Chapter 1: The Study of Life

Biology

Mrs. Haase

Biology Study of life Biologists explore life

at levels ranging from the biosphere to the molecules that make up cells.

Biologists recognize that all living things share certain characteristics

Characteristics of Life1. Have an orderly

structure All living things

made of one or more cells

Cells are the smallest unit capable of all life functions

Characteristics of Life2. Reproduction

The production of offspring

Species A group of

organisms that can interbreed and produce fertile offspring.

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Characteristics of Life3. Growth and

Development Increase in the

amount of living material and the formation of new structures

DNA directs pattern of growth and development

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Characteristics of Life4. Response to the Environment

Environment includes air, water, weather, temperature other organisms in the area and other factors

Examples? Stimulus and Response

S: Anything in the organism’s internal or external environment that causes it to react

R: A reaction to a stimulus

Characteristics of LifeResponses to the internal

environment---Homeostasis Maintenance of internal conditions

suitable for survival despite changes in external conditions

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Characteristics of Life Orderly structure Growth and Development Response to the environment Reproduction

Characteristics of LifeAccomplishing 1-4

requires energy! All energy originates

from the sun Plants convert solar

energy into sugar Animal use/store

energy in own tissues

Characteristics of Life Adaptation

Any inherited structure, behavior or internal process that promotes the likelihood of an organism’s survival and reproduction.

Evolution Genetic change of a population or species

over time (generations)

Chapter 1 Section 2

The Methods of Biology

The Methods of Biology Science explains nature through

Observations Setting up experiments Creating representative models

Scientific Method: the common steps that scientists use to gather information and answer questions.

Scientific Method Observations Question Hypothesis

Prediction Experiment Data Conclusion Retest Communicate Results

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Observation You observe something in the material

world, using your senses or machines which are basically extensions of those senses.

AH—Look at this!

Question You ask a question about what you observe. State the problem or question.

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Hypothesis An explanation for a question or a problem

that can be formally tested. Based on research

You should be able to give reasons for why you chose your hypothesis

If/then… statement

Experiment You figure out a way to test whether the hypothesis

is supported through an investigation

Control group– the standard group used for comparison which does NOT receive the experimental treatment.

Experimental group – one variable changed (group that receives the experimental treatment)

The outcome must be measurable (quantifiable).

Record and analyze data.

Biologists developed a hypothesis regarding mimicry in snakes.

If an animal has certain color patterns, then it will not be preyed upon.

They tested the hypothesis by making artificial snakes and observing how often they were attacked by predators.

Figure 1.20

Figure 1.21

This is an example of a controlled experiment. Such an experiment is designed to compare an

experimental group with a control group.

Variables

Independent Variable adjusted by the experimenter (what you vary)

Dependent Variable changes in response to the indep. variable what you measure

Constants: variables that remain the same in all groups

Analyze Results You do the experiment using

the method you came up with and record the results.

Create data tables, graphs to represent data

Perform calculations that will determine what results mean (averages, percentages, totals)

Identify possible sources of errors

Table 1. Percent of total attacks on different colored artificial snakes.

Draw Conclusions You state whether your

hypothesis was supported or not and try to explain your results.

Table 1. Percent of total attacks on different colored artificial snakes.

Retest In order to verify the results, experiments

must be retested.

Communicate Results Share results with science community

Scientific Theories and Laws

Hypothesis - testable prediction

Theory - explanation of “why”. based on many observations & experimental

results

Scientific Law - prediction of “what” happens in nature.

Theories can explain a law

Practice

Worm Behavior Demo Observations/current knowledge about worm behavior Prediction/Hypothesis: Experiment

400 ml soil 125 ml of water 10 worms Pre-determined #/mass of apple peel Cover with paper. One cold, one room temp

Chapter 1 Section 3

The Nature of Biology

Kinds of Information Quantitative Information

Numerical data Can be used to make a graph or a table to communicate

data more easily

Qualitative Information Data that can be observed but not measured

Measuring in the International System

International System of Measurement (SI) Common units:

Length = meters Mass = grams Volume = liters Time = seconds Temperature = kelvin and Celsius

Variable: A factor in an experiment. Independent variable: The factor that is

different between groups. The topic of interest in an experiment.

On graphs, theindependent variablealways goes on theX-axis.

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Graphing Review

Fig. 1

Dependent variable: The factor being measured in the experiment.

Almost always numerical On graphs, the

dependent variable isalways on the Y-axis.

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Fig. 1

Types of Graphs• Two common types of graphs:

– Bar graphs

– Line graphs

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Biology Test Scores

Absences vs. Scores

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Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Fig. 2

Fig. 3

Types of Graphs

Bar graphs are used when the independent variable has categories.

•Boys/girls •Adults/children •Salt water/distilled water /tap water

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Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Fig. 2

Types of Graphs•Line graphs are used when the independent variable has numbers.•Hours of television watched •Age (in years) •Calories eaten per day •Etc.

•Both line graphs and bar graphs show the relationship between independent variables and dependent variables.

Absences vs. Scores

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Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Fig. 3

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Making a Graph

1) Choose a scale for each axis that includes all values. Number your gridlines evenly.

Fig. 1

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Making a Graph

2) Label both axes, including units. Fig. 1

Making a Graph

3) Plot each data point and connect your dots with a line.

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Fig. 1

Making a Graph

4) Give your graph a descriptive title.

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation.

Fig. 1