chapter 1 biology exploring life. chapter 1: biology: the study of life what is life?

Chapter 1

Biology Exploring Life

Chapter 1: Biology: the study of life

What is Life?

Section 1.1Levels of Organization

BIOSPHERE ECOSYSTEM COMMUNITY

POPULATION ORGANISM

ORGAN SYSTEM

ORGANS TISSUES

CELL ORGANELLE MOLECULE

ATOM

Cover the broad scope of biology

Section 1.2 Living organisms and their environment for interconnecting webs

Food Web Producers Consumers Decomposer

Dynamic of an Ecosystem

Energy Flow Recycling

chemical nutrients

Section 1.3 Cells are the structural and functional units of life

Perform all activities required for lifeProkaryotic cell

Simpler, smallEukaryotic cell

More complex largerNucleus

(contains DNA)

Eukar yotic cell

Prokar yotic cell

DNA(no nucleus)

Organelles

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1.4 The unity of life: All living things have common characteristics

All living things have common characteristics DNA Order Regulation

homeostasis Growth and Development Energy utilization

metabolism Response to environment Reproduction Evolution

mutation

1.5 Diversity of Life

Extent of diversity has led to classification schemes

K-P-C-O-F-G-S Six Kingdoms

Eubacteria Archeabacteria Protista-one-celled organisms Fungi-mold and mushrooms Plantae- multicellular plants Animalia; multicellular animals

1.6 Evolution explains the unity and diversity of life

Charles Darwin Artificial

selection

Natural Selection Observation # 1

Individual variation Observation # 2

Overproduction and Competition

INFERENCE Unequal reproductive success Those with heritable traits best fit the environment

will survive and reproduce

Accumulation of favorable variation in a population over time

The Galapagos Islands

Finches Beak size

1

2

3

Populations with varied inherited traits

Elimination of individuals with certain traits

Reproduction of survivors

Teddy Graham Lab

1.7 The Nature of Science

Science is way of knowing Seeks causes for natural phenomena

Discovery Science Inductive reasoning

Hypothesis Based ScienceDeductive reasoning

1.8 The Scientific Method

Make an observation Ask a Question Make a Hypothesis using all known information Predict what the outcome would be if the hypothesis is

valid Test the hypothesis by experiments, models, and

observations Repeat the tests for consistency Examine alternative hypotheses in the same manner Report objectively on the tests and conclusions

Scientific Method

Independent VariableThe variable you have control over

Dependent VariableChanges in response to the independent

variableControlled Variables

Remain constant so results of the experiment are valid

What is a scientific theory?

A theory is a related set of hypothesis that for a broad-ranging explanation of many phenomena

Theories are rejected and accepted on the basis of tests and are subject to revision

Scientists must be content with relative certainty the theory is valid

Theories can change if new scientific evidence is provided

Does Science have Limits?

It is limited to questions that can be tested

Subjective questions cannot be addressed

Science may be controversial when it offers an explanation for something previously thought the be supernatural

Chapter 2

The Chemical Basis of Life

Nature’s Chemical Language The rattlebox moth

Produces chemicals important for mating and defense

2.1-2.2 The human body, as all of nature, is made of chemical elements.

element: cannot be broken down to other substances by ordinary chemical means

Most common in human body (96%)Oxygen (O)Carbon (C)Hydrogen (H)Nitrogen (N)

Trace element: small amount is essential

2.3 Elements can combine to form compounds

Compound: a substance containing two or more elements in a fixed ratioMore common than pure elements

ex. Vitamin A, Proteins

Sodium Chlorine Sodium Chloride

Trace elements are common additives to food and water

Dietary deficiencies in trace elements Can cause various physiological conditions

Figure 2.2A

2.4 Atoms consist of protons, neutrons, and electrons

Atom: the smallest unit of matter that still retains the properties of an element

Three subatomic particles

Protons (p+) atomic nucleus single positive charge

Neutrons part of the atomic nucleus they have no charge

Electrons (e-) have a negative charge; they circle around the nucleus # of e = # of p

