Atomic Structure and Hypotheses Quiz

Scientific Hypotheses

• A scientific hypothesis is an explanation for an observation, phenomenon, or problem.
• It must be testable and falsifiable (capable of being proven false).
• Example: The hypothesis "all swans are white" is falsifiable (provable false) because observing a black swan would disprove it.

Atomic Structure

• Atomic Number: The number of protons in an atom's nucleus. This determines the element.
• Atomic Mass Number: The total number of protons and neutrons in the nucleus.
• Electrons: Negatively charged particles orbiting the nucleus in specific energy levels (shells).
• Protons: Positively charged particles in the nucleus.
• Neutrons: Neutral particles in the nucleus.

Electron Energy Levels and Valence Electrons

• Electron Energy Levels: Electrons occupy specific energy levels around the nucleus; first shell holds 2 electrons, second 8 etc.
• Valence Electrons: Electrons in the outermost shell, determining chemical reactivity.

Chemical Bonds

• Covalent Bonds: Atoms share valence electrons to achieve a more stable configuration.
• Ionic Bonds: One atom donates electrons to another, forming oppositely charged ions that attract.
• Hydrogen Bonds: Weak attraction between a hydrogen atom and a highly electronegative atom (like oxygen or nitrogen).
• Van der Waals Forces: Weak attractions between molecules due to temporary electron fluctuations.

Hydrophobic and Hydrophilic Molecules

• Hydrophobic: Molecules that do not interact well with water (typically nonpolar, like fats and oils).
• Hydrophilic: Molecules that interact readily with water (typically polar, like sugars and ions).
• Lipophilic: Molecules that interact readily with fats and oils (typically synonymous with hydrophobic).

Macromolecules

• Macromolecules are large polymers assembled from smaller repeating monomers.
• Carbohydrates: Monosaccharides, serving as energy sources and structural components (cellulose).
• Proteins: Amino acids, with diverse functions including catalysis (enzymes), structure, transport, and regulation.
• Nucleic Acids: Nucleotides, storing and transmitting genetic information (DNA and RNA).
• Lipids: Fats, phospholipids, and steroids, serving as energy stores, structural components, and signaling molecules.

Storage vs. Structural Polysaccharides

• Storage Polysaccharides: Store energy (starch in plants, glycogen in animals).
• Structural Polysaccharides: Provide structural support (cellulose in plant cell walls, chitin in exoskeletons).

Protein Structure

• Primary Structure: Linear sequence of amino acids.
• Secondary Structure: Localized folding or coiling (alpha helices, beta pleated sheets).
• Tertiary Structure: Overall 3D shape of a polypeptide due to interactions between R groups.
• Quaternary Structure: The structure formed when multiple polypeptide chains interact.

Endomembrane System

• A network of membranes in eukaryotic cells (nuclear envelope, ER, Golgi, lysosomes, vacuoles, plasma membrane).
• They modify, package, and transport proteins/lipids.

Diffusion and Transport

• Diffusion: Passive movement of molecules from high to low concentration.
• Facilitated Diffusion: Passive movement with the help of transport proteins (channels or carriers).
• Osmosis: Diffusion of water across a selectively permeable membrane (from low to high solute concentration).
• Active Transport: Movement against the concentration gradient, requiring energy (ATP).

Cellular Respiration & Photosynthesis

• Cellular Respiration: Exergonic process that breaks down glucose to generate ATP.
• Photosynthesis: Endergonic process that converts CO2 and H2O into glucose using light energy.

Cellular Respiration: Oxidation/Reduction

• Oxidation: Loss of electrons.
• Reduction: Gain of electrons.

Cellular Respiration: Glycolysis/Krebs Cycle

• Glycolysis: Occurs in the cytoplasm, converting glucose into pyruvate (producing ATP and NADH).
• Citric Acid/Krebs Cycle: Occurs in the mitochondrial matrix, completely oxidizing pyruvate (producing ATP, NADH, and FADH2).

Cell Cycle and Cell Division

• Mitosis: Produces two identical daughter cells (growth, repair, asexual reproduction).
• Meiosis: Produces four genetically distinct haploid daughter cells (essential for sexual reproduction).
• Crossing Over: Exchange of genetic material between homologous chromosomes during meiosis (contributes to genetic diversity).

Genetics

• Complete Dominance: Dominant allele masks the recessive.
• Incomplete Dominance: Heterozygote phenotype is intermediate.
• Codominance: Both alleles are expressed equally in the heterozygote.
• Sex-linked: Genes located on sex chromosomes (X or Y).

Replication, Transcription, Translation

• Replication: Copying DNA.
• Transcription: Synthesizing RNA from DNA.
• Translation: Synthesizing protein from RNA.

Chromosomes and Chromatids

• Chromosome Number: Does not change after replication.
• Chromatid Number: Doubles after replication.
• Prions: Infectious proteins causing diseases.
• Viroids: Small circular RNA molecules infecting plants.

Ecology Concepts

• Populations, Communities, Ecosystems, etc: Different levels of ecological organization.
• Dispersion patterns (random, uniform, clumped)
• Survivorship curves.
• Reproduction (semelparity vs iteroparity)
• Demographic Transition
• Energy Transfer.
• Dominant/Keystone Species
• Succession (primary, secondary)
• Competition, Predation, Parasitism, Mutualism, Commensalism.
• Mullerian Mimicry, Batesian Mimicry, Aposematic Coloration, Cryptic Coloration.
• Adaptation and Interactions.