ap bio uni 1

Themes of ap bio

Evolution: allows organisms to pass on traits from generations. Occurs through natural selection

Energetics: the properties & distribution of energy, which fuels the abilities of organisms. 2 sources: the sun or chemical compounds

Information storage and transmission: instructions that determine a cells function stored in its DNA

Gene: unit of heredity

Genome: all genetic info that an organism contains

Cells: simplest self reproducing unit that can exist on its own

Species: group of interbreeding organisms producing fertile offspring

Systems interactions: functional group including interactions with abiotic and biotic components at different levels, leading to emergent properties (system combined independent parts)

All ensure the survival and reproduction of organisms

the components of a science experiment

Scientific inquiry: process used to ask questions and find answers about the world. 3 parts: exploration/observation, investigation, communication

Hypothesis: tentative explanation or prediction of an observation that can be tested, cannot be proven but can be modified or rejected

Controlled experiment: two identical groups with an introduced change/variable to see the effect.

Test group: experiences the variable

Controlled group; is not exposed to the variable

Independent variable: manipulated variable

Dependent variable: result of experiment

Negative control group: expect no effect, opposite of positive control group.

Null hypothesis: expect no effect. Opposite of alternative hypothesis.

Qualitative data are descriptive, quantitative data are expressed numerically

P-value: expresses the likelihood of a random result

Theory: general explanation of the world backed by experimental evidence and observations

Percent change

Final value - first value divided by the first value multiplied by 100

significant figures

Numbers above zero are significant 315 has 3 sig figs

Zeros between significant numbers are significant 3405 has 4 sig figs

Leading zeros located left are not significant (0.02) has 1 sig fig

Trailing zeros located right are not significant except in numbers with a decimal point 120,000 has 2 sig figs. 120,000.0 has 7 sig figs

Types of averages: Mean median mode

Mean: adding all values and dividing by the number of values.

Median: list values in numerical order, identify the middle value. If there are two values, calculate their mean.

Mode: the value that shows up the most frequently in a dataset

Spread of data:

Normal distribution: measurments forming smooth bell-curved graph. Mean median and mode are all the same value

Range: highest value minus lowest value. Highly influenced by an outlier

Standard of deviation: how far the dataset values are from the mean. Small=measurements are clustered around the mean. Large=measurements are wider spread. Calculated by subtracting the mean from each data point, squaring the result, adding them, & dividing by total number of data points, taking the square root.

Standard error of the mean: how close the estimated mean is to the true mean. Calculated by dividing standard deviation by the square root of the number of samples

Error bars: vertical line on a graph that indicates a failure of true value. Usually represent the mean plus or minus two standard errors of the mean (95 confidence interval) If error bars of two groups dont overlap, there is a significant difference between the groups

1.1

Matter: anything with mass and takes up space (gas, liquid, solid)

Atom: basic unit of matter

Molecules: chemical bonds enable atoms to form molecules

Organic molecules: made of carbon

Carbon cycle: matter moves through organisms and the physical environment repeatedly, also transferring energy. Energy is constantly required and does not move in a cycle, unlike matter and carbon

Organisms transfer energy into a chemical form their cells can use, which is used to do work and dissipated as heat

The flow of matter depends on energy because it provides the power to influence atoms/molecules

1.2

essential functions of life depend on the chemical characteristics of organic molecules.

Atom: contains a dense nucleus, consisting of protons and neutrons, each having 1 atomic mass unit. Electrons, negatively charged, move around the nucleus, typically the same number as protons, making most electrically neutral.

Atomic mass: determined by protons and neutrons to get the total mass of an atom. Indicated by a superscript

Atomic number: number of protons, identifies the atoms particular element, a chemical that cannot be broken down. Indicated by a subscript

4 elements found in all organisms: CHON

Isotopes: atoms of the same element with differing neutrons

Energy transfer: involves the movement/sharing of electrons from one atom to another atom to complete an atoms outermost energy levels/number of valence electrons, often resulting in molecules. Elements in the same group (vertical) have the same number of valence electrons

Energy level/electron shell: an area where electrons circle around the nucleus. The innermost shell may contain 1-2 electrons, which have less energy and are less reactive, meaning theyre stable. Elements in the same row (horizontal) have the same number of shells. When an electron gains energy, it jumps to a level away from the nucleus, making it less stable. Essential elements (CHON) contain 2 levels, the 2nd shell may hold up to eight electrons.

Hydrogen ion: formed when an electron is lost (has an extra proton)

The periodic table of elements: describes valence electrons & properties of elements arranged in order of increasing atomic number (rows), and the same number of valence electrons (groups/columns).

1.3

molecule example: hydrogen gas, made when two atoms of hydrogen (H) bond.

Chemical formula: written as letter abbreviation for an element followed by a subscript showing the number of identical atoms in that element. eg. H2O. CH4.

Chemical stability: when an atom/molecule has the lowest possible energy state, it is less likely to react because it requires energy to bond during chemical reactions

Chemical bond: an attraction holding two atoms together to form a molecule

Covalent bonds: atoms share valence electrons with each-other. A single bond is when two atoms share two electrons, denoted by a single line. a double bond is when two atoms share two pairs of electrons (4), denoted by a double line that connects 2 symbols (equal sign)

Polar covalent bonds: electrons are not shared equally (eg. H2O. H slight positive charge, O slight negative charge) occurs because of electronegativity, the ability of atoms to pull shared electrons towards itself. atoms with higher electronegativity pull shared electrons closer, making it slightly negative

Nonpolar covalent bonds: electrons are shared equally between atoms. eg. H2, O2. atoms usually have similar electronegativities. C and H frequently form these bonds.

Electronegativity increases across a row as protons increase, because electrons will increase.

Ionic bonds: when the difference of electronegativity between two atoms is too large, the more electronegative atom steals the electron, creating an electrically charged ion that is negative. Two ions with opposite electrical charges attract to form ionic bonds. More than one electron may be gained or lost when atoms form ionic bonds. Indicated by superscripts showing charge.

Chemicals that dissolve well in water tend to have polar/charged regions.

Chemical reaction: process in which atoms/molecules are transformed into different molecules. Atoms that are changed are called reactants. Molecules formed from the reaction are called products. Provides a way to harness energy

why water is essential for life

molecular shape (2 hydrogen, 1 oxygen sharing electrons unevenly) allows polar (slightly neg and slightly pos) covalent bonds to form inbetween

The opposite charges form hydrogen bonds, which pull together water molecules (cohesion)

Because of cohesion, water has a high specific heat capacity, which makes it easier for organisms to regulate their internal temperature (eg. evaporative cooling)

Hydrogen bonds allow

Cohesion

Water molecules stick to other water molecules, causing surface tension

Adhesion

Water molecules stick to other polar surfaces allows for capillary action in vascular plants

Surface tension

takes force to break the surface of water

carbon

All molecules have carbon as the primary element. Known as Organic molecules

Carbon, hydrogen, oxygen found in all biological molecules (carbohydrates, lipids, proteins, nucleic acids)

Carbs - CHO

Lipids - CHOP (phosphorus)

Proteins - CHONS (nitrogen, sulfur)

Nucleic acids - CHONPS (nitrogen, phos, sul)

Carbon atoms can form 4 different covalent bonds