What are the four main organic components that compose the fluid mosaic model of the plasma membrane?

Phospholipids, cholesterol, proteins, and carbohydrates.

What structural property characterizes an amphiphilic molecule?

It contains both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

How do glycolipids differ from glycoproteins in the cell membrane?

Glycolipids consist of carbohydrates attached to lipids, whereas glycoproteins consist of carbohydrates attached to proteins.

What is the key positional difference between integral proteins and peripheral proteins?

Integral proteins are integrated completely into the phospholipid bilayer, while peripheral proteins occur only on the inner or outer membrane surfaces.

How does active transport differ from passive transport in terms of energy and transport mechanisms?

Passive transport occurs naturally without cellular energy expenditure, while active transport requires cellular energy (ATP) and uses carrier proteins.

The movement of water molecules across a semipermeable membrane is called _____.

Osmosis

How does facilitated diffusion differ from simple diffusion?

Facilitated diffusion requires membrane proteins to help substances cross the plasma membrane down their concentration gradient.

What happens to a cell's water volume when placed in a hypertonic extracellular solution?

Water leaves the cell because the extracellular fluid has higher osmolarity (more solutes, less water) than the cytoplasm.

What happens to a cell's water volume when placed in a hypotonic extracellular solution?

Water enters the cell because the extracellular fluid has lower osmolarity (fewer solutes, more water) than the cytoplasm.

How do symporter and antiporter carrier proteins differ in direction of transport?

A symporter carries two molecules/ions in the same direction, while an antiporter carries two molecules/ions in opposite directions.

How do endocytosis and exocytosis differ in the movement of materials relative to the cell?

Endocytosis moves bulk materials into a cell, whereas exocytosis passes bulk materials out of a cell.

Contrast phagocytosis and pinocytosis.

Phagocytosis ("cellular eating") engulfs large particles, whereas pinocytosis ("cellular drinking") invaginates fluid to absorb small volumes of liquid.

What is a substrate in the context of enzymatic reactions?

The specific chemical reactant to which an enzyme binds.

How does competitive inhibition differ from allosteric inhibition?

Competitive inhibitors block binding at the active site directly, whereas allosteric inhibitors bind to a secondary site to induce a conformational change.

Contrast anabolism and catabolism, giving one example of each.

Anabolism builds complex molecules from simpler ones (e.g., protein synthesis); catabolism breaks down complex molecules into simpler ones (e.g., glucose breakdown).

What is the core principle stated by the First Law of Thermodynamics?

The total amount of energy in the universe is constant; energy cannot be created or destroyed.

According to the Second Law of Thermodynamics, every energy transfer leads to an increase in _____.

Entropy (a state of disorder, usually released as heat).

How do photoautotrophs and chemoautotrophs differ in their sources of energy for organic synthesis?

Photoautotrophs use light energy from sunlight, whereas chemoautotrophs extract energy from inorganic chemicals.

What primary reaction occurs at Photosystem II (PSII) during photosynthesis?

Light energy extracts electrons from water molecules, generating protons and releasing oxygen (O2) as a byproduct.

What primary reduction event occurs at Photosystem I (PSI) during photosynthesis?

Electrons transported from plastocyanin are re-energized by light and transferred to reduce NADP+ into NADPH.

What crucial role does the enzyme Rubisco perform in plants?

It catalyzes carbon fixation by incorporating atmospheric carbon dioxide (CO2) into RuBP during the Calvin cycle.

What 3-carbon sugar is the primary end product of photosynthesis used to synthesize glucose and other macromolecular building blocks?

Glyceraldehyde 3-phosphate (GA3P).

How do the daughter cell outputs of mitosis and meiosis compare in ploidy and gene identity?

Mitosis yields two genetically identical diploid (2n) cells; meiosis yields four genetically unique haploid (n) cells.

What is the difference between diploid cells (2n) and haploid cells (n)?

Diploid cells contain two full sets of chromosomes (2n), whereas haploid cells contain one set of chromosomes (n).

How do somatic cells differ from gametic cells?

Somatic cells are non-reproductive body cells, whereas gametic cells are reproductive cells (sperm and oocytes) used in sexual reproduction.

What specialized region connects sister chromatids together in a condensed chromosome?

The centromere.

During which specific sub-stage of meiosis does crossing over occur?

Prophase I.

Name four physical or chemical factors that influence the rate of molecular diffusion.

Concentration gradient, mass of molecules, temperature, solvent density, solubility, surface area, distance, or pressure.

What three environmental and biochemical factors directly regulate enzyme activity?

Optimal temperature, optimal pH, and the availability of cofactors or coenzymes.

List the four main sequential stages of cellular respiration.

