Exam 1 Study Guide: The Scientific Method, Chemistry of Life, and Cell Biology

Flashcard practice set containing 200 question-and-answer pairs covering scientific method, organic chemistry, macromolecules, cell biology, membrane transport, and experimental design based on the lecture notes.

What is science as defined in the lecture notes?

A process of using observations and experiments to draw evidence-based conclusions that aims to explain the natural world.

What is a scientific claim?

Statements about how the world works that can be tested using the scientific method.

What is anecdotal evidence?

Unreliable evidence based on personal stories or individual experiences due to small sample sizes.

How many data points does one anecdote represent?

One anecdote equals $1$ data point.

What example of anecdotal evidence is given regarding COVID-19?

"My family and I all had the same first symptom when we contracted the virus that causes COVID-19: excessive sneezing"

What is the primary purpose of peer review in scientific research?

It ensures that other scientists have read and reviewed research before publication to weed out sloppy research.

What is a hypothesis?

An explanation for a scientific observation that must be testable.

Can a hypothesis ever be proven?

No, hypotheses can never be proven, only supported or unsupported by evidence.

What is an independent variable?

In an experiment, the variable that is deliberately changed or manipulated to test the hypothesis.

Which axis on a graph typically represents the independent variable?

The X-axis.

What is a dependent variable?

The variable that responds to changes in the independent variable and is measured or recorded by experimenters.

Which axis on a graph typically represents the dependent variable?

The Y-axis.

What is a controlled variable?

Aspects of an experiment that are kept identical across all samples.

What is an experimental group?

The subjects in an experiment that receive the treatment (the independent variable).

What is a control group?

A group that receives no treatment and acts as a baseline for comparison with the experimental group.

What is a placebo?

A treatment that mimics the experience of the experimental group (such as sugar pills) without containing the active treatment.

What does sample size measure, and how is it represented in science?

The number of subjects or repetitions in an experiment, represented by the letter $n$.

What does $n = 100$ mean in an experimental context?

It means the experiment had $100$ test subjects.

What is statistical significance?

The chance that the results are a "real effect" from the independent variable and not just due to chance.

What is a scientific theory?

A unified set of insights or hypotheses; a general set of principles supported by evidence that explains some aspect of nature.

Which five theories are listed as having overall scientific acceptance despite ongoing detail refinement?

Cell Theory, Germ Theory, Big Bang Theory, Evolutionary Theory, and Gravity.

What is correlation?

A consistent relationship between two variables, which does not prove that one variable causes another.

What is causation?

The relation of cause to effect.

What phrase do scientists frequently say regarding correlation?

Correlation does not imply causation!

What is epidemiology?

The study of the incidence of disease in a population.

What is a randomized clinical trial?

Research studies intended to find better ways to treat or prevent diseases and/or determine the safety and efficacy of new treatments or medicines used by humans.

What types of drugs are evaluated in randomized clinical trials?

Brand new drugs with no international health authority approval, or current drugs with improved formulas or new intended usages.

What is matter?

Anything that has mass and takes up space, made of one or more elements.

What is an element?

A pure substance that cannot be broken down any further and consists of only one sort of atom.

What is an atom?

The smallest unit of an element.

What is a proton?

A positively charged subatomic particle found in the nucleus, denoted by the atomic number.

What is a neutron?

A neutral subatomic particle found in the nucleus.

What atomic change creates isotopes of an element?

Changes in the number of neutrons.

What is an electron?

A negatively charged subatomic particle found in the electron cloud, important for bonding atoms together to make molecules.

What is an isotope?

Atoms with the same atomic number (number of protons) but a different number of neutrons, giving them a different mass number.

What is a molecule?

An arrangement of $2$ or more bonded atoms.

What is an organic molecule?

A molecule that has a carbon-based backbone and at least one $\text{C-H}$ bond.

What is an inorganic molecule?

Any molecule that does not have a carbon-based backbone or $\text{C-H}$ bonds, even if it contains carbon.

What is a monomer?

An individual subunit of a biomolecule ("mono-" = $1$).

What is a polymer?

A chain of monomers ("poly-" = many).

What are biological macromolecules?

Large organic molecules that make up living things, including Carbohydrates, Lipids, Proteins, and Nucleic Acids.

What are the monomer and polymer forms of carbohydrates?

Monomer = Monosaccharide; Polymer = Polysaccharide.

What are the primary functions of carbohydrates?

Energy storage (glucose, fructose, sucrose) and structural support (cellulose).

What elemental ratio is found in carbohydrates?

Carbohydrates contain $\text{C:H:O}$ in a ratio of $1:2:1$.

What alphabetical rule distinguishes monosaccharide examples from disaccharide examples in the notes?

Monosaccharides start with the first half of the alphabet (Fructose, Glucose, Galactose), while disaccharides start with the second half (Lactose, Maltose, Sucrose).

Which monosaccharides are listed as examples in the study guide?

Fructose, Glucose, and Galactose.

Which disaccharides are listed as examples in the study guide?

Lactose, Maltose, and Sucrose.

What suffix rule distinguishes polysaccharide examples from mono- and disaccharides?

None of the polysaccharide examples end in -ose.

What carbohydrate makes up plant cell walls?

Cellulose.

What is a protein?

Chains of covalently linked amino acids that fold into unique shapes to perform cellular functions.

