Chapter 1 & 2: Introduction to the Science Life, Chemistry of Life

What are the 7 characteristics of life?

1. order 2. cells 3. growth & development 4. energy utilization 5. Response to the Environment (Stimulus)

6. Reproduction 7. Evolution

Levels of organization

cell, tissue, organ, organ system, organism

ecological organization

organism, population, community, ecosystem, biome, biosphere

What is the scientific method?

is a "recipe for discovery" used across all sciences.

Four components of the scientific method

1. Observation

2. Hypothesis

3. Experimentation

4. Analysis/Conclusion

What is a hypothesis?

A hypothesis is an "if-then" statement that must be specific and testable.

What is a theory?

a well-substantiated, comprehensive explanation, and is much broader in scope than a hypothesis.

A controlled experiment is one that

consists of two parallel tests comparing the experimental sample against a control sample.

experimental group vs. control group

EXPERIMENTAL GROUP is the group receiving the independent variable

CONTROL GROUP does not receive anything, in order to act as a comparison

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied.

dependent variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

Controlled variables

remain constant across experiments

single-blind study

study in which the subjects do not know if they are in the experimental or the control group

double-blind study

study in which neither the experimenter nor the subjects know if the subjects are in the experimental or control group

placebo effect

substance or treatment with no therapeutic effect

Pseudoscience

is falsely represented as having a scientific basis

Ex: Astrology, Fortune Telling, Etc.

peer review

A process that maintains scientific integrity must be reviewed by other scientists

Matter

anything that has mass and takes up space

Atom

the smallest unit of matter

Molecules

two or more atoms joined together

What are the 6 essential elements of life?

carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur (CHONPS)

3 major subatomic particles

protons, neutrons, electrons

Protons

Positively charged particles

Neutrons

no charge

Electrons

Negatively charged particles

atomic number

the number of protons in the nucleus of an atom

atomic mass

Number of protons and neutrons

K shell orbital

Holds 2 electrons

The ( L&M) shells hold...

8 electrons

valence electrons

Electrons on the outermost energy level of an atom

When are atoms the most stable?

when all of the electron orbitals in the valence shell are filled

What are the 4 major types of chemical bonds?

- Ionic

- Polar Covalent

- Non-Polar Covalent

- Hydrogen

Ionic Bonds

Electrons are transferred from one atom to another.

Ions

are charged atoms that have gained or lost electrons

Cations

positively charged ions, when you lose electrons

Anions

negatively charged ions, gaining of electrons

Covalent bonds

Bonds created by sharing electrons with other atoms. Strongest bonds

Polar covalent bonds

Bonds in which electrons are not shared equally between atoms of different elements in a compound

nonpolar covalent bond

a covalent bond in which the electrons are shared equally by the two atoms

Polarity is determined by

difference in electronegativity

What are important polar molecules?

water

Non-polar molecules are _______ in water

insoluble

Polar molecules are _______ in water

soluble

Hydrogen bonding

form between a hydrogen atom and an atom that is negatively charges. WEAKEST BOND!

7 special properties of water

- High specific heat

- High surface tension

- High Boiling Point

- Cohesion

- Adhesion

- Higher density as a liquid than a solid

Cohesion

Attraction between molecules of the same substance

Adhesion

An attraction between molecules of different substances

Solvent

the dissolving agent in a solution

Solute

The thing getting dissolved

Solution

solute + solvent: final product

Hydrophilic

water loving

Hydrophobic

Water fearing (oils)

pH scale

scale with values from 0 to 14, used to measure the concentration of H+ ions in a solution; a pH of 0 to 7 is acidic, a pH of 7 is neutral, and a pH of 7 to 14 is basic

pH is measured on a scale of

10 log

Buffers

chemical substance that resists changes in pH ( can either accept or donate hydrogen ions)