Midterm (Chapter 1-7)

Chapter 1: Introduction to Biology

Biology and Society: A Passion for Life

Biology is the scientific study of life, driven by human curiosity about the natural world. Biological knowledge impacts health, environment, and society.

• Curiosity about Life: Humans have an inherent interest in living things and the environment.

• Relevance: Biological knowledge helps us make informed decisions about health, resources, and society.

The Scientific Study of Life

Science is a systematic approach to understanding the natural world through inquiry, observation, and evidence-based reasoning.

• Scientific Inquiry: Involves searching for information, evidence, and answers to specific questions.

• Natural Causation: Focuses on phenomena that can be observed and measured.

Exploration in Science

• Data: Recorded observations that serve as evidence for scientific inquiry.

• Discovery Science: Uses observations and data collection, which forms the basis for hypotheses and experiments.

Testing Hypotheses

• A hypothesis is a tentative, falsifiable explanation for a set of observations.

• Controlled Testing: Tests hypotheses under controlled conditions to gather reliable evidence.

Hypotheses, Theories, and Facts

• Theory: A comprehensive, well-substantiated explanation supported by extensive evidence.

• Fact: Objectively true information based on direct observation or measurement.

Controlled Experiments

• Experimental Groups: Groups that differ in only one variable to test hypotheses.

• Variables: Factors that change in an experiment.

• Independent Variable: Manipulated by researchers as a potential cause.

• Dependent Variable: Measured as the response of the system to the independent variable.

Blind and Double-Blind Studies

Type of Study	Test Subjects Know Which Group Is Which?	Researchers Know Which Group Is Which?
Not Blind	Yes	Yes
Single Blind	No	Yes
Double Blind	No	No

Evaluating Scientific Claims

• Pseudoscience: Falsely presented as scientific, often based on anecdotal evidence and lacking repeatability or peer review.

• Science: Adheres to established methods, produces repeatable results, and is open to external review.

Features of Science	Features of Pseudoscience
Adheres to scientific method	Does not adhere to accepted processes
Repeatable results	Results cannot be duplicated
Testable claims	Unprovable or unreliable claims
Open to outside review	Rejection of external review
Multiple lines of evidence	Observation as anecdotal evidence

The Properties of Life

• Order

• Cells

• Growth and Development

• Energy Processing

• Regulation

• Response to Environment

• Reproduction

• Evolution

Property	Description
Order	Highly organized structure
Cells	Basic unit of life
Growth and Development	Increase in size and change over time
Energy Processing	Use of energy to power activities
Regulation	Maintaining internal stability
Response to Environment	Reacting to stimuli
Reproduction	Producing new organisms
Evolution	Change over generations

Chapter 2: Essential Chemistry for Biology

Biology and Society: Nuclear Medicine

• Chemistry is fundamental to understanding biological processes, including the use of radioactivity in medicine.

• Radiation: Emission of high-energy particles that can damage DNA and kill cells.

• Radioactive Isotopes: Used in cancer treatment, where radiation targets specific body tissues.

• Example: PET scans use radioactive tracers to highlight tissues in organs.

Matter: Elements and Compounds

• Matter: Anything that occupies space and has mass.

• Elements: Substances that cannot be broken down by chemical means.

• Compounds: Substances of two or more elements joined by chemical bonds.

Atoms

• Atoms are the basic units of elements and consist of subatomic particles: protons, neutrons, and electrons.

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons.

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

Chemical Bonding and Molecules

• Ionic Bonds: Formed when atoms transfer electrons, becoming ions.

• Covalent Bonds: Formed when atoms share one or more pairs of electrons.

• Hydrogen Bonds: Weak electrical attractions between polar molecules, especially water.

Chemical Reactions

• Chemical reactions rearrange molecules but do not create or destroy matter.

• Reactants: Starting materials.

• Products: End materials.

Water and Life

• Water is essential for life and has unique properties due to its molecular structure and hydrogen bonding.

• Cohesion: Tendency of molecules to stick together.

• Surface Tension: Difficulty in stretching or breaking the surface of a liquid.

• Temperature Moderation: Water resists temperature changes due to hydrogen bonding.

• Ice Floats: Solid water is less dense than liquid water.

• Solvent of Life: Water dissolves many substances, forming aqueous solutions.

Acids, Bases, and pH

• Acid: Releases H+ ions into solution.

• Base: Accepts H+ ions and removes them from solution.

• pH Scale: Measures hydrogen ion concentration; lower pH is more acidic, higher pH is more basic.

• Buffer: Minimizes changes in pH.

