General Biology: Foundational Concepts and Atomic Structure Study Guide

Scientific Method and Experimental Design

Formulating Hypotheses and Scientific Arguments

The scientific method is a systematic approach used in biology to investigate phenomena, acquire new knowledge, or correct and integrate previous knowledge. It involves making observations, forming hypotheses, conducting experiments, and drawing conclusions.

• Hypothesis: A testable and falsifiable statement that explains an observation or answers a scientific question.

• Testable: The hypothesis can be evaluated through experimentation or observation.

• Falsifiable: There must be a possible outcome that could show the hypothesis is incorrect.

• Scientific Argument: Consists of three parts: claim, evidence, and reasoning.

Example: "If plants are given more sunlight, then they will grow taller." This is testable and falsifiable.

• Inductive Reasoning: Drawing general conclusions from specific observations.

• Deductive Reasoning: Making specific predictions based on general principles or premises.

Scientific Argument Structure:

• Claim: Statement or conclusion.

• Evidence: Data or observations supporting the claim.

• Reasoning: Explanation connecting the evidence to the claim.

Biology Themes and Feedback Mechanisms

Major Themes in Biology

Biology is the study of living organisms and their interactions with the environment. Major themes include:

• Evolution: The process by which species change over time.

• Structure and Function: How the shape of something relates to its purpose.

• Information Flow: How genetic information is stored, transmitted, and expressed.

• Energy and Matter Pathways: How organisms obtain and use energy and matter.

• Systems: How different parts of organisms interact as a whole.

Feedback Mechanisms

• Positive Feedback: A process that amplifies a change or signal. Example: Blood clotting, where each step accelerates the next.

• Negative Feedback: A process that reduces or counteracts a change, maintaining homeostasis. Example: Regulation of body temperature.

Biology as a Science

• Core of Biology: The study of life and living organisms, including their structure, function, growth, evolution, and interactions.

Adaptation, Acclimation, and Atomic Structure

Adaptation vs. Acclimation

• Adaptation: Genetic changes in a population over generations that enhance survival and reproduction.

• Acclimation: Short-term physiological changes in an individual in response to environmental changes.

Atomic Structure

Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

• Protons: Positively charged particles in the nucleus.

• Neutrons: Neutral particles in the nucleus.

• Electrons: Negatively charged particles orbiting the nucleus.

Atomic Number: Number of protons in an atom.

Mass Number: Sum of protons and neutrons.

Determining Subatomic Particles:

• Number of protons = atomic number

• Number of neutrons = mass number - atomic number

• Number of electrons = number of protons (in a neutral atom)

Charge of an Atom: Determined by the difference between the number of protons and electrons.

Chemical Bonds and Molecular Properties

Types of Chemical Bonds

• Covalent Bonds: Atoms share electrons. Example: H2O (water)

• Ionic Bonds: Atoms transfer electrons, resulting in charged ions. Example: NaCl (table salt)

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (often oxygen or nitrogen).

Polarity and Water Properties

• Polar Molecules: Have regions of partial positive and negative charge due to unequal sharing of electrons. Example: Water (H2O)

• Nonpolar Molecules: Electrons are shared equally; no distinct charge regions.

Water's Emergent Properties:

• Cohesion: Water molecules stick to each other.

• Adhesion: Water molecules stick to other surfaces.

• Surface Tension: Water's surface resists external force.

• High Specific Heat: Water absorbs heat without a large temperature change.

• Solvent Abilities: Water dissolves many substances due to its polarity.

Importance: These properties are vital for biological processes such as nutrient transport and temperature regulation.

Hydrogen Bonds and Water Interactions

• Hydrogen Bonds: Responsible for water's unique properties.

• Gecko Adhesion: Geckos use van der Waals forces to cling to surfaces, not hydrogen bonds.

Valence Electrons and Reactivity

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom and determine chemical reactivity.

• First shell: up to 2 electrons

• Second and third shells: up to 8 electrons each

Example: Oxygen has 6 valence electrons; needs 2 more to fill its shell.

Reactivity Determination

• Atoms with incomplete valence shells are more reactive.

• Atoms tend to gain, lose, or share electrons to achieve a full valence shell.

Polarity and Solubility

Polarity and Dissolving Ability

• Polarity: Molecules with uneven charge distribution are polar and dissolve well in water.

• Nonpolar Molecules: Do not dissolve easily in water.

Example: Salt (NaCl) dissolves in water due to ionic and polar interactions.

Polarity and Solubility: The more polar a molecule, the more likely it is to dissolve in water.

Summary Table: Types of Chemical Bonds

Bond Type	Description	Example
Covalent	Atoms share electrons	H2O, O2
Ionic	Atoms transfer electrons	NaCl
Hydrogen	Weak attraction between H and electronegative atom	Between water molecules

Key Equations

• Number of neutrons: $\text{Neutrons} = \text{Mass Number} - \text{Atomic Number}$

• Number of electrons (neutral atom): $\text{Electrons} = \text{Atomic Number}$

Additional info: Some context and examples have been inferred to ensure completeness and clarity for exam preparation.