Scientific Method

Biology

Coach Hamilton

Introduction

¨ Science: A system for investigation.

¨ Biology: “The study of life”

The Scientific Method involves a series of steps that are used to

investigate a natural

occurrence.

Problem/Question

Observation/Research

Formulate a Hypothesis

Experiment

Collect and Analyze Results

Conclusion

Communicate the Results

Scientific Method

¨ 1. Problem/Question: Develop a question or problem that can be solved through experimentation.

Steps of the Scientific Method

¨ 2. Observation/Research: Make observations and research your topic of interest.

Steps of the Scientific Method

Do you remember the next step?

¨ 3. Formulate a Hypothesis: Predict a possible answer to the problem or question.

¨ Example: If soil temperatures rise, then plant growth will increase.

Steps of the Scientific Method

Steps of the Scientific Method

¨ 4. Experiment: Develop and follow a procedure.

¨ Include a detailed materials list.¨ The outcome must be measurable

(quantifiable).

Steps of the Scientific Method

¨ 5. Collect and Analyze Results: Modify the procedure if needed.

¨ Confirm the results by retesting.¨ Include tables, graphs, and

photographs.

Steps of the Scientific Method

¨ 6. Conclusion: Include a statement that accepts or rejects the hypothesis.

¨ Make recommendations for further study and possible improvements to the procedure.

Steps of the Scientific Method

¨ 7. Communicate the Results: Be prepared to present the project to an audience.

¨ Expect questions from the audience.

Think you can name all seven steps?

Problem/Question

Scientific MethodA system of steps that scientists use to investigate

questions.– Observations: Questioning, wandering or

noticing something.– Hypothesis: Explanation that might be true—

educated guess. IT MUST BE TESTABLE!– Prediction: What you expect to happen if the

hypothesis is true. “If…then” statement.– Experiment: Planned and controlled procedure

to test hypothesis.

Controlled experiment

¨ Control group: Group that receives no experimental treatment. [What we may think of as “Normal”]

¨ Experimental group: Receives some type of experimental treatment.– Independent variable: The variable that

changes or varies in an experiment.

[You change this variable]– Dependent variable: Variable that is measured

in an experiment. What is observed in the end.

Scientific Method

– Conclusions: Decisions about whether hypothesis was supported based on analysis of data. Many experiments may lead to a theory.

Theory: Set of related hypotheses that have been tested over and over by many different scientists.

Which variable do you change in an experiment?

Contro

l gro

up

Dep

enden

t var

iabl

e

Exp

erim

enta

l gro

up

Inde

pende

nt var

iable

0% 0%0%0%

A. Control group

B. Dependent variable

C. Experimental group

D. Independent variable

20

Jim thinks that higher temperatures will cause crickets to chirp more. This is a(n)…

Concl

usion

Exp

erim

ent

Hyp

othe

sis

Obse

rvat

ion

0% 0%0%0%

A. Conclusion

B. Experiment

C. Hypothesis

D. Observation

20

When Shawn performed the experiment, he kept one group of flowers in regular light while increasing the amount of light using grow bulbs with the other groups. He monitored their color over three weeks. What is the dependent variable?

Colo

r of f

lower

s

Thre

e w

eeks

Diff

eren

t am

t of l

ight

Gro

up with

regula

r lig

ht

0% 0%0%0%

A. Color of flowers

B. Three weeks

C. Different amt of light

D. Group with regular light

20

Chemistry

¨ Atoms are composed of protons, neutrons and electrons.

¨ The interaction between

the outer electrons

cause bonding.

Carbon¨ Basis for all living thing is the Carbon

atom.¨ It has four outer electrons enabling it to

bond with other elements as well as itself.¨ Carbon helps form millions of different

large/complex structures.¨ It is organic if it contains carbon.¨ Macromolecules containing carbon are

formed from polymerization. ¨ There are four that exist in living systems.

Lipids—Fatty acids

¨ Made mostly from Carbon and Hydrogen.¨ Are not soluble in water.¨ Can be saturated (C-C) or unsaturated

(C=C) which refers to the bonding.

