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Two types of Science

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249 Terms

Two types of Science

Induction and Hypothesis based science

Induction Based Science

A predictive generalization Ex. Cell theory - generalizations about cells

Hypothesis Based Science

Deductive Reasoning Hypothesis - explanation for an observations

Occam's Razor

If several explanation work with your evidence, then go for the simplest one. The razor shaves off unnecessary details.

What happens if there is no control in an experiment

No support for hypothesis

Negative Control

Did nothing

Positive Control

A known characterized treatment. It will give a well known effect that is no surprise

Progress in Science

Explanatory power New ideas are formed, and the old rejected

Theories

Need a huge amount of evidence Ex. Theory of natural selection Theories are excepted only because of the evidence behind them.

Replication

Sample size does not equal 1 Has a greater chance of convincing results with replicates Did all results do the same thing ?

Reproducibility

Can others do your experiment? The same results should be from the same experiment, regardless of where and when.

Composition of an Atom

Nucleus has protons (1+) and neutrons (0) Electrons (1-) are in orbitals around nucleus

What defines an atom

The number of protons and the number of neutrons

Isotopes

Have the same atomic number, but a different number of neutrons

What are bonds based on

Electrons

How many bonds does Carbon have

4

How many bonds does Hydrogen have

1

How many bonds does Oxygen have

2

Hydrogen

Smallest atom H+ are important for cellular metabolism

What is left over if Hydrogen loses an electron

Only a proton

Cations

positively charged ion

Anion

a negatively charged ion

Helium

Second smallest atom Two protons atom is mostly empty space Noble gas

What does a chemical bond require

one pair of electrons each atom providing one electron

What type of bond is N

3

Non polar

no partial charge on atoms Share equal

Covalent

Bonds are shared

Electronegativity (EN)

The ability of some atoms to attract electrons to itself

Polar Covalent Bonds

Shared unequally in a covalent bonds - if moderate difference

Polar

Refers to the fact that partial charges due to unequal sharing

What is water held together by

two polar bonds - example of a polar molecule

Examples of Non polar covalent bonds

O-H, N-H, 0-C, N-C

Ionic Bonds

No sharing Taking electrons (higher EN) Ex. Salts Form between between atoms with different EN

Hydrogen Bonds

Constantly breaking and reforming (transient) Consequence of polar covalent bonds containing hydrogen Water molecules stick together due to hydrogen bonds

Water

Cells are 80% water Water is the solvent of life

Universal Solvent

Does not exist

What does water exhibit

Cohesion

Hydrophilic

Water liking Polar/Charged

Hydrophobic

Water fearing Non polar covalent bonds not soluble in water

What is water attracted to

Large polar/ charged molecules Ex. Sugars

What is more soluble

Small hydrophilic molecules

Large polar molecule solubility

They are also hydrophilic But can be too big to be soluble

What are Hydrophobic molecules composed of

Non polar covalent bonds Ex. C-C, C-H Fats are hydrophobic

What can water do

Reverse disassociate

Strong acid

Complete dissociation unlike equilibrium for water dissociation HCl-->H+ +Cl-

Acidity

protons (H+) More than High acidity

pH

Measure of acidity -log[H+]

What is pH 7

Neutral/water

Higher than 7 pH

Acidic