Describe the "charm bracelet" analogy for proteins.

The 'chain' is made of covalently linked amino and carboxyl groups, while the 'charms' are side chains whose properties determine how the protein folds.

What key principle governs protein biological activity?

STRUCTURE DETERMINES FUNCTION.

What is an amino acid?

The subunit of a protein, consisting of an amino group and carboxyl group backbone with a variable side chain.

How many different amino acids exist?

There are $20$ different amino acids.

What are the monomer and main types of nucleic acids?

Monomer = nucleotide; Types = DNA and RNA.

What is the function of nucleic acids?

Stores genetic instructions for cells to follow.

What three components construct a nucleotide?

A sugar, a phosphate group, and a variable base.

Which nitrogenous bases are present in DNA versus RNA?

DNA uses Adenine (A), Cytosine (C), Guanine (G), and Thymine (T); RNA uses Adenine (A), Cytosine (C), Guanine (G), and Uracil (U).

Which component allows nucleotide sugars to link together into a backbone?

The phosphate group.

What does hydrophobic mean?

Does not mix with water ("hydro-" = water, "-phobic" = fearing).

What does hydrophilic mean?

Water-loving ("hydro-" = water, "-philic" = loving).

What four major classes of molecules are classified as lipids?

Fatty Acids, Sterols, Triglycerides, and Phospholipids.

Are lipids composed of linked identical or similar monomers?

No, lipids are not made of linked monomers like other macromolecules.

How does lipid energy storage compare to carbohydrate energy storage?

Lipids provide more stable storage but take longer to use than carbohydrates.

What does "saturated" mean regarding fatty acids?

Saturated means FULL—all Carbon atoms are full and cannot bond to any more Hydrogen atoms.

What is the molecular structure of a phospholipid?

A hydrophilic head containing a phosphate group and glycerol, attached to $2$ hydrophobic fatty acid tails.

What is a phospholipid bilayer?

A cell membrane component made of $2$ sheets of phospholipids with hydrophobic tails facing inward and hydrophilic heads facing outward.

What is a cell?

The basic unit of life.

What makes a water molecule polar?

One side of the molecule is more negative and the other is more positive, giving it positive and negative poles like a magnet.

What structural shape does a water molecule have?

It is V-shaped, with Oxygen (O) in the middle and Hydrogen ($\text{H}^+$) at the ends.

What is a hydrogen bond in water?

The attraction of the positive Hydrogen ($\text{H}^+$) in one water molecule to the negative Oxygen ($\text{O}^-$) end of another water molecule.

What is cohesion?

Water sticking to itself using hydrogen bonding.

What is adhesion?

Water sticking to other surfaces.

How do cohesion and adhesion benefit plant transport?

They allow water to flow upward from roots through plant stems.

What is specific heat?

The amount of heat that must be added to one unit of mass of a substance to cause an increase of one unit in temperature.

What is the biological importance of water having a high specific heat?

It is able to absorb a lot of energy before changing temperature.

What is a solution?

A mixture of a solute and a solvent.

What is a solute?

The substance that is dissolved into the solvent in a solution.

What is a solvent?

The substance in a solution that dissolves the solute.

What does pH measure?

The concentration of $\text{H}^+$ ions in a solution.

What defines an acid?

Low pH (below $7$) with many $\text{H}^+$ ions.

What defines a base?

High pH (above $7$) with more $\text{OH}^-$ ions than $\text{H}^+$ ions.

What is homeostasis?

A state of internal balance that your body works to maintain at all times.

What is a stimulus?

A detectable change (physical or chemical) from the external environment that causes functional activity in an organism.

What is a scatterplot best used for?

Visualizing correlation between $2$ factors using discrete (separate, unrelated) data points.

What is a line graph best used for?

Showing change in one or a few subjects over time.

What parameters are typically on the X-axis and Y-axis of a line graph?

Time is often the X-axis, while the Y-axis is the dependent variable responding to a treatment.

What is a bar graph best used for?

Showing frequencies in discrete categories that may otherwise be difficult to compare.

What is a pie chart best used for?

Representing percentages, or parts of a whole, where all pieces total $100\%$.

What are the three statements of Cell Theory?

All living things are made of cells; Cells are the basic unit of structure in organisms; All cells come from other cells.

What do the word roots of "prokaryotic" mean?

"Pro-" = before, "-kary" = nucleus.

Which two domains are prokaryotic?

Domains Archaea and Bacteria.

What does "eukaryotic" mean, and what organisms does it encompass?

"Eu" = True (true nucleus); encompasses all plants, animals, and fungi in domain Eukarya.

What memory phrase is given for eukaryotic cells?

"Eu" as You—"You"karyotic cells are the kind of cells you are made of!

What is the cell membrane?

A semipermeable plasma membrane made of a phospholipid bilayer and proteins that encapsulates the cell.

What is an organelle?

Membrane-bound structures within eukaryotic cells that perform specific functions.

What is cytoplasm?

The gelatinous aqueous interior of cells.

What is a ribosome and what is its function?

A complex of RNA and protein that functions in protein synthesis.

What stands for DNA and what is its role?

Deoxyribose Nucleic Acid; genetic instructions for the cell.

What is the function of the nucleus in eukaryotic cells?

Houses DNA and serves as the location for reactions that interpret DNA information.