BIO 120 Lecture Notes - 100 Practice Flashcards

100 Q&A flashcards covering key concepts from the lecture notes, including science process, atoms and bonding, water chemistry, pH, and buffers.

What is Scientific Inquiry?

Search for information and explanation, often focusing on a specific question.

How is scientific inquiry typically carried out?

Hypothesis-based testing that explains nature.

What is a Scientific Theory?

A well-supported explanation that unifies a broad range of observations and hypotheses.

In the scientific method, what comes after Observations?

Hypothesis.

If results are not consistent with the hypothesis, what should you do?

Reject or revise the hypothesis.

What are Predictions in the scientific method?

Statements about what will happen if the hypothesis is tested.

When are results considered to support a theory?

When results are consistent over many experiments based on many related hypotheses.

Name some common elements found in living matter.

Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Phosphorus (P), Sulfur (S), Calcium (Ca), Potassium (K), Chlorine (Cl), Magnesium (Mg), and trace elements.

What is the solvent of life?

Water.

What are the three basic components of an atom?

Protons, neutrons, and electrons.

What is contained in the nucleus of an atom?

Protons and neutrons.

Where do electrons reside in an atom?

In orbitals or shells around the nucleus.

Do elements contain more than one type of atom?

No, elements contain only one type of atom.

What determines whether atoms will bond?

The number of valence electrons in the outermost shell.

How are ionic bonds formed?

When two atoms have unequal attraction for valence electrons; electrons are transferred, forming ions.

What are the two ions called in an ionic bond?

Cation and Anion.

What is a covalent bond?

A bond formed when valence electrons are shared between atoms.

What is a nonpolar covalent bond?

A covalent bond in which electrons are shared equally between atoms.

What is a polar covalent bond?

A covalent bond where electrons are not shared equally, producing partial charges.

In a water molecule, which atom is more electronegative?

Oxygen.

What is a hydrogen bond?

A weak attraction between the partial positive hydrogen of one polar molecule and a partial negative atom on another molecule.

What does molecular mimicry refer to?

The shape of a molecule determines its function; similar shapes can have similar functions.

What happens in a chemical reaction?

Bonds are broken and formed, leading to changes in the composition of matter.

What does the law of conservation of matter state?

Matter is neither created nor destroyed, just rearranged.

What is chemical equilibrium?

When the forward and reverse reaction rates are equal in a reversible reaction.

What is a solvent?

The liquid medium in which substances are dissolved.

What is a solute?

Dissolved particles in the solvent.

What is a solution?

A homogeneous mixture of solute(s) and solvent with uniform composition.

In aqueous solutions, what is the solvent?

Water.

What makes water capable of forming many hydrogen bonds?

Its polarity; partial positive on hydrogen and partial negative on oxygen.

What are the properties arising from water's hydrogen bonding?

Cohesion, adhesion, surface tension, and high specific heat.

What does cohesion mean in water?

Hydrogen bonds between water molecules hold them together.

What does adhesion mean in water?

Hydrogen bonding between water and polar surfaces.

What is surface tension?

A measure of how difficult it is to stretch or break the surface of a liquid.

Why does water have a high specific heat?

Due to extensive hydrogen bonding.

Why is water called the solvent of life?

Because water forms hydrogen bonds with polar molecules and dissolves many essential substances.

What is the difference between hydrophilic and hydrophobic substances?

Hydrophilic substances have an affinity for water and dissolve; hydrophobic substances do not dissolve and are non-polar.

Give examples of hydrophilic substances.

Ionic compounds (e.g., NaCl) and polar compounds that form hydrogen bonds with water (e.g., NH3).

Give examples of hydrophobic substances.

Non-polar substances that do not form hydrogen bonds with water (e.g., oils).

What happens when water dissociates?

A water molecule can separate into H+ and OH− ions.

Are H+ and OH− concentrations equal in pure water?

Yes, they are equal in pure water.

What does the pH scale measure?

The concentration of hydrogen ions (H+) in a solution.

What is neutral on the pH scale?

pH 7.

Are acids associated with low pH?

Yes; acids increase H+ concentration, lowering pH below 7.

Are bases associated with high pH?

Yes; bases increase OH− concentration, raising pH above 7.

What is a logarithmic pH scale?

Each unit change corresponds to a ten-fold change in H+ (or OH−) concentration.

What are buffers?

Substances that minimize changes in pH by balancing H+ and OH− concentrations.

What are buffer systems composed of?

A weak acid and its conjugate weak base.

How do buffers respond to excess acid?

The acid form (carbonic acid) donates H+, forming bicarbonate (HCO3−) to correct pH.

How do buffers respond to excess base?

The basic form (bicarbonate, HCO3−) accepts H+ to form carbonic acid (H2CO3).

What is the role of carbonic acid (H2CO3) in buffering?

It acts as the weak acid that donates H+ when needed.

