University of Florida BSC2005 Exam 1 Study Guide

What are the differences between observational and experimental studies? Are there situations where one is more useful than the other? What kind of information can we get / conclusions can we draw from each?

Observational studies (when, where, how many, how much)

- shows patterns, no manipulation of variables

Experimental studies (changing variables in controlled environment)

- demonstrates causation

What is a natural experiment? How is it similar to / different from observational vs. experimental studies?

Natural experiment (no direct manipulation of variable, still groups that differ naturally)

- like banning smoking in a town and watching cancer numbers

What are the steps of the scientific method? Come up with a case of "everyday science" from your real life and describe how it fits into each of the steps.

Observations

Questions

Hypotheses (must be testable)

Predictions

Testing

Conclusion

What is a hypothesis?

A tentative explanation for a scientific observation or question.

Hypothesis

1. Alternative hypothesis (there is a relationship)

2. Null (there is no relationship)

What does it mean for a hypothesis to be falsifiable? Why is this important?

It can be proven wrong, otherwise you could claim something is true even if it isn't

Can a hypothesis be proven? Can it be disproven?

It can never be proven, but it can be disproven

Define the terms "independent variable" and "dependent variable". In your case of "everyday science" from the earlier question, which is which?

1. Dependent Variables

Thing you're measuring

2. Independent Variables

Thing you're changing

What's the difference between an alternative hypothesis and a null hypothesis? Identify both for your "everyday science".

A hypothesis is always framed as a "null" - which means there is no difference when we do something.

if we reject the null hypothesis, we can say our alternative hypothesis is true. if we cannot find this evidence, we will continue with the assumption that the null hypothesis is true.

What are controls, and why are they important?

Control groups are the original situation with nothing changed

- one can study the outcome of a situation with no applied variables to it

What's the difference between qualitative vs. quantitative variables?

One is numerical (quantitative), the other is descriptive (qualitative)

Why is the sample size (amount of data you collect) important?

The larger the sample size, the more likely the results will have statistical significance.

If we see a relationship between two variables, can we say that changes in one variable cause the change in the other? What would we need to do in order to make that claim?

No, correlation does not equal causation. We would need rigorous and supportive testing to make that claim.

What are the qualities that determine whether something counts as alive? Are there any exceptions?

1. Growing

2. Reproducing

3. Maintain homeostasis

4. Sense and respond to environment

5. Obtain and use energy

Things like viruses(?)

What are organic molecules? How can we differentiate them from inorganic molecules?

Organic - backbone of carbon and at least one C-H bond

Inorganic - has carbon but not those characteristics ^

What are the properties of carbon that make it so important for life on Earth?

Ability to form bonds with other atoms, including itself

- 4 outer layer electrons

What are the main types of organic macromolecules? What are the monomers that make up the polymers of each type? What are the major uses/functions of each type of macromolecule?

Macromolecules - what large organic molecules are

Composed of subunits monomers

Macromolecules and their monomers:

1. Carbs - monosaccharides

act as energy-storing molecules in many organisms. others provide structural support for cells

2. Proteins - amino acids

help speed up the rates of chemical reactions. they also move things through and around cells and even help entire cells move

3. Nucleic acids - nucleotides

they are critical for storage, transmission, and execution of genetic instructions

4. Lipids - NOT POLYMERS

help control what goes in and out of your cells. They help with moving and storing energy, absorbing vitamins and making hormones

What is the basic structure of monosaccharides, disaccharides, and complex carbohydrates?

Monosaccharides - exist as a linear chain or as ring-shaped molecules (-ose)

Disaccharides - two monosaccharide units linked together by a glycosidic bond; include lactose, maltose, and sucrose

Complex carbs exist in a long chain

What's the basic structure of an amino acid, and how do they join together? Why are the side chains important?

Each AA consists of a central carbon atom, also known as the alpha (α) carbon, bonded to an amino group, a carboxyl group, and to a H atom. Every AA also has another atom or group of atoms bonded to the central atom known as the R group side chain

The chemical nature of the side chain determines the nature of the amino acid (that is, whether it is acidic, basic, polar, or nonpolar)

Each amino acid is attached to another amino acid by a covalent bond

What's the basic structure of a nucleotide, and how do they join together?

