Biol 1500 - 1,2,3
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168 Terms
What is matter?
Anything that takes up space and has mass.
What is an element?
A substance that cannot be broken down by ordinary chemical reactions.
What is a compound?
A substance containing two or more elements in fixed ratios.
Why can a compound have very different properties from the elements that make it?
Biological properties emerge from how atoms are arranged and bonded.
What four elements make up about 96% of living matter?
Carbon, hydrogen, oxygen, and nitrogen (CHON).
What determines an element's identity?
The number of protons in its nucleus.
What charge does a proton have?
Positive.
What charge does a neutron have?
No charge/neutral.
What charge does an electron have?
Negative.
Where are protons and neutrons found?
In the nucleus.
Where are electrons found?
In the space around the nucleus.
What determines an atom's atomic number?
Its number of protons.
What is the mass number?
The number of protons + neutrons.
What are isotopes?
Forms of an element with the same number of protons but different numbers of neutrons.
What is a radioactive isotope?
An isotope that spontaneously decays, releasing energy and particles.
What is half-life?
The time required for half of a parent isotope to decay.
What is a radioactive tracer?
A labeled molecule that can be followed through a biological system.
What do PET scans use radioactive tracers to detect?
Areas of high metabolic activity.
What is energy?
The capacity to cause change.
What is potential energy?
Energy related to an object's location or structure.
What are electron shells?
Regions associated with characteristic electron energy levels.
What are valence electrons?
Electrons in an atom's outermost electron shell.
Why are valence electrons important?
They largely determine an atom's bonding behavior and chemical reactivity.
What happens when an atom has an incomplete valence shell?
It tends to react.
What happens when an atom has a full valence shell?
It tends to be chemically inert.
What is a covalent bond?
A bond in which atoms share pairs of valence electrons.
What is an ionic bond?
An attraction between oppositely charged ions after electrons are transferred.
What is a cation?
A positively charged ion.
What is an anion?
A negatively charged ion.
What is a single covalent bond?
A bond in which one pair of electrons is shared.
What is a double covalent bond?
A bond in which two pairs of electrons are shared.
What is electronegativity?
An atom's attraction for shared electrons.
What is a nonpolar covalent bond?
A covalent bond in which electrons are shared nearly equally.
What is a polar covalent bond?
A covalent bond in which electrons are shared unequally.
What causes partial charges?
Unequal sharing of electrons.
What is a hydrogen bond?
An attraction between a partially positive H attached to an electronegative atom and another electronegative atom.
What are van der Waals interactions?
Weak attractions caused by temporary uneven distributions of electrons.
Why are weak interactions biologically important?
Many weak interactions together can stabilize structures while allowing reversible binding and change.
Why does molecular shape matter?
Biological molecules recognize one another through three-dimensional fit, charge, and local chemistry.
What are reactants?
The starting materials in a chemical reaction.
What are products?
The outcomes of a chemical reaction.
What is chemical equilibrium?
A state in which forward and reverse reactions occur at the same rate.
Why is water a polar molecule?
Electrons spend more time near oxygen than hydrogen, creating partial charges.
What partial charge does oxygen have in water?
Partial negative.
What partial charge do the hydrogen atoms have in water?
Partial positive.
What causes hydrogen bonds between water molecules?
Attraction between opposite partial charges.
What are the four major emergent properties of water discussed in lecture?
Cohesion, temperature moderation, ice floating, and versatile solvent properties.
What is cohesion?
Attraction between molecules of the same substance.
What causes cohesion in water?
Hydrogen bonds between water molecules.
What is surface tension?
A measure of how difficult it is to stretch or break a liquid surface.
What is adhesion?
Attraction between different substances.
How do cohesion and adhesion help transport water through plants?
Adhesion helps water interact with plant cell walls, while cohesion keeps the water column intact.
What pulls water upward through a plant?
Evaporation from leaves, along with cohesion and adhesion.
What is temperature?
A measure related to the average kinetic energy of molecules.
What is heat?
