CLEP Biology flashcards
CLEP Biology · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Activation energy
- The minimum energy input required for a chemical reaction to proceed; enzymes lower this barrier by stabilizing transition states without altering the overall free-energy change.
- Competitive inhibition
- An inhibitor binds the enzyme active site, competing with substrate. Apparent Km increases while Vmax stays the same because inhibition can be overcome by more substrate.
- Semiconservative replication
- Each daughter DNA molecule contains one original parental strand and one newly synthesized strand, as shown by the Meselson-Stahl experiment using density-gradient centrifugation.
- Codon
- A three-nucleotide sequence of mRNA that specifies one amino acid or a stop signal during translation; the genetic code is redundant but nearly universal across organisms.
- Glycolysis
- The oxygen-independent breakdown of one glucose into two pyruvate molecules in the cytoplasm, netting two ATP and two NADH per glucose.
- Oxidative phosphorylation
- ATP production driven by an electrochemical proton gradient across the inner mitochondrial membrane; electrons pass through the electron transport chain to oxygen as final acceptor.
- Osmosis
- The passive diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
- Mitosis
- Nuclear division producing two daughter cells with chromosome number identical to the parent cell; used for growth and repair in multicellular organisms.
- Meiosis
- Two successive divisions producing four haploid gametes; crossing over in prophase I and independent assortment in metaphase I generate genetic variation.
- Photosynthesis light reactions
- Thylakoid-membrane processes in which light energy drives electron transport, splitting water to release oxygen and producing ATP and NADPH for carbon fixation.
- Calvin cycle
- Stroma reactions that use ATP and NADPH to fix carbon dioxide into three-carbon sugars, catalyzed by the enzyme RuBisCO; independent of direct light.
- Negative feedback
- A regulatory mechanism in which a change in a variable triggers a response that counteracts the change, keeping internal conditions near a set point such as body temperature.
- Xylem
- Vascular plant tissue that conducts water and dissolved minerals from roots to shoots; flow is driven mainly by transpiration from leaves.
- Phloem
- Vascular plant tissue that transports sugars and other organic solutes from sources such as leaves to sinks such as roots and fruits.
- Alveoli
- Tiny thin-walled air sacs in the lungs where oxygen and carbon dioxide diffuse between air and blood across a large, moist surface area.
- Hemoglobin
- Iron-containing respiratory protein in red blood cells that binds oxygen cooperatively, giving a sigmoid dissociation curve sensitive to pH, CO2, and temperature.
- Action potential
- A rapid electrical signal along a neuron caused by Na+ influx and K+ efflux; it is all-or-none and followed by a refractory period preventing backward travel.
- Antibody
- A Y-shaped protein produced by plasma cells that binds specific antigens, marking pathogens for neutralization or destruction by immune cells.
- Double circulation
- A circulatory arrangement in which blood passes through the heart twice per circuit, separating pulmonary and systemic flow at higher pressure.
- Steroid hormone
- A lipid-soluble signaling molecule that crosses the plasma membrane and binds intracellular receptors, typically altering gene transcription in target cells.
- Osmoregulation
- The control of water and solute balance in an organism, achieved by structures such as kidneys or contractile vacuoles to keep internal concentrations stable.
- Carrying capacity
- The maximum population size an environment can sustain indefinitely given available resources; symbolized K in the logistic growth equation.
- Exponential growth
- Population increase at a constant per-capita rate r with no resource limits, producing a J-shaped curve described by N(t) = N0 * e^(rt).
- Hardy-Weinberg equilibrium
- A null model in which allele and genotype frequencies remain constant across generations absent mutation, migration, selection, and drift, with random mating in a large population.
- Genetic drift
- Random fluctuation of allele frequencies between generations due to chance sampling; its effects are strongest in small populations and can fix alleles.
- Founder effect
- A form of genetic drift in which a small group colonizes a new area, carrying only a subset of the original gene pool and reducing genetic diversity.
- Directional selection
- Natural selection that favors individuals at one phenotypic extreme, shifting the population mean for that trait over successive generations.
- Competitive exclusion
- The principle that two species competing for the same limiting resource cannot coexist indefinitely; one typically outcompetes and displaces the other.
- Trophic level
- A feeding position in a food chain, such as producer or primary consumer; only about ten percent of energy passes to the next level.
- Primary succession
- Ecological development beginning on newly exposed substrate lacking soil, such as bare rock or lava flows, typically initiated by pioneer species like lichens.
- Allopatric speciation
- Formation of new species when populations are separated by a geographic barrier, preventing gene flow and allowing independent evolutionary divergence.
- Mark-recapture estimate
- A population size estimate computed as N = (M * C) / R, where M is the number initially marked, C the second sample size, and R the recaptures.