Chapter 1The Science of Biology

1-1 What is Science? Goal of science Observations vs. inferences What is a hypothesis?

Goal of science

To investigate and understand nature To explain events in nature Use those explanations to make useful

predictions Science- organized way of using evidence

to learn about the natural world It’s a process! Term can also refer to the body of knowledge

scientists have built up after years using this process

Observations vs. Inferences Observation- gather information using

one or more of the senses Information gathered is called evidence or

data Two types of observations

Qualitative- involves characteristics that cannot be easily measured or counted

Quantitative- involves numbers like when measuring or counting objects

Observations vs. Inferences Inference-logical interpretation based

on prior knowledge and experience

Observations vs. Inferences

Statement Observation Inference

Object A is round and orange.

Object A is a basketball.

Object C is round and black and white.

Object C is larger than Object B.

Object B is smooth.

Object B is a table-tennis ball.

Each object is used in a different sport.

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Explaining the Evidence A hypothesis is a possible explanation

for a set of observations or an answer to a scientific question Must be TESTABLE!

Formulating a HypothesisMystery WormsA teacher collected some beetles from a rotting log and placed them in a container of dry oatmeal in her classroom. She kept the box covered with a light cloth so that the beetles could not escape. She also asked one of her students to add potato and apple pieces once a week to provide food and moisture for the beetles. After several weeks, the student reported that there were some strange-looking, wormlike organisms in the container.

• 1. Formulate a hypothesis that might explain the presence of the “worms” in the container.

• 2. How could you test your hypothesis?

1-2 How Scientists Work Designing an Experiment Publishing and Repeating Investigations When Experiments are Not Possible How a Theory Develops

Designing an Experiment

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

Controlled Experiment Only one variable must be changed at

a time All other variables should be kept

unchanged or controlled Manipulated (independent) variable-

variable that is deliberately changed Responding (dependent) variable-

variable that is observed and changes in response to the manipulated variable

Redi’s Experiment, designed to refute Spontaneous Generation- the idea that life could arise from nonliving matterOBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.PROCEDURE

Controlled Variables:jars, type of meat,location, temperature,time

Manipulated Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appearResponding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Recording and Analyzing Results Lab reports Scientific drawings Online storage

Drawing a Conclusion After testing your hypothesis…Option 1: Data supports it

“data supports the hypothesis” Never proves it

Option 2: Data proves it wrong “hypothesis is refuted” Rewrite and test again

Repeating Redi Key assumption in science- experimental

results can be reproduced because nature acts in a consistent manner

Redi’s work followed by Needham-used an experiment with

“animalcules” to attack Redi’s work Spallanzani- improved upon Needham’s

experiment Pasteur-allowed broth to come into contact

with the air

Spallanzani’s Experiment

Gravy is boiled. Flask isopen.

Gravy is boiled. Flask issealed.

Gravy is free of microorganisms.

Pasteur’s Experiment

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Showed that all living things come from other living things

When Experiments are Not Possible Examples:

Observing animals Prohibited by ethical considerations

Attempting to maintain a controlled experiment Study large groups of subjects ID as many relevant variables as possible

Developing a Theory Theory- well-tested explanation that

unifies a wide range of observations Happens when a hypothesis is so well

supported by the scientific community No theory is considered absolute truth May be revised or replaced by a more

useful explanation

1-3 Studying Life Characteristics of living things Branches of biology Biology in everyday life

Characteristics of Living Things 1. Made Up of Cells 2. Reproduce 3. Based on a Genetic Code 4. Grow and Develop 5. Need Materials and

Energy 6. Respond to the

Environment 7. Maintain Internal Balance 8. Evolve

Characteristic ExamplesLiving things are made up of units called cells.Living things reproduce.

Living things are based on a universal genetic code.

Living things grow and develop.

Living things obtain and use materials and energy.

Living things respond to their environment.Living things maintain a stable internal environment.

Taken as a group, living things change over time.

Many microorganisms consist of only a single cell. Animals and trees are multicellular.Maple trees reproduce sexually. A hydra can reproduce asexually by budding.Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees.Flies begin life as eggs, then become maggots, and then become adult flies.Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.

Leaves and stems of plants grow toward light.

Despite changes in the temperature of the environment, a robin maintains a constant body temperature.

Plants that live in the desert survive because they have become adapted to the conditions of the desert.