Thermal energy transferred between bodies of matter.
What is specific heat?
The amount of heat needed to change 1 g of a substance by 1°C.
Why does water have a high specific heat?
Hydrogen bonds absorb heat energy before molecular motion increases substantially.
Why does water resist rapid temperature changes?
Heat energy is used to disrupt hydrogen bonds before it greatly increases molecular motion.
What happens to hydrogen bonds when water cools?
They form and release heat into the surroundings.
What is evaporation?
The transformation of liquid water into gas.
What is heat of vaporization?
The heat required to convert 1 g of liquid into gas.
Why does evaporation cool a surface?
The fastest-moving molecules leave as vapor, removing heat from the remaining liquid.
How do sweating and panting cool organisms?
Through evaporative cooling.
Why does ice float?
Solid water is less dense than liquid water because hydrogen bonds create an open lattice.
About how much less dense is ice than liquid water?
About 10% less dense.
Why is floating ice biologically important?
It insulates the water beneath it, allowing aquatic organisms to survive winter.
What is a solution?
A homogeneous mixture of substances.
What is a solvent?
The substance that does the dissolving.
What is a solute?
The substance that is dissolved.
What is an aqueous solution?
A solution in which water is the solvent.
Why is water an excellent solvent for many biological substances?
Its polarity allows it to dissolve ions and polar molecules.
What is a hydration shell?
Water molecules surrounding dissolved ions.
What does hydrophilic mean?
Having an affinity for water; often ionic or polar.
What does hydrophobic mean?
Lacking an affinity for water; often nonpolar.
Why are hydrophilic and hydrophobic properties important for membranes?
Membrane lipids contain hydrophilic and hydrophobic regions that self-organize into barriers.
What is a mole?
6.022 × 10²³ particles.
What is molarity?
Moles of solute per liter of solution.
Why does concentration matter biologically?
Cells and enzymes respond to the concentration of solutes, which affects molecular collisions and reactions.
Why do scientists searching for extraterrestrial life often look for water?
Water can dissolve and transport solutes needed for chemical reactions and molecular interactions.
What happens when water dissociates?
A proton transfers between water molecules, producing hydronium/H⁺ and hydroxide/OH⁻.
What does an acid do to H⁺ concentration?
Increases it.
What does a base do to H⁺ concentration?
Reduces it, often by accepting H⁺ or adding OH⁻.
What is pH?
A logarithmic way to describe acidity: pH = −log[H⁺].
What pH is acidic?
Below 7.
What pH is basic?
Above 7.
What do buffers do?
Resist changes in H⁺ and OH⁻ concentrations and minimize changes in pH.
What are most biological buffers made of?
A weak acid and its corresponding base.
How does a buffer respond when acid is added?
The base component accepts H⁺.
How does a buffer respond when base is added?
The acid component donates H⁺.
What causes ocean acidification?
Increased CO₂ dissolving into seawater and shifting carbonate chemistry.
What happens when CO₂ reacts with water?
Carbonic acid forms.
How does carbonic acid affect ocean pH?
It releases H⁺, lowering pH.
How does increased H⁺ affect carbonate ions?
It reduces the amount of carbonate available.
Why is carbonate important to marine organisms?
It is needed to form calcium carbonate structures.
What is calcification?
The production of calcium carbonate (CaCO₃).
How can ocean acidification affect corals and other marine organisms?
Reduced carbonate availability can reduce skeletal or shell-building rates.
When you eat pizza, the molecules in the pizza are broken down in your cells and carbon is released to the air in the form of carbon dioxide. This is an example of which theme?
Matter cycles between an organism and its environment.
Which of the following attributes is common to both prokaryotic cells and eukaryotic cells?
The use of DNA as the information-storage molecule.
Why doesn't a skin cell make crystallin protein? Select all that apply.
Skin cells do not need crystallin for their function; skin cells have the crystallin gene but do not express it.
Which of the following statements is true regarding evolution?
Evolution is a process of biological change in which species accumulate differences from their ancestors as they adapt to different environments over time.