CHAPTER 1Exploring & Classifying Life

Ch 1.1 – What is Science?

A. Scientists are like detectives trying to solve mysteries

1. They gather information and evidence in their search for

answers to questions

B. Science is a process of observing, studying and thinking about things to gain knowledge in order to better understand the world

1. Any attempt to find out how and why things behave the way they do is a performance of science

2. Critical Thinking – applies knowledge already known to new information presented to determine if it could be true

3. There are 3 branches of science:

a) Earth – study of Earth & Space

b) Life – study of living organisms

c) Physical – study of matter & energy

C. Scientists use a problem-solving procedure called the scientific method

1. Identify the problem

2. Gather Information

3. Make a hypothesis

a) an educated and testable prediction

4. Test the hypothesis (Experiment)

5. Collect and analyze the data

6. Draw conclusion

7. Repeat

8. Report

D. Experimenting

1. Variables are different factors that can change in an experiment

a) Controlled Experiment – designed so that only one variable is tested at a time

b) Independent Variable – the variable that changes/ is being tested

c) Dependent Variable – changes depending on the independent; typically is the thing being measured

d) Constants – variables that you do not want to change

2. Control – a standard to which results of an experiment can be compared to

a) Achieved by doing the same experiment but omitting the independent variable

E. Theories & Laws

1. Scientific Theory – an explanation of things or events based on scientific knowledge; the result of many observations and experiments

2. Scientific Law – statement about how things work or occur

F. Technology – the use of scientific discoveries for practical purposes

G. International System of Units (SI) – standard system of measurements used by scientists

1. Understood worldwide and across all language barriers

2. Units of measure:

a) Length – meter

b) Volume – liter

c) Mass - gram

Ch 1.2 – Living Things

A. All living things share 5 characteristics

1. Living things are organized into cells

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

2. Living things respond

a) Stimulus – anything that causes some change in an organism

b) Response – the way an organism reacts to a stimulus

c) Homeostasis – maintaining the proper conditions inside an organism

3. Living things use energy

a) All the energy that supports life comes from the Sun

b) Producers are organisms that can convert light energy into a usable form (food)

c) Consumers are organisms that must eat other organisms in order to acquire energy

4. Living things grow & develop

a) Growth of many-celled organisms is due to an increase in the number of cells

b) Growth in one-celled organisms is due to an increase in the size of the cell

c) Development – changes that take place during the life of the organism

5. Living things reproduce

a) This ability is essential for life in order for a species to continue to exist

B. What do living things need?

1. Raw materials – such as water and food (proteins, sugars, fats)

2. A Habitat – locations that provides organisms with the essential raw materials and shelter

Ch 1.3 – Where does life come from?

A. Spontaneous generation – early theory that living things could come from nonliving things

1. Was disproved with the use of controlled experiments by Louis Pasteur, a French chemist, in the mid-1800’s

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

1. Scientists want to know if this is the case, then how did life begin?

C. Oparin’s Hypothesis

1. In 1924, Russian scientist Alexander Oparin suggested that gases found in Earth’s early atmosphere combined to form more complex compounds found in living things

a) Gases included: ammonia, hydrogen, methane and water vapor

2. In 1953, scientists Stanley Miller and Harold Urey set up an experiment to test Oparin’s hypothesis

a) Showed that the chemicals found in living things could be produced, however it did not prove that this is how life began

Ch 1.4 – How Living Things are Classified

A. Classification System

1. Over 2,000 years ago, Aristotle first classified all living things as plants or animals

2. Carolus Linnaeus later developed a system to classify organisms based on similar structures

a) His most important contribution was developing binomial nomeclature

3. Modern systems are based on phylogeny

a) Phylogeny – the evolutionary history of an organism

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

a) Kingdoms are the first and largest category

b) The smallest classification category is a species

c) Organisms belonging to the same species are able to mate and produce fertile offspring

Categories Name of Category for

Humans

Kingdom Animalia

Phylum Chordata

Class Mammalia

Order Primates

Family Hominidae

Genus Homo

Species Sapien

B. Binomial Nomenclature – 2 word naming system used by Linnaeus to name species

1. First word identifies the genus or group of species

2. Second word tells something about the species – what it looks like, where it is found or who discovered it

3. Why use Scientific names?

a) To avoid mistakes – they are universal; also within our language some common names can be misleading

b) To show organisms in the same genus are closely related

c) To give descriptive information

C. Tools for Identifying Organisms

1. Field Guides – give descriptions and illustrations of organisms

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