General Biology: Foundations, Classification, Chemistry, and Water

Introduction to Biology

What is Biology?

Biology is the scientific study of living organisms and life processes. It encompasses the structure, function, growth, origin, evolution, and distribution of living things.

• Definition: The study of living organisms (life).

• Example: Investigating how plants convert sunlight into energy through photosynthesis.

Homeostasis

Homeostasis is the ability of an organism to maintain a stable internal environment despite changes in external conditions.

• Key Point: Organisms regulate factors such as temperature, pH, and water balance to survive.

• Example: Humans sweat to cool down when body temperature rises.

Cell Theory

Cell theory is a fundamental concept in biology stating that all living things are composed of cells, and all cells arise from pre-existing cells.

• Key Point: The cell is the basic unit of life.

• Example: Bacteria, plants, and animals are all made up of cells.

Biological Classification

Taxonomic Hierarchy

Organisms are classified into a hierarchical system to show relationships and evolutionary history. The main ranks are Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

• Mnemonic: "Dear King Philip Came Over For Good Soup" helps remember the order.

Rank	Example for Humans
Domain	Eukaryota (organisms with a nucleus in their cells)
Kingdom	Animalia (animals)
Phylum	Chordata (animals with a spinal cord)
Class	Mammalia (mammals)
Order	Primates (primates)
Family	Hominidae (great apes and humans)
Genus	Homo (modern and extinct humans)
Species	Homo sapiens

Domains and Kingdoms

• Three Domains: Bacteria, Archaea, Eukarya

• Four Kingdoms in Eukarya: Protists, Fungi, Plantae, Animalia

Characteristics of Life

Traits of Living Things

To be considered living, an entity must possess all of the following traits:

• Regulation

• Energy processing

• Reproduction

• Response to environment

• Growth and development

• Evolution

• Cells

Mnemonic: ROGERRCE (Regulation, Organization, Growth, Energy, Response, Reproduction, Cells, Evolution)

Themes in Biology

• Structure and function

• Information flow

• Energy transformations

• Interactions within systems

The Scientific Method

Definition and Steps

The scientific method is a systematic process scientists use to acquire knowledge and understand the natural world through observation, experimentation, and the creation of testable explanations (theories).

1. Ask a question

2. Form a hypothesis

3. Test the hypothesis (experiment)

4. Analyze data

5. Draw conclusions

Hypothesis vs. Prediction vs. Control

• Hypothesis: A testable, educated guess about the outcome of an experiment or observation.

• Prediction: A specific, expected outcome based on the hypothesis.

• Control: A standard for comparison in an experiment, kept constant to isolate the effect of the variable being tested.

Qualities of a Good Hypothesis

• Testable and falsifiable

• Clear and specific

• Predictive

• Grounded in research

• Concise and empirical

Theory

A theory is a well-tested, comprehensive explanation for a broad range of observations, supported by a large body of evidence.

Evaluating Science

• Testable and falsifiable

• Relies on evidence

• Systematic and community-based

• Objective and self-correcting

Basic Chemistry for Biology

Atoms and Elements

• Atom: The smallest unit of matter that retains the properties of an element.

• Element: A substance that cannot be broken down into other substances by chemical means.

Subatomic Particles

Particle	Charge	Mass (amu)	Location
Proton	+1	1	Nucleus
Neutron	0	1	Nucleus
Electron	-1	~0	Electron cloud

Ions and Isotopes

• Ion: An atom or molecule with a net electric charge due to the loss or gain of electrons.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Radioactive Isotope: An unstable isotope that releases energy as it decays.

Atomic Number and Mass Number

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons in the nucleus.

Electron Shells

• First shell: up to 2 electrons

• Second shell: up to 8 electrons

• Third shell: up to 18 electrons

Types of Chemical Bonds

• Ionic Bond: Transfer of electrons from one atom to another, resulting in oppositely charged ions.

• Covalent Bond: Sharing of electron pairs between atoms.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

Water and Its Properties

Importance of Water Chemistry

Water's unique properties make it essential for life. Its polarity and hydrogen bonding contribute to its behavior as a solvent and its role in biological processes.

Properties of Water

• High heat of vaporization

• High specific heat

• Solvent abilities

• Cohesion and adhesion

• Density (ice is less dense than liquid water)

Hydrogen Bonding

Hydrogen bonds form between water molecules, leading to high cohesion, surface tension, and the ability to dissolve many substances.

Acids, Bases, and pH

• Acid: A substance that increases the hydrogen ion concentration in a solution (pH < 7).

• Base: A substance that reduces the hydrogen ion concentration (pH > 7).

• pH Scale: Measures how acidic or basic a solution is, ranging from 0 (most acidic) to 14 (most basic).

Solutions and Solvents

• Solution: A homogeneous mixture of two or more substances.

• Solvent: The dissolving agent (e.g., water).

• Solute: The substance being dissolved.

Additional Key Terms

• Trace Element: Chemical elements required by living organisms in minute quantities for essential physiological functions (e.g., iron, iodine).

• Reactant: A substance that enters into and is changed during a chemical reaction.

• Product: A substance formed as a result of a chemical reaction.