Chapter 1: the Science of Biology

Chapter 1: The World of Life Science

What is Science?

· Science –

· Biology –

What are your ideas about what specifically makes science the most powerful method we have for understanding nature?

Section 1-2: How Scientists Work

Using the Scientific Method

· “The Scientific Method” =

#1: Ask a Question

Ask a Question Example

· Some peaches are juicy and sweet. Others are spongy with very little flavor.

o What makes some peaches juicier than others?

· My neighbor has thick, green grass. Mine is brown in spots and is thin.

o What does grass need to be healthy?

Ask a Question Practice

Make observations and form a scientific question regarding the figures below.

Observations: Observations:

Question: Question:

#2: Form a Hypothesis

· Hypothesis –

•

· Prediction –

•

Form a Hypothesis Example

· Hypothesis: Thick skin on apples is due to cold autumn temperatures.

· Prediction: If apples are exposed to cold autumn temperatures, then they will have thicker skin than other apples.

Form a Hypothesis Practice

Write a possible hypothesis and prediction for each of the following observations.

Ø The plants in Mr. Smith’s living room are large, healthy and green but the plants in Mr. Smith’s dining room are small and yellowish in color.

Hypothesis:

Prediction:

Ø All of the fish in the classroom fish tank are healthy except for the algae eaters that keep dying.

Hypothesis:

Prediction:

#3: Test the Hypothesis

* Whenever possible, an experiment should be designed to have ___________ variable that is changed at a time. (AKA: Controlled Experiment)

· Controlled Variable/s –

· Manipulated Variable –

· Responding Variable –

· Experimental Group –

· Control or Control Group –

Test the Hypothesis Example

Hypothesis: Tomato plants given fertilizer will produce more tomatoes than plants that are not fertilized.

Plant A Plant B

* Both plants are given the same soil, amount of water and sun, temperature, pot size, and growth time.

* Plant B is fertilized once a week.

Ø Controlled Variables –

Ø Manipulated Variable –

Ø Responding Variable –

Ø Control Group –

Ø Experimental Group –

Why change only one variable?

Experimental Design Practice

Examine the hypothesis and experiment below. Re-design the experiment to make it better. Identify all variables and groups.

Hypothesis: Bacteria exposed to antibiotics will be killed.

Original Experiment:

Plate A Plate B

Stored on counter (22° C) Stored in incubator (35° C)

Given penicillin Given ampicillin

Stored in light Stored in dark

Not given nutrients Given nutrients

Re-Designed Experiment:

Plate A Plate B

Ø Controlled Variables –

Ø Manipulated Variable –

Ø Responding Variable –

Ø Control Group –

Ø Experimental Group –

#4: Analyzing the Results

Analyzing the Results Example

Effects of Storage Temperature on Seed Germination
Storage Temperature / Inside
68°F / Inside
25°F / Outside
25°F
Germinated seeds / 0% / 80% / 85%

Analyze the Results Practice

Examine the results of a frog experiment and the table and graph used to represent the data. Fix the data table and graph to improve them.

Results: Frogs given caffeine jumped 27cm and frogs not given caffeine jumped 20 cm.

No Caffeine / Caffeine
Distance of jump / 20 / 27

Bar vs Line Graphs

Should you use a bar or a line graph?

Number of American Thrushes living in each of five forests. ______

100 students’ choices for their favorite lunch. ______

Comparing the number of chromosomes to the number of genes. ______

The number of mates attracted by red vs. yellow vs. blue-beaked parrots. ______

The growth of a seedling (days old vs. height) ______

#5: Draw Conclusions

· Conclusion –

(Add at least one “note to remember” to each step, based upon in-class discussion)

· A conclusion should do the following:

1. State the purpose in your own words.

2. Summarize the scientific idea the lab is about, and define any vocab words.

3. Restate the hypothesis and prediction, not copying exactly how they were already written.

4. Summarize (1-2 sentences) the procedure.

5. State whether the results support or refute the hypothesis/prediction.

6. Support the evaluation you made in step 5 with specific evidence (data).

“The average height in group A was 2 cm higher than group B.” = Specific.

“Group A grew more.” = Not specific.

7. Give a final concluding statement.

If your hypothesis was supported, summarize that.

If it was refuted, give a new and improved hypothesis.

Draw Conclusions Example

Label the paragraph with numbers 1-7, marking where each of the 7 steps listed above occurs.

The experiment was designed to test whether caffeine would increase the distance frogs could jump. Caffeine is a stimulant. Stimulants are psychoactive drugs, meaning that they affect the nervous system. Jumping involves the nervous and muscular systems, so it’s possible that caffeine could affect jumping. It was hypothesized that caffeine improves muscle action, and it was predicted that the more caffeine a frog has, the farther it will jump. To test this, some frogs were given caffeine and others were not, and the lengths of their jumps were measured.

The results supported the hypothesis and prediction, showing that frogs given caffeine jumped an average of 7cm farther than frogs that were not given caffeine. Caffeine does indeed increase the distance that frogs can jump.

Draw Conclusions Practice

Examine the hypothesis and experimental results below, and write an appropriate conclusion.

Hypothesis: Carrots require high nitrogen levels for best growth.

Prediction: The more nitrogen there is in the soil, the longer the carrot will grow to be.

Effects of Nitrogen Levels on Carrot Growth
Level of Nitrogen / None / Low / High
Average Carrot Length / 6 in. / 10 in. / 4 in.

Results:

Conclusion (for step 4, make up a reasonable procedure you could have done for this study):

#6: Communicate Results

· This allows others to repeat the investigation, skeptically evaluate the validity of the results, and can lead to further questions and investigations.

Scientific Language

§ “Science words” can be different from English words even when they look exactly the same.

Meaning in “normal English” / Meaning in “scientific English” / Example of scientific usage
Observation
Fact
Law
Theory

Section 1-3: Studying Life

What does it mean to be alive?

What characteristics make something living versus non-living?

Characteristics of Living Things

Living things… are made of cells.

· Cell –

· Cells are the smallest units of life in all organisms.

§ Unicellular organisms –

§ Multi-cellular organisms –

Living things… reproduce.

· Reproduction –

§ Sexual Reproduction: two cells from different parents unite to

produce the first cell of a new organism

§ Asexual Reproduction: a single-celled organism divides in half

to form two new organisms, OR, a portion of an organism splits off

to form a new organism.

Living things… have a universal genetic code.

Living things… grow and develop.

· Growth –

§ Unicellular organisms:

§ Multi-cellular organisms:

· Development –

Living things… need materials and energy.

· Metabolism –

· Organisms vary in how they obtain energy:

§ Autotrophs:

§ Heterotrophs:

Living things… respond to the environment.

· Organisms live in constantly changing environments (living and

nonliving parts).

Living things…maintain internal balance.

Living things… evolve.

· Natural Selection –