Base, Sugar, and Phosphate

Sugar and Phosphate make up the backbone

Bases make up the "rungs" (ATCG)

What's the difference between DNA and RNA?

RNA is mainly involved in the process of protein synthesis under the direction of DNA

DNA = Double Helix, RNA = Single

How do lipids differ from the other types of macromolecules?

The are not Polymers, and are Hydrophobic

What's the structure of water molecules? What does it mean that water is polar? Why is this important?

Water (H2O) is polar because the Oxygen has a slightly stronger pull on the shared electrons of the covalent bond, leaving the oxygen slightly negative and the hydrogen slightly positive. This allows water to bond to itself as well as form hydrogen bonds.

What are hydrogen bonds? Why are they important?

Not between atom itself, but rather between multiple atoms (intermolecular); Strongest of this kind

Provide many of the critical, life-sustaining properties of water and also stabilize the structures of proteins and DNA

- Creates surface tension

What is a solvent? A solute? A solution?

Solvent - a substance in which another substance dissolves

Solute - a dissolved substance

Solution - mixture of solute and solvent

Water can dissolve other polar molecules and things that split into positive and negatively charged ions

What is pH? What does a very low pH mean, chemically? What about a high pH? What is considered neutral?

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

What is the difference between catabolic reactions and anabolic reactions?

Anabolic reactions use energy to build complex molecules

Catabolic reactions break complex molecules down into simpler ones, releasing chemical energy.

What are enzymes? How do they assist in the process of chemical reactions?

Enzymes speed up chemical reactions

Begins by binding to substrates in the active site

Each enzyme is specific to the reaction it is a catalyst for

Reduce the activation energy for any given reaction

What is the active site of an enzyme? How does it specify which substrates fit?

Where the reaction takes place. A specific chemical substrate matches this site like a jigsaw puzzle piece and makes the enzyme specific to its substrate.

What happens to an enzyme after the chemical reaction has occurred?

It is unchanged, and is not "used up" during the reaction

What are the basic tenets of Cell Theory?

Cell Theory

1. Cell is the basic unit of life

2. All living things are composed of cells

3. Cells come from preexisting cells

What are prokaryotes? What are eukaryotes? What features do they share? What organelles/structures are unique to one or the other?

Prokaryotic - no nucleus, no membrane-bound organelles

Eukaryotic - nucleus, organelles

Both have cell membrane and ribosomes, among other qualities

Which groups have unicellular individuals? Which groups have multicellular individuals?

Both, only Eukaryotic is multicellular

Where are prokaryotes found? What roles do they play in their environments?

Everywhere, they photosynthesize energy and create the base of the food pyramid/web

What are protists?

A protist is any eukaryotic organism that is not an animal, plant, or fungus

What is endosymbiont theory? Which organelles are involved? What evidence supports this theory?

Endosymbiosis - theory that organelles used to be prokaryotic and then were engulfed and became part of eukaryotic

- Mitochondria and Chloroplasts

- Mitochondria has its own membrane

What organelles/structures are found in both plant and animal cells? Which ones are unique to one or the other?

Both: Mitochondria, Vacuoles

Plant: Chloroplasts, Cell Wall

Animals: Lysosomes

Cell Membrane

the semipermeable membrane surrounding the cytoplasm of a cell, controls which substances get in and out

Cytoplasm & Cytoskeleton

The gel like substance that fills the cell that helps the cell move and transport things around the cell.

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction; sorrounded by double membrane (envelope)

Endoplasmic Reticulum (ER)

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions. The ribosomes make proteins and the smooth ER is the site of lipid production

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

Lysosome

An organelle containing digestive enzymes

Cell Wall

A rigid structure that surrounds the cell membrane and provides support to the cell

Vacoule

a organelle that stores water, food or other substances; plant cells have a large central vacoule

Chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

Which organelles have single membranes vs. double membranes?

Single: Vacuole, Lysosome, Golgi Apparatus, Endoplasmic Reticulum

Double: Nucleus, mitochondria and chloroplast

What's the structure within a chloroplast?

Two distinct regions present inside a chloroplast known as the grana and stroma. Grana are made up of stacks of disc-shaped structures known as thylakoids or lamellae. The grana of the chloroplast consists of chlorophyll pigments and are the functional units of chloroplasts

Why are cell membranes important? What's their basic structure?

