BSC2005 Exam 1

Elements of the Scientific Method

o Observations
o Questions
o Hypothesis
o Predictions
o Testing (experiments)
o Conclusions

Why is falsifiability important to a scientific hypothesis?

Falsifiability is the fundamental mechanism that gives a statement truth

Null Hypothesis

There is no statistical difference between the two variables

Alternative Hypothesis

The hypothesis accepted to be true if the null is rejected

Independent Variable

the thing that you are changing

Dependent Variable

the thing that you are measuring

Control Groups

represent the original situation with nothing changed

Experimental Groups

those with a variable changed

Data

all the information we have gathered about a particular subject

Quantitative Data

number or a measurement

Qualitative Data

categorical, like a color or size

Why is a larger sample size better than smaller?

The larger the sample size, the more likely the results will have statistical significance. It is easier to generalize

Statistical Significance

measure of confidence that the results obtained are "real," rather than due to random chance

Correlation and Causation

Just because two variables are related does not mean that one caused the other - there need to be a mechanism for statistical results to make sense

Peer Review

evaluation of scientific, academic, or professional work by others working in the same field.

Why is peer review important?

It allows researchers to share ideas and to test and evaluate each other's work.

Everyday theory

an idea based on personal experience and knowledge

Scientific theory

A well-tested explanation for a wide range of observations or experimental results.

6 characteristics of life

Growth, Reproduction, Obtain and use energy, Homeostasis, Sense and respond to stimuli, Evolve and adapt

Growth

the process of increasing in physical size.

Reproduction

the process of producing offspring

Ability to obtain and use energy

allowing them to do work. we require an input of energy to power our activities

Homeostasis

The maintenance of stable internal conditions

Sense and respond to stimuli

the process of reacting to their environment

Evolve and adapt

Living organisms adapt to their environment and evolve.

atoms

smallest unit of matter

molecules

chemicals that result from atoms linking together

elements

a molecule composed of one kind of atom; cannot be broken into simpler units by chemical reactions.

matter

anything that takes up space and has mass

protons

positively charged subatomic particles. contribute to the mass

electrons

negatively charged subatomic particles.

neutrons

the particles of the nucleus that have no charge

periodic table

A chart of the elements showing the repeating pattern of their properties

atomic number

the number of protons in an atom

Why is carbon the key element of life?

o It can form multiple covalent bonds, the sharing of a pair of electrons between two atoms
o fourth most common element in the universe, second most common element in the human body

organic molecules

carbon-based backbones and at least one C-H bond

inorganic molecules

lack carbon-based backbones and C-H bonds

Carbohydrates

made of repeating subunits of simple sugars

Proteins

folded polymers made of repeating units of amino acids
-amino group and carboxyl group
-the R group differentiates amino acids from each other

Lipids

are NOT made of repeating monomers

Nucleic Acids

Polymers made of repeating nucleotide subunits

Mechanism for phospholipids to assemble into membranes

In water, phospholipids spontaneously form a double layer called a lipid bilayer in which the hydrophobic tails of phospholipid molecules are sandwiched between two layers of hydrophilic heads

pH

the concentration of hydrogen ions (H+) in a solution
ranges from 0 to 14
0-6 acidic
7 neutral
8-14 basic

Properties of water

o Cohesion: water molecules cling together
o Adhesion: water molecules cling to surfaces
o Large liquid range (freezing at 0o C boiling at 100o C)
o Solid water is less dense than liquid water, so ice floats
Surface tension
• Due to polarity, hydrogen bonds form at the surface of water, forming an "elastic film."

iconically bonded compounds dissolve in water

When you place an ionic substance in water, the water molecules attract the positive and negative ions from the crystal

antibiotic

a chemical that can slow or stop the growth of bacteria; many antibiotics are produced by living organisms

cell theory

the concept that all living organisms are made of cells and that cells are formed by the division of existing cells

prokaryotic cells

cells that lack internal membrane-bound organelles

eukaryotic cells

cells that contain membrane-bound organelles, including a central nucleus

organelles

the membrane-bound compartments of eukaryotic cells that carry out specific functions

cell membrane

a phospholipid bilayer with embedded proteins that forms the boundary of all cells

cytoplasm

the gelatinous, aqueous interior of all cells

ribosome

a complex of RNA and proteins that carries out protein synthesis in all cells

nucleus

the organelle in eukaryotic cells that contains the genetic material

cell wall

a rigid structure present in some cells that encloses the cell membrane and helps the cell maintain its integrity

