SCIENCE

1-1 What is Science? Humans have a great capacity for wonderment and problem-solving. Our brains look for patterns and make connections Humans have been around for about 200,000 years. Humans have only been using the scientific method for about 400 years.

Simple Timeline of Great Thinkers 400 BC Ancient Greeks Aristotle & Democritus Conclusions based on logic and untested observations 1300s Monks and Theologians Started to think about proper methods of science 1600s Microscope & Telescope invented 1637 First Scientific Method Making conclusions by testing observations

The goal of science is to: investigate and understand the natural world. explain events in the natural world. use those explanations to make useful predictions. Science is: an organized way of using evidence to learn about the natural world. The Scientific method is: A way to ask and answer questions about the natural world by first observing, then TESTING, then making conclusions.

The Scientific Method

The Scientific Method Observations: process of gathering information in an orderly way Data: the information gathered Qualitative: descriptive information without measurements Quantitative: measured information expressed as numbers Inference: a logical interpretation based on prior knowledge or experience

The Scientific Method Hypothesis: a proposed scientific explanation for a set of observations; based on prior knowledge Often called “an educated guess” MUST be able to be tested by experimentation! Conclusion: results or answers based on experiments. Peer review helps ensure that conclusions are valid.

1-2 How Do Scientists Work? Asking a Question Many years ago, people asked: How do organisms come into being? Forming a Hypothesis One early hypothesis was spontaneous generation, : the idea that life could come from nonliving matter. People thought that maggots spontaneously appeared on meat. In 1668, Redi proposed a new hypothesis: maggots come from eggs that flies laid on meat.

How do scientists test hypotheses? Whenever possible, a hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or controlled.

Setting Up a Controlled Experiment There are 3 types of variables: Controlled: things that stay the same ex: Manipulated: variable you deliberately change ex: 3. Responding: variable that changes in response to the manipulated variable (the thing you changed)

Redi’s Experiment

Redi’s Experiment

Repeating Investigations Needham's Test of Redi's Findings Needham challenged Redi’s results by claiming that spontaneous generation could occur under the right conditions. He sealed a flask of gravy & heated it. After several days the gravy had microorganisms.

Repeating Investigations Spallanzani’s Test of Redi's Findings Two flasks of gravy were boiled. One was sealed & one left open. The open flask grew microorganisms.

Repeating Investigations: Pasteur’s Experiment

Pasteur's Test of Spontaneous Generation Louis Pasteur conclusively disproved the hypothesis of spontaneous generation. Pasteur showed that all living things come from other living things.

How a theory develops As evidence from numerous investigations builds up, a hypothesis may become so well supported that scientists consider it a theory. A theory is a well-tested explanation that pulls together a broad range of observations. Theories are revised as new evidence is uncovered

1-3 Studying Life The Characteristics of Living Things Are made up of cells A cell is the smallest unit of an organism that can be considered alive Reproduce Sexual reproduction: cells from two different parents unite to form the first cell of the new organism Asexual reproduction: a single parent produces offspring that are identical to itself

The Characteristics of Living Things Are based on a universal genetic code Organisms store the information they need to live, grow, and reproduce in a genetic code in a molecule called DNA. (deoxyribonucleic acid) Grow and develop Its cells differentiate: they look different and perform different functions UNICELLULAR – increase in size MULTICELLULAR – increase in size & number of cells

The Characteristics of Living Things Obtain and use materials and energy Ex: food, water, minerals The combination of chemical reactions through which an organism builds up or breaks down materials is called metabolism. Respond to their environment A stimulus is a signal to which an organism responds. It is what causes a response. Ex: light, temperature, noise A response is the reaction.

The Characteristics of Living Things Maintain a stable internal environment Although conditions outside an organism may change, conditions inside an organism tend to remain constant. This process is called homeostasis. Ex: internal temp. of 98.6 – regulate by sweating or goose bumps Fluids- too little(dehydrate), too much (cells swell) Birds puff up feathers to stay warm Evolve – over time and many generations

How can life be studied at different levels?