EXPLORING AND CLASSIFYING LIFE WHAT IS SCIENCE Science

EXPLORING AND CLASSIFYING LIFE

WHAT IS SCIENCE • Science is an organized way of studying things and finding answers to questions. • Scientific methods are procedures used to solve problems and answer questions. • Hypothesis- an explanation that can be tested. • Control- the standard to which the outcome of a test is compared. • Variable- something in an experiment that can change.

WHAT IS SCIENCE • Steps of the Scientific Method • Make an observation • Ask a question • Research • Form a hypothesis • Complete experiment • Observations • Results/ Conclusion

WHAT IS SCIENCE • A theory is an explanation based on many scientific observations. • Scientists use the SI system for measurements. • A scientific law is a statement about how things work in nature that seems to be true all the time. • Example- Law of heredity- explains how genes are inherited

LIVING THINGS • Organism- any living thing. • A cell is the smallest unit of an organism that carries on the functions of life. • Homeostasis- the ability to keep the proper internal conditions of an organism’s life. • Organisms use energy to stay organized and perform activities like homeostasis.

LIVING THINGS • All of the changes that take place during an organism’s life are call development • All living things need a place to live, water, and food.

LIVING THINGS • ORDER +A • O- Organized by cells • R-Reproduce • D-Develop and Grow • E- Energy • R- Respond to change. • Anything that causes some change in an organism is a stimulus. A- Adapt

WHERE DOES LIFE COME FROM? • Spontaneous generation- the idea that living things come from nonliving things. • The work of Louis Pasteur in 1859 disproved theory of spontaneous generation. • Louis Pasteur replaced theory of spontaneous generation with biogenesis. • Biogenesis is theory that living things come only from other living things.

WHERE DOES LIFE COME FROM? • Turn to page 21

HOW ARE LIVING THINGS CLASSIFIED? • Phylogeny- the evolutionary history of an organism, how it has changed over time. • The classification system used today groups organisms into 6 kingdoms. • Kingdom is the first and largest category. • Turn to page 23

HOW ARE LIVING THINGS CLASSIFIED? • Binomial nomenclature is the two-word naming system that gives organisms their scientific names. • The first word of the two-word name identifies the genus of the organism. • Genus-a group of similar species. • The second word of the name identifies the species. • Example- Felis Domesticus (house cat)

HOW ARE LIVING THINGS CLASSIFIED? • Four reasons scientific names are used: 1. Avoid mistakes 2. Organisms with similar evolutionary histories are classified together. • Organisms in the same genus are related. 3. Gives descriptive information about the species. 4. Allow information about organisms to be organized easily.

HOW ARE LIVING THINGS CLASSIFIED? • Dichotomous key- a detailed list of identifying characteristics that includes scientific names • Dichotomous keys are arranged in steps with two descriptive statements. • Turn to page 26