Principles of Biology Unit 1

Science

latin for “knowledge”; a way of knowing about the natural world

Making observations and testing hypotheses

Inquiry

the heart of science; the search for information and explainations of natural phenomena

Scientific Method - definition

basis of science

• testable

• repeatable

• ongoing

• relies on communication

• human endeavor

Deductive Reasoning

• summarize information at hand

• draw conclusions from information

• proceeds from the general to specific

Inductive Reasoning

• Generalization from several specific observations

• proceeds from specific to general

• impossible to prove the accuracy of the generalization

What kind of scientific reasoning is this?

Initial general assumptions are true, therefore the conclusion must be true.

1. All birds have wings.

2. Sparrows are birds.

Conclusion: Sparrows have wings.

Deductive

What kind of scientific reasoning is this?

1. Sparrows are birds, they have wings

2. Falcons are birds, they have wings.

3. All birds I have seen or heard of have wings.

Conclusion: All birds have wings.

Inductive reasoning

(draws conclusion from several specific observations; impossible to prove accuracy)

Steps of the Scientific Method:

1. Summarize existing observations

2. Create a testable hypothesis

3. Conduct an experiment

4. Analysis of data

5. Accept or Reject Hypothesis

Characteristics of a Hypothesis

• explains existing observations

• makes predictions that can be tested

• can never be proven true (only supported or disproved)

Experimental/Treatment Group

individuals given specific treatment or condition being tested

Control Group

individuals not given the specific treatment

What makes an experiment more reliable?

Testing a larger sample size to better represent an estimate of the entire population

Theory

a well supported hypothesis that links together a large body of observations; BROAD FRAMEWORK

generates more specific, testable hypotheses

Principle/Law

a theory that links together significant bodies of thought and yields unvarying and uniform predictions over a long period of time

True or False: Scientific models can be proven true.

False; scientific methods can only be proven false or “supported” by experimentation

True or False: Correlation = Causation

False; correlation of two things does NOT mean one causes the other

Can supernatural ideas be included in testable predictions or hypotheses?

No because the supernatural is outside the realm of science

Characteristics of Living Things

1. Made up of cells

2. capable of growth and development

3. regulate metabolism

4. perceive and respond to stimuli

5. reproduce

6. contains an information system (DNA)

7. requires water

8. carbon based

Cells

• basic unit of life in structure and function

• come from and give rise to more cells

• unicellular/multicellular

Growth

increase in size or number of cells

Development

changes in roles of cells during life cycle of an organism

Metabolism

sum of chemical reactions and energy transformations that exist within a cell

Homeostasis

tendency of an organism to maintain a relatively constant internal environment

Stimulus

Physical or chemical changes in the internal or external environment of an organism

Asexual Reproduction

“copying”; cells simply split; typical among unicellular organisms

variations by mutated genes

Sexual Reproduction

sex = genetic recombination; genes come from parents providing for variation in offspring

involves egg and sperm to create a zygote

Deoxyribonucleic Acid (DNA)

Heritable information is stored in regions of DNA called genes

Genes

instructions that use a special code generally for the production of specific proteins

True or False: The nucleic acid code is virtually identical in all species.

True

Hormones

chemical signals used for intercellular signaling

Biological Organization

1. Biosphere

2. Ecosystem

3. Community

4. Population

5. Organism

6. Organs

• tissues

• cells

• organelles

1. Molecules

2. Atoms

Classification of Biological Diversity (Taxonomy)

1. Domain

2. Kingdon

3. Phylum

4. Class

5. Order

6. Family

7. Genus

8. Species

Three Domains of Life

Bacteria, Archaea, Eukarya

Prokaryotes

organisms with no true cellular nucleus

contained by archaea and bacteria

Domain Archaea → Kingdom Archaebacteria

bacteria found in extreme environments; distinguished by RNA sequence

Domain Bacteria → Kingdom Eubacteria

very diverse group of bacteria

Eukaryotes

organisms with a distinct cellular nucleus

Domain: Eukarya

Domain Eukarya → Kingdom Protista

Single and simple multicellular organisms with nuclei

Fungi

• organisms with cell walls made of chitin

• multicellular, multi-tissued

• molds, yeasts, mushrooms

• Decomposers

Plantae

• complex multicellular organisms with tissues and organs

• cell walls contain cellulose

• contain chlorophyll in chloroplasts in order to perform photosynthesis

• nonvascular (moss) and vascular (flowering plants)

• Producers

Animalia

• complex multicellular organisms that depend on other organisms for nourishment

• lack cell walls

• have organs and organ systems

• most forms are motile

How does life use energy?

to maintain cellular structures, produce materials for growth, development, and reproduction, and to support movement, signaling, and other cell work

Producers (Autotrophs)

make their own food from simple materials; releases energy mostly by oxidative respiration

(ex: photosynthesis)

Consumers (Heterotrophs)

obtain energy by eating other organisms

Decomposers (Heterotrophs)

obtain energy by breaking down waste products, by-products, and dead bodies of producers and consumers; recycle nutrients from dead things to living things

Matter

anything that takes up space and has mass; composes all organisms

States:

• Solid

• Liquid

• Gas

Element

a substance that cannot be broken down to other substances by chemical reaction

Compound

two or more elements in a fixed ratio

What elements make up 96% of living matter?