What is the role of bicarbonate (HCO3−) in buffering?

It acts as the weak base that accepts H+ when needed.

What happens to pH when a buffer neutralizes added base?

Buffer absorbs the base, limiting pH rise (formation of carbonic acid).

What is the chemical formula for bicarbonate ion?

HCO3−.

What is the chemical formula for carbonic acid?

H2CO3.

What are the two forms of buffer in the carbonic acid system?

Acid form (H2CO3) and basic form (HCO3−).

Do buffers resist changes in pH?

Yes; they minimize changes in H+ and OH− concentrations.

Why are buffers important in biology?

They help maintain stable pH essential for biochemical processes.

What does electronegativity influence in bonding?

Whether electrons are shared or transferred, affecting bond type (ionic, polar covalent, nonpolar covalent).

What are the electrons in the outermost shell called?

Valence electrons.

What is a valence electron?

An electron in the outermost shell used for bonding.

What are orbitals or shells around the nucleus?

Regions where electrons are likely to be found in an atom.

What defines a polar molecule?

A molecule with regions of partial positive and partial negative charge.

What is the difference between bonds and molecules?

Bonds hold atoms together to form molecules; the arrangement (shape) determines function.

What is the relationship between bond type and electronegativity difference?

A larger difference tends to ionic or polar covalent bonds; small difference tends to nonpolar covalent bonds.

What is meant by bond strength hierarchy?

Covalent bonds are stronger than hydrogen bonds, which are weaker than ionic interactions in many contexts.

What is the significance of water being a polar molecule?

It enables hydrogen bonding, cohesion, adhesion, and acting as a versatile solvent.

What is meant by ‘solvent of life’ in the notes?

Water—its properties support dissolving essential molecules for life.

What is the role of hydrogen bonds in surface tension?

Extensive hydrogen bonding at the surface of water increases surface tension.

What is a covalent bond example mentioned in the notes?

Methane (CH4) involves covalent sharing of electrons.

What is an ionic bond example mentioned in the notes?

Not specified by compound, but described by transfer of electrons creating cations and anions.

What does a polar covalent bond do to electron distribution?

Creates partial positive and partial negative charges due to unequal sharing.

What happens to water’s properties due to hydrogen bonding?

Cohesion, adhesion, surface tension, and high specific heat.

What is the effect of solutes on water’s pH?

Acids and bases can change H+ and OH− concentrations, affecting pH.

What is the role of ammonia (NH3) in hydrogen bonding?

Acts as a molecule that can participate in hydrogen bonding due to electronegative nitrogen.

What is the difference between a solvent and a solute in a solution?

Solvent is the dissolving medium; solute is the substance dissolved.

What does ‘aqueous’ mean?

A solution in which the solvent is water.

What is the function of valence electrons in bonding?

They participate in forming bonds to achieve stable electron configurations.

What is meant by ‘valence’ in chemistry?

The outer shell used for bonding and determining bond capacity.

What is the role of shells in energy storage for electrons?

Each shell has a greater amount of stored energy as you move outward.

What is a cation?

A positively charged ion formed in ionic bonding.

What is an anion?

A negatively charged ion formed in ionic bonding.

What is the general result of ionic bonding on charge distribution?

Two oppositely charged ions remain associated due to electrostatic attraction.

Why do covalent bonds share electrons rather than transfer them?

When atoms have similar electronegativity, electrons are shared to achieve stable outer shells.

How does the concept of molecular shape relate to function?

The shape determines how a molecule interacts with other molecules and thus its function.

What is the term for the attraction that forms between water molecules?

Hydrogen bonding.

What are the charges within the different ions of a covalently-bonded water molecule?

Partial positive charge on hydrogen and partial negative charge on oxygen drive interactions.

What is meant by ‘specific heat’ and which substance has a high value for it?

The amount of heat required to change temperature; water has a high specific heat.

What is the term for substances that dissolve in water easily?

Hydrophilic substances.

What is the term for substances that do not dissolve in water easily?

Hydrophobic substances.

What determines whether water will dissolve a substance?

Whether the substance can form hydrogen bonds or interact with water’s polarity.

What is the effect of pH on biological molecules?

pH affects function and structure; buffers help maintain stability.

What type of reaction rearranges matter but does not create or destroy it?

All.

What is a key concept of the notes related to 'THEORY' in the scientific method?

A theory is formed when results are consistent across many experiments and hypotheses.

What is the difference between a theory and a hypothesis?

A hypothesis is a testable statement; a theory is a well-supported, broad explanation.

What is the relationship between H+ and pH on the scale?

Lower pH means higher H+ concentration; higher pH means lower H+ concentration.

What happens to H+ concentration as pH increases by 1 unit?

H+ concentration decreases ten-fold.

What is the term for a solution that has equal numbers of H+ and OH−?

A neutral solution (pH 7).