Chapter 1: Introduction to Biology and Scientific Inquiry

Definition and Scope of Biology

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

• Science: A systematic approach to understanding the natural world through observation and experimentation.

• Biology: The branch of science focused on living things.

Experimental Design in Biology

Scientific experiments are structured to test hypotheses and draw conclusions about biological phenomena.

• Hypothesis: A testable statement or prediction about a natural phenomenon.

• Control: A standard for comparison in experiments, not exposed to the experimental variable.

The Scientific Method

The scientific method is a logical process used to investigate questions and test hypotheses.

• Steps include:

  1. Observation

  2. Question

  3. Hypothesis

  4. Prediction

  5. Experiment

  6. Analysis

  7. Conclusion

• Ability to recognize hypothesis, prediction, control, or observation in examples.

Properties of Life

Living organisms share several key characteristics:

• Order and organization

• Response to stimuli

• Reproduction

• Growth and development

• Regulation (homeostasis)

• Energy processing

• Evolutionary adaptation

Pseudoscience

Pseudoscience refers to beliefs or practices mistakenly regarded as being based on the scientific method.

• Recognize signs of pseudoscientific studies (lack of peer review, untestable claims, etc.).

Chapter 2: Chemistry of Life

Trace Elements

Trace elements are required by organisms in minute quantities but are essential for proper physiological functioning.

• Examples: Iron (Fe), Iodine (I), Zinc (Zn)

Atomic Structure

Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

• Protons: Positively charged particles in the nucleus.

• Neutrons: Neutral particles in the nucleus.

• Electrons: Negatively charged particles orbiting the nucleus.

• Atomic number: Number of protons in an atom.

• Mass number: Sum of protons and neutrons.

• Atoms are neutral when protons = electrons.

• Atoms with unequal protons and electrons are called ions (positive: cations, negative: anions).

Electron Arrangement and Valence

Electrons are arranged in shells around the nucleus. The outermost shell is called the valence shell.

• Atoms are most stable when their valence shell is full (octet rule: 8 electrons for most atoms).

Compounds, Elements, and Isotopes

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

• Compound: A substance formed from two or more elements chemically combined in fixed ratios.

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

Chemical Bonds

Atoms form bonds to achieve stable electron configurations.

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

• Covalent bonds: Sharing of electron pairs between atoms.

• Polar covalent bonds: Unequal sharing of electrons, resulting in partial charges.

• Nonpolar covalent bonds: Equal sharing of electrons.

Water and Its Properties

Water is a polar molecule, giving it unique properties essential for life.

• Polarity: Oxygen is more electronegative, creating partial charges.

• Hydrogen bonding: Weak bonds between water molecules, leading to cohesion and surface tension.

• Allows small insects to walk on water (surface tension).

• Ice floats because it is less dense than liquid water.

Solutions, Solvents, and Solutes

• Solution: Homogeneous mixture of two or more substances.

• Solvent: Substance that dissolves another (water is the universal solvent).

• Solute: Substance being dissolved.

Acids, Bases, and pH

• Acid: Substance that increases hydrogen ion (H+) concentration.

• Base: Substance that decreases H+ concentration (or increases OH-).

• pH: Measure of H+ concentration;

• Buffer: Substance that minimizes changes in pH.

Conservation of Matter

• Matter is neither created nor destroyed in chemical reactions.

• Reactants are transformed into products.

Chapter 3: Biological Molecules

Carbon and Molecular Diversity

Carbon's ability to form four covalent bonds makes it the backbone of organic molecules.

• Can form single, double, or triple bonds.

• Forms chains, rings, and complex structures.

Dehydration and Hydrolysis

• Dehydration: Removal of water to form a bond between monomers (polymerization).

• Hydrolysis: Addition of water to break a bond (depolymerization).

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• Carbohydrates are used for energy storage and structural support.

Lipids

• Saturated fats: No double bonds between carbon atoms; solid at room temperature.

• Unsaturated fats: One or more double bonds; liquid at room temperature.

• Steroids: Lipids with four fused rings (e.g., cholesterol, estrogen, testosterone).

• Hydrophobic: Repels water; Hydrophilic: Attracts water.

Proteins

• Monomer: Amino acid

• Polymer: Polypeptide or protein

• Proteins perform structural, enzymatic, and regulatory functions.

Nucleic Acids

• Monomer: Nucleotide

• Polymer: DNA or RNA

• DNA is double stranded; RNA is single stranded.

• DNA contains thymine; RNA contains uracil.

• Double helix: Structure of DNA with complementary base pairing.

• Base pairs: Adenine (A) pairs with Thymine (T), Cytosine (C) pairs with Guanine (G).

Isomers

• Isomers are molecules with the same molecular formula but different structures and properties.

Summary Table: Types of Biological Molecules