Introduction to Evolution, Scientific Method, and Basic Chemistry in Biology

What type of data did Jane Goodall collect in her studies of chimpanzee behavior?

Both qualitative and quantitative data.

Which option is an example of quantitative data in chimpanzee behavior?

D) Mothers and their infants typically nap for two to three hours each afternoon.

What does the process of science involve testing?

B) a hypothesis.

What characterizes a controlled experiment?

C) An experiment with at least two groups, one of which does not receive the experimental treatment.

What is a requirement for a good scientific hypothesis?

C) It must lead to testable predictions.

Why is it important to include a control group in an experiment?

A) A control group provides a reference by which to determine if a particular outcome may reasonably result from the variable being tested.

Which description constitutes a controlled experiment?

C) Growing one set of 10 seedlings under white light and one set under red light and measuring their growth over two weeks.

What is a controlled experiment?

B) Tests experimental and control groups in parallel.

How do hypotheses differ from theories in science?

C) Hypotheses usually are relatively narrow in scope; theories have broad explanatory power.

What best describes the logic of scientific inquiry?

D) If my hypothesis is correct, I can expect certain test results.

Which four elements make up approximately 96% of the mass of the human body?

D) carbon, hydrogen, nitrogen, oxygen.

What is a trace element required by humans and other vertebrates?

C) iodine.

What can be deduced from a mass number in an atom?

The number of neutrons in each atom of an element.

What is the common property of elements in the same column of the periodic table?

They have the same number of electrons in their valence shell.

What property is shared by elements in the same row of the periodic table?

They have the same number of electron shells.

What is the mass number and atomic number of a nitrogen atom with 8 neutrons and 7 protons?

Mass number is 15 and atomic number is 7.

What primarily determines the chemical behavior of an atom?

The number of electrons in the valence shell.

If an atom has 6 electrons in its outer shell, how many unpaired electrons does it have?

2 unpaired electrons.

What is true about argon, which has atomic number 18?

It is inert.

What does the atomic number of sulfur, which is 16, indicate?

It indicates that a sulfur atom contains 16 protons.

Which atom has the same number of valence electrons as carbon (C)?

Silicon (Si) has the same number of valence electrons as carbon.

What must two atoms with the same mass number have in common?

They must have the same number of protons plus neutrons.

What is a covalent chemical bond?

A bond where outer-shell electrons of two atoms are shared.

What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen?

2 covalent bonds.

In ammonia (NH3), what charge do the atoms have due to nitrogen's electronegativity?

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

What type of bond is formed when two atoms are equally electronegative?

Nonpolar covalent bonds.

What interaction results from unequal sharing of electrons between atoms?

A polar covalent bond.

When is a covalent bond likely to be polar?

When one of the atoms sharing electrons is much more electronegative than the other.

Which types of molecules contain polar covalent bonds?

Molecules where there is an unequal sharing of electrons between different atoms.

What are the main differences between covalent and ionic bonds?

Covalent bonds involve the sharing of pairs of electrons between atoms, while ionic bonds involve the transfer of electrons from one atom to another.

What is the cation in ammonium chloride (NH4Cl)?

NH4, with a charge of +1.

Which bond is most difficult to disrupt in water?

Covalent bond.

Which of the following are considered compounds?

H2O and CH4, but not O2.

What does chemical equilibrium indicate about forward and reverse reactions?

Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.

What characterizes a reaction that has reached chemical equilibrium?

The rate of the forward reaction is equal to the rate of the reverse reaction.

What type of bonds do water molecules form with each other in an aqueous solution?

Hydrogen bonds.

If a salamander clings to surfaces through hydrogen bonds, which surface would it have difficulty clinging to?

A surface coated with a thin film of vegetable oil.

What type of bonds exist between hydrogen and oxygen atoms in a water molecule?

Polar covalent bonds.

What effect does the high surface tension of water produce?

A water strider can walk across the surface of a small pond.

What type of bonds must be broken to convert liquid water to water vapor?

Hydrogen bonds.

Why does ice float in liquid water?

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

What are hydrophobic substances like vegetable oil?

Nonpolar substances that repel water molecules.

What can be concluded about a substance with a pH of 2 in a 0.01 M solution?

It is a strong acid that ionizes completely in water.

What can be concluded about a substance that ionizes completely in water?

It is either a strong acid or a strong base.

How is a solution with 0.0000001 moles of hydroxyl ions (OH-) per liter best described?

It is neutral.

What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10^-12 M?

pH 12.

What is the pH of a 10^-3 M NaOH solution?

pH 11.

Which solution requires the greatest amount of base to reach neutral pH?

Gastric juice at pH 2.

