ancestor: A predecessor. It could be a family forebear, such as a parent, grandparent or great-great-great grandparent. Or it could be a species, genus, family or other order of organisms from which some later one evolved. For instance, ancient dinosaurs are the ancestors of today’s birds. (antonym: descendant)
ape: A group of rather large primates, all of which lack a tail. They include gorillas, chimpanzees, bonobos, orangutans, gibbons and humans. Most people tend to group humans into their own separate subcategory owing to a number of special traits. These include a larger brain, greater mental abilities (including being able to talk) and their ability to walk on two legs.
bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.
bat: A type of winged mammal comprising more than 1,400 separate species — or one in every four known species of mammal. (in sports) The usually wooden piece of athletic equipment that a player uses to forcefully swat at a ball. (v.) Or the act of swinging a machine-tooled stick or flat bat with hopes of hitting a ball.
blood vessel: A tubular structure that carries blood through the tissues and organs.
calorie: The amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius. It is typically used as a measurement of the energy contained in some defined amount of food. The exception: when referring to the energy in food, the convention is to call a kilocalorie, or 1,000 of these calories, a “calorie.” Here, a food calorie is the amount of energy needed to raise 1 kilogram of water 1 degree C.
canine: (in anatomy) The pointed tooth in a mammal that separates its incisors from its premolars. These canine teeth tend to be especially long in carnivores.
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
diet: (n.) The foods and liquids ingested by an animal to provide the nutrition it needs to grow and maintain health. Sometimes this is a specific food-intake plan.
digest: (noun: digestion) To break down food into simple compounds that the body can absorb and use for growth. Some sewage-treatment plants harness microbes to digest — or degrade — wastes so that the breakdown products can be recycled for use elsewhere in the environment.
digestive tract: The tissues and organs through which foods enter and move through the body. In people, these organs include the esophagus, stomach, intestines, rectum and anus. Foods are digested — broken down — and absorbed along the way. Any materials not used will exit as wastes (feces and urine).
diversity: A broad spectrum of similar items, ideas or people. In a social context, it may refer to a diversity of experiences and cultural backgrounds.
ecologist: A scientist who works in a branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
enamel: The glossy, hard substance that covers a tooth.
enzymes: Molecules made by living things to speed up chemical reactions.
evolution: (v. to evolve) A process by which species undergo changes over time, usually through genetic variation and natural selection. These changes usually result in a new type of organism better suited for its environment than the earlier type. The newer type is not necessarily more “advanced,” just better adapted to the particular conditions in which it developed. Or the term can refer to changes that occur as some natural progression within the non-living world (such as computer chips evolving to smaller devices which operate at an ever faster speed).
evolutionary: An adjective that refers to changes that occur within a species over time as it adapts to its environment. Such evolutionary changes usually reflect genetic variation and natural selection, which leave a new type of organism better suited for its environment than its ancestors. The newer type is not necessarily more “advanced,” just better adapted to the conditions in which it developed.
excrete: To remove waste products from the body, such as in the urine.
fiction: (adj. fictional) An idea or a story that is made-up, not a depiction of real events.
fire: The burning of some fuel, creating a flame that releases light and heat.
gene: (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
gut: An informal term for the gastrointestinal tract, especially the intestines.
incision: (v. to incise) A cut with some blade-like object or marking that has been cut into some material. Surgeons, for instance, use scalpels to make incisions through the skin and muscle to reach internal organs.
iron: A metallic element that is common within minerals in Earth’s crust and in its hot core. This metal also is found in cosmic dust and in many meteorites.
livestock: Animals raised for meat or dairy products, including cattle, sheep, goats, pigs, chickens and geese. In some cases, farmed insects are referred to as mini-livestock.
malnutrition: (adj. malnourished) A condition that develops when an individual gets too little energy (calories) and/or not enough of the proper nutrients to support growth and health. Malnutrition can lead to stunted growth and susceptibility to disease.
mammal: An animal distinguished by possessing hair or fur, the secretion of milk by females for the feeding of their young, and (typically) the bearing of live young. They also are warm-blooded (or endothermic).
mineral: Crystal-forming substances that make up rock, such as quartz, apatite or various carbonates. Most rocks contain several different minerals mish-mashed together. A mineral usually is solid and stable at room temperatures and has a specific formula, or recipe (with atoms occurring in certain proportions) and a specific crystalline structure (meaning that its atoms are organized in regular three-dimensional patterns). (in physiology) The same chemicals that are needed by the body to make and feed tissues to maintain health.
molar: A type of broad, flat-topped tooth in mammals used for grinding food.
nervous system: The network of nerve cells and fibers that transmits signals between parts of the body.
nutrient: A vitamin, mineral, fat, carbohydrate or protein that a plant, animal or other organism requires as part of its food in order to survive.
organ: (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.
oxygen: A gas that makes up about 21 percent of Earth’s atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).
paleoanthropologist: A scientist who studies ancient humans and hominid biology, also the behavior and evolution of hominids evolved. This field is based on the analysis of fossils, remnants, artifacts or markings created or used by hominids.
parasite: An organism that gets benefits (such as food) from another species, called a host, while usually causing some degree of harm or discomfort to the host. Classic examples of parasites include ticks, fleas and tapeworms.
pressure: Force applied uniformly over a surface, measured as force per unit of area.
prey: (n.) Animal species eaten by others. (v.) To attack and eat another species.
primate: The order of mammals that includes humans, apes, monkeys and related animals (such as tarsiers, the Daubentonia and other lemurs).
protein: A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Antibodies, hemoglobin and enzymes are all examples of proteins. Medicines frequently work by latching onto proteins.
red blood cell: Colored red by hemoglobin, these cells move oxygen from the lungs to all tissues of the body. Red blood cells are too small to be seen by the unaided eye.
rodent: A mammal of the order Rodentia, a group that includes mice, rats, squirrels, guinea pigs, hamsters and porcupines.
skull: The skeleton of a person’s or animal’s head.
species: A group of similar organisms capable of producing offspring that can survive and reproduce.
spider: A type of arthropod with four pairs of legs that usually spin threads of silk that they can use to create webs or other structures.
starch: A soft white chemical made by all green plants. It’s a relatively long molecule made from linking together a lot of smaller, identical building blocks — all of them glucose, a simple sugar. Plants and animals use glucose as an energy source. Plants store that glucose, in the form of starch, as a reserve supply of energy. Animals that consume starch can break down the starch into glucose molecules to extract the useful energy.
system: A network of parts that together work to achieve some function. For instance, the blood, vessels and heart are primary components of the human body’s circulatory system. Similarly, trains, platforms, tracks, roadway signals and overpasses are among the potential components of a nation’s railway system. System can even be applied to the processes or ideas that are part of some method or ordered set of procedures for getting a task done.
taste: One of the basic properties the body uses to sense its environment, especially foods, using receptors (taste buds) on the tongue (and some other organs).
tick: A small eight-legged blood-sucking arthropod, related to spiders and mites. Although they look like bugs, these are not insects. They attach themselves to the skin of their host and feed on their blood. But in the process, they may spread any germs that could have been present in the blood of an earlier host.
toxic: Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.
vegan: One that eats no animal or dairy products. Such “strict vegetarians” also may avoid using goods made from animals, such as leather, wool or even silk.
vitamin: Any of a group of chemicals that are essential for normal growth and nutrition and are required in small quantities in the diet because either they cannot be made by the body or the body cannot easily make them in sufficient amounts to support health.
waste: Any materials that are left over from biological or other systems that have no value, so they can be disposed of as trash or recycled for some new use.