Welcome to Biology

Mrs. WebsterRoom 243

List the steps of the scientific method.

List characteristics of life.

What is the difference between growth and development?

Place the following terms in order of least to most highly organized:

tissue, atom, cell, organ system, molecule, organism, organ, biosphere, population, ecosystem, community

The Scientific Process

• MAKE OBSERVATIONS• FORM QUESTIONS BASED ON

OBSERVATIONS• FORMULATE A HYPOTHESIS• TEST HYPOTHESIS - REPEAT TESTS• ANALYZE RESULTS• CONCLUSION

THEORY PRINCIPLE

Set of ideas that form a general frame of reference for further study

Explanations have high probability of being valid

Evidence is so over- whelming that the explanation is further elevated

fundamental doctrine on which other concepts are based objectivity

WHAT IS A HYPOTHESIS?

• A tentative explanation• To be scientific must be testable• Constructed to provide framework for stating

the results of an experiment• Must be more specific than problem

TESTING THE HYPOTHESIS

• INDEPENDENT VARIABLE• DEPENDENT VARIABLE• CONTROLLED VARIABLE

INDEPENDENT VARIABLE

THE CONDITION OR EVENT UNDER STUDY

(What is being changed in the experiment?)

DEPENDENT VARIABLE

Variables that can possibly change because of the presence of or change in an

independent variable (What is measured in an experiment)

CONTROLLED VARIABLES(CONSTANTS)

Conditions that could affect the outcome of an experiment but do

not because they are held constant

RANDOM SAMPLING

Subjects are randomly assorted into either experimental group or

control group (ensures both groups are representative samples of the

original population)

SAMPLING ERROR

When a test group is not equivalent to a natural population, a sampling error is

introduced to the experiment

SYSTEMATIC ERROR

• ERROR THAT OCCURS IN THE SAME DIRECTION EACH TIME AND IS ALWAYS EITHER TOO HIGH OR TOO LOW

Random error

uncontrolled variation between observed or measured value &

the value predicted by a standard or model (the “true” value)

Measurements have an equalprobability of being too high or too low.

ORGANIZING TEST RESULTS

DATA TABLESGRAPHS

2005-2206 annual and seasonal home ranges (km2) for female black bear (Ursus americanus) in Garrett

County, MD

Bear # 14 19 48 81 x

Annual 46.9 34.4 -------- 38.1 39.8

Spr./Sum.

27.4 27.6 25.0 33.7 28.4

Fall 38.0 27.4 -------- 27.5 31.0

2005-2006 annual and seasonal home ranges (km2) for female black bear (Ursus americanus) in Garrett County, MD

05

101520253035

404550

Spr./Sum. Fall Annual

Bear #19

Bear #81

Bear #14

km2

Statistical Tests

determine if differences between experimental data and control data are significant or likely due only to chance.

GENERALIZING FROM TEST RESULTS

• Hypothesis is accepted or rejected on basis of conclusions drawn

• Statement is written about new insights gained

• Apparent trends are noted• Further problems and hypotheses are posed

IN SCIENCE THERE ARE NO ABSOLUTE TRUTHS

AN IDEA IS CORRECT WITHIN THE FRAMEWORK OF OBSERVATIONS &

TESTS WHICH IT IS DERIVED

THEORY PRINCIPLE

Set of ideas that form a general frame of reference for further study

Explanations have high probability of being valid

Evidence is so over- whelming that the explanation is further elevated

fundamental doctrine on which other concepts are based objectivity

WHAT IS A HYPOTHESIS?

• A tentative explanation• To be scientific must be testable• Constructed to provide framework for stating

the results of an experiment• Must be more specific than problem

TESTING THE HYPOTHESIS

• INDEPENDENT VARIABLE• DEPENDENT VARIABLE• CONTROLLED VARIABLE

INDEPENDENT VARIABLE

THE CONDITION OR EVENT UNDER STUDY

(what is changed in the experiment)

DEPENDENT VARIABLE

Variables that can possibly change because of the presence of or change in an

independent variable (What is measured in an experiment)

CONTROLLED VARIABLES(CONSTANTS)

Conditions that could affect the outcome of an experiment but do

not because they are held constant

RANDOM SAMPLING

Subjects are randomly assorted into either experimental group or

control group (ensures both groups are representative samples of the

original or natural population)

SAMPLING ERROR

When a test group is not equivalent to a natural population, a sampling error is

introduced to the experiment

SYSTEMATIC ERROR

• ERROR THAT OCCURS IN THE SAME DIRECTION EACH TIME AND IS ALWAYS EITHER TOO HIGH OR TOO LOW

Random error

uncontrolled variation between observed or measured value &

the value predicted by a standard or model (the “true” value)

Measurements have an equalprobability of being too high or too low.

ORGANIZING TEST RESULTS

DATA TABLESGRAPHS

2005-2206 annual and seasonal home ranges (km2) for female black bear (Ursus americanus) in Garrett

County, MD

Bear # 14 19 48 81 x

Annual 46.9 34.4 -------- 38.1 39.8

Spr./Sum.

27.4 27.6 25.0 33.7 28.4

Fall 38.0 27.4 -------- 27.5 31.0

2005-2206 annual and seasonal home ranges (km2) for female black bear (Ursus americanus) in Garrett County, MD

05

101520253035

404550

Spr./Sum. Fall Annual

Bear #19

Bear #81

Bear #14

km2

Statistical Tests

determine if differences between experimental data and control data are significant or likely due only to chance.

GENERALIZING FROM TEST RESULTS

• Hypothesis is accepted or rejected on basis of conclusions drawn

• Statement is written about new insights gained

• Apparent trends are noted• Further problems and hypotheses are posed

What is biology?

What makes something living?

Characteristics of Life (textbook pp 16-20):

1. Living Things are Composed of Cells: Single-cell organisms have everything they need to be self-sufficient. In multicellular organisms, specialization increases until some cells do only certain things.

2. Living things have Levels of Organization and they are highly organized:

•Both molecular and cellular organization.

•Living things must be able to organize simple substances into complex ones.

•Living things organize cells at several levels:  

• Tissue - a group of cells that perform a common function. •Organ - a group of tissues that perform a common function. •Organ system - a group of organs that perform a common function.

(p. 21 in textbook)

Living Things Obtain and Use Energy:•Living things take in energy and use it for maintenance and growth.

Living Things Grow and Develop:

•Cell division - the orderly formation of new cells. •Cell enlargement - the increase in size of a cell. •Cells grow to a certain size and then divide. •An organism gets larger as the number of its cells increases.

Development – change in form or function

Living Things Reproduce:

•All living things reproduce in one of the following ways: • Asexual repoduction - Producing offspring without the

use of gametes.

• Sexual reproduction - Producing offspring by the joining of sex cells.

•Reproduction is not essential for the survival of individual organisms, but must occur for a species to survive.

Living Things Adapt To Their Environment: Adaptations are traits giving an organism an advantage in a certain environment. Variation of individuals is important for a healthy species.

Living things react to a stimuli

-

Maintain homeostasis