What is the hydrogen ion (H+) concentration of a solution with pH 8?

8 × 10^-6 M.

What is the hydroxyl ion (OH-) concentration of a solution with pH 8?

10^-6 M.

What happens to the H+ concentration when the pH decreases from 8 to 6?

The concentration of H+ is 100 times greater than it was at pH 8.

What is true about buffer solutions?

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

What happens to carbonic acid (H2CO3) when blood pH decreases?

There is an increase in the concentration of H2CO3 and a decrease in the concentration of HCO3-.

How does acid precipitation affect marine corals?

It decreases the concentration of carbonate ions in oceans.

What percentage of human-generated atmospheric CO2 is absorbed by the oceans?

Approximately 25%.

What happens when the concentration of H2CO3 increases in the oceans?

Ocean pH will decrease.

What effect does CO2 from respiring cells have on blood pH?

Blood pH will decrease slightly.

What is the effect of increased atmospheric CO2 concentrations on seawater?

Seawater will become more acidic, and carbonate concentrations will decrease.

How does acidification of seawater affect marine organisms?

Acidification would decrease dissolved carbonate concentrations, negatively impacting corals and shell-building animals.

What effect does acidification have on dissolved carbonate concentrations and coral growth?

Acidification decreases dissolved carbonate concentrations and hinders the growth of corals and shell-building animals.

If carbon is absent, which element might fill its role in compounds essential to life?

Silicon.

Which drawing depicts the electron configuration of an element with properties similar to helium?

The drawing that matches the electron configuration of helium.

How many electrons does nitrogen have in its valence shell?

5 electrons.

How many electrons does sulfur (S) have in its valence shell?

6 electrons.

Which pairs of atoms are most likely to form a polar covalent bond?

Pairs with different electronegativities.

Which pairs of atoms are most likely to form ions and thus an ionic bond?

Pairs of atoms with significantly different electronegativities.

What happens when CO2 is bubbled into pure water?

Carbon dioxide forms carbonic acid, affecting the pH.

What is the pH of a mixture after combining equal volumes of HCl at pH 1.0 and NaOH at pH 13?

The pH will be approximately 7.0.

What causes the reactivity of an atom?

The existence of unpaired electrons in the valence shell.

Which property of water allows sweat to lower body temperature?

The absorption of heat by the breaking of hydrogen bonds.

What is the hydrogen ion concentration of a lake with a pH of 4.0?

10−4 M.

How many electron pairs does carbon share to complete its valence shell?

4 electron pairs.

What type of bonds is a carbon atom most likely to form?

Covalent bonds.

What are enantiomers?

Molecules that are mirror images of one another.

Which organic compounds are most soluble in water?

Organic hydrocarbons with hydroxyl groups attached.

Which functional group confers acidic properties on amino acids?

Carboxyl group.

What functional groups are mentioned in the notes?

Amino, carbonyl, carboxyl, phosphate, hydroxyl.

What happens when a carbon skeleton is bonded to both an amino group and a carboxyl group in water?

It will function as both an acid and a base.

Which functional group can act as a base?

Amino.

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

Dehydration reactions.

Which chemical equation describes a hydrolysis reaction?

Disaccharide + H2O = monosaccharide + monosaccharide.

Which chemical equation describes a dehydration reaction?

Monosaccharide + monosaccharide = disaccharide + H2O.

How many water molecules are needed to completely hydrolyze a polysaccharide that is 10 monomers long?

11

What summarizes the relationship between dehydration reactions and hydrolysis?

Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.

What is the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?

C18H32O16.

What is true of both starch and cellulose?

They are both polymers of glucose.

What is true regarding cellulose?

It is a primary structural component of plant cell walls.

What does the term insoluble fiber generally refer to?

Cellulose.

How is lactose classified?

As a disaccharide.

Which of the following is the smallest carbohydrate?

Sucrose.

What is true about saturated fats?

They are generally solid at room temperature.

What is a molecule with the formula C18H36O2 most likely?

A fatty acid.

What is true regarding lipids?

They are insoluble in water.

What is a molecule with the chemical formula C6H12O6 most likely?

A monosaccharide.

Which large biological molecules will self-assemble into a bilayer when mixed with water?

Phospholipids.

Why are vertebrate sex hormones like estrogen and testosterone considered lipids?

Their carbon skeletons are composed of primarily C—C and C—H bonds.

Which two functional groups are always found in amino acids?

Carboxyl and amino.

What biochemical reaction joins two amino acids to form a dipeptide?

The release of a water molecule.

How are polysaccharides, triacylglycerols, and proteins similar?

They are synthesized from subunits by dehydration reactions.

Which molecule lacks amino acids?

Cholesterol.