THE SCIENCE OF BIOLOGY Chapter 1 Understanding the

THE SCIENCE OF BIOLOGY Chapter 1

Understanding the Black Death Killed 1/3 of the population in Europe People in the 13 th century thought it was caused by “bad air” or demons How do we find out? Why do we care?

The Goals of Science to investigate and understand nature to explain events in nature to use those explanations to make useful predictions Investigations of disease led to antibiotics and antivirals

The Methods of Scientists collect and organize information (data) in a careful, orderly manner look for patterns in data propose explanations that can be tested by examining the evidence

Observation Based on five senses: sight, hearing, taste, smell, touch Quantitative – numerical n Ex- how many, how big, how fast Qualitative – descriptive n Ex – color, texture, smell, behavior

Hypothesis Good Bad 1. Plants will Logical, testable, grow taller grow better tentative explanation when given for a set of Miracle Grow. observations or a 2. Girls will 2. Girls are possible answer to a score higher smarter than scientific question on math boys. tests than Arise from prior boys. knowledge, logical inferences, or imaginative guesses

Testing hypotheses Can be done through further observation Usually done through controlled experiments A hypothesis proven to be wrong still adds to the body of scientific knowledge

THE CASE OF THE CHUNKY MILK You wake up in the morning very thirsty. Accidentally, you reach over and grab the glass of milk you left out yesterday. After one swallow, you start gagging and want to throw up. What happened? How can we PROVE it?

Observations n n n Smells nasty White in color Looks chunky like cottage cheese Tastes like #%$^#@ Feels warm The gallon in the fridge is NOT expired yet

BAD: The milk is bad. GOOD: If the milk is allowed to sit out of the fridge for approximately 24 hours, then the milk will spoil.

Designing an Experiment State the problem: milk tastes gross, looks chunky Form the hypothesis: If the milk is allowed to sit out of the fridge for approximately 24 hours, then the milk will spoil. Set up Experiment

Leave a cup of milk out of the fridge for 24 hours and see what happens. Cup of milk in cool environment Cup of milk at room temperature Variables involved in the experiment n n Milk Temperature Amount of milk Time Independent (Manipulated) Dependent (Responding) What happens?

What are the results? Accept or Reject Hypothesis

Scientific Method There is a logical way of thinking found in all scientific experiments n n n Observe a problem Ask a question Create a hypothesis Design a controlled experiment Collect and analyze data Share results

Spontaneous Generation In the past, people thought life could just appear from non living matter Ex – maggots just appear on meat

Redi’s Experiment 1668 – proposed hypothesis that the maggots came from flies Tested hypothesis by placing meat in jars and covering some of the jars Everything was controlled (kept the same) except the variable (covering jars)

Redi’s Experiment Uncovered jars Covered jars Several days pass Maggots appear No maggots appear

Types of Variables Independent: the variable being manipulated n Redi controlled the covering of the jars Dependent: the variable that changes in response to the independent variable n The presence of maggots in Redi’s experiment

Spallanzani’s Experiment Tested Redi’s results Boiled to kill microorganisms Gravy is boiled. What are the independent and dependent variables? ? Gravy is boiled. Flask is open. Gravy is teeming with microorganisms. Flask is sealed. Gravy is free of microorganisms.

Pasteur's Experiment Provided final proof that spontaneous generation did not occur

Figure 1 -11 Pasteur’s Experiment Pasteur's Experiment Section 1 -2 Broth is boiled. Go to Section: Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.

Pasteur's Experiment What was Pasteur’s hypothesis? n Microorganisms would not just appear Independent variable? n Curved neck of flask Dependent variable? n Presence of microorganisms

A Theory in Science A very well supported hypothesis When a hypothesis has been verified many times by different scientists, it becomes a theory Redi’s, Spallanzani’s, and Pasteur’s experiments led to theory of biogenesis (life comes from life) Theories explain phenomena in nature

What makes something alive? n n n Is a book alive? Is a tree alive? Is a computer alive?

Characteristics of Life Made of one or more cells Reproduction – sexual or asexual Contain RNA and/or DNA – universal genetic code Growth (getting bigger) and development (changing, ex: puberty)

Characteristics of Life Need energy – metabolism is the sum of all chemical reactions in body Respond to their environment Maintain homeostasis – stable internal environment Evolve (change) over time

Tools and Procedures SI = System International n The international, metric standard for reporting units Necessary to ensure scientific data can be interpreted by all scientists everywhere Easy to use because it is based in 10 n To convert between units, you only have to move decimals

Metric Units Length Mass Volume Temper -ature Meter Gram Liter Celsius Second m g L C s Length = distance Mass = amount of matter in an object Volume = amount of space an object occupies Temperature = measurement of heat energy Time = too abstract for me to define… Time

Tools of the Trade Metric Ruler n Measures in meters, centimeters, millimeters Longer lines mark cm Smaller lines mark mm

Tools of the Trade Graduated Cylinder n Measures liquid volume in Liters and milliliters Measurement is made at the “meniscus, ” the curve of the liquid line that occurs when a liquid is added

Tools of the Trade Thermometer n Measures in degrees Celsius Metric Scale n n Measures in grams or kilograms Can be manual or electric

Metric Prefixes kilo k 1000 hecto deka h 100 m = meter g = gram L = liter dk 10 Base deci m, g, L 1 d 0. 1 centi milli c 0. 01 m. 001

Some Common Examples… Mass mg = milligram g= gram kg = kilogram Length mm = millimeter cm = centimeter m= meter km = kilometer Volume ml or m. L = milliliter L= Liter kl or k. L = kiloliter

Converting Metric Units Metric conversions are WAY simple because the metric system is based in 10’s Changing between metric units simply requires movement of a decimal. Changing from the English to metric system requires the use of conversion factors (and usually a calculator!).

Let’s Practice Metrics 1. 2. 3. 4. 5. 6. 7. 1 m = ? cm 1 kg = ? g 1 m. L = ? L 286 g = ? mg 48. 7 mm = ? m 147. 965 kg = ? hg 280, 000 mg = ? kg 8. 23 cc = ? ml 1. 2. 3. 4. 5. 6. 7. 8. 1000 0. 001 286, 000 0. 0487 1479. 65 0. 28 23