Lesson 1: Scientific Method, Spontaneous Generation, and Biological Classification

Flashcards reviewing experimental design, experiments testing spontaneous generation, traits of life, taxonomy, binomial nomenclature, and dichotomous keys.

What rule should be followed regarding variables when conducting an experiment?

Change one variable and keep everything else the same.

What is an independent variable?

The variable in an experiment that is subject to change.

What is a dependent variable?

The variable in an experiment that undergoes change according to the independent variable.

What is a constant in an experiment?

A factor that does not change throughout the experiment.

In Galileo's experiment, what were the independent variable, dependent variable, and constants?

The independent variable was the weight of the ball, the dependent variable was the speed of the balls dropping, and constants included height, shape, weather, etc.

What are the five steps of designing an experiment?

1. State the problem, 2. Form a hypothesis, 3. Setup a controlled experiment, 4. Record and analyze data, 5. Draw a conclusion.

What is the theory of spontaneous generation?

The theory that life can develop from nonliving matter.

What was Redi's experiment and its conclusion regarding spontaneous generation?

Redi placed meat in an open jar and a closed jar. Maggots appeared only in the uncovered jar, helping disprove spontaneous generation.

In Redi's experiment, what were the independent variable and dependent variable?

The independent variable was covering the jars, and the dependent variable was the presence of maggots.

What primary error led Needham to incorrectly conclude that spontaneous generation is real?

Needham did not boil the flask thoroughly (only briefly boiled the gravy) and only ran the experiment once.

How did Spallanzani improve upon Needham's experiment, and what was his finding?

Spallanzani fully boiled flasks containing gravy and found that fully boiled, sealed flasks yielded no life.

How did Pasteur disprove spontaneous generation using swan-neck flasks?

He boiled gravy in swan-neck flasks; when air entered through the swan neck, no microorganisms appeared, but when the swan neck was removed, microorganisms grew in the gravy.

What were the independent and dependent variables in Pasteur's experiment?

The independent variable was the use of the swan-neck, and the dependent variable was the presence of microorganisms.

What eight traits characterize living things?

Living things are made up of cells, reproduce, are based on DNA, grow and develop, obtain and use energy, respond to their environment, maintain a stable internal environment, and change over time.

How is a species defined?

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

Why is a mule considered sterile rather than a distinct breeding species?

A mule is produced by crossing a donkey and a horse, and breeding two mules results in no offspring (sterile).

What is taxonomy?

The study and practice of scientific classification.

How did Carolus organize living organisms?

He organized living things based on relatedness, originally splitting them into plants and animals, and subdividing them into Phylum, Class, Order, Family, Genus, and Species.

What are the naming rules of binomial nomenclature?

The scientific name is written in italics, where the first word denotes the genus (capitalized) and the second word denotes the species (lowercase).

What is a dichotomous key?

A series of paired statements describing physical characteristics of different organisms, leading step-by-step to identification.