General Biology: Key Concepts from Chapters 1-3

in any order: forming and testing hypotheses, exploration and discovery, societal benefits and outcomes, and community analysis and feedback

an explanation, based on observations and assumptions, that leads to a testable prediction

A good hypothesis has a clear set of what will be tested and what the result will be, a good hypothesis will be testable, falsifiable, specific, unbiased, financially okay, explainable, and ethical

Claim, evidence, and justification

is the one that is manipulated by the researchers

is the one predicted to be affected in response

A group in an experiment where a known response is expected, ensuring the experiment works.

A group where no response is expected, used to detect contamination or bias.

 A substance that cannot be broken down to other substances by chemical reactions

• Acompound is a substance consisting of two or more elements in a fixed ratio

  • A compound has characteristics (emergent properties) different from those of its elements

Elements required for life, e.g., carbon, hydrogen, oxygen, nitrogen.

Elements required in very small amounts, e.g., iron, iodine.

• Atomic number is the number of protons in its nucleus

• Atomic mass, the atom’s total mass, can be approximated by the mass number

• Isotopes are two atoms of an element that differ in the number of neutrons

• Valence electrons are those in the outermost shell, or valence shell

• Electronegativity is an atom’s attraction for the electrons in a covalent bond

  • The more electronegative an atom is, the more strongly it pulls shared electrons toward itself

Cation: positively charged ion; Anion: negatively charged ion.

A chemical bond formed by sharing electron pairs between atoms.

giving up of electrons. Ionic bonds are the complete sharing of electrons through a complete transfer from an

• A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom

Nonpolar: electrons shared equally; Polar: electrons shared unequally due to electronegativity differences.

• Chemical reactions are the making and breaking of chemical bonds

• The starting molecules of a chemical reaction are called reactants

• The resulting molecules of a chemical reaction are called products

• Chemical equilibrium is reached when the forward and reverse reactions occur at the same rate 

• In the water molecule, the electrons of the polar covalent bonds spend more time near the oxygen than the hydrogen

• The water molecule is thus a polar molecule; the overall charge is unevenly distributed

• Polarity allows water molecules to form hydrogen bonds with each other

1. Cohesion of Water

1. Moderation of Temperature by Water

1. Floating of Ice on Liquid Water

1. Water is the Solvent of Life

• Van der Waals interactions are attractions between molecules that are close together as a result of these charges

  • weak, short-range electrostatic attractions between neutral atoms or molecules, caused by temporary shifts in electron density that create fleeting, opposite charges

• Cohesion – hydrogen bonding among water molecules

  • Cohesion contributes to the transport of water and dissolved nutrients against gravity in plants

• Adhesion - between different substances

  • Ex: water and plant cell walls

  • This helps to counter the downward pull of gravity

• The combination of both allows for transpiration to occur (driving force that moves water from the roots to the leaves against gravity).

• Surface tension is a measure of how hard it is to break the surface of a liquid

• Water has an unusually high surface tension due to hydrogen bonding

• A calorie (cal) is the amount of heat required to raise the temperature of 1 g of water by 1°C

  • It is also the amount of heat released when 1 g of water cools by 1ºC

• Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas

• A single covalent bond, or single bond, is the sharing of one pair of valence electrons

• shown by the - symbol H:H and H-H

A double covalent bond, or double bond, is the sharing of two pairs of valence electrons

• shown by the symbol O=O

• Electronegativity is an atom’s attraction for the electrons in a covalent bond

  • The more electronegative an atom is, the more strongly it pulls shared electrons toward itself

Factors that influence electronegativity:

• Nuclear charge (higher # protons exert stronger pull on electrons)

• Atomic radius (smaller atoms have higher electronegativity b/c nucleus is closer to the shared electrons)

• Organisms are composed of matter

• Matter is anything that takes up space and has mass

• Matter is made up of elements 

• An orbital is the three-dimensional space where an electron is found 90% of the time

• Each electron shell can contain a limited number of electrons. the first shell has two and each other can have up to 8 electrons

• Each species is given a two-part name: The genus, to which the species belongs, and a species name unique to that species

• E.g., Homo sapiens, is the name of our species

Life can be studied at different levels, from molecules to the entire living planet. That's organization; everything in biology is connected through systems

Reductionism is an approach that reduces complex systems to simple components that are manageable to study

Everything is encoded in DNA Central dogma of biology

• When organisms use energy , it is lost to the surroundings as heat

• As a result, energy flows through an ecosystem, usually entering as light and exiting as heat

• Chemicals cycle within an ecosystem, where they are used and then recycled

• producers consumers and decomposers

• Interactions between the components of the system ensure smooth integration of all the parts

• This holds true equally well for molecules in a cell and the components of an ecosystem

Explains how all living things are unified and diverse. 

Evolution is the process of change that transforms life on earth from its earliest beginnings evolution is the fundamental organizing principle of biology.