AP Biology Fall 2017 Final Exam

Study Guide Answers

Chapter 5

1

• Carbohydrates: C, H, O (1:2:1)

• Lipids: C, H, O (Not 1:2:1)

• Proteins: C, H, O, N

• Nucleic Acids: C, H, O, N, P

2

• Cellulose and chitin have β-1,4 linkages.

• Strings of glucose monomers as starch have α-1,4 linkages

3

• Plant cell walls

4

• Fungal cell walls and in the exoskeletons of certain invertebrates.

5

• Carb: monosaccharide

• Lipid: isn’t one

• Protein: amino acid

• Nucleic Acid: nucleotide

6

• Dehydration synthesis is an anabolic process that joins monomers by removal of a water molecule.

• Hydrolysis is a catabolic process that breaks down polymers by adding a water molecule.

7

• Saturated FA: Fully saturated with hydrogens; solid at room temp; usually animal fats.

• Unsaturated FA: not fully saturated with hydrogen; where hydrogen have been removed, c=c double bonds have been generated; usually plant oils…and some fish oils.

8

• Peptide bonds

9

• Hydrogen bonds

10

• Alpha helix & beta-pleated sheet

11

• A, T, C, G, U

12

• Purines: A, G

• Pyrimidines: T, C, U

CHAPTER 6

1

• Prokaryotic– Small– Unicellular– Ex: bacteria– Lack:

• Nucleus• Membrane-bound

organelles

– Have:• Cytoplasm• Cell wall• Cell membrane• Ribosomes• DNA

• Eukaryotic– Small to large– Uni to multicellular– Ex: everything but bacteria– Have:

• Cytoplasm• Cell wall• Cell membrane• Membrane-bound

organelles• DNA & nucleus

2

• 1.) Surface area to volume ratio

• 2.) Genome to volume ratio

3

• Make proteins

4

• Lysosome

– Used proteolytic enzymes

– Found in animal cells

5

• Chloroplast

• Cell Wall

• Central Vacuole

6

• Centrioles

• Lysosomes

7

• Mitochondria & chloroplasts

8

• Mitochondria & chloroplasts

9

• 9 + 2 arrangement of microtubules

CHAPTER 7

1

• Bilayer made of phospholipids, proteins, cholesterol, glycoproteins, glycolipids.

2

3

• Simple diffusion

• Osmosis

• Facilitated diffusion

• All are passive

• All move molecules down a concentration gradient.

4

• Gases

5

• glucose

6

• Sodium potassium pump is used to move Na+ & K+ across the cell membrane against their gradients.

• In nerve physiology, Na+ rushes into the cell and K+ rushed out. The Na+/K+ pump is used to repolarize the neuron by sending the ions back to where they started.

Nervous System

1

• CNS & PNS

2

• Somatic NS

3

• Autonomic NS

4

• Sympathetic & Parasympathetic

5

• Sympathetic NS

6

• A.) S

• B.) PS

• C.) PS

• D.) S

• E.) S

• F.) PS

7

• To speed up nervous conductions

8

• These gaps in the myelin sheath serve as conduction points.

• The signal jumps from node to node, speeding up conduction.

9

• Myelinated = faster & white

• Non-myelinated = slower & grey

10

• Unequal charge inside & outside the neuron.

11

• Sodium-potassium pumps

12

• During the refractory period, Na/K pumps move the ions back to their original sides, against the concentration gradient.

13.) Steps of a nerve impulse

• 1.) Resting potential

• This is the unstimulated, polarized state of the neuron (about -70 mV).

• 2.) Action Potential

• In response to a stimulus, gated ion channels in the membrane suddenly open and permit the Na+ from the outside to rush into the cell.

• As the positively charged ions rush in, the charge on the cell membrane becomes depolarized (more positive), on the inside.

13 CONTINUED

• If the stimulus is strong enough (if it is above a certain threshold level), more Na+ gates open, increasing the flow of Na+ even more.

• This results in an action potential, or complete depolarization.

• This in turn stimulates the opening of adjacent Na+ gates and the stimulus travels down the neuron.

• The action potential is all or nothing, meaning that if the stimulus fails to produce a depolarzation that exceeds the threshold potential, no action potential will result.

13 CONTINUED

• However, when the threshold potential is exceeded, complete depolarization occurs.

