NYSTCE Biology CST key terms

The maintenance of stable internal conditions, such as temperature, pH, and glucose concentration, within narrow limits despite changes in the external environment. Cells, organs, and body systems cooperate to detect deviations and correct them.

A control mechanism in which a change from the set point triggers a response that reverses the change, restoring balance. Examples include insulin lowering blood glucose and sweating cooling the body after overheating.

A control mechanism in which a change amplifies itself, driving a process rapidly to completion rather than restoring a set point. Examples include oxytocin-driven uterine contractions during childbirth and platelet plug formation during clotting.

The passive movement of water across a selectively permeable membrane from a region of lower solute concentration to one of higher solute concentration. It continues until water potential is equalized or pressure opposes further flow.

The net movement of particles from regions of higher concentration to lower concentration caused by random thermal motion. It requires no energy input and continues until the concentration gradient disappears or equilibrium is reached.

Movement of substances across a membrane against their concentration gradient using energy, typically from ATP hydrolysis. Protein pumps such as the sodium-potassium pump establish gradients used for nerve signaling and nutrient uptake.

A protein that speeds a biochemical reaction by lowering activation energy without being consumed. Each enzyme binds specific substrates at its active site, and activity is affected by temperature, pH, and inhibitors.

Loss of a protein's functional three-dimensional shape caused by heat, extreme pH, or chemicals that disrupt bonds maintaining secondary and tertiary structure. Denatured enzymes lose catalytic activity, often irreversibly.

The minimum energy that colliding reactant molecules must possess for a reaction to proceed. Enzymes lower this barrier, increasing reaction rate without altering the overall energy change of the reaction.

Adenosine triphosphate, the primary energy currency of cells. Hydrolysis of its terminal phosphate bond releases usable energy that powers transport, synthesis, movement, and other cellular work.

The set of metabolic pathways, including glycolysis, the Krebs cycle, and oxidative phosphorylation, that harvest energy from glucose and other fuels to produce ATP, releasing carbon dioxide and water as byproducts.

The first stage of cellular respiration, occurring in the cytoplasm, in which one glucose molecule is split into two pyruvate molecules, yielding a small net gain of ATP and reduced electron carriers.

An anaerobic pathway that regenerates oxidized electron carriers by transferring electrons to organic molecules such as pyruvate, allowing glycolysis to continue when oxygen is unavailable. It yields far less ATP than aerobic respiration.

The process by which chlorophyll-containing organisms convert light energy into chemical energy, using carbon dioxide and water to synthesize glucose and release oxygen. It occurs in chloroplasts through light-dependent and light-independent reactions.

The light-independent series of reactions in the chloroplast stroma that uses ATP and NADPH to fix carbon dioxide into organic molecules, ultimately producing sugars. The enzyme rubisco catalyzes the initial carbon fixation step.

The green pigment in chloroplasts that absorbs primarily red and blue wavelengths of light and reflects green, capturing energy used in photosynthesis. Different forms absorb slightly different wavelengths.

Nuclear division producing two genetically identical daughter nuclei with the same chromosome number as the parent cell. It supports growth, repair, and asexual reproduction in eukaryotes.

Two successive nuclear divisions that produce four haploid cells from one diploid parent cell, with crossing over and independent assortment generating genetic variation in gametes.

Exchange of corresponding segments between non-sister chromatids of homologous chromosomes during prophase I of meiosis, creating new combinations of alleles on a chromosome.

The random orientation of homologous chromosome pairs at the metaphase plate during meiosis I, so that alleles of different genes are distributed to gametes independently, increasing genetic variation.

Patterns of inheritance based on segregation of alleles and independent assortment of genes, in which dominant alleles mask recessive ones in heterozygotes. These principles predict offspring ratios from parental genotypes.

The specific combination of alleles an organism carries for a gene or set of genes. Genotype, together with environmental influences, determines the observable phenotype.

The observable characteristics of an organism, such as traits, appearance, or biochemical properties, resulting from the interaction of genotype with the environment.

A grid diagram used to predict the possible genotypes and their expected proportions among offspring of a cross, based on the alleles each parent can contribute.

The semiconservative process in which a double-stranded DNA molecule is copied, with each strand serving as a template for a new complementary strand, ensuring genetic information is passed to daughter cells.

The synthesis of an RNA molecule from a DNA template, catalyzed by RNA polymerase, producing messenger RNA that carries genetic instructions from the nucleus to the cytoplasm in eukaryotes.

The process in which ribosomes read messenger RNA codons and assemble the corresponding amino acids into a polypeptide chain, using transfer RNA to deliver amino acids.

A sequence of three nucleotides in messenger RNA that specifies a particular amino acid or signals the start or stop of translation. The genetic code is nearly universal across organisms.

A heritable change in the nucleotide sequence of DNA, ranging from single-base substitutions to insertions, deletions, or chromosomal rearrangements. Mutations are a source of genetic variation and may alter phenotype.

The differential survival and reproduction of individuals whose inherited traits make them better adapted to their environment, causing favorable allele frequencies to increase over generations.

An inherited characteristic that enhances an organism's ability to survive and reproduce in its environment, arising through natural selection acting over many generations.

Change in the inherited characteristics of populations over generations, driven by mechanisms including natural selection, mutation, gene flow, and genetic drift. It can lead to speciation and biodiversity.

The formation of new and distinct species, typically when populations become reproductively isolated and diverge genetically over time through mutation, selection, and drift.

A feeding position in a food web, such as producer, primary consumer, or secondary consumer. Energy transfer between levels is inefficient, so higher levels support fewer organisms.

The maximum population size of a species that a given environment can sustain indefinitely, given available resources, space, and other limiting factors. Populations may overshoot it temporarily.

An environmental resource or condition, such as food, water, space, or light, whose scarcity constrains population growth or the distribution and abundance of organisms.

A close and long-term interaction between individuals of different species, including mutualism, commensalism, and parasitism, in which the relationship affects the survival or reproduction of participants.