KBIT-2 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Prokaryote vs. eukaryote

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes possess both, enabling compartmentalized metabolism such as separating glycolysis from mitochondrial oxidative phosphorylation.

Enzyme Km

The substrate concentration at which an enzyme reaches half its maximal velocity. A lower Km indicates tighter substrate binding and higher apparent affinity under standard conditions.

Competitive inhibition kinetics

A reversible inhibitor competing with substrate at the active site raises apparent Km but leaves Vmax unchanged, because saturating substrate can outcompete the inhibitor.

Na+/K+-ATPase stoichiometry

The pump exports three sodium ions and imports two potassium ions per ATP hydrolyzed. This unequal exchange is electrogenic and helps set resting membrane potential.

Semiconservative replication

Each parental DNA strand serves as a template, so every daughter double helix contains one original strand and one newly synthesized strand.

Hardy-Weinberg conditions

Equilibrium requires no mutation, no migration, no selection, infinite population size, and random mating. Departures from these conditions cause allele frequencies to change.

Recombination frequency

The proportion of offspring showing crossover between two loci. It equals map distance in centimorgans for linked genes and approaches 50% for unlinked loci.

X-linked recessive inheritance

Males are hemizygous and express the trait from one copy; affected fathers pass the allele to daughters but never to sons.

Cardiac output formula

Cardiac output equals heart rate multiplied by stroke volume. Stroke volume itself depends on preload, afterload, and myocardial contractility.

Frank-Starling relationship

Within physiological limits, greater ventricular filling (preload) stretches cardiac muscle and increases stroke volume, matching output to venous return.

Bohr effect

A rightward shift of the oxygen-hemoglobin dissociation curve caused by increased CO2, hydrogen ions, or temperature, promoting oxygen release in active tissues.

Logistic growth equation

dN/dt = rN(1 - N/K). Growth slows as population size N approaches carrying capacity K, and the maximum growth rate occurs at N = K/2.

Trophic energy transfer

Only about ten percent of energy at one trophic level passes to the next; the remainder is lost mainly as heat from respiration, limiting food chain length.

Primary vs. secondary succession

Primary succession starts on bare substrate lacking soil, such as new lava; secondary succession follows disturbance where soil and propagules remain, so it proceeds faster.

Density-dependent limitation

Factors whose effect intensifies with population density, such as competition, predation, and disease, often producing logistic-style population regulation.

Genetic drift

Random change in allele frequencies across generations, strongest in small populations. Bottlenecks and founder events sharply reduce genetic diversity.

Homology vs. analogy

Homologous structures share common ancestry despite possibly different functions; analogous structures perform similar functions without shared ancestry, reflecting convergent evolution.

Biological species concept

A species is a group whose members interbreed in nature and produce fertile offspring. It does not apply to asexual organisms, which require other species criteria.

Allopatric speciation

Speciation following geographic isolation of populations, which then diverge through mutation, drift, and selection until reproductive isolation evolves.

Calvin cycle inputs

The stroma reactions use ATP and NADPH from the light reactions to fix CO2 with rubisco, producing triose phosphates that build sugars.

C4 vs. CAM photosynthesis

C4 plants separate initial CO2 fixation from the Calvin cycle spatially in different cell types; CAM plants separate them temporally, fixing CO2 at night.

Xylem and phloem transport

Xylem carries water and dissolved minerals upward, driven by transpiration tension; phloem transports sugars bidirectionally by pressure flow from source to sink.

Guard cell mechanism

Stomata open when guard cells accumulate potassium ions and water, become turgid, and bow apart. The hormone ABA promotes closure during drought.

Gram stain basis

Gram-positive cells retain crystal violet because of a thick peptidoglycan layer; Gram-negative cells have a thin layer and an outer membrane, so they stain pink.

Innate vs. adaptive immunity

Innate responses are rapid and nonspecific, involving barriers, phagocytes, and complement. Adaptive responses are slower, antigen-specific, and generate immunological memory.

Helper T cell role

CD4+ helper T cells recognize antigen presented on MHC class II and activate B cells and cytotoxic T cells by releasing cytokines, coordinating the adaptive response.

Antibody class functions

IgM acts first in a primary response; IgG is most abundant and crosses the placenta; IgA guards mucosa; IgE mediates allergic reactions.

Action potential phases

Depolarization reflects opening of voltage-gated sodium channels; repolarization follows potassium efflux. The refractory period prevents backward conduction along the axon.

Hamilton's rule

Altruism is favored when rB > C: relatedness to the recipient times benefit received must exceed the cost to the actor.

Fixed action pattern

An innate behavior triggered by a sign stimulus that runs to completion once started, even if the stimulus is removed.

Control group purpose

A control group receives no treatment or a neutral treatment, providing a baseline against which the experimental group is compared to isolate the independent variable's effect.

Correlation and causation

An association between variables does not prove one causes the other; confounding variables or reverse causation may explain the observed relationship.