BIO 101 Study Guide: Foundations of Biology (Chapters 1-3)

Chapter 1: The Study of Life

Attributes of Life

Living organisms share a set of fundamental characteristics that distinguish them from non-living matter.

• Order: Living things exhibit complex but ordered organization.

• Regulation: Organisms maintain stable internal conditions (homeostasis).

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

• Energy Processing: Living things acquire and use energy to power activities and chemical reactions.

• Response to Environment: Organisms respond to environmental stimuli.

• Reproduction: Organisms reproduce their own kind.

• Evolutionary Adaptation: Populations evolve over generations through adaptations that enhance survival and reproduction.

Example: A plant bends toward sunlight (response to environment), grows (growth), and produces seeds (reproduction).

Emergent Properties and Biological Hierarchy

Emergent properties arise when components interact at higher levels of organization, resulting in new characteristics not present at lower levels.

• Biological Hierarchy: Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

• Emergent Property Example: Life emerges at the cellular level, even though individual molecules are not alive.

Domains of Life

All living organisms are classified into three domains based on cell type and genetic characteristics.

• Bacteria: Prokaryotic cells (no nucleus)

• Archaea: Prokaryotic cells (distinct biochemistry from bacteria)

• Eukarya: Eukaryotic cells (with nucleus; includes plants, animals, fungi, protists)

Table: Domains and Cell Types

Domain	Cell Type
Bacteria	Prokaryotic
Archaea	Prokaryotic
Eukarya	Eukaryotic

Information Transfer in Biological Systems

Information in biological systems is stored, transmitted, and used to direct cellular activities, primarily through genetic material (DNA).

• Example: DNA → RNA → Protein (the central dogma of molecular biology)

Structure Determines Function

The shape and structure of biological molecules and organisms are closely related to their function.

• Example: The structure of red blood cells (biconcave shape) increases surface area for oxygen transport.

Interactions Within and Between Biological Systems

Organisms interact with each other and their environment, forming complex systems.

• Example: Bees pollinate flowers (mutualistic interaction).

Energy Flow and Matter Recycling in Ecosystems

Energy flows through ecosystems, while matter is recycled.

• Producers: (e.g., plants) convert solar energy into chemical energy via photosynthesis.

• Consumers: (e.g., animals) obtain energy by eating other organisms.

• Decomposers: (e.g., fungi, bacteria) break down dead matter, recycling nutrients.

• Ultimate Source of Energy: The Sun; energy eventually dissipates as heat.

Natural Selection and Evolution

Natural selection is the process by which individuals with advantageous traits survive and reproduce more successfully, leading to evolution over generations.

• Evolution: Change in the genetic composition of a population over time.

• Example: Antibiotic resistance in bacteria is a current example of evolution.

Chapter 2: The Chemical Context of Life

Phases of Matter

Matter exists in three primary phases:

• Solid

• Liquid

• Gas

Elements and Compounds

Elements are pure substances consisting of only one type of atom. Compounds are substances formed from two or more elements chemically combined in fixed ratios.

• Example: Water (H2O) is a compound; oxygen (O2) is an element.

Major Elements in the Human Body

The four most prevalent elements in the human body are:

• Oxygen (O)

• Carbon (C)

• Hydrogen (H)

• Nitrogen (N)

Trace Elements

Trace elements are required in minute amounts but are essential for health (e.g., iron, iodine).

• Example: Iodine is necessary for thyroid hormone production.

Atomic Structure, Atomic Number, and Mass Number

Atoms consist of protons, neutrons, and electrons.

• Atomic Number (Z): Number of protons; defines the element.

• Mass Number (A): Number of protons plus neutrons.

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

• Number of Electrons: In a neutral atom, equals the number of protons.

Subatomic Particle Defining an Element

The number of protons (atomic number) defines the identity of an element.

Isotopes

Isotopes are atoms of the same element with different numbers of neutrons.

• Example: Carbon-12, Carbon-13, and Carbon-14 are isotopes of carbon.

• Medical Application: Radioactive isotopes (e.g., iodine-131) are used in medical imaging and treatment.

Chemical Bonding and Subatomic Particles Involved

Chemical bonds form through interactions between electrons of atoms.

• Ionic Bonds: Transfer of electrons from one atom to another.

• Covalent Bonds: Sharing of electron pairs between atoms.

Formation of Ions

Ions are formed when atoms gain or lose electrons.

• Cation: Positively charged ion (loss of electrons).

• Anion: Negatively charged ion (gain of electrons).

Ionic, Polar Covalent, and Non-Polar Covalent Bonds

Bonds differ in how electrons are distributed between atoms.

• Ionic Bond: Complete transfer of electrons.

• Polar Covalent Bond: Unequal sharing of electrons (creates partial charges).

• Non-Polar Covalent Bond: Equal sharing of electrons.

Polar Covalent Bonds vs. Hydrogen Bonds

Polar covalent bonds occur within molecules, while hydrogen bonds are weak attractions between molecules or parts of molecules.

• Example: Water molecules are held together by hydrogen bonds, while the bonds within a water molecule are polar covalent.