Chapter 1: Foundations of Biology

What is Science?

Science is a systematic approach to understanding the natural world through observation, experimentation, and reasoning. It relies on evidence and the scientific method to build knowledge.

• Definition: Science is the pursuit of knowledge about the natural world based on facts learned through experiments and observation.

• Key Features: Empirical evidence, repeatability, skepticism, and peer review.

• Example: Studying how plants grow under different light conditions.

What is Biology?

Biology is the scientific study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy.

• Key Areas: Cell biology, genetics, evolution, ecology, physiology, and anatomy.

• Example: Investigating how bacteria develop resistance to antibiotics.

The Scientific Method

The scientific method is a logical process used to investigate questions and test hypotheses about the natural world.

• Steps: Observations → Questions → Hypotheses → Experiments → Conclusions

• Hypothesis: A testable and falsifiable statement that explains observations.

• Testing: Experiments are designed to support or refute hypotheses.

• Provisional Nature: Scientific assertions are always open to revision with new evidence.

• Example: Testing whether plants grow faster with fertilizer.

Truth in Science

Scientific knowledge is provisional and subject to change as new evidence emerges. "Truth" in science means the best explanation based on current evidence.

• Scientific Theory: A well-substantiated explanation of some aspect of the natural world, based on a body of evidence.

• Common Speech vs. Scientific Theory: In science, a theory is not a guess but a comprehensive explanation.

Correlation vs. Causation

Correlation is when two variables are related, but it does not imply that one causes the other. Causation means one event is the result of the occurrence of the other event.

• Example: Ice cream sales and drowning rates both increase in summer (correlated, but not causally related).

Chapter 2: Chemistry of Life

Characteristics of Life

Living organisms share common characteristics such as organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and evolution.

• Example: All living things are made of cells and use energy.

Basic Chemistry Concepts

• Element: A pure substance consisting of one type of atom.

• Atom: The smallest unit of an element, composed of protons, neutrons, and electrons.

• Molecule: Two or more atoms bonded together.

• Compound: A substance made of atoms of different elements bonded together.

Atomic Structure

• Subatomic Particles: Protons (+), neutrons (neutral), electrons (-).

• Electron Shells: Electrons occupy energy levels around the nucleus.

• Stability: Atoms are most stable when their outer electron shell is full.

Chemical Bonds

• Covalent Bonds: Sharing of electrons between atoms.

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

• Hydrogen Bonds: Weak bonds between polar molecules, important in water and DNA structure.

• Relative Strength: Covalent > Ionic > Hydrogen bonds.

Water and Its Properties

• Cohesion: Water molecules stick together due to hydrogen bonding.

• Solvent of Life: Water dissolves many substances, facilitating chemical reactions.

• Heat Capacity: Water absorbs and retains heat, stabilizing temperatures.

• pH Scale: Measures acidity or alkalinity;

Organic Molecules

• Carbohydrates: Sugars and starches; energy source and structural components.

• Proteins: Made of amino acids; function as enzymes, structural elements, and more.

• Lipids: Fats, oils, steroids, phospholipids; energy storage and membrane structure.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Macromolecules Table

Cell Theory and Types of Cells

• Cell Theory: All organisms are made of cells; the cell is the fundamental unit of life.

• Unicellular vs. Multicellular: Single-celled vs. many-celled organisms.

• Prokaryotic vs. Eukaryotic: Prokaryotes lack a nucleus; eukaryotes have a nucleus and organelles.

Chapter 3: Nutrients and Cells

Nutrients

• Macronutrients: Needed in large amounts (water, carbohydrates, proteins, fats).

• Micronutrients: Needed in small amounts (vitamins, minerals, antioxidants).

• Essential Nutrients: Cannot be synthesized by the body; must be obtained from diet.

• Whole Foods vs. Processed Foods: Whole foods are less processed and retain more nutrients.

Macronutrients Table

Cell Structure and Function

• Animal Cell Organelles: Nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, cytoskeleton.

• Plant Cell Organelles: All of the above plus chloroplasts, central vacuole, cell wall.

• Prokaryotic Cells: Lack membrane-bound organelles; have a plasma membrane, cytoplasm, ribosomes, and DNA.

Transport Across Membranes

• Passive Transport: No energy required; includes diffusion, facilitated diffusion, and osmosis.

• Active Transport: Requires energy (ATP); moves substances against a concentration gradient.

• Osmosis: Movement of water across a semipermeable membrane.

• Solutions:

  • Hypotonic: Lower solute concentration outside; cell swells.

  • Hypertonic: Higher solute concentration outside; the cell shrinks.

  • Isotonic: Equal solute concentration; no net movement.

• Bulk Transport: Endocytosis (into cell), exocytosis (out of cell).

Chapter 4: Metabolism and Energy

Enzymes and Metabolism

• Enzymes: Biological catalysts that speed up chemical reactions by lowering activation energy.

• Induced Fit Model: Enzyme changes shape to fit the substrate.

• Specificity: Each enzyme acts on a specific substrate.

• Energy Requirement: Enzymes need energy to function.

Energy in Cells

• ATP (Adenosine Triphosphate): The main energy currency of the cell.

• Calorie: Unit of energy; amount of energy needed to raise the temperature of 1 gram of water by 1°C.

• Basal Metabolic Rate (BMR): The rate at which the body uses energy at rest.

Cellular Respiration

• Purpose: To convert biochemical energy from nutrients into ATP.

• Stages:

  1. Glycolysis (cytoplasm, does not require oxygen)

  2. Krebs Cycle (mitochondria, requires oxygen)

  3. Electron Transport Chain (mitochondria, requires oxygen)

• NAD+/NADH: Electron carriers involved in redox reactions.

• ATP Yield: Most ATP is produced in the electron transport chain.

Fermentation

• Definition: Anaerobic process that allows ATP production without oxygen.

• Types: Lactic acid fermentation (in muscles), alcoholic fermentation (in yeast).

Macromolecules and Energy

• Proteins and Fats: Can be used for energy if carbohydrates are not available.

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard General Biology curriculum.