osmosis

the diffusion of water across a membrane from an area of lower solute concentration to an area of higher solute concentration

hypotonic

describes a solution surrounding a cell that has a lower concentration of solutes than the cell's cytoplasm

hypertonic

describes a solution surrounding a cell that has a higher concentration of solutes than the cell's cytoplasm

isotonic

describes a solution surrounding a cell that has the same solute concentration as the cell's cytoplasm

peptidoglycan

the macromolecule found in all bacterial cell walls that gives the cell wall its rigidity

gram-positive

describes bacteria with a cell wall that includes a thick layer of peptidoglycan that retains the Gram stain

gram-negative

describes bacteria with a cell wall that includes a thin layer of peptidoglycan surrounded by an outer lipid membrane that does not retain the Gram stain

simple diffusion

the movement of small, uncharged solutes across a membrane from an area of higher concentration to an area of lower concentration without the aid of transport proteins; does not require an input of energy

transport proteins

proteins involved in the movement of molecules and ions across the cell membrane

facilitated diffusion

the process by which large, hydrophilic, or charged solutes move across a membrane from an area of higher concentration to an area of lower concentration with the help of transport proteins; does not require an input of energy

active transport

the process by which solutes are pumped from an area of lower concentration to an area of higher concentration with the help of transport proteins; requires an input of energy

nuclear envelope

the double membrane surrounding the nucleus of a eukaryotic cell

mitochondria

membrane-bound organelles responsible for important energy-conversion reactions in eukaryotes

endoplasmic reticulum

a network of membranes in eukaryotic cells where proteins and lipids are synthesized

golgi apparatus

an organelle made up of stacked membrane-enclosed discs that packages proteins and prepares them for transport

lysosome

an organelle in eukaryotic cells that is filled with enzymes that can degrade worn-out cellular structures

cytoskeleton

a network of protein fibers in eukaryotic cells that provides structure and facilitates cell movement

chloroplast

an organelle in plant and algal cells that is the site of photosynthesis

endosymbiosis

the scientific theory that free-living prokaryotic cells engulfed other free-living prokaryotic cells billions of years ago, forming eukaryotic organelles such as mitochondria and chloroplasts

malnutrition

the medical condition resulting from the lack of essential nutrients in the diet; often, but not always, associated with starvation

nutrients

components in food that the body needs to grow, develop, and repair itself

energy

the ability to do work, including the work of building complex molecules

macronutrients

nutrients, including carbohydrates, proteins, and fats, that organisms must ingest in large amounts to maintain health

essential nutrients

nutrients that can't be made by the body, and so must be obtained from the diet

starch

a complex plant carbohydrate made of linked chains of glucose molecules; a source of stored energy

essential amino acids

amino acids that can't be made by the body, and so must be obtained preassembled from the diet

catabolic reaction

any chemical reaction that breaks down complex molecules into simpler molecules

anabolic reaction

any chemical reaction that combines simple molecules to build more complex molecules

metabolism

all biochemical reactions occurring in an organism, including reactions that break down food molecules an reactions that build new cell structures

enzyme

a protein that speeds up the rate of a chemical reaction

catalysis

the process of speeding up the rate of a chemical reaction (e.g., by an enzyme)

substrate

a molecule to which an enzyme binds and on which the enzyme acts

active site

the part of an enzyme that binds to a substrate

activation energy

the energy required for a chemical reaction to proceed; accelerate reactions by reducing their activation energy

mineral

an inorganic chemical element required by organisms for normal growth, reproduction, and tissue maintenance; examples are calcium, iron, potassium, and zinc

micronutrients

nutrients, including vitamins and minerals, that organisms must ingest in small amounts to maintain health

vitamin

an organic molecule required in small amounts for normal growth, reproduction, and tissue maintenance

cofactor

an inorganic substance, such as a metal ion, required to activate an enzyme

covalent bond

a strong interaction resulting from the sharing of a pair of electrons between two atoms

organic

describes a molecule with a carbon-based backbone and at least one C-H bond

inorganic

describes a molecule that lacks a carbon-based backbone and C-H bonds

macromolecules

very large organic molecules that make up living organisms; they include carbohydrates, proteins, and nucleic acids

monomer

one chemical subunit of a polymer

polymer

a molecule made up of individual subunits, called monomers, linked together in a chain

monosaccharide

the building block, or monomer, of a carbohydrate