Atomic Number

Defines the elementequal to the number of of protonsIs equal to the number of electrons in a

neutral atomAlways the whole number

Mass number: equal to the number of protons plus the number of neutrons in its nucleus

Atomic Mass

Is equal to the number of protons and neutrons in the nucleus of the atom (mass number)

May not be a whole number on the periodic table

In biology you may round the atomic mass to a whole number

2.5 Radioactive isotopes can help or harm us

Isotopes: different forms of atoms Atoms with the same number of protons

and electrons but a different number of neutrons

Radioactive isotopes Nucleus decays spontaneously giving off

particles of energy Research/Medicine

Radioactive tracers Dangers

Damage molecules (DNA)

2.6 Electron arrangement determines the chemical properties of an atom

electron shells: certain energy levels where electrons occur Each shell holds up to a certain # of e-

the # of e- in the outermost energy level determines the chemical properties of an atom

(how it will bond w/other atoms)

Chemical bond: attractions holding atoms together

Ion – charged atom

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)

Transferof electron

Protons +11Electrons -11Charge 0

Protons +17Electrons -17Charge 0

Protons +11Electrons -10Charge +1

Protons +17Electrons -18Charge -1

Section 2-1

Figure 2-3 Ionic Bonding

Ionic bonding

Transfer of Electrons from one atom to another

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)

Transferof electron

Protons +11Electrons -11Charge 0

Protons +17Electrons -17Charge 0

Protons +11Electrons -10Charge +1

Protons +17Electrons -18Charge -1

Section 2-1

Figure 2-3 Ionic Bonding

Transfer of electrons

Covalent Bond

Sharing of electronsElectrons are not completely transferred

to another atom

Rules for drawing covalent bonded molecules

2 electrons 1 bond 1 line You can form more than one bond between

atoms Carbon 4 bonds Oxygen always has 2 bonds and 2 lone pairs Hydrogen always has 1 bond Nitrogen has 4 bonds or 3 bonds and a lone

pair of electron

some organic molecules

Methane Acetylene Butadiene Benzene Isooctane

Section 2-3

Figure 2-11 Carbon Compounds

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2.9 Unequal electron sharing creates polar molecules

Atoms in a covalent bond are in a constant tug-of-war for the shared electrons

Electronegativity: an atom’s attraction for its electrons, including shared electrons

Nonpolar: atoms exert an equal pull on the electrons

Polar: unequal sharing of electrons

Waterpolar molecule

Hydrogen Bonding

In a hydrogen bond, an atom or molecule interacts weakly with a hydrogen atom already taking part in a polar covalent bond

Hydrogen Bonds

Hydrogen bonds form any time a hydrogen atom is bonded to an F, O, N

They are weak bonds between to molecules

Hydrogen bonds make liquid water cohesive

Properties of water

Water is polar Hydrophilic; water

loving Hydrophobic; water

hating Cohesive properties

due to hydrogen bonding

Universal solvent

2.12 Water’s hydrogen bonds moderate temp.

Heat The amount of energy associated with the movement of

atoms and molecules in the body

Warming Disrupts (H) bonds then speeds up molecules Store large amounts of heat while warming a few degrees

Cooling Heat energy is released when (H) bonds form, slowing

the cooling process

2.13 Ice is less dense than liquid

2.14 Water is the solvent of life

Solution: liquid consisting of a uniform mixture of two or more substances

Solvent: dissolving agentSolute: substance that is dissolved

Water as a Solvent

Cl-

Water

Cl-

Na+

Water

Na+

Section 2-2

Figure 2-9 NaCI Solution

Go to Section:

NaCl as the solute

Acids, Bases and Salts

Acid is a proton donor (H+), have a pH less than 7

Base is an proton acceptor; has a pH greater than 7

A salt is formed when and acid reacts with a base

Buffer is a solution that is resistance to pH change

The pH scale

pH is a measure of the H+ concentration in a solution

The greater the H+ the lower the pH