From the tiniest cells to whole ecosystems, biology science explores how life works.
This set covers essential cell biology, genetics, evolution, anatomy, microbiology, plants, ecology, zoology, biotechnology, and the people who made major discoveries, starting easy and ramping up in difficulty.
Cell Biology Essentials
Q: What is the basic unit of life?
A: The cell—every organism is made of one or more cells, and all cells come from pre-existing cells.
Q: Which organelle is often called the cell’s “powerhouse”?
A: The mitochondrion, which generates most ATP through oxidative phosphorylation.
Q: What two places are ribosomes commonly found in eukaryotic cells?
A: Free in the cytosol and bound to the rough endoplasmic reticulum.
Q: What molecule carries genetic information in most living things?
A: DNA (deoxyribonucleic acid), encoded in sequences of four bases: A, T, C, and G.
Q: Which organelle packages, modifies, and ships proteins and lipids?
A: The Golgi apparatus, a stack of flattened sacs that sorts cellular cargo.
Q: What cytoskeletal protein forms microtubules?
A: Tubulin; microtubules help with cell shape, transport, and chromosome movement.
Q: During which cell-cycle phase is DNA replicated?
A: S phase (synthesis), before mitosis or meiosis begins.
Q: What does the Na⁺/K⁺ pump move per ATP hydrolyzed?
A: Three sodium ions out and two potassium ions in, helping maintain membrane potential.
Q: Where in the mitochondrion does the electron transport chain reside?
A: The inner mitochondrial membrane (cristae), where proton gradients drive ATP synthase.
Q: What are Okazaki fragments?
A: Short DNA pieces synthesized on the lagging strand during replication and later joined by ligase.
Genetics & Heredity
Q: How many chromosome pairs do humans have?
A: Twenty-three pairs (46 total), including one pair of sex chromosomes.
Q: What is the central dogma of molecular biology?
A: Information flows DNA → RNA → protein, via transcription and translation.
Q: What is a codon?
A: A three-nucleotide mRNA sequence that specifies an amino acid or a stop signal.
Q: Which codon typically signals the start of translation?
A: AUG, which codes for methionine (formyl-methionine in bacteria).
Q: What is the difference between genotype and phenotype?
A: Genotype is an organism’s genetic makeup; phenotype is the observable traits produced.
Q: What does “dominant allele” mean?
A: An allele that expresses its effect in the heterozygote, masking a recessive counterpart.
Q: What is mitochondrial DNA usually inherited from?
A: The mother; mtDNA is typically maternally transmitted in humans.
Q: What is the Hardy–Weinberg equation used for?
A: Modeling allele and genotype frequencies (p² + 2pq + q² = 1) under equilibrium conditions.
Q: What is genetic linkage?
A: Tendency of genes close together on a chromosome to be inherited together due to reduced recombination.
Q: What is epigenetics?
A: Heritable changes in gene activity without altering DNA sequence—often via DNA methylation or histone modification.
Evolution & Natural Selection
Q: Who co-presented the idea of natural selection before “On the Origin of Species” was published?
A: Charles Darwin and Alfred Russel Wallace in 1858.
Q: What is natural selection?
A: Differential survival and reproduction based on heritable variation, shifting trait frequencies over generations.
Q: What is a fossil record’s main evolutionary value?
A: It documents historical life forms and transitional features over deep time.
Q: What are homologous structures?
A: Similar anatomical features due to shared ancestry (e.g., vertebrate forelimbs), despite different functions.
Q: What does “adaptive radiation” mean?
A: Rapid diversification of a lineage into multiple niches, as seen in Darwin’s finches.
Q: Distinguish allopatric and sympatric speciation.
A: Allopatric occurs via geographic separation; sympatric arises without physical barriers, often through ecological or genetic shifts.
Q: What is genetic drift?
A: Random changes in allele frequencies, especially in small populations (e.g., bottlenecks, founder effects).
Q: What are HOX genes?
A: Master regulatory genes that pattern body axes and segment identity in animals.
Q: What is coevolution?
A: Reciprocal evolutionary change in interacting species, such as predator–prey or host–parasite pairs.
Q: What does stabilizing selection favor?
A: Intermediate phenotypes, reducing extremes and often maintaining the status quo around an optimal trait value.
Human Anatomy & Physiology
Q: What is the largest organ of the human body by surface area?
A: The skin, forming a protective, temperature-regulating barrier.
Q: Which blood cells carry oxygen?
A: Red blood cells via hemoglobin, an iron-containing protein that binds O₂.
Q: What is the primary muscle of breathing?
