NY Regents Life Science: Biology key terms

A thin, flexible barrier of lipids and proteins that surrounds every cell and controls which substances enter or leave, allowing the cell to stay stable while exchanging materials with its surroundings.

A specialized structure inside a eukaryotic cell that performs one particular job, such as making energy, building proteins, or packaging materials for export. Each has a shape suited to its function.

An organelle with folded inner membranes where cellular respiration takes place, releasing usable energy from glucose and storing it in ATP. Cells with high energy demands, such as muscle cells, contain many of them.

A green organelle found in plant cells and algae that contains chlorophyll and carries out photosynthesis, capturing light energy to build glucose from carbon dioxide and water.

A small structure, free in the cytoplasm or attached to the endoplasmic reticulum, that assembles amino acids into proteins by following instructions carried by messenger RNA.

The net movement of particles from an area of higher concentration to an area of lower concentration, driven by random motion and requiring no added energy from the cell.

The diffusion of water across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration, which can swell or shrink cells.

The process by which an organism keeps internal conditions such as temperature, water balance, and blood sugar within a narrow range despite changes in the outside environment.

A control loop in which the output of a process affects the process itself. Negative feedback reverses a change to restore balance, while positive feedback amplifies a change.

A protein that speeds up a specific chemical reaction by lowering the energy needed for it to occur, without being consumed. Its shape determines which molecules it can act on.

The loss of a protein's functional three-dimensional shape caused by heat, extreme pH, or other conditions, which permanently destroys the protein's ability to do its job.

The process in which organisms with chlorophyll use light energy to convert carbon dioxide and water into glucose and oxygen, storing energy in chemical bonds.

The process in which cells break down glucose, using oxygen in aerobic organisms, to release energy that is captured in ATP, with carbon dioxide and water as waste products.

The double-stranded molecule that stores genetic instructions in the sequence of its bases, adenine, thymine, guanine, and cytosine. It is copied before a cell divides and is passed to offspring.

A segment of DNA that carries the instructions for building a particular protein or for controlling a trait. Genes are passed from parents to offspring and come in variant forms called alleles.

One of the alternative forms of a gene, such as the version that produces a dominant trait or the version that produces a recessive one. An organism inherits one allele from each parent.

A structure of tightly coiled DNA and protein that carries genes. Human body cells contain 23 pairs, with one chromosome of each pair inherited from each parent.

A trait that appears in an organism when at least one copy of the controlling allele is present, masking the effect of a recessive allele paired with it.

A trait that appears only when both inherited alleles are the recessive form, because a dominant allele present alongside it would mask its expression.

A grid used to predict the possible genotypes and their relative probabilities among offspring when the alleles of two parents are combined.

The combination of alleles an organism carries for a particular gene, described as homozygous when the two alleles match and heterozygous when they differ.

The observable characteristics of an organism, such as eye color or height, produced by the interaction of its genotype with environmental influences.

A change in the base sequence of DNA that may alter a protein or how much of it is made. Mutations are a source of new alleles and can be harmful, neutral, or beneficial.

A type of cell division that halves the chromosome number and produces genetically varied gametes, which combine at fertilization to restore the full chromosome number in the offspring.

The process by which individuals with inherited traits that improve survival and reproduction in a given environment leave more offspring, so those traits become more common over generations.

An inherited feature or behavior that increases an organism's chance of surviving and reproducing in its environment, having arisen over many generations through natural selection.

Differences in alleles among members of a population, produced by mutation, sexual reproduction, and recombination. Variation is the raw material on which natural selection acts.

The formation of new species, usually when populations become reproductively isolated so that they no longer interbreed and accumulate different genetic changes over time.

The principle that organisms share ancestors, so similarities in anatomy, embryos, DNA, or fossils reflect shared evolutionary history and can be used to build relationships among groups.

The ordered collection of preserved remains and traces of past life in rock layers, providing evidence of organisms that lived long ago, their relative ages, and patterns of change.

The largest population of a species that a given environment can support over time, limited by food, water, space, and other resources available there.

Any resource or condition, such as nutrients, light, predators, or disease, that restricts the growth, distribution, or size of a population in an ecosystem.

All the individuals of the same species living in a defined area at the same time, which can grow, shrink, and change in genetic makeup over generations.

A model showing the feeding relationships in an ecosystem as interconnected chains, tracing how energy and matter pass from producers to consumers and decomposers.

An organism that makes its own food, usually by photosynthesis, forming the base of a food web and supplying energy to all the consumers in the ecosystem.

A diagram showing that only about ten percent of the energy at one feeding level is passed to the next, so higher levels support fewer organisms and less total energy.

The variety of living things in an area, measured as the number of species and the genetic differences within them. Greater biodiversity generally helps ecosystems resist disturbance.

A non-native organism introduced into an ecosystem where it spreads rapidly, often lacking natural predators, and outcompetes or harms native species and their habitats.

Managing natural resources so they are consumed no faster than they can be replaced or renewed, preserving them for future generations while meeting present needs.

The effects people have on ecosystems, including habitat destruction, pollution, climate change, and overuse of resources, which can reduce biodiversity and disrupt natural cycles.