• 3.) Repolarization

• In response to the inflow of Na+, another ion channel opens allowing K+ to leave the cell.

• The movement of K+ out causes repolarization by restoring the original membrane polarization.

• Unlike the resting potential, however, the K+ and Na+ are now on the wrong sides.

• The K+ gates close soon after the Na+ gates close.

13 CONTINUED

• 4.) Hyperpolarization• By the time the K+ channels close, more K+ has moved

out than is necessary to to establish the original polarized potential.

• Thus the membrane becomes hyperpolarized.

13 CONTINUED

• 5.) Refractory Period• After the action potential has passed, the membrane is

in a weird state: – the membrane is polarized, but the Na+/K+ are on the wrong

sides.

• During the refractory period, the neuron will not respond to a new stimulus.

• To reestablish the original distribution of the ions, Na+/K+ pumps are used to pump Na+ out of the cell and K+ into the cell.

• Once the ions are on the proper sides, the neuron is ready for another stimulus.

14

Feedback

1

Positive Feedback

• Stimulus causes a response, which reinforces the stimulus…reinforcing and intensifying the response.

• Usually bad.

• Ex: hyperventilating fainting

Negative Feedback

• Stimulus causes a response, which removes the stimulus.

• How homeostasis is maintained.

2

• A reflex arc is a negative feedback loop.

• A cramp is positive feedback.

Genetics

#1

• OK.

#2

• The farther apart two genes are on a chromosome, the more likely they are to be subjected to crossing over.

#3

• Hydrogen bond

#4

• The 5’ to 3’ direction of one DNA strand (side) is opposite that of the other 5’ to 3’ strand.

#5

• Fragments of copied DNA on the lagging strand that result from the DNA polymerase only being able to move in the 3’-5’ direction.

#6

• DNA Polymerase only works in the 3’ to 5’ direction.

#7

• A 5’ cap prevents degradation of the mRNA from nucleases in the cytoplasm.

• Poly-A tail streamlines the mRNA so that it can easily fit through the nuclear pores.

#8

• Introns are non-coding sections of DNA.

– (AKA “junk DNA”)

• Exons are regions of DNA that code for proteins.

#9 Types of mutations

• Point mutation:

– Examples:

• insertion,

• deletion,

• substitution,

• frameshift (results from insertion or deletion)

#9 Effects of mutations

• 1.) Silent mutation• Has no effect, because the new codon codes for the

same amino acid as the old codon.– Example: CUU, CUG, CUA, CUC all code for the amino acid

Leucine. So long as the 3rd nucleotide is the only one that is changed, the effect is zero.

#9

• 2.) Missense Mutation• The mutation causes a new codon that codes for a new

amino acid.

• This may have only a minor effect or it may result in the production of a protein that is unable to form into its proper 3-D shape and, therefore, is unable to carry out its normal function.

• The hemoglobin protein that causes sickle-cell disease is caused by a missense mutation.

#9

• 3.) Non-sense Mutation• Occurs when the new codon is a stop codon.

Photosynthesis & Cell Respiration

#1

• C6H12O6 + 6 O2 6 CO2 + 6 H20

+ ENERGY

#2

• 1.) Glycolysis

• 2.) Krebs Cycle

• 3.) ETC

#3

• Glycolysis

#4

• In the cytoplasm (cytosol) of the cell

#5

• Glucose 2 Pyruvate

2NAD+ 2NADH 4ADP 4 ATP

2 ATP 2 ADP

#6

• 2 NADH

• 2 Pyruvate

• 2 ATP (net)

#7

• They carry high energy e- to the electron transport chain.

#8

• Molecule B has been reduced.

• Molecule A has been oxidized.

#9

• Krebs cycle

– AKA:

• The Citric Acid Cycle

• TCA cycle

#10

• In the mitochondrial matrix

#11

• Pyruvate must combine with Coenzyme A

(Co-A) (changing pyruvate to Acetyl Co-A) before entering the Krebs cycle.

#12

• Per turn of the cycle you get:

+ 1 ATP

+ 3 NADH

+ 1 FADH2

+ 2 CO2

#13

• 2 turns (1 for each pyruvate molecule)

#14

• 2 total ATP are produced

#15

• The Electron Transport Chain (E.T.C.)

#16

• In the inner membranes of the mitochondria.

#17

• They bring high energy electrons from the first two steps in cell respiration to the E.T.C.

