LIFE SCIENCE (copy)

Cells

The basic unit of life, from which all living organisms are made.

Unicellular

Organisms that consist of a single cell.

Multicellular

Organisms consisting of many different types of specialized cells.

Cell Membrane

A structure that keeps the cell’s contents separate from its external environment.

Cytoplasm

A watery, jellylike substance inside the cell membrane that can include other structures.

Genetic Material

Contains coded instructions for carrying out the cell’s activities.

Prokaryotes

Cells, such as bacteria, that do not have a nucleus.

Eukaryotic Cells

Cells that contain their genetic material within a nucleus; includes all plant and animal cells.

Cell Wall

A structure that gives plant cells shape and rigidity.

Photosynthesis

The process by which green plants, some algae, and bacteria use energy from sunlight to make food.

Glucose

A simple sugar produced during photosynthesis.

Chlorophyll

The pigment that gives plants their green color, absorbs light energy for photosynthesis.

Carbohydrates

Energy-storing molecules in plants as a result of photosynthesis.

Cellular Respiration

The process by which cells break down carbohydrates to release energy.

Circulatory System

The system that consists of the heart and blood vessels, moving blood throughout the body.

Heart

The major organ of the circulatory system, a muscle that contracts to pump blood.

Arteries

Large blood vessels that carry blood away from the heart.

Capillaries

Small blood vessels where the exchange of substances occurs.

Respiratory System

The system that takes oxygen from the air into the body and removes carbon dioxide.

Trachea

The windpipe that connects the throat to the lungs.

Bronchi

The two tubes that branch from the trachea into each lung.

Bronchioles

Smaller tubes that branch from the bronchi, leading to the alveoli.

Alveolus

A tiny spherical sac in the lungs where gas exchange occurs.

Digestive System

The system that breaks down food into nutrients and removes waste.

Saliva

The fluid that begins the chemical breakdown of food in the mouth.

Enzymes

Proteins that speed up chemical reactions, such as breaking down food.

Nervous System

The system that receives, processes, and transmits information, controlling body activities.

Brain

The organ that coordinates most body activities and functions.

Infection

The invasion of the body by germs that cause disease.

Bacteria

Single-celled microorganisms that can cause infections.

Virus

Microscopic infectious agents that can only replicate inside a living host.

Immune System

The body’s defense system that produces antibodies to destroy germs.

Nutrients

Substances needed for growth and maintenance of cells.

Proteins

Essential nutrients composed of amino acids needed for body functions.

Drug Abuse

The nonmedical use of drugs that interferes with normal functioning.

Addiction

A severe form of dependence on a substance that causes withdrawal symptoms.

Habituation

A milder form of dependence where the urge to take a drug is strong without withdrawal symptoms.

Genes

Factors that control the inheritance of specific traits.

Alleles

Different forms of a gene.

Dominant Allele

An allele that determines the appearance of a trait in an organism.

Recessive Allele

An allele that is hidden when a dominant allele is present.

Hybrid

An offspring with two different alleles for a trait.

Chromosomes

Rod-shaped structures in the nucleus of cells that carry genes.

DNA

Deoxyribonucleic acid, a molecule that contains the genetic code.

Protein Synthesis

The process by which proteins are produced from the information in genes.

Codon

A set of three base pairs on mRNA that instructs the creation of an amino acid.

Genetic Engineering

The manipulation of an organism's DNA to produce desired traits.

Evolution

The scientific theory explaining how species change over time.

Adaptations

Traits that help organisms survive in their environments.

Natural Selection

The process by which individuals better adapted to their environment are more likely to survive.

Ecosystem

A community of organisms interacting with their physical environment.

Biosphere

The global sum of all ecosystems; the zone of life on Earth.

Producers

Organisms that produce their own food using sunlight.

Consumers

Organisms that depend on producers for energy.

Food Web

A complex network of feeding relationships in an ecosystem.