Unit 1: What is Biology

I. What is Biology?

A. Biology – study of life, of all living things1. Many branches: biochemistry, cell biology,

genetics, evolutionary theory, microbiology, botany, zoology, et.

B. Six (6) Major Themes in Biology1. Cell Structure & Function

a) Unicellular – organisms made of one cell

b) Multicelluar – organisms made of more than one cell

2. Stability & Homeostasisa) Homeostasis – a level or stable internal

environment in cells/living things

3. Reproduction & Inheritancea) Sexual Reproduction – DNA from 2 parts or 2

organisms is combined

b) Asexual Reproduction – DNA is not combined, rather an organism copies its DNA and splits

4. Evolutiona) Evolution – how organisms change and come to

exist

b) Natural Selection – “survival of the fittest”; drives evolution

5. Interdependence of Organisms

6. Matter, Energy, & Organizationa) Organisms obtain, use, & transfer energy &

matter

b) Autotrophs – organisms that can make their own food to obtain energy

c) Heterotrophs – orgnanisms that cannot make their own food, but must take it in for energy

C. Characteristics of Life1. Made of units called cells.

• Prokaryote Cell – cell that lacks a true nucleus and true organelles

• Eukaryote Cell – cell that has a true nucleus and true organelles

2. Reproduce

3. Based on a universal genetic code

4. Grow & develop

5. Obtain and use materials, and energy• Metabolism (Energy use) – sum of all

chemical reactions in an organism

6. Respond to external environment

7. Homeostasis – maintain a stable internal environment

8. As a group, living things change over time

FSGPT: Discuss examples of sexual & asexual reproduction. Give an example of a prokaryote and a eukaryote

II. Spontaneous Generation vs. BiogenesisA. Spontaneous Generation – early theory

that nonliving material could give rise to living organisms

B. Francesco Redi - In 1668, tested the theory of spontaneous generation, specifically that maggots come from rotting meat.

Control Group Experimental Group

- Placed raw meat in an - placed meat in a jar

open jar covered with netting

- In a few weeks, maggots - in a few weeks, maggots

were on the meat were on the netting

- Flies layed eggs on meat, - flies could smell meat,

maggots are fly larva but only lay eggs on netting

3rd Experiment by Redi- Placed meat in a sealed jar- Maggots never appeared- Flies could not smell the meat

Redi’s Experiment

C. Lazzaro Spallanzani – 1768, microscopes have been invented & microorganisms are known to exist; tests the spontaneous generation of microorganisms.

Control Group Experimental Group- Boiled broth to sterilize - boiled broth- Left flask open to air - sealed flask immediately- in several days, broth - in several days, broth

remains

was cloudy clear

Spallanzani’s Experiment

D. Louis Pasteur – 18621. Many refused to give up their belief in

spontaneous generation. They argued that life required a “vital force”, and that Spallanzani killed this force and prevented it from entering by sealing the flask.

2. Pasteur completely disproved spontaneous generation and the idea of a “vital force”.

Pasteur cont.3. Pasteur boiled broth in a flask with a curved

neck. This allowed him to sterilize the broth and leave in open for the “vital force”. After 1 year, the broth remained clear and sterile.

FSGPT – Discuss and write down similarities and differences between the three scientists experiments.

E. Biogenesis – current, accepted theory that living organisms can only arise from preexisting living organisms.

III. Scientific Method

Steps:

A.Observing & Asking Questions

1. Observation – act of noting or perceiving objects or events by using the senses

B. Formulating a Hypothesis

1. Hypothesis – possible explanation that can be tested by observation or experimentation.

C. Perform an Experiment

1. Experiment – carried out under controlled conditions to test a hypothesis.

A. Control Group – group used as a comparison; results are known

B. Experimental Group – identical to control group except for one factor, making the outcome unknown.

i. Independent Variable – the factor that is different in the experimental group

ii. Dependent Variable – During the experiment, this is what is being observed or measured

2. Example: FSGPT

Hypothesis – adding food coloring to a white flower’s water will change the flower’s color

Control Group -

Experimental Group -

Independent Variable -

Dependent Variable -

D. Analyzing Results – complete calculations, plot data, summarize observations, etc.

E. Draw Conclusions & Verify Results 1. Draw conclusions that explain experimental

results.

2. Verify conclusions by repeating experiments & checking other scientists results.

F. Scientific Theories – highly tested, generally accepted principle that explains a vast number of observations and experimental data– Hypothesis = specific, testable prediction for

a limited set of conditions– Theory = general explanation for a broad

range of data