Chapter 2 biology

Match each property to the appropriate subatomic particle.
Drag each property into the correct bin.

Proton: Symbol p, +1 charge Neutron: Symbol n, 0 charge Electron: Symbol e, -1 charge -The proton, neutron, and electron are the three main subatomic particles that make up all the elements.

Sort the subatomic particles according to their masses.
Drag each subatomic particles into the correct bin.

Mass of ~1 amu: neutron, proton Mass of~ 1/2000 amu: electron -The proton and neutron both have masses of about 1 amu, whereas the electron mass is only about 5.5×10^-4 amu.

What type of bond is joining the two hydrogen atoms?

Covalent -A covalent bond is one in which electron pairs are shared.

A(n)______refers to two or more atoms held together by covalent bonds.

Molecule -A molecule is defined as two or more atoms held together by covalent bonds.

This atom can form up to ______single covalent bond(s).

4 electrons in the outermost electron shell.

A(n)_____ bond joins these two oxygen atoms.

Double covalent -The oxygen atoms are sharing two pairs of electrons.

Which of the following statements most accurately describes the relative positions of the shared electrons in methane (CH4) and ammonia (NH3)?

Electrons are shared equally in CH4 and unequally in NH3. C and H have approximately equal electronegativities, so electrons are shared equally in CH4. N is significantly more electronegative than H, so electrons are shared unequally in NH3.

The brackets are indicating a(n) _____ bond.

hydrogen A hydrogen atom with a net positive charge is attracted to an oxygen atom with a net negative charge.

What name is given to the bond between water molecules?

Hydrogen -A hydrogen atom with a net positive charge is attracted to an oxygen atom with a net negative charge.

What is the arrow pointing to?

hydrogen ion The arrow is indicating a single proton, a hydrogen ion (H+).

What is the arrow pointing to?

hydroxide ion The arrow is indicating a hydroxide ion (OH-).

In a neutral solution the concentration of _____.

Hydrogen ions is equal to the concentration of hydroxide ions. This is the definition of a neutral solution.

How does the pH of the solution on the right compare with that of the solution on the left?

The solution on the right is basic relative to the solution on the left The solution on the right has a lower concentration of hydrogen ions relative to hydroxide ions than does the solution on the left.

Which statement best explains the physical basis for why oil (molecules containing only carbon and hydrogen) and water do not mix?

Oils are nonpolar molecules that cannot interact with water molecules via hydrogen bonding. Because oils are neither polar nor charged, they cannot interact with the partial charges on water molecules.

The hydrogen bonds among water molecules endow water with which property?

Water has a high specific heat. It takes a lot of energy to raise the temperature of water. Temperature measures the movement of molecules and energy must first go into breaking the hydrogen bonds before the energy can allow increased movement.

Which statement best explains the energy transformation that occurs when methane burns (CH4 + 2 O2 → CO2 + 2 H2O)?

A decrease in potential energy from reactants to products is released as heat

What type of energy is stored in the chemical bonds of a molecule?

potential energy Potential energy is energy based on position. Chemical bonds will vary in the amount of chemical potential energy they have based on the location of their electrons.

The first law of thermodynamics states that _____.

energy is neither created nor destroyed The first law of thermodynamics states that energy is conserved—it cannot be created or destroyed, only transferred and transformed.

Which of the following is true of Miller’s spark discharge experiment?

The experiment tested the prebiotic soup model of chemical evolution. Miller attempted to simulate an early Earth ocean and atmosphere to see if simple organic molecules could form.

Hydrocarbons are molecules consisting of only carbon atoms and hydrogen atoms. Hydrocarbons form the basis of many types of organic molecules.

…

In addition to carbon atoms and hydrogen atoms, many organic molecules also have groups of atoms called functional groups. These functional groups may be substituted for one or more of the hydrogen atoms of a hydrocarbon. The functional groups present in an organic molecule determine the chemical behavior of that molecule

…

Which molecules show an appropriate number of bonds around each carbon atom?

Since carbon atoms are tetravalent (able to form four bonds), atoms may branch off a carbon atom in as many as four places. The ability of a carbon atom to form four different bonds allows carbon to form many different sizes and types of molecules. Carbon atoms may form chains, rings, or combinations of chains and rings. The tetravalence of carbon makes it particularly well-suited to forming the backbone of a huge diversity of organic molecules.

The molecule shown here contains four functional groups.
The molecule shown here contains four functional groups.
Highlight all the atoms of the four functional groups by clicking on them. When you click on each atom, it will change color. To deselect an atom, click on it again. Do not highlight any bonds.

A functional group is a group of atoms bonded together in a specific way that can replace a hydrogen atom in a hydrocarbon. The molecule shown here contains four functional groups (−OH, −SH, −NH2, and −OPO2−3) attached to a carbon chain that is six carbon atoms long. H-S PO4 O-H NH2

Functional groups confer specific chemical properties to the molecules of which they are a part. In this activity, you will identify which compounds exhibit certain chemical properties as well as examples of those six different compounds.
Drag one molecule (white label) and one chemical property (blue label) to each bin.

alcohol: is highly polar andmay act as a weak acid (OH) carboxylic acid: acts as an acid (COOH) aldehyde: may be a structural isomer of a ketone (C=O) thiol: forms disulfide bonds (S-H) amine: acts as a base (NH2) organic phosphate: contributes negative charge (PO4)

Some biologically important functional groups include the hydroxyl group, the carbonyl group, the carboxyl group, the amino group, the sulfhydryl group, and the phosphate group. Phosphate groups, for example, are an important part of the structure of ATP (adenosine triphosphate), an energy storage molecule in cells

Some biologically important functional groups include the hydroxyl group, the carbonyl group, the carboxyl group, the amino group, the sulfhydryl group, and the phosphate group. Phosphate groups, for example, are an important part of the structure of ATP (adenosine triphosphate), an energy storage molecule in cells

What is the molecular formula for the molecule shown in the figure?

C8H18 The compound is octane, which has 8 carbons and 18 hydrogens.

This figure shows aspartate. How many carboxylic acid groups does this compound contain?
Aspartate

There are two carboxylic acid groups.

The bond in the figure represents a _____. Oxygen

Double covalent bonds are represented by two lines

Compare the structural formulas shown in the figure. What is different about the two compounds?

The double bond is between a different carbon and oxygen The first structure is an aldose, the second is a ketose.

What is special about the bonds in the figure? wate

There are polar covalent bonds in water. The oxygen pulls the electrons away from the hydrogen nuclei, making the water polar.

What factors determine whether a chemical reaction is spontaneous or not?

entropy potential energy

Which of the following is most likely to have been the energy source responsible for the formation of acetic acid in deep-sea hydrothermal vents?

chemical energy present in the reactants

In the bottom-up approach to investigating chemical evolution, researchers _____.

focus on the small molecules and environmental conditions that were present in early Earth Bottom-up refers to the synthesis of more complex molecules from the simpler precursors available at the time.