungi?

chitin

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

covalent

Which bond or interaction would be difficult to disrupt when compounds are put into water?

covalent bonds between carbon atoms

One of the primary functions of RNA molecules is to ________.

function in the synthesis of proteins

The process by which the information in a gene directs the synthesis of a protein is called ________.

gene expression

A scientist, who wants to study the effects of nitrogen on wheat plants, sets up an experiment with 4 groups of wheat plants: group A gets 20 pounds per acre, group B gets 40 pounds per acre, group C gets 60 pounds per acre, and group D gets 0 pounds per acre. Which of the following is the control group?

group D

Liquid water ________.

has a heat of vaporization higher than that of most other substances

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

have different functional groups attached to the same carbon skeleton

The best experimental design ________.

includes a large sample size and a control, and alters only one condition between the controls and the experimental condition

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions ________.

is 10 times higher in the cytoplasm than in the mitochondrial matrix

The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. Hydrogenated vegetable oil ________.

is solid at room temperature

Carbon-14 has the same ________.

number of protons but more neutrons than carbon-12

You disrupt all hydrogen bonds in a protein. What level of structure will be preserved?

primary structure

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?

single, double, or triple

Plants convert ________.

sunlight to chemical energy.

A salamander relies on hydrogen bonding to stick to various surfaces. Therefore, a salamander would have the greatest difficulty clinging to a ________.

surface of hydrocarbons

Which branch of biology is concerned with the naming and classifying of organisms? evolution

taxonomy

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). If the pH of blood drops, one would expect ________.

the HCO3- to act as a base and remove excess H+ by the formation of H2CO3

What component of amino acid structure varies among different amino acids?

the components of the R group

Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that ________.

the concentration of hydrogen ions in solution X is 1000 times as great as the concentration of hydrogen ions in solution Y

Organic chemistry is currently defined as

the study of carbon compounds.