Membrane - made of phospholipids and proteins

Phospholipids: hydrophilic head, hydrophobic tail

Proteins sit inside, moving some nutrients in that would not be able to otherwise cross and some wastes out

What is diffusion?

The movement of particles from an area of high concentration to an area of low concentration.

Define simple diffusion, facilitated diffusion, and active transport. Which types of molecules will use each? Which require a specialized protein? Which require additional input of energy?

Crossing the membrane

1. Simple diffusion (o2, CO2, testosterone)

2. Facilitated diffusion (amino acids, fructose)

Large and hydrophilic molecules

Carrier proteins

High to low concentration

3. Active transport (sodium and potassium)

Low to hight

Requires ATP

What is osmosis? How is it similar to diffusion? How is it different?

Osmosis is the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane.

What does it mean to be hypertonic vs. hypotonic? Which direction will water move across a membrane separating a hypertonic solution from a hypotonic solution?

Hypertonic: more solutes, shriveled, water goes out

Hypotonic: less solutes, swells, water comes in

What's the difference between potential energy and kinetic energy?

Potential energy: stored energy

Kinetic: the energy of motion or movement

Where does all of the energy on earth originally come from?

The sun

What is the second law of thermodynamics, and how does it apply to biological systems?

Disorder (entropy) tends to increase. When energy is converted from one form to another, some of that energy is lost as heat.

Does breaking chemical bonds take energy, or release energy? What about making new chemical bonds?

Takes energy to break bonds

When bonds made, energy is released

- Stronger bonds require more energy to break

What are autotrophs vs. heterotrophs? Which organisms are which?

Autotrophs

-Organisms that can convert sunlight to usable chemical energy

- All plants, many bacteria and most algae

Heterotrophs

-Herbivores and carnivores

What is the basic chemical reaction for photosynthesis?

Light energy + CO2 + H2O -> Glucose + O2

Where do the light reactions of photosynthesis take place? What about the synthesis reactions? Where is chlorophyll located?

1. Light is in grana (thylakoid membranes)

2. Synthesis is in stroma

3. Cholorphyll is in the grana too

What are the inputs of the light reactions? What are the outputs? Which atoms go where?

Inputs: Light, water, NADP+, ADP

Outputs: O2, ATP, NADPH

Water is oxidized to O2, passing electrons to NADP+, some light energy converts ADP

What are the inputs of the synthesis reactions? What are the outputs? Which atoms go where?

Inputs: ATP, NADPH, CO2

Outputs: ADP, NADP+, G3P

Energy converts CO2 into sugar G3P, ATP and NADPH are used and returned to their form and sent back for previous reaction

How do the colors that are absorbed and/or reflected by a pigment affect the color that we see?

The set of wavelengths that a pigment doesn't absorb are reflected, and the reflected light is what we see as color.

What are photons? Where are they involved in the photosynthesis process, and what happens to them?

Light energy that comes in the form of photons enter the cell, and excite electrons. The excited electrons, together with H+, produce ATP and NADPH

What is the role of photosynthesis in the ecosystem as a whole?

Provides the basis of energy

What molecule is the primary "energy currency" of cells?

ATP

In redox reactions, what happens to the molecule being oxidized? To the molecule being reduced?

A redox reaction is when one molecule loses electrons and is oxidized, while another molecule gains electrons (the ones lost by the first molecule) and is reduced. Handy mnemonic: "LEO goes GER": Lose Electrons, Oxidized; Gain Electrons, Reduced

What's the basic chemical reaction for aerobic respiration?

Glucose + Oxygen => CO2 + H2O + Energy

Fermentation

A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

(1) Glycolysis

the breakdown of glucose by enzymes, releasing energy and pyruvic acid (2 ATP)

Citric Acid Cycle (Krebs Cycle)

Strips electron, exhales CO2

- Purivate reduced

- NAD+ takes an electron, becoming NADH

Electron Transport Chain (ETC)

Electrons attach to NADH, beginning the electron transport chain

- Proton pressure drives ATP synthesis

- 10 times more ATP made than other two stages

- Electrons are transferred to oxygen, making water