Unit 8 and 9 Biology

Variation

Individual organisms demonstrate different traits.

Adaptations

Some variation gives an organism a survival advantage.

Inheritance Traits

Favorable traits that get passed down from parent to offspring.

Fossil Record

A record of ancient past life, never complete.

Biogeography

The study of where organisms lived and how their ancestors lived.

Homologous Structure

Structures that are anatomically similar but perform different functions.

Analogous Structure

Structures that share the same functions but are not anatomically similar.

Vestigial Structure

A structure that is evidence of the past but does not serve a current purpose.

Directional Selection

When an extreme trait helps organisms survive better, becoming more common in the population.

Stabilizing Selection

When the average trait is best and extreme traits are selected against.

Disruptive Selection

When both extreme traits are favored and the average trait is selected against.

Fitness

How well an organism survives and reproduces.

Binomial Nomenclature

The two-part naming system used to classify organisms.

Gene Pool

All gene variations within a population.

Allele Frequency

How often a certain allele appears in a population.

Genotype Frequency

The frequency a genotype appears in a population.

Population

A group of individuals of the same species that live in the same area and interbreed.

Environmental Pressures

Factors in an organism's surroundings that favor certain traits.

Charles Darwin

The father of evolution, known for studying finches' beak variation.

Natural Selection

A mechanism of evolution where organisms with advantageous traits are more likely to survive.

Genetic Drift

A change in allele frequencies in a population due to chance.

Speciation

The development of new species, often from isolated populations.

Hardy-Weinberg Equilibrium

A situation in which allele and genotype frequencies remain constant unless evolution is acting.

Ecology

The scientific study of interactions among organisms and their environment.

Biotic Factors

All living organisms in an environment.

Abiotic Factors

All the nonliving things found in an environment.

Climate

Patterns and averages of temperature and precipitation over many years.

Weather

Short-term changes in weather conditions.

Primary Succession

Occurs only on bare rock, starting new ecological communities.

Pioneer Species

First organisms to colonize newly formed rock areas.

Trophic Level

An organism's position in a food chain or web.

10% Rule

Only 10% of the energy at one trophic level is available to the next.

Greenhouse Effect

A natural process that keeps Earth warm by trapping heat in the atmosphere.

Limiting Factors

Any factor that controls the growth of a population.

Niche

The specific role that an organism plays in its environment.

Mutualism

A symbiotic relationship where both organisms benefit.

Commensalism

A symbiotic relationship where one organism benefits and the other is unaffected.

Parasitism

A symbiotic relationship where one organism benefits and the other is harmed.