Ch.1 Exploring and Classifying Life Life Science

Section 1 – What is science? Learning Objectives Apply scientific methods to problem solving. Demonstrate how to measure using scientific units.

Section 1 – What is science? A. Science – an organized way of studying things and finding answers to questions.

B. Critical thinking – a process that uses certain skills to solve problems.

C. Scientific methods – an organized way to solve a problem using a series of procedures. 1. State the problem. 2. Gather information. 3. Form a hypothesis, or a prediction that can be tested. 4. Test the hypothesis with an experiment. a. Variable is something in an experiment that can change. b. Control is the standard of comparison in an experiment; cannot change 5. Analyze data. 6. Draw conclusions 7. Report results.

Scientific Methods 1 2 3 4 5 + 6 7

D. Theories and laws 1. Scientific theory – an explanation of things or events based on scientific knowledge; the result of many observations and experiments. Example: Scientific theory of plate tectonics 2. Scientific law – a statement about how things work in nature; obvious and undeniable Example: Scientific law of gravity

E. International System of Units (SI) – Standard system of measurements used by scientists.

Discussion Question Why is it important to form a hypothesis?

Discussion Question Why is it important to form a hypothesis? A hypothesis helps you to develop an experiment… …and can help you figure out what the variable and controls should be.

Section 2 – Living Things Learning Objectives Distinguish between living and nonliving things. Identify what living things need to survive.

Section 2 – Living Things A. How are living things, or organisms, alike? 1. Living things are organized. a. Cell – the smallest unit of an organism that carries on the functions of life b. Each cell has an orderly structure and contains hereditary material (DNA).

2. Living things respond. a. Stimulus – anything that causes some change in an organism. b. Response – the way an organism reacts to a stimulus, often results in movement.

c. Homeostasis – maintaining the proper conditions inside an organism

3. Living things use energy. 4. Living things grow and develop. a. Growth of many-celled organisms (multicellular) is due to an increase in the number of cells.

b. Growth of one-celled (unicellular) organisms is due to an increase in the size of the cell. c. Development – changes that take place during the life of an organism 5. Living things reproduce.

B. What do living things need? 1. A place to live that provides for all of the organism’s needs 2. Raw materials, like water, proteins, fats, and sugars.

Discussion Question What do you have in common with a flower?

Discussion Question What do you have in common with a flower? Both: are organized and have cells respond to stimuli and maintain homeostasis. take in and use energy: a plant from the Sun, a person from food. grow and develop. reproduce. need a place to live and raw materials like water.

Section 3 – Where does life come from? Learning Objectives Describe experiments about spontaneous generation. Explain how scientific methods led to the idea of biogenesis.

Section 3 – Where does life come from? A. Spontaneous generation – early theory that living things could come from non-living things; disproved by Louis Pasteur in the mid-1800s.

B. Biogenesis – theory that living things come only from other living things.

C. Alexander I. Oparin’s hypothesis on the origins of life  gases in Earth’s early atmosphere combined to form more complex compounds found in living things. 1. Gases: (Earth’s early atmosphere) a. ammonia b. hydrogen c. methane d. water vapor

2. Stanley L. Miller and Harold Urey tested Oparin’s hypothesis and showed that chemicals found in living things could be produced… …however, the chemicals did not form new life.

Discussion Question Why didn’t Miller and Urey’s experiment prove Oparin’s hypothesis?

Discussion Question Why didn’t Miller and Urey’s experiment prove Oparin’s hypothesis? Miller and Urey proved that it is possible to produce some chemicals found in living things using ammonia, hydrogen, methane, and water vapor. However, they could not prove that in nature the combination of gases produced life…(next slide)

Much more research and experiments have been done since then…

Section 4 – How are living things classified? Learning Objectives Describe how early scientists classified living things. Explain how similarities are used to classify organisms. Explain the system of binomial nomenclature. Demonstrate how to use a dichotomous key.

Section 4 – How are living things classified? A. Classification systems 1. Aristotle classified organisms more than 2,000 years ago. (First to classify living things) 2. Carolus Linnaeus introduced a system based on similar structures of organisms. (He thought changes in parent’s life time were passed down to their offspring)

3. Modern systems based on phylogeny – the evolutionary history of an organism.

4. Today’s classification system separates organisms into 6 kingdoms.

a. Kingdoms are the first and largest category b. The smallest classification category is species. c. Organisms that belong to the same species can mate and produce fertile offspring.

B. Binomial nomenclature – two-word system used by Linnaeus to name species.  Scientific name 1. First word identifies the genus, or group of similar species. (CAPITALIZED) 2. Second word tells something about the species – what it looks like, where it is found, or who discovered it. (lowercase)

3. Why use scientific names? a. To avoid mistakes b. To show that organisms in the same genus are related c. To give descriptive information d. To allow information to be organized easily

C. Tools for identifying organisms 1. Field guides – descriptions and illustrations of organisms

2. Dichotomous keys – detailed lists of identifying characteristics that include scientific names

Discussion Question How do scientific names show you that organisms are related?

Discussion Question How do scientific names show you that organisms are related? Organisms with similar evolutionary histories are classified together… …because of this, you know that organisms in the same genus are related.