4th Quarter Vocabulary - Life Science - 8th Grade

Allele

One of two or more versions of a gene.

Asexual reproduction

Reproduction without the joining of sperm and egg (single parent produces offspring).

Biological evolution

The process by which species changes over time through variation and natural selection.

Centriole

A tiny part in the cell that helps the cell split into two during cell division.

Chromosome

Structure in a cell’s nucleus that contains DNA and genes.

Classification

The system of grouping organisms based on similarities and differences.

Dominant trait

A trait that appears when at least one dominant allele is present.

Extinction

The complete disappearance of a species.

Fossil record

The history of life as documented by fossils preserved in rock layers.

Gene

A segment of DNA that codes for a particular trait.

Genotype

The genetic makeup of an organism (the alleles it has).

Heredity

The passing of traits from parent to offspring.

Heterozygous

Having two different alleles of a particular gene.

Homozygous

Having two identical alleles for a gene.

Mutation

A change in a gene or chromosome that can lead to variation.

Natural selection

The process where organisms that are better adapted to their environment tend to survive and produce more offspring.

Pedigree

A chart showing the inheritance of a trait through several generations.

Phenotype

The physical appearance or expression of a trait.

Recessive trait

A trait that only appears when two recessive alleles are present.

Sexual reproduction

Reproduction involving the fusion of sperm and egg producing offspring with genetic variation.

Species

A group of organisms that can interbreed and produce fertile offspring.

Symbiosis

A close relationship between organisms of different species.

Trait

A characteristic of an organism (such as eye color or leaf shape).

Variation

Differences among individuals of the same species.

Vestigial structure

A body part that no longer serves its original function but was important in an ancestor.

Cell division

When one cell splits into two new cells so living things can grow or heal.

DNA

The instructions inside the nucleus that tell how the living thing looks and works.

Habitat

The natural home or environment of an organism.

Adaptation

A special characteristic or behavior that helps a living thing survive in its environment.

Cell

The tiny building block that makes up all living things.

Dependent variable

In an experiment, the factor that you measure in response to changes you make.

Ecosystem

The community of organisms that live in a particular area, along with their nonliving environment.

Independent variable

The factor you change in an experiment to see how it affects the outcome.

Mitochondria

The part of the cell that makes energy, like a tiny power plant.

Nucleus

The 'boss' of the cell that tells the cell what to do.

Organelle

The small parts inside a cell that each have a special job.