Substance	pH Value
Battery acid	1
Lemon juice	2
Human blood	7.4
Household bleach	13

Key Equations

• Mass number = Number of Protons + Number of Neutrons

• Half-life calculation: $N_t = N_0 \times (1/2)^{t/t_{1/2}}$

Chapter 3: The Molecules of Life

Organic Compounds

• Organic compounds are molecules primarily composed of carbon atoms bonded with hydrogen, oxygen, and others.

• Carbon's ability to form large, complex, and diverse molecules is fundamental to life's functions.

Macromolecules and Polymers

• Macromolecules: Large molecules essential for life, including carbohydrates, proteins, lipids, and nucleic acids.

• Polymers: Built by linking smaller units called monomers.

Equation:

$\text{Monomer} + \text{Monomer} \rightarrow \text{Dehydration/Polymer} + H_2O$

Large Biological Molecules

• Carbohydrates: Sugars and polymers of sugars; main source of energy for most organisms.

• Lipids: Hydrophobic molecules; energy storage, insulation, and cell membranes.

• Proteins: Polymers of amino acids; structural support, catalysis, transport, and more.

• Nucleic Acids: Store genetic information (DNA, RNA).

Summary Table: Major Biological Macromolecules

Macromolecule	Monomer	Function
Carbohydrates	Monosaccharides	Energy, structure
Lipids	Fatty acids, glycerol	Energy storage, insulation
Proteins	Amino acids	Structure, catalysis, transport
Nucleic acids	Nucleotides	Genetic information

Chapter 4: A Tour of the Cell

Cell Theory and Cellular Diversity

• All living organisms are composed of cells, the basic units of life.

• Cells are classified as prokaryotic (no nucleus) or eukaryotic (nucleus and organelles).

The Two Major Categories of Cells

Prokaryotic Cells	Eukaryotic Cells
No nucleus, smaller, simpler	Nucleus, larger, more complex
Bacteria, Archaea	Plants, animals, fungi, protists

Cell Structure: Prokaryotic and Eukaryotic Cells

• Prokaryotic: Plasma membrane, cell wall, capsule, nucleoid, ribosomes, flagella.

• Eukaryotic: Plasma membrane, nucleus, organelles (ER, Golgi, mitochondria, etc.).

Membrane Structure

• The plasma membrane separates the living cell from its environment and is composed mainly of a phospholipid bilayer with embedded proteins.

Chapter 5: The Working Cell

Energy and Its Forms

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy due to position or structure.

ATP and Cellular Work

• ATP (adenosine triphosphate) is the primary energy carrier in cells.

• Energy is released when ATP is converted to ADP (adenosine diphosphate) and a phosphate group.

Equation:

$\text{ATP} \rightarrow \text{ADP} + P_i + \text{energy}$

Enzymes and Metabolism

• Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy.

• Enzyme inhibitors can block enzyme activity by binding to the active site or changing the enzyme's shape.

Membrane Structure and Function

• The plasma membrane regulates the flow of materials into and out of the cell.

• Transport can be passive (diffusion, facilitated diffusion) or active (requires energy).

Chapter 6: Cellular Respiration

Cellular Respiration: Obtaining Energy from Food

• Cellular respiration is the process by which living organisms extract energy from food molecules, primarily glucose, to produce ATP.

• It involves glycolysis, the citric acid cycle, and electron transport.

Overall equation:

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

Main Stages

1. Glycolysis: Occurs in the cytoplasm; splits glucose into pyruvic acid, producing ATP and NADH.

2. The Citric Acid Cycle: Occurs in mitochondria; completes the breakdown of glucose, producing CO2, NADH, FADH2, and ATP.

3. Electron Transport: Uses NADH and FADH2 to generate ATP via oxidative phosphorylation.

Fermentation

• Anaerobic process of harvesting energy from food without oxygen, producing less ATP.

• Produces lactic acid in muscles or ethanol in yeast.

Chapter 7: Photosynthesis

Photosynthesis: Using Light to Make Food

• Photosynthesis is the process by which plants, algae, and some bacteria convert solar energy into chemical energy, producing glucose and oxygen from CO2 and water.

Equation:

$6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$

Chloroplasts: Sites of Photosynthesis

• Chloroplasts contain chlorophyll, which captures light energy for photosynthesis.

• Photosynthesis occurs in two stages: the light reactions (in thylakoids) and the Calvin cycle (in stroma).

The Light Reactions

• Convert solar energy to chemical energy (ATP and NADPH).

• Release oxygen as a byproduct.

The Calvin Cycle

• Uses ATP and NADPH to convert CO2 into glucose.

Summary Table: Key Components of Photosynthesis

Component	Function
Chlorophyll	Site of photosynthesis
Thylakoid	Location of light reactions
Stroma	Location of Calvin cycle
Photosystem	Light gathering antenna
ATP & NADPH	Energy carriers for Calvin cycle
G3P	Product of Calvin cycle, precursor to glucose