Science: Hypothesis, Theory, and Law

• Science explores the natural world through observation, experimentation, evidence, and logic.
• Scientists study plant growth under different conditions for photosynthesis research.
• Researchers test medicines to check their effectiveness against diseases.
• Science uses data to develop hypotheses, theories, and laws.

Hypothesis

• A hypothesis is an educated guess.
• Example: "Plants grow faster with more sunlight."

Theory

• A theory explains why something happens.
• Example: the Theory of Evolution explains species adaptation.

Law

• A law describes what happens.
• Example: Newton's Law of Gravity describes how objects fall.

Science vs. Pseudoscience

• Science relies on evidence, repeatable experiments, and testable hypotheses.
• The Germ Theory of Disease explains how bacteria and viruses cause illnesses.
• Climate change science uses data from temperature records, ice cores, and atmospheric measurements.
• Pseudoscience lacks evidence and cannot be tested.
• Astrology claims star positions affect personality, but it cannot be proven scientifically.
• Crystal healing lacks empirical support for its health claims.

Scientific Questions

• Science answers questions about observable and measurable phenomena.
• Examples of questions it answers include "How do vaccines work?" and "What causes earthquakes?".
• Science does not answer questions about opinions or beliefs, such as "What is the meaning of life?" or "Is this painting beautiful?".

Scientific Method

• Ask a question, such as "Why does my plant wilt?"
• Conduct background research like "Plants need water and sunlight to survive".
• Form a hypothesis: The plant wilts because it isn't getting enough water.
• Test the hypothesis by watering one plant daily and leaving another unwatered.
• Analyze results: Compare the watered plant, which stays healthy, to the unwatered one, which wilts.
• Draw a conclusion: Plants need water to survive.

Laws vs. Theories

• Laws describe what happens in nature, such as Newton's Laws of Motion.
• Theories explain why phenomena occur, such as the Theory of Plate Tectonics.
• Both are supported by evidence but serve different purposes.

Biological Macromolecules

• Macromolecules are essential for life because they perform critical functions.
• Carbohydrates provide quick energy (e.g., glucose in fruits).
• Lipids store long-term energy and form cell membranes (e.g., fats in butter).
• Proteins build muscles, transport oxygen, and act as enzymes (e.g., hemoglobin in blood).
• Nucleic acids store genetic information (DNA and RNA).

Macromolecule Structures and Functions

• Carbohydrates consist of carbon, hydrogen, and oxygen in ring shapes, providing quick energy. Examples: Glucose, starch.
• Lipids have long hydrocarbon chains, storing energy and forming cell membranes. Examples: Fats, oils.
• Proteins are chains of amino acids that build tissues and act as enzymes. Examples: Meat, beans.
• Nucleic Acids are nucleotides with a sugar-phosphate base, storing genetic information. Examples: DNA, RNA.

Enzymes

• Enzymes are proteins that speed up chemical reactions by lowering activation energy.
• For example, amylase in saliva breaks down starch into sugar during digestion.
• Enzymes are specific to their substrates (like a lock and key) and work best under specific conditions such as body temperature or neutral pH.

Importance of Carbon

• Carbon can form four covalent bonds with other atoms, creating complex molecules
• Carbon forms structure such as chains, rings, or branches.
• This it the backbone of all macromolecules.

Macromolecule Structure

• Carbohydrates: Simple sugars like glucose link to form starches, storing energy.
• Lipids: Fatty acids form triglycerides for long-term energy storage and phospholipids for cell membranes.
• Proteins: Amino acids fold into shapes to perform tasks, like building tissues or acting as enzymes.

Chemical Formulas

• Carbohydrates: Cn(H2O)n, e.g., glucose is C6H12O6
• Lipids: Long hydrocarbon chains with few oxygen atoms.
• Proteins: Contain nitrogen-carbon-carbon backbones from amino acids.

Early Earth

• Billions of years ago, Earth's atmosphere was very different: no oxygen was present.
• Gases like methane, ammonia, hydrogen, and water vapor dominated.
• The surface was hot due to volcanic activity and constant meteor impacts.

Origin of Life Theories

• Oparin-Haldane Hypothesis: Organic molecules formed from simple gases when exposed to lightning or UV radiation.
• The Miller-Urey experiment simulated early Earth conditions and produced amino acids.
• RNA World Hypothesis: RNA was likely the first molecule capable of self-replication and storing genetic information.

Organic Compounds

• Organic compounds like amino acids combined to form nucleotides
• They eventually created RNA/DNA, the molecules that store genetic information.

Early Cells

• Early cells (protocells) were simple structures capable of basic metabolism and replication.
• Photosynthetic cells evolved later and released oxygen into the atmosphere.
• This allowed more complex life forms to develop over time.

Science explores the natural world using observation, experimentation and evidence. A hypothesis is an educated guess, while a theory explains phenomena. A law describes what happens, and science differs from pseudoscience with its reliance on evidence and testable hypotheses.