Lipids Continued…

Carbohydrates

¨ Made from Carbon, Hydrogen and Oxygen (O is typically spread throughout)

¨ Living things use carbohydrates as main source of energy.

¨ Glucose is an instant

form of energy.

Proteins—Amino Acids

¨ Proteins are macromolecules that contain Carbon, Hydrogen, Oxygen, and Nitrogen.

¨ Proteins are polymers of molecules called Amino Acids.

¨ Proteins are needed by the body for growth and repair and to make up enzymes.

Proteins Continued…

¨ These amino acids are compounds with an amino group (NH2) on one end and a carboxyl (-COOH) on the other end.

Nucleic Acids¨ Nucleic Acids are macromolecules that

contain Carbon, Hydrogen, Oxygen, Nitrogen, and Phosphorus.

¨ Nucleic acids are polymers assembled from individual monomers known as nucleotides.

¨ Two Types: Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA).

¨ Nucleic acids store and transmit heredity, or genetic, information.

Nucleic Acids Continued…

¨ Nucleotides consist of 3 parts: a 5-Carbon Sugar, a Phosphate group, and a Nitrogenous base.

Carbon is the basis for all living things.

A. True

B. False

True

False

0%0%

If something contains carbon, it is said to be inorganic.

True

False

0%0%

A. True

B. False

There are three major macromolecules that we will be discussing in this class.

True

False

0%0%

A. True

B. False

Lipids are mostly carbon and oxygen.

True

False

0%0%

A. True

B. False

Carbohydrates, such as pasta, are used as a good source of energy.

True

False

0%0%

A. True

B. False

Proteins contain carbon, hydrogen, oxygen, and a Nitrogen group.

True

False

0%0%

A. True

B. False

Nucleic Acids contain carbon, oxygen, nitrogen, hydrogen, but no phosphorus.

True

False

0%0%

A. True

B. False

This is a Carbohydrate.

True

False

0%0%

A. True

B. False

This is a Nucleic Acid.

True

False

0%0%

A. True

B. False

This is an example of a lipid.

True

False

0%0%

A. True

B. False

This is a Nucleic Acid.

True

False

0%0%

A. True

B. False

This is a Nucleic Acid.

True

False

0%0%

A. True

B. False

This is a Carbohydrate.

True

False

0%0%

A. True

B. False

Energy¨ Ability to cause changes on matter.¨ Chemical reactions either use or give off

energy. ¨ Metabolism includes all chemical and

physical reactions that occur to make energy available to an organism.

¨ Homeostasis is our bodies ability to maintain a balance.

Examples of Homeostasis

– Blood pressure– Body temperature– Blood sugar levels

¨ Metabolism helps us maintain homeostasis.

Which is not an example of how the body maintains homeostasis?

Mai

ntain

ing p

roper

b...

Get

ting

a hai

rcut

Kee

ping

cons

tant b

o..

Kee

ping

blood

sugar

...

0% 0%0%0%

A. Maintaining proper blood pressure

B. Getting a haircut

C. Keeping constant body temperature

D. Keeping blood sugar levels balanced.

20

Chemical Energy in the Body¨ Homeostasis and metabolism depend on the

chemistry of the body.¨ Enzymes assist with keeping metabolism

and homeostasis balanced.

Enzymes

¨ Enzymes help chemical reactions take place.

¨ Enzymes: are proteins that help speed up chemical reactions (catalyst) by lowering activation energy—energy needed to start reactions.

¨ They bond based on size and shape.¨ They end in –ase and if they don’t work

properly it could result in death.

Induced Fit Model¨ This model states that the active site of the

enzyme will slightly change shape in order to firmly bind with the substrate.

The substrate bound to the active site

makes up the “Enzyme-Substrate

Complex”

¨ Things that alter enzymes:– Enzymes can be denatured (structure gets

broken down and they don’t do their job) by temperature or pH changes.

