Chapter 1: The Science of Biology

  Science is: The Goal of Science is to investigate and

understand nature, to explain events in nature and to use those explanations to make predictions.

Scientists collect and organize information carefully and look for patterns or connections between events.

Scientists propose explanations for events that can be tested through experimentation.

Science: an organized way of using evidence to learn about the natural world.

The word science also refers to the body of knowledge that has been built up over the years

Evidence is based on observation Observation: using one or more of the senses to

gather information. Any information gathered through observation is

known as Data. There are two types of Observations: Qualitative

and Quantitative. Qualitative: involve characteristics that can not be

counted or numbered such as color and texture Quantitative: involve numbers or calculations

Interpreting the Evidence Observations alone have little meaning in

science, because they do not tell us how anything actually works.

Scientists often follow up their observations by making inferences Inference: a logical interpretation based on

prior knowledge and experience.

Explaining the Evidence Inferences can be taken a step further and become a

hypothesis Hypothesis: a possible explanation for a set of

observations that can be tested through experimentation

A hypothesis can arise in several ways. It can come from prior knowledge, logical inferences or even educated guesses

The key to any hypothesis is that it is testable The best way to test a hypothesis is through a

Controlled Experiment

Designing an Experiment When a scientist designs an experiment to test

his/her hypothesis, they should follow the scientific method

The scientific method has 5 main parts 1.  State the Problem 2.  Form a hypothesis 3.  Set up a controlled experiment 4.  Record and Analyze your data 5. Draw a Conclusion

An example of following the scientific method:

Francesco Redi’s Experiment For centuries, people noticed that maggots would

appear on meat after a certain amount of time had passed

People believed that Spontaneous Generation, which essentially means that life could arise from non-living things, was causing the maggots presence

In 1668 an Italian physician named Francesco Redi proposed a different hypothesis about where these maggots were coming from

Redi 2 He noticed that the maggots were appearing a few

days after flies had been observed on the meat and proposed that the flies were laying eggs that were too small to be seen on the meat

Redi designed a controlled experiment in which he could test his theory

Controlled Experiment: type of experiment I which only one variable is changed at a time, while all other variables are unchanged and used as a control

Redi 3 Manipulated Variable: variable that is

deliberately changed in an experiment to see how it effects the outcome of the experiment.

Responding Variable: variable that changes in response to the change in the manipulated variable

Redi 4 Redi set up two sets of jars. In both sets of jars he

placed identical pieces of meat (at the same time and temperature). He covered one set of jars and left the other set uncovered

After several days passed, Redi observed flies around both jars. When he checked the contents of the jars, the uncovered jars contained maggots, but the covered jars did not

With this experiment, Redi was able to disprove the theory of Spontaneous Generation

Repeating Investigations In order for experimental results to be

considered valid, the experiment must be repeatable

If the results of the experiment are generally the same every time it is performed, once can conclude that the findings are sound

Several scientists tried to confirm or refute Redi’s work After Redi performed his experiment, Anton van

Leeuwenhoek invented the microscope, which allowed scientists to see objects that are not readily visible to the naked eye

After the invention of the microscope, scientists discovered several miniscule moving objects on the surface of larger objects

They were not sure if these “things” were alive or not, so they decided to call them animalcule. (Animal + Molecule)

Needham In the mid 1700s, John Needham tried to prove

that these animalcules were the product of spontaneous generation

He boiled a flask filled with gravy, killing any living things inside of the gravy

He then let the flask sit for several days and discovered that it was filled with animalcules

He inferred that these animalcules could only have come from the gravy

Spallanzani Later, another scientist, Lazzaro

Spallanzani decided to test Needham’s work to see if it held up

He set up two separate flasks of gravy and boiled them both

He then sealed one of the flasks and let the other remain open

Spallanzani 2 When Spallanzani checked the flasks he found

that the sealed flask had no new organisms in it, while the open flask was filled with organisms

He believed that the organisms had to come from the air

Despite these findings, several people still refused to accept that spontaneous generation could not exist

Pasteur Louis Pasteur finally put this issue to rest in 1864 He set up a flask with a long curved neck. This

allowed for the air to reach the broth, but the curvature prevented any microorganisms from reaching the broth

He found that as long as the neck was attached, no new organisms grew in the broth, but as soon as the neck was removed, the organisms began to grow

Pasteur 2 He proved that the microorganisms were in

the air, but did not come from the air Pasteur proved once and for all that

spontaneous generation did not exist

How a Theory Develops When a hypothesis has be well supported by

repeated experimentation, it may be considered a Theory

Theory: a well tested explanation that unifies a broad range of observations

A theory will allow scientists to make accurate predictions about future events

No theory can be considered the absolute truth, because as new evidence is discovered, theories can be altered or updated