• The E.T.C. cannot run without these electrons.

#18

• The purpose of the E.T.C. is to pump hydrogens (protons) from the matrix into the Intermembrane space in order to create a gradient for chemiosmosis so that the oxidative phosphorylation of ADP into ATP can occur.

#19

• It is the force generated by the chemiosmotic movement of protons down a concentration gradient.

• This force is used to drive the ATP synthase “motor”.

#20

• H+ are pumped into the intermembrane space by protein pumps in the E.T.C.

• Then, via chemiosmosis, the H+ travel back into the matrix through a tunnel in the ATP synthasemolecule.

• The force of the H+ traveling through the ATP synthase (the proton motive force) drives the “machinery” that creates ATP via oxidative phosphorylation.

#21

• Oxygen

#22

• ATP

• Water

• NAD+

• FAD+

#23

• 36 - 38

#24

• Fermentation is necessary if there is not enough oxygen present to run the E.T.C.

• Why ?

• Without O2, NADH will accumulate.

• Once all the NAD+ has been converted to NADH, the Krebs cycle and glycolysis both stop. (both need NAD+ to accept e-)

• End result: no ATP is produced and the cell dies.

#25

• Alcoholic fermentation produces ethanol.

• Lactic acid fermentation produces lactic acid.

#25 continued…

• Alcoholic fermentation occurs in 2 steps:

• 2Pyruvate 2 Acetaldehyde + 2 CO2

• 2 Acetaldehyde 2 ethanol

2NADH 2NAD+

#25 continued

• Lactic Acid fermentation occurs in one step:

• 2 Pyruvate 2 lactate (lactic acid)2NADH 2NAD+

In humans and other mammals, most lactate is transported to the liver where it is converted back into glucose when there is enough ATP

#26

• Yeast (a fungus), plants and bacteria

#27

• When you exercise, need more ATP. Therefore, you increase your need for oxygen.

• If you exercise too hard too fast, you enter a state of oxygen “debt” – creating an anaerobic state where there is not enough O2 to run the E.T.C.

• So, you begin lactic acid fermentation in order to release some NAD+.

• Problem: lactic acid can be toxic to cells, which some researchers link to the pain you get during exercise.

#28

• 6 CO2 + 6 H20 + Light glucose + 6O2

#29

• 1.) Light reactions

• 2.) Calvin cycle

#30

• P680 1o e- acceptor 1st E.T.C. P700

A 2nd 1o e- acceptor 2nd E.T.C.

NADPH reductase NADPH

#31

• Cyclic only produces ATP

• Non-cyclic (Linear) produces both ATP and NADPH.

#32

• Carboxylation:

– 6 CO2 + 6 RuBP 12 PGA

• Reduction:

– 12 PGA + 12 ATP + 12 NADPH 12 G3P

• Regeneration:

– 10 G3P + 6 ATP 6 RuBP

#32…the next #32… because I’m an idiot and numbered it incorrectly. • 2 reasons:

– 1.) if rubisco is fixing O2, it thereby reduces the amount of CO2 that can be fixed.

– 2.) RuBP + O2 destruction of RuBP via oxidation

#33

• Through the stomata

#34

• In hot environments, like the tropics (high daytime temps and intense sunlight), plants often have to close their stomata in order to conserve water. By closing the stomata, there is a build up of waste O2, which is then fixed by rubisco into a useless product.

• To combat this, C4 plants separate their C3 and C4 pathways into separate into different parts of the leaf. CO2 is incorporated into PEP to create OAA. The OAA is converted to malate which is shuttled into the bundle sheath cells. This results in a higher rate of photosynthesis.

#34 continued

• Because there is a higher rate of photosynthesis, the C4 plants can reduce the time that the stomata are open, thereby reducing water loss.

• Example plants: sugarcane, crab grass, corn, sorghum

#35

• Bundle sheath cells

#36

• By storing CO2 in malic acid during the night, the CAM plants are able to run photosynthesis during the daytime with the stomata closed, greatly reducing water loss.

• Example plants: cacti, pineapple, other epiphytes.

#37

• Both take more ATP than normal C3 photosynthesis.

#38

• It is spatially segregated because the overall effect is to move CO2 from the mesophyll cells to the bundle sheath cells.

#39

• It is temporally segregated because the overall effect is to store CO2 so that it is only used during the day.

#40

• At night