CHAPTER 1 THE SCIENCE OF BIOLOGY

1-1 What is Science?- organized way of using evidence to learn about the natural world

Why do we study science?

1. investigate and understand nature2. explain events that occur in nature3. to make predictions based on those explanations

How do we gain evidence to support our predictions?

1. Observation- use one or more of our senses

2. Collect data- information gathered from observation

Observations can be of 2 types:

1. quantitative - involves numbers Ex. measurement or counting objects2. qualitative - characteristics not easily measured Ex. color or texture

**data (evidence) must be interpreted (analyzed) involves the formation of an inference

Inference - a logical interpretation based on prior knowledge or experience 

Explanation of evidence

Form a hypothesis - a possible explanation for what was observed - can be tested through a controlled experiment

Scientific Inquiry - a collection of data to obtain a better understandingof nature - scientists make recommendations based on theirfindings

1-2 How scientists work to test their hypothesis1668 Francesco Redi's experiment on spontaneous generation1. State the problem: How do living things come to be?2. Form a hypothesis: Maggots arise from rotting meat (spontaneous generation)

3. Set up a controlled experiment: a. variables - factors that can change; time, temp, etc. - one variable is changed at a time (manipulative value or independent variable) b. control - the unchanged variable c. responding variable - what is observed and changes in response to the manipulative variable (dependent variable)

4 Observation - flies left on uncovered meat; later maggots appeared5. Hypothesis - flies produce the maggots6. Prediction - keeping flies away from meat will prevent the appearance of maggots7. Conclusion - maggots formed only when flies came in contact with meat; therefore, no spontaneous generation

Redi's test was repeated by:1. John Needham (l700 's) - Needham experiment lent support to spontaneous generation

2. Lazarro Spallanzani3. Louis Pasteur (1800)

Development of a theoryNumerous investigations support a particular

hypothesis, therefore, a theory is a well-tested explanation that comes from many observations

Theories allow for accurate predictions about new situations

Theories may be revised or replaced by new evidence

1-3 Characteristics of living things1. Made up of cells - smallest unit of life - they can: grow respond reproduce - complex and highly organized

unicellular - one cell; amoeba, paramecium

amoeba

multicellular - many cells; plants and animals

- cells come in a variety of sizes and shapes, each specialized to perform a special function

2. Reproduce - production of new organisms - two kinds: a. asexual - single parent Ex. fission and budding b. sexual - two cells (sex) from different parents fuse

Hydra – asexual reproduction (budding)

3. Uniform genetic code - offspring resemble parents - flies make flies - dogs make dogs, etc. - DNA (deoxyribonucleic acid) contains the genetic codes that determines inherited traits

4. Grow and develop - distinctive life cycle and pattern of growth with changes that occur during life span

- cells grow in size and specialize (differentiate)

5. Obtain and use materials and energy - occurs through metabolic processes that build (synthesis or anabolism) and break down (catabolism); together these are metabolism

6. Respond to the environment - changes in light and temperature cause organisms to respond in their own way

7. Maintain an internal balance (homeostasis) - always threatened by environmental changes - lack of homeostasis leads to illness and possibly death.

8. Change over time (evolution) - change not apparent for thousands to millions of years - maintains survival of an organism in a world that is always changing

Branches of Biology

Biology is organized into branches or divisions: Zoology - study of animals  Botany - study of plants  Ethology - study of animal behavior  Paleontology - study of life from long ago

- Life is studied at different levels of organization- Levels differ in size and complexity

Moleculescellsgroups of cells (tissues) organism population communityecosystembiosphere

See Fig. 1-21 pg 21

1-4 Tools and Procedures used in Biology A. Common Measurement System - metric: decimal system of measurement; each unit is a multiple of 10 Ex. 1.5, 1.51, 1.512

B. Analyzing Biological Data - to find out whether certain information has changed or stayed the same - recorded in a table from which a graph is made - today, computers are used to make sense of the data

C. Microscopes - produce magnified images of structures that cannot be seen with the naked eye - used to test cell responses under controlledconditions - show cell to cell interactions - used to select specific cells for study

Two types: 1. light microscope - magnifies images by focusing visible light rays - magnifies 1000 times - light passes through the specimen and then through 2 lenses - chemical stains (dyes) used to show specific structures

Compound light microscope

2. electron microscope - magnifies images by focusing beams of electrons on specimen - objects usually smaller than 0.2 micrometers - magnifies images 1000 times smaller than thoseseen under the light microscope

Two types: a. transmission electron microscope (TEM) - beam of electrons passes through the specimen - good for studying cell interiors

Cell organelles

b. scanning electron microscope (SEM) - pencil-like beam runs back and forth across thesurface; good 3 dimensional image of surface

Insect head

Disadvantage of EM - specimens are dead and preserved; they are killedby the process

3. Phase Contrast Microscope - enhances contrast of living, unstained cellsa. Differential interference contrast

b. Phase contrast

D. Laboratory Techniques

1. Cell cultures - groups of cells that develop from a single cell - used to test cell responses under controlled conditions - show cell to cell interactions - used to select specific cells for study

Cell culture

2. Cell fractionation - separates out different cell parts for study - cells put in blenderbroken cell parts added toliquid and placed in tube centrifugecell partsseparate out according to density

E. Working Safely in Biology - Review lab safety