Carbon, Hydrogen, Oxygen, and Nitrogen

What elements make up the other 4% of living matter?

Calcium, Phosphorus, Potassium, and Sulfur

Atom

smallest unit of matter that still retains properties of an element

• proton (+)

• neutron (no charge)

• electron (-)

Atomic Nucleus

made of neutrons and protons

Electrons

form a “cloud” of negative charge around the nucleus

Atomic Mass

measured in daltons, atomic mass units, or gram-atoms; atom’s total/average mass

Atomic Number

number of protons in nucleus (subscript)

Mass Number

sum of protons and neutrons in nucleus (superscript)

Isotopes

element with the same number of protons but different number of neutrons; different mass

Radioactive Isotopes

unstable nucleus; loses particles or releases energy

• used in medicine for diagnostics or to track atoms through metabolism

Radioactivity

occurs naturally with a stable rate of decay

Energy

Capability to do work; potential or kinetic

Potential energy

energy of matter due to location or structure

Why do electrons differ in amounts of potential energy?

Due to the organization of an atoms valence electrons

Electron Shells

determine an atoms chemical behavior by distribution of electrons

When are atoms most stable?

When the valence electron shell is full (inner shell - 2; outer shells - 8)

Electron Orbital

3d space where an electron is found 90% of the time; each shell has a specific number of orbitals

Chemical Bonds

interactions between atoms with incomplete valence shells attempting to share or transfer electrons with other atoms

Covalent bond

chemical bond where 2 atoms SHARE a pair of electrons

• stronger than ionic bonds

• non-polar bonds caused by unequal sharing of electrons

Single Covalent Bond

sharing of 1 pair of valence electrons

Double Covalent Bond

sharing of 2 pairs of valence electrons

Electronegativity

an atom’s attraction for electrons in a covalent bond; the more electronegative the more an atom pulls electrons towards itself

Nonpolar Covalent Bond

atoms share electons equally

Polar Covalent Bond

one atoms is more electronegative and pulls electrons from the other atom; partial positive and negative charges on molecule

Ionic Bond

transfer of an electron giving both atoms charges; forms between a cation and anion

called ionic compound or salts

What kind of bond is this?

Chlorine takes an electron from sodium because it is very electonegative. Now, Chlorine has a slight positive charge, and sodium has a slight negative charge.

ionic bond

Cation

positively charged ion

Anion

negatively charged ion

Hydrogen Bond

when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom; water binding

Van der Waals attraction

Electrons accumulate in one part of atom; atoms are very weakly attracted by partial charges (gecko toes)

Chemical Reactions

Making and breaking of chemical bonds

Reactants

Starting molecules of a chemical reaction

Products

Ending molecules of a chemical reaction

All chemical reactions are reversible

The products of the forward reaction become the reactants of the backwards reaction

Chemical equilibrium

When the rate of the backward reaction is equal to the rate of the forward reaction; relative concentration of reactants and products do not change

Oxidation

Removal of electrons; doesn’t require oxygen but often involves it

Redox reaction

One atom is oxidized one is reduced

Water properties

1. Critical for life

2. Polar

3. Physical and chemical properties

4. Acids and bases

Explain why water is a polar molecule.

Oxygen is highly electronegative and thus pulls hydrogen electrons towards it giving water an unequal electric charge.

Properties of water that facilitate life

1. Cohesive behavior

2. Temperature moderation

3. Polar solvent

4. Ice floats

Cohesion

Hydrogen bonds keeps water together and allows transport against gravity and gives water surface tension

Adhesion

Attraction of different substances; water adheres to plant walls and spider webs

Surface tension

Measure of how difficult it is to break the surface of a liquid; water has a very high surface tension

High specific heat

The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C

• waters is 1*C per gram (very high)

Kinetic Energy

The energy of motion

Thermal energy

Kinetic energy of random motion of particles

Temperature

Average kinetic energy of molecules in matter

Heat

Transfer of thermal energy from one body to another

What has greater temperature?

What has greater heat?

Pool or cup of hot coffee

• hot coffee has greater avg temperature

• Pool has more heat because more particles in motion

Calorie (cal)

Heat required to raise 1 g or water 1*C and vice versa

Temperature moderation by water

Water can absorb/release heat with minimal change to its own temperature due to high specific heat

Waters high specific heat is due to hydrogen bonding. Explain the correlation.

• heat is released when bonds FORM

• heat is absorbed when bonds BREAK