MTLE Life Science (Grades 9-12) flashcards

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

Fluid mosaic model

Describes the plasma membrane as a phospholipid bilayer studded with proteins, cholesterol, and carbohydrates that move laterally, giving the membrane a dynamic, mosaic-like structure.

Osmosis

Net movement of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration, driven by the water potential gradient.

Competitive inhibition

An inhibitor binds the enzyme active site, competing with substrate; this raises apparent Km while leaving Vmax unchanged because high substrate can outcompete the inhibitor.

Noncompetitive inhibition

An inhibitor binds a site other than the active site, altering enzyme shape; this lowers Vmax without changing Km because some enzyme molecules are permanently inactivated.

Chemiosmosis

ATP synthesis driven by a proton gradient across a membrane; protons flow through ATP synthase, coupling electron transport in mitochondria or thylakoids to phosphorylation of ADP.

Central dogma

The flow of genetic information from DNA to RNA by transcription, then to protein by translation; retroviruses reverse the first step using reverse transcriptase.

Calvin cycle

Light-independent reactions in the chloroplast stroma where RuBisCO fixes carbon dioxide into sugar precursors using ATP and NADPH produced by the light reactions.

Semi-conservative replication

DNA replication in which each new double helix contains one original parental strand and one newly synthesized strand, preserving half of the original molecule.

Law of segregation

Mendel's principle that the two alleles of a gene separate during gamete formation, so each gamete carries only one allele for that trait.

Testcross

A cross of an individual showing a dominant phenotype with a homozygous recessive individual; offspring ratios reveal whether the unknown parent was homozygous or heterozygous.

Incomplete dominance

A pattern where the heterozygote shows an intermediate phenotype between the two homozygotes, such as pink flowers from red and white parents.

Codominance

A pattern where both alleles are fully expressed in the heterozygote, as in AB blood type, rather than blending into an intermediate phenotype.

X-linked recessive

A trait encoded on the X chromosome; males with one copy express it, while females usually need two copies, so the trait appears more often in males.

Hardy-Weinberg equilibrium

A null model in which allele and genotype frequencies stay constant across generations absent mutation, migration, selection, nonrandom mating, and genetic drift.

Reproductive isolation

Any barrier preventing members of different populations from interbreeding and producing fertile offspring; it is required for biological speciation to occur.

Allopatric speciation

Speciation that follows geographic separation of populations, which then diverge through mutation, drift, and different selective pressures until reproductive isolation evolves.

Homologous structures

Anatomical features shared by related species that derive from a common ancestor, such as forelimb bones in mammals, even when functions differ.

Negative feedback

A regulatory loop in which a change in a variable triggers a response that counteracts the change, restoring the set point and stabilizing internal conditions.

Transpiration pull

Upward movement of water in xylem driven by evaporation from leaves; cohesion between water molecules and adhesion to vessel walls sustain the continuous column.

Carrying capacity

The maximum population size an environment can sustain indefinitely given available resources; logistic growth slows as population size approaches this value, symbolized K.

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.

Ecological niche

The full set of resources, conditions, and interactions a species uses in its habitat, including its role and its tolerance ranges.

Primary succession

Community development that begins on newly formed substrate lacking soil and seeds, such as bare rock or lava flows, starting with pioneer species like lichens.

Nitrogen fixation

Conversion of atmospheric nitrogen gas into ammonia by bacteria such as Rhizobium in root nodules, making nitrogen available for building amino acids and nucleic acids.

Independent variable

The factor deliberately manipulated or selected by the investigator in an experiment; it is plotted on the horizontal axis and its effect on the dependent variable is measured.

Control group

The comparison group that does not receive the experimental treatment, establishing a baseline against which the effect of the independent variable is judged.

Falsifiable hypothesis

A testable statement predicting a relationship between variables that could be shown false by observation or experiment; untestable claims fall outside scientific inquiry.

Reliability

The consistency of repeated measurements under the same conditions; high reliability means trials yield similar results, though it does not guarantee the measurement is valid.

Safety Data Sheet

A standardized document listing a chemical's hazards, handling precautions, storage requirements, exposure limits, and first-aid and spill-response procedures.

Eyewash station

Emergency equipment that flushes chemicals from the eyes with running water for at least fifteen minutes; its location must be unobstructed and known before lab work begins.

Formative assessment

Ongoing checks during instruction, such as questioning or exit tickets, used to adjust teaching and give feedback rather than to assign a final grade.

5E instructional model

A lesson sequence of engage, explore, explain, elaborate, and evaluate that builds student understanding through investigation before formal explanation is introduced.