Glycolysis Oxidation of Pyruvate Citric Acid Cycle (Krebs Cycle) Electron Transport Chain (Oxidative Phosphorylation)

What is the net gain of ATP molecules produced per molecule of glucose during glycolysis?

Net gain of 2 ATP (4 ATP formed minus 2 ATP invested).

Where in the cell does glycolysis occur, and does it require oxygen?

It occurs in the cytoplasm and does not require oxygen (anaerobic).

What are the net products resulting from the oxidation of two pyruvate molecules?

2 Acetyl-CoA molecules, 2 NADH molecules, and 2 CO2 molecules.

In the initial step of the Citric Acid Cycle, Acetyl-CoA combines with which 4-carbon compound to produce citric acid?

Oxaloacetate.

Which reduced electron carriers are produced during the Citric Acid Cycle to transport electrons to the Electron Transport Chain?

NADH and FADH2.

How many ATP molecules are generated specifically by the Electron Transport Chain during complete aerobic cellular respiration?

28 ATP molecules.

What molecule acts as the final electron acceptor in the mitochondrial Electron Transport Chain during aerobic respiration?

Oxygen (O2), which is reduced to form water (H2O).

How does the final electron acceptor in anaerobic respiration differ from that in aerobic respiration?

Anaerobic respiration uses an inorganic molecule other than molecular oxygen (O2) as its final electron acceptor.

Compare the primary end products of lactic acid fermentation and alcohol fermentation.

Lactic acid fermentation yields lactate (lactic acid); alcohol fermentation yields ethanol and carbon dioxide (CO2).

Contrast the structural roles of the thylakoid membrane and stroma within a chloroplast.

Thylakoid membranes contain chlorophyll for light-dependent reactions; the stroma is the surrounding fluid-filled space hosting Calvin cycle enzymes.

A stack of thylakoid membranes within a chloroplast is called a _____.

Granum (plural: grana)

What three major products are produced during the light-dependent reactions of photosynthesis?

ATP, NADPH, and oxygen (O2).

List the three main stages of the light-independent reactions (Calvin cycle) in order.

Carbon Fixation Reduction Regeneration of RuBP

State two metabolic features shared by both cellular respiration and photosynthesis.

Both involve energy transformation, utilize an Electron Transport Chain, depend on coenzyme electron carriers (NADH/NADPH), and feature cyclical biochemical pathways.

What critical nuclear event takes place during the Synthesis (S) phase of interphase?

DNA replication occurs, producing identical copies of the cell's chromosomes.

Describe the positioning of chromosomes during metaphase of mitosis.

Chromosomes align along the metaphase plate in the center of the cell, attached to spindle fibers.

What structural change happens to sister chromatids during anaphase of mitosis?

Sister chromatids are cleaved apart and pulled by spindle fibers toward opposite poles of the cell.

How does chromosome separation in Anaphase I of meiosis differ from Anaphase II of meiosis?

Anaphase I separates homologous chromosome pairs (tetrads), while Anaphase II separates sister chromatids.

What primary energy-yielding function do mitochondria perform in eukaryotic cells?

They generate adenosine triphosphate (ATP), the primary energy currency of the cell, via aerobic cellular respiration.

What is the specialized function of lysosomes in animal cells?

They contain digestive enzymes to break down proteins, lipids, nucleic acids, and worn-out organelles.

How do the structural features and metabolic roles of the Rough ER and Smooth ER differ?

Rough ER is studded with ribosomes and synthesizes proteins; Smooth ER lacks ribosomes and synthesizes lipids, metabolizes carbohydrates, and detoxifies chemicals.

What is the primary function of the Golgi apparatus?

It modifies, manufactures, packages, and ships proteins and lipids received from the endoplasmic reticulum.

What biochemical task do peroxisomes perform inside eukaryotic cells?

They carry out oxidation reactions that break down fatty acids and amino acids, and neutralize cellular toxins.

What primary role does the central vacuole play in plant cell physiology?

It regulates cellular water concentration under fluctuating environmental conditions and maintains turgor pressure.

What is homeostasis in living organisms?

The biological mechanism of maintaining a dynamic, relatively stable internal environment essential for survival.

What is activation energy?

The minimum threshold of energy required to initiate a chemical reaction.

The physical exchange of genetic material between homologous non-sister chromatids is known as _____.

Crossing over

What is the defining characteristic of a biological catalyst?

It accelerates the rate of a chemical reaction without undergoing permanent chemical alteration itself.

How does a uniporter transport membrane protein function?

It transports a single specific molecule or ion across the membrane in one direction.

List the three sequential phases that constitute interphase prior to cell division.

G1 phase (first gap) S phase (synthesis of DNA) G2 phase (second gap)