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General Biology: Cellular Respiration, Photosynthesis, and Cell Division

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  • What happens in oxidation-reduction (redox) reactions?

    Electrons are transferred between molecules, changing their oxidation states. Oxidation is loss of electrons; reduction is gain of electrons, affecting potential energy.

  • How are NAD+ and NADH related?

    NAD+ is the oxidized form that accepts electrons and a proton to become NADH, the reduced form carrying high-energy electrons.

  • What are the reactants and products of glycolysis?

    Reactants: Glucose and ATP; Products: Pyruvate, ATP, and NADH.

  • How is ATP produced in glycolysis?

    ATP is produced by substrate-level phosphorylation, transferring a phosphate group directly to ADP from a phosphorylated intermediate.

  • What are the main stages of aerobic respiration in order?

    Glycolysis, Pyruvate oxidation, Krebs cycle, and Electron Transport Chain with oxidative phosphorylation.

  • What is substrate-level phosphorylation?

    Direct synthesis of ATP by transferring a phosphate group from a substrate molecule to ADP during glycolysis and Krebs cycle.

  • What percent of ATP is formed by substrate-level phosphorylation in cellular respiration?

    Only about 10% of total ATP is formed by substrate-level phosphorylation; most is made by oxidative phosphorylation.

  • What is chemiosmosis in cellular respiration?

    Movement of H+ ions down their gradient through ATP synthase, producing ATP as protons flow from the intermembrane space back into the mitochondrial matrix.

  • How does chemiosmosis differ in photosynthesis compared to cellular respiration?

    In photosynthesis, protons flow from the stroma into the thylakoid lumen, then back through ATP synthase to the stroma, opposite to mitochondria.

  • What are the reactants and products of the Krebs cycle?

    Reactants: Acetyl-CoA; Products: CO2, NADH, FADH2, and ATP (or GTP).

  • What are the reactants and products of the light reactions of photosynthesis?

    Reactants: Light, water; Products: ATP, NADPH, and O2.

  • What are the reactants and products of the dark reactions (Calvin cycle) of photosynthesis?

    Reactants: CO2, ATP, NADPH; Products: Glucose (G3P) and ADP, NADP+.

  • What is the structure of chloroplasts relevant to photosynthesis?

    Chloroplasts have thylakoid membranes where light reactions occur and the stroma where the Calvin cycle takes place.

  • During photosynthesis, what is oxidized and what is reduced?

    Water is oxidized to O2; CO2 is reduced to glucose.

  • What are the stages of the cell cycle?

    Interphase (G0, G1, S, G2 phases) followed by Mitosis and Cytokinesis.

  • What happens during the G0 phase?

    Cells exit the cycle and do not divide; they are metabolically active but not preparing for division.

  • What occurs during the S phase of interphase?

    DNA replication occurs, duplicating chromosomes into sister chromatids.

  • What are sister chromatids and centromeres?

    Sister chromatids are identical copies of a chromosome joined at the centromere.

  • What happens during prophase of mitosis?

    Chromatin condenses into visible chromosomes; spindle fibers form; nuclear envelope breaks down.

  • What occurs during metaphase of mitosis?

    Chromosomes align at the cell's equator (metaphase plate) attached to spindle fibers.

  • What happens during anaphase of mitosis?

    Sister chromatids separate and move toward opposite poles of the cell.

  • What occurs during telophase of mitosis?

    Chromosomes decondense; nuclear envelopes reform around each set of chromosomes.

  • How does cytokinesis differ between plant and animal cells?

    Animal cells form a cleavage furrow; plant cells build a cell plate to divide the cytoplasm.

  • What is the difference between asexual and sexual reproduction in terms of DNA transfer?

    Asexual reproduction passes identical DNA to offspring; sexual reproduction combines DNA from two parents, increasing genetic diversity.

  • When do cells become haploid during meiosis?

    Cells become haploid at the end of Meiosis I after homologous chromosomes separate.

  • When do sister chromatids separate during meiosis?

    Sister chromatids separate during Meiosis II, similar to mitosis.

  • What is crossing-over and when does it occur?

    Exchange of genetic material between homologous chromosomes during Prophase I of meiosis, increasing genetic variation.

  • How many ovum and sperm cells are produced by meiosis?

    Meiosis produces 1 ovum and 3 polar bodies in females; 4 sperm cells in males.