– Temperature: Extreme temperatures cause enzymes to change shape and they can’t function

– pH: scale runs 0-14 with 7 being neutral. Low numbers are acids and high numbers are bases.

– Poisons denature enzymes leaving them unable to function resulting in death in many instances.

Types of Enzymes ¨ Amylase: an enzyme that catalyzes the

breakdown of starch into smaller sugars. ¨ Protease: an enzyme that helps to

breakdown or digest proteins.¨ Sucrase: an enzyme that catalyzes the

breakdown of sucrose (a type of sugar) to glucose and fructose.

¨ Lipase: an enzyme that catalyzes the breakdown of lipids (fats).

Carbonic Anhydrase¨ Carbonic anhydrase: an enzyme that

catalyzes the rapid conversion of carbon dioxide and water to bicarbonate and protons.

Which is not a characteristic of an enzyme?

Cat

alys

t

Pro

tein

Sugar

Lower

act

ivat

ion

ener

gy

0% 0%0%0%

A. Catalyst

B. Protein

C. Sugar

D. Lower activation energy

20

According to the graph, how does the reaction change with enzymes?

Spee

ds u

p

Slo

ws

down

Use

s m

ore e

nerg

y

Sto

ps th

e re

actio

n

0% 0%0%0%

A. Speeds up B. Slows downC. Uses more energyD. Stops the reaction

20

Chemistry Continued…¨ Matter is composed of atoms.

¨ Atoms interact with one another to form compounds.

¨ Electrons around the outside of atoms interact to form bonds.

Three Types of Bonds – Ionic Bond: When atoms gain or lose electrons

to form compounds. Na+1 loses its one electron to Cl-1 which only needs one.

– Covalent Bond: Atoms can share electrons so that each of their outer shells are full part of the time because the electrons are in constant motion.

– Hydrogen Bond: Weak bonds form between hydrogen and other atoms. Ex: bonds holding water molecules together. Ex. H2O

Acids/Bases¨ Acid: Will form H+ (hydrogen ions) when

dissolved in water.¨ Base: Will for OH- (hydroxide ions) when

dissolved in water.¨ pH: A measure of the amount of H+ ions

in solution. ¨ The scale goes from 0-14 with the low end

of the scale (below pH of 7) being acidic and the high end (above pH of 7) being basic. 7 is neutral (ex. Pure water)

More Acidic

MoreBasic

Neutral

More H+, Less OH-

Less H+, More OH-

Which pH would be considered acid rain?

6.4 7. 7.

27.

6

0% 0%0%0%

A. 6.4

B. 7.0

C. 7.2

D. 7.6

20

Which pH would represent the strongest base?

6.7.8

11.512.4

0% 0%0%0%

A. 6.0

B. 7.8

C. 11.5

D. 12.4

Which pH would represent the strongest acid?

2.1.3

12.2 7.

0% 0%0%0%

A. 2.0

B. 1.3

C. 12.2

D. 7.0

Alice decides to conduct an experiment with only basic solutions. Which solution would she not use?

Solution A (1

0...

Solution B (1

3...

Solution C (6

....

Solution D

(7....

0% 0%0%0%

A. Solution A (10.0)

B. Solution B (13.5)

C. Solution C (6.9)

D. Solution D (7.1)

Which would have a higher concentration of H+ ions?

Pure Wate

r

Liquid D

rain Cleaner

Lemon Ju

ice

Black Coffee

0% 0%0%0%

A. Pure Water

B. Liquid Drain Cleaner

C. Lemon Juice

D. Black Coffee

Which of the following would have the highest concentration of OH- ions?

Pure Wate

r

Liquid D

rain C...

Lemon Ju

ice

Black Coffee

25% 25%25%25%A. Pure Water

B. Liquid Drain Cleaner

C. Lemon Juice

D. Black Coffee

¨ Describe cell regulation (enzyme function, diffusion, osmosis, homeostasis);

¨ Predict consequences of internal/external environmental change on cell function/regulation.