Biology Chapter 2: Sampling and Scientific Methods

Sampling and Scientific Approach

• Results from subsets may not represent the whole population, leading to inaccuracies.
• Random sampling and larger sample sizes enhance reliability and accuracy of scientific findings.
• Pseudoscience lacks empirical support and often cannot be tested through scientific methods.

Natural Science vs Pseudoscience

• Natural Science: Based on observation, experimentation, and the scientific method (e.g. Biology, Chemistry).
• Pseudoscience: Lacks adherence to scientific methods; examples include astrology and conspiracy theories like vaccines causing autism.

Key Terms in Biology (Chapter 2)

• Acid: Substance that can donate protons in a solution.
• ATP (Adenosine Triphosphate): Key energy carrier in cells.
• Carbohydrates: Composed of monosaccharides (e.g., glucose); provide energy and structural support.
• Lipids: Diverse group including triglycerides; key in cell membranes (phospholipid bilayer).
• Proteins: Made of amino acids; function through their structure.
• Nucleic Acids: DNA and RNA, crucial for genetic information storage and transmission.

Subatomic Particles and Their Charges

• Protons: Positively charged particles in the nucleus.
• Neutrons: Neutral particles in the nucleus.
• Electrons: Negatively charged particles surrounding the nucleus.
• A neutral atom has equal numbers of protons and electrons; positive charge indicates a loss of electrons, negative charge indicates a gain.

Chemical Bonds

• Chemical bonds connect atoms to form molecules, primarily including ionic, covalent, and hydrogen bonds.
• Buffers help maintain pH balance by absorbing excess H+ or OH- ions.

pH and Its Importance

• pH Scale: Ranges from 0 (acidic) to 14 (basic), with 7 being neutral.
• Acidic solutions have high H+ concentrations, while basic solutions have more hydroxide ions.

Organic Molecules

• Carbohydrates: Structural and energy roles; polysaccharides include glycogen (energy storage) and cellulose (structure in plants).
• Lipids: Composed of fatty acids; saturated fats have no double bonds while unsaturated fats have one or more double bonds.
• Proteins: Function through specific amino acid sequences; enzymes speed up biochemical reactions.
• Nucleic Acids: Nucleotides form the building blocks; essential for storing and processing genetic information.

Cell Theory

• All organisms consist of one or more cells, which are the basic units of life.
• Cells arise from pre-existing cells and pass hereditary material to offspring.

Cellular Structures and Functions

• Nucleus: Stores genetic information; site of DNA replication.
• Mitochondria: Produces ATP via aerobic respiration.
• Ribosomes: Sites of protein synthesis; can be free-floating or attached to the Rough Endoplasmic Reticulum.
• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; Smooth ER synthesizes lipids and detoxifies substances.
• Lysosomes: Digestive organelles that break down waste material.

Transport Mechanisms

• Passive Transport: No energy required; moves molecules down their concentration gradient (e.g., diffusion, osmosis).
• Active Transport: Requires energy to move molecules against their concentration gradient.

Solutions and Concentrations

• Hypertonic Solution: Higher solute concentration outside the cell; causes water to exit cells leading to shrinkage.
• Hypotonic Solution: Lower solute concentration outside the cell; causes water to enter cells, potentially leading to swelling or rupture.

Enzyme Functionality

• Enzymes catalyze biochemical reactions, affected by temperature, pH, and ion concentrations.
• Proper enzyme function is essential for maintaining metabolic pathways.