A: The diaphragm; its contraction draws air into the lungs.
Q: Which chamber of the heart pumps oxygenated blood to the body?
A: The left ventricle, through the aorta and systemic circulation.
Q: What is the functional unit of the kidney?
A: The nephron, where filtration, reabsorption, and secretion fine-tune fluid and electrolyte balance.
Q: Which hormone lowers blood glucose?
A: Insulin from pancreatic β-cells; glucagon from α-cells raises it.
Q: What part of the brain is critical for forming new declarative memories?
A: The hippocampus, important for consolidation and spatial memory.
Q: Which glial cells myelinate axons in the central nervous system?
A: Oligodendrocytes; Schwann cells myelinate in the peripheral nervous system.
Q: What is the smallest bone in the human body?
A: The stapes in the middle ear, part of the ossicles that transmit sound.
Q: In blood typing, who is the universal red-cell donor?
A: Type O negative for red-cell transfusions (plasma compatibility follows different rules).
Microbiology & Immunology
Q: What shapes commonly describe bacteria?
A: Cocci (spherical), bacilli (rod-shaped), and spirilla/spirochetes (spiral).
Q: What does Gram staining primarily differentiate?
A: Bacteria with thick peptidoglycan walls (Gram-positive) from those with an outer membrane and thin wall (Gram-negative).
Q: What is a bacteriophage?
A: A virus that infects bacteria, often used as a tool in molecular biology.
Q: Which scientist famously observed Penicillium inhibiting bacterial growth?
A: Alexander Fleming, leading to penicillin’s discovery.
Q: What immune cells produce antibodies?
A: B cells that differentiate into antibody-secreting plasma cells.
Q: What distinguishes CD8⁺ cytotoxic T cells from CD4⁺ helper T cells?
A: CD8⁺ kill infected cells; CD4⁺ coordinate immune responses via cytokines.
Q: What part of Gram-negative bacteria contains endotoxin activity?
A: Lipid A of lipopolysaccharide (LPS) in the outer membrane.
Q: What are the five major antibody classes?
A: IgM, IgG, IgA, IgE, and IgD—each with distinct roles and distributions.
Q: What is herd immunity?
A: Indirect protection when enough people are immune, reducing pathogen spread to vulnerable individuals.
Q: What is a prion?
A: A misfolded protein that induces misfolding in others, causing transmissible spongiform encephalopathies.
Botany & Plant Science
Q: What pigment primarily captures light for photosynthesis?
A: Chlorophyll a, which absorbs blue/red light and reflects green.
Q: Where do light reactions occur in chloroplasts?
A: In thylakoid membranes, producing ATP and NADPH.
Q: Where does the Calvin cycle take place?
A: In the stroma, fixing CO₂ into carbohydrates using ATP and NADPH.
Q: What structures control gas exchange in leaves?
A: Stomata, pores regulated by guard cells to balance CO₂ intake and water loss.
Q: What tissue transports water upward in plants?
A: Xylem (tracheids and vessel elements) via cohesion-tension and transpiration pull.
Q: What tissue transports sugars?
A: Phloem (sieve tube elements with companion cells) via pressure-flow.
Q: What is double fertilization in angiosperms?
A: One sperm fertilizes the egg (zygote), another fuses with polar nuclei (triploid endosperm).
Q: Which plant hormone promotes cell elongation and phototropism?
A: Auxin (IAA), redistributing to the shaded side to bend shoots toward light.
Q: How do C₄ plants reduce photorespiration?
A: They concentrate CO₂ in bundle sheath cells using a separate initial fixation step (PEP carboxylase).
Q: What are mycorrhizae?
A: Symbiotic associations between fungi and plant roots that enhance nutrient uptake, especially phosphorus.
Ecology & Ecosystems
Q: What is a trophic level?
A: A position in a food chain—producers, consumers, and decomposers—through which energy flows.
Q: Roughly what fraction of energy typically transfers between trophic levels?
A: About 10% on average, with the rest lost as heat and metabolic work.
Q: What is an ecological niche?
A: The role and conditions a species occupies, including resources used and interactions with other species.
Q: What is a keystone species?
A: A species with a disproportionately large effect on community structure relative to its abundance.
Q: Distinguish exponential and logistic growth.
A: Exponential growth accelerates unchecked; logistic growth levels off at carrying capacity due to resource limits.
Q: What is eutrophication?
A: Nutrient enrichment (often nitrogen or phosphorus) causing algal blooms and oxygen depletion in waters.
Q: Name two major global biogeochemical cycles.