Section 1-3

Studying Life

Characteristics of Living Things Biology: the science, which seeks to

understand the living world There are 8 Characteristics of living things 1.  Living things are made up of cells 2.  Living things reproduce 3.  Living things are based on a genetic

code 4.  Living things grow and develop

More Characteristics 5.  Living things obtain and use Energy 6.  Living things respond to their

environment 7.  Living things maintain a stable internal

environment

8. Living things change over time

Made up of Cells All living things, or organisms, are made up of

small self contained units called cells a Cell is a collection of living matter enclosed by

a barrier that separates the cell from its environment

Cells are the smallest unit of an organism that can be considered alive

Cells can grow, respond to their environment and reproduce

Cells 2 Cells are complex and highly organized Organisms can be unicellular (having only

one cell) or multi-cellular (having more than one cell)

In multi-cellular organisms, each type of cell is specialized to perform a different function

Reproduction All organisms produce new organisms through a

process called reproduction There are two types of Reproduction Sexual Reproduction is a type of reproduction in

which two cells from different organisms are combined to produce the first cell of a new organism

Asexual Reproduction is a type of reproduction in which there is only one parent Either a single celled organism divides to produce a

new single celled organism or a portion of an organisms breaks off the parent organism and produces an offspring (Budding)

Genetic Code Offspring tend to look somewhat similar to

their parents This is due to the passing on of genetic

information through DNA DNA determines the inherited traits of all

organisms

Growth and Development Each type of organism has a distinct life

cycle A life cycle is a particular pattern of

growth and changes that occur over the lifespan of an organism

Development is a process through which organisms change to meet sexual maturity

Need for Energy Organisms need Energy to maintain their

Metabolism Metabolism: set of chemical reactions

through which an organism builds up or breaks down materials as it carries out life processes

Most organisms acquire Energy from either Photosynthesis or Cellular Respiratration

Response to Environment All organisms respond to external stimuli

from their environment

Maintain Homeostasis Homeostasis: process by which organisms

keep their internal conditions relatively stable

Organisms are constantly regulating their internal environment

Organisms Evolve Organisms as a group will change over

time Over a generation or two theses changes

may seem small, but over thousands of years, species can change dramatically

Branches of Biology The diversity of life is so great that no biologist

can study everything Biology is organized into branches or divisions Some branches are based on the type of organism

being studies such as botany and zoology, while other branches like Paleontology are based on specific perspectives

No matter what the branch of biology is, the same approach is taken

Branches 2 Things must be understood at different levels of

organization Each level is a system made up of smaller parts,

and often each level is part of the level above it The levels of organization are as follows:

Biosphere, Ecosystem, Community, Population, Organism, Groups of Cells, Cells and Molecules

Section 1-4

Tools and Procedures

A Common Measuring System Most scientists use the metric system when

collecting data and performing experiments. The Metric System is a decimal system based on

certain physical standards who’s units are scaled in multiples of 10

Scientists uses a revised version of the metric system known as the SI System of measure.

Common SI Units Length is measured in Meters Volume is measured in Liters Mass is measured in Kilograms Temperature is measured in Kelvin

Length Some common conversions involving

length 1m = 100 cm 1m = 1000mm 1km = 1000m 1inch = 2.54cm 1ft = 12 in 3ft = 1 yard 1 mile = 1760 yards = 5280 ft

Volume Some common conversions involving

volume 1L = 1000 ml 1 kL = 1000 L 1ml = 1 cm3

Mass Some common conversions involving mass

1kg = 1000g 1g = 1000mg 1g = 100 cg 1kg = 2.2 lbs (pounds)

Temperature Some common temperature conversions

K = oC + 273o

oC = K – 273o

oF = 9/5 oC + 32 oC = 5/9 (oF – 32)

Analyzing Biological Data Biologists often use graphs and tables to

organize the data they have collected. This is done so that they can visualize

changes over time. Good examples of biological graphs and

tables appear on page 25 in your text book

Microscopes Microscope: a device which produces

magnified images of structures that are too small to see with the unaided eye.

The most commonly used type of microscope is the Light Microscope.

Light Microscopes produce magnified images by focusing visible light rays.

Light Microscopes Light microscopes can have a

magnification up to 1000x. Compound Light Microscopes: allow light

to pass through the specimen and uses two lenses to form a magnified image.

Electron Microscopes Electron Microscopes produce magnified images by

focusing beams of electrons. These microscopes are capable of 1000x the

magnification of a light microscope. All specimen placed under an electron microscope

must be completely dried out. There are two sub-types of electron microscopes The transmission electrom microscope (TEM)

shines a beam of electrons through the specimen while the scanning electron microscope (SEM) runs a beam of electrons repeatedly over the surface of the specimen. (The SEM produces 3-D images)

Laboratory Techniques To obtain enough material to study,

biologists often create a cell culture. Cell Culture: group of cells grown in a

nutrient solution from a single cell. Once the culture is grown, the cells can be

subjected to tests to see how they respond to various stimuli.

Laboratory Techniques 2 Cells can be broken down into their component

parts through the process of Cell Fractionation. The cells are places in a special blender to break

the cell into bits. Then the bits are submerged in a liquid inside of a

test tube. The tube is then placed into a centrifuge that

spins the tube causing the parts to separate. The parts separate based on their density and the

biologist can then go pick out what they want.