Biology Exam 1 Study Guide: Characteristics, Chemistry, and Scientific Method

Characteristics of Life

The essential features that define living organisms, including homeostasis, secretion, and excretion.

Ecology

The branch of biology that studies the interactions between organisms and their environment.

Scientific Method

A systematic approach to research that involves making observations, forming hypotheses, conducting experiments, and drawing conclusions.

Control Group

The group in an experiment that does not receive the treatment and is used as a benchmark to measure how the other tested subjects do.

Independent Variable

The variable that is manipulated or changed in an experiment to test its effects on the dependent variable.

Dependent Variable

The variable that is measured or observed in an experiment, which is affected by changes in the independent variable.

Null Hypothesis

A statement that there is no effect or no difference, used as a starting point for statistical testing.

Replication in Experiments

The repetition of an experiment to ensure reliability and validity of the results.

Labeling a Graph

The process of adding titles, axes labels, and units of measure to a graph for clarity.

Atomic Number

The number of protons in the nucleus of an atom, which determines the element's identity.

Atomic Mass

The weighted average mass of an atom's isotopes, measured in atomic mass units (amu).

Isotopes

Variants of a chemical element that have the same number of protons but different numbers of neutrons.

Atomic Structure

The arrangement of protons, neutrons, and electrons in an atom, typically represented in a diagram.

Valence Electrons

Electrons in the outermost shell of an atom that are involved in chemical bonding.

Ionic Bond

A chemical bond formed through the transfer of electrons from one atom to another, resulting in charged ions.

Non-polar Covalent Bond

A type of chemical bond where two atoms share a pair of electrons equally.

Polar Covalent Bond

A type of chemical bond where two atoms share a pair of electrons unequally, leading to partial charges.

Polar Molecules

Molecules that have a partial positive charge on one side and a partial negative charge on the other, such as water (H2O).

Hydrogen Bonds

Weak attractions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Hydrophilic Molecules

Molecules that are attracted to water and can dissolve in it, typically polar substances.

Hydrophobic Molecules

Molecules that repel water and do not dissolve in it, typically nonpolar substances.

Properties of Water

Characteristics of water, such as cohesion, adhesion, and its solvent capabilities, that are due to hydrogen bonding.

pH

A measure of the acidity or basicity of a solution, based on the concentration of hydrogen ions (H+).

Acids and Bases

Substances that can donate protons (H+) are acids, while substances that can accept protons are bases.

Ocean Acidification

The decrease in pH of ocean water due to the absorption of excess atmospheric CO2, leading to increased H+ ion concentration.

Impact of H+ Ions

Increased H+ ions can react with carbonate ions (CO32-) in seawater, affecting marine organisms that rely on carbonate for shells.

Small Changes in Chemistry

Minor alterations in chemical composition can have significant biological impacts, affecting processes like digestion and tooth decay.

Homeostasis

The maintenance of internal conditions within boundaries in living organisms.

Secretion

The process of making and releasing a useful substance within a living organism.

Excretion

The process of eliminating and releasing a non-useful substance from a living organism.

Ecology

The study of interactions between organisms and their environment.

Independent Variable

The variable that you change or manipulate in an experiment.

Dependent Variable

The response or outcome that is measured in an experiment.

Control Group

A baseline for comparison in an experiment, which includes everything in the experimental group except the variable being tested.

Null Hypothesis

A baseline hypothesis stating that the experimental treatment will have no effect or cause no difference in the outcome.

Replication

Conducting an experiment through multiple trials or repetitions to increase reliability and reveal data patterns.

Isotopes

Atoms of the same element that have the same atomic number but different atomic masses due to varying numbers of neutrons.

Valence Electrons

Electrons located in the outermost shell of an atom, which possess the highest amount of energy.

First Shell Electrons

Electrons located in the innermost electron shell closest to the nucleus, which possess the least amount of energy.

Ionic Bond

A chemical bond formed when one or more electrons are transferred from one atom to another, resulting in charged ions such as $\text{Na}^+$ and $\text{Cl}^-$.

Non-polar Covalent Bond

A covalent bond formed when electrons are shared equally between atoms.

Polar Covalent Bond

A covalent bond formed when electrons are shared unequally between atoms, resulting in slight charges across the molecule.

Hydrogen Bond

A weak bond that holds separate polar molecules together, such as distinct $\text{H}_2\text{O}$ molecules or strands of DNA.

Hydrophilic Molecules

Polar molecules that readily interact with and dissolve in water.

Hydrophobic Molecules

Non-polar molecules that do not dissolve in water.

pH

A logarithmic measure of the concentration of $\text{H}^+$ ions in a solution.

Ocean Acidification

The lowering of ocean pH caused by increased atmospheric $\text{CO}_2$ dissolving into seawater, releasing $\text{H}^+$ ions that react with carbonate ($\text{CO}_3^{2-}$) ions.

Atomic Structure Diagram (H, He, C, Ne)

Diagram showing the arrangement of protons in the nucleus and electrons in surrounding shells for Hydrogen ($\text{H}$), Helium ($\text{He}$), Carbon ($\text{C}$), and Neon ($\text{Ne}$).

Carbon Dioxide Structure Diagram

Illustration showing the chemical bonding and valence electron sharing between Carbon and Oxygen atoms to form $\text{CO}_2$.

Venom Sac Weight Graph

Bar graph comparing venom sac weight in grams ($\text{g}$) for cottonmouth snakes exposed to L frog ($5\,\text{g}$), B frog ($7\,\text{g}$), and Nutria ($15\,\text{g}$).