A: The carbon cycle and the nitrogen cycle, which move elements through biotic and abiotic reservoirs.
Q: What is biological magnification?
A: Increasing concentration of persistent toxins up food chains, as with certain pesticides or mercury.
Q: What is island biogeography’s key insight?
A: Species richness reflects island size and isolation—bigger, nearer islands tend to host more species.
Q: Define habitat fragmentation.
A: Breaking continuous habitats into smaller patches, which can reduce gene flow and biodiversity.
Zoology & Animal Behavior
Q: What phylum includes insects, spiders, and crustaceans?
A: Arthropoda—animals with jointed legs and chitinous exoskeletons.
Q: What defines chordates?
A: Presence at some stage of a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
Q: What are the three mammal groups by reproduction?
A: Monotremes (egg-laying), marsupials (pouched), and placental mammals.
Q: Why are birds’ bones often hollow?
A: Pneumatized bones reduce weight while retaining strength, aiding powered flight.
Q: What is imprinting in ethology?
A: A rapid, early learning process forming strong attachments, famously studied by Konrad Lorenz in geese.
Q: What is a fixed action pattern (FAP)?
A: An instinctive, stereotyped behavior sequence triggered by a specific stimulus.
Q: What is kin selection?
A: Evolution of altruistic behaviors that benefit relatives, explained by inclusive fitness (Hamilton’s rule).
Q: What are eusocial animals?
A: Species with cooperative brood care, overlapping generations, and reproductive division of labor (e.g., bees, ants).
Q: What guides circadian rhythms in animals?
A: Internal biological clocks synchronized by environmental cues like light (entrainment).
Q: Why do some species migrate seasonally?
A: To track resources, breeding sites, or favorable climates, balancing energetic costs with survival and reproduction.
Biotechnology & Lab Techniques
Q: What does PCR do?
A: Amplifies specific DNA segments through cycles of denaturation, annealing, and extension using a thermostable polymerase.
Q: What enzyme seals DNA fragments during cloning?
A: DNA ligase, which forms phosphodiester bonds at nicks.
Q: How do restriction enzymes assist cloning?
A: They cut DNA at specific sequences, creating compatible ends for insertion into vectors.
Q: What is gel electrophoresis used for?
A: Separating DNA, RNA, or proteins by size/charge through a gel matrix under an electric field.
Q: What is Sanger sequencing’s key trick?
A: Chain-terminating dideoxynucleotides that stop extension at specific bases to read sequence.
Q: What is CRISPR-Cas9?
A: A programmable gene-editing system adapted from bacterial immunity that uses guide RNA to direct precise DNA cuts.
Q: What is qPCR (real-time PCR) good for?
A: Quantifying nucleic acids as amplification proceeds, often for gene expression or pathogen load.
Q: What are plasmids?
A: Circular DNA molecules used as cloning vectors in bacteria; they can carry selectable markers and inserts.
Q: What is an ELISA?
A: An enzyme-linked immunosorbent assay to detect and quantify specific proteins or antibodies.
Q: What advantage do fluorescent proteins like GFP provide?
A: They allow live imaging of gene expression, protein localization, and cell dynamics under a microscope.
History-Makers in Biology
Q: Who is considered the father of modern taxonomy?
A: Carl Linnaeus, who popularized binomial nomenclature for naming species.
Q: Who uncovered the basic laws of inheritance with pea plants?
A: Gregor Mendel, describing segregation and independent assortment.
Q: Who’s credited with determining DNA’s double-helix structure?
A: James Watson and Francis Crick, informed by Rosalind Franklin’s X-ray diffraction data.
Q: Who proposed that mitochondria and chloroplasts originated via endosymbiosis?
A: Lynn Margulis, whose theory is now widely accepted.
Q: Which scientist developed pasteurization and vaccines for rabies and anthrax?
A: Louis Pasteur, a pioneer of germ theory.
Q: What are Koch’s postulates associated with?
A: Robert Koch’s criteria linking specific microbes to specific diseases (since refined for modern contexts).
Q: Who created the first widely used polio vaccine?
A: Jonas Salk, with an inactivated (killed) polio vaccine.
Q: Who discovered transposable elements (“jumping genes”) in maize?
A: Barbara McClintock, later awarded the Nobel Prize.
Q: Who shared the 2020 Nobel Prize for CRISPR gene editing?
A: Emmanuelle Charpentier and Jennifer Doudna for developing CRISPR-Cas9 as a genome-editing tool.
Q: Whose cells became the first immortal human cell line used widely in research?
A: HeLa cells, derived from Henrietta Lacks; their use raised lasting bioethics discussions.
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