BSCI 170 Final 2025

please let me pass this

About 2.6 billion years ago, prokaryotic cells started photosynthesizing—making oxygen from CO2, water, and sunlight—directly contributing to about 50% of the oxygen in our atmosphere, and paving the way for the evolution of aerobic metabolism. These prokaryotic cells are called:

cyanobacteria

What are the three shared properties f all living things?

Reproduction, Homeostasis, Growth and Development

What are the 4 classes of macromolecules (the monomers from which they are made)

Protein (Amino Acids), Lipids (fatty acids), Nucleic Acid (nucleotides), carbohydrates (sugar)

Water is essential to life. Which property of water has the least impact on life compared to the others?

Near-colorless appearance

How many covalent bonds does sulfur need to form to have a full valence shell

2

How many electron shells does sulfur have?

3

How many s and p orbitals contain paired electrons in sulfur’s valence shell?

1 s orbital and 1 p orbital

For a covalent bond to be nonpolar, the two atoms that form the bond must have

similar electronegativites

-OH

Hydroxyl

C=O

Carbonyl

-COOH or COO^-

Carboxyl

-NH₂ or -NH₃^-

Amino or Amines

-OPO₃²

Phosphate

-CH₃

Methyl

-SH

Sulfydryl

-COH (c=o)

Aldehyde group

what is implied about charged functional groups?

polar

Components of a Nucleotide

a pentose (deoxyribose or ribose), a phosphate group, and a nitrogenous base (Adenine, Guanine, Cytosine, Thymine, or Uracil)

what is this?

uracil

how can you tell the difference between deoxyribose and ribose?

deoxyribose has OH and H while ribose has two OH

what is this

Adenine

what is this

thymine

what is this

cytosine

what is this

guanine

what is the combination of a pentose sugar and a base called?

nucleoside

Phospholipids differ from triglycerides in that phospholipids ______

are amphipathic (have both nonpolar and polar parts)

what is the complementary RNA sequence for the DNA sequence of 5’ TAC ACC GCA TAG GAT 3’

3’ AUG UGG CGU AUC CUA 5’

Triglycerides (fats/oils) are composed of _____ and _______.

3 fatty acids; 1 glycerol

Identify the true statement applicable to ALL carbohydrates from the options

They follow the general formula (CH₂O)_n

Complementary base pairing _____

takes place between purine and pyrimidine bases

what are adenine and guanine

purines

what are cytosine, thymine, and uracil

pyrimidines

The Central Dogma dictates that in cells, _____, the intermediary molecule between _____ and _____, is synthesized in a process called _______.

RNA; DNA; Proteins; Transcription

Which solution has the lowest [H+}

pH=10

Compounds with the same molecular formula but different covalent arrangements

structural isomers

Which of the following statements best describes the difference between saturated and unsaturated fatty acids in triglycerides?

Unsaturated fatty acids have double bonds, while saturated fatty acids do not.

Phospholipids form a bilayer that _____

has a hydrophobic core

A storage polysaccharide composed of glucose monomers in plants

Starch

Bond connecting a carbohydrate molecule to another group, formed through dehydration

Glycosidic bond

Three-dimensional structure of polypeptide

Tertiary structure of proteins

Distance-dependent interaction between nonpolar functional groups

van der Waals interactions

Type of interaction between two water molecules

Hydrogen bond

Structure of polypeptide maintained by hydrogen bonding interactions between amino acid backbone atoms

Secondary structure of proteins

Interaction between positively charged and negatively charged ions

Ionic bonds

linear sequence of amino acids in the polypeptide chain

Primary structure of proteins

Protein structure level involving more than one polypeptide

Quaternary structure of proteins

Chemical bond that occurs when two atoms share a pair of electrons

Covalent bond

A monosaccharide found in milk

Galactose

Covalent bond made by sidechain atoms of cysteine

Disulfide bond

are nonpolar molecules hydrophobic or hydrophilic

hydrophobic

are polar molecules hydrophilic or hydrophobic

hydrophilic

A protein that changes shape in response to binding two molecules in the same direction is an example of a:

symporter carrier protein

what is the y-axis on endergonic and exergonic graphs

Free Energy

what is the x-axis on endergonic and exergonic graphs

time of reaction

endergonic

positive ΔG

exergonic

negative ΔG

E_a

activation energy; the difference between the reactions or products (whichever is higher) and the top of the curve

ΔG

free energy; the difference between the reactants and products; id products are lower than reactants than its negative

Explain why adding an enzyme is not enough to make an endergonic reaction proceed?

Endergonic reactions require an input of energy to proceed, and while enzymes can speed up reactions, they cannot provide the energy needed to drive the reaction forward. This requires reaction coupling, which is when one reaction borrows energy from another.

Which statement about diffusion is false?

During diffusion, the cell membrane becomes increasing less permeable to the diffusing substance

Osmosis is _____

the movement of water across selectively permeable membranes

A cell with an interior concentration of 25% salt is placed in a solution, Solution X, with a 5% salt concentration. Which statement accurateky describes about solution X relative to the cell?

Solution X is hypotonic to the cell

Three types of endocytosis in bult transport are

Phagocytosis, Pinocytosis, and receptor mediated endocytosis

Which specific type of bulk transport involves the formation of small vesicles to ingest fluid and tiny dissolved solutes from the extracellular environment?

Pinocytosis

The cell engulfs large solid particles by surrounding them with the cell membrane to form a vesicle

Phagocytosis

The cell takes in extracellular fluid and dissolved substances by forming small vesicles

Pinocytosis

The cell selectively internalizes specific molecules when they bind to receptors on the cell membrane

receptor mediated endocytosis

Tay-Sachs disease is a genetic disorder that results in the destruction of neurons due to a buildup of sphingolipids in the cells. Which organelle in malfunctioning in Tay-Sachs?

lysosome

Which of the following sequences correctly lists in order the steps involved in the incorporation of a proteinaceous molecule within a cell

synthesis of the protein on the ribosome; modification in the endoplasmic reticulum; tagging in the Golgi; distribution via the vesicle; distribution via the Golgi; tagging in the endoplasmic reticulum

An allosteric inhibitor does which of the following

Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate

Who is the measure of the available energy in a system that can do work, ΔG, is named after?

Gibbs

Uses energy from ATP hydrolysis to move ions/compounds against their concentration gradient. (channel proteins, carrier proteins, both neither)

Neither

Moves compounds across the membrane, down their concentration gradient, by binding to the compound on one side of the membrane

carrier proteins

facilitates diffusion of ions/compounds across the cell membrane

carrier and channel proteins

Forms a very selective pore in the cell membrane that allows for one type of ion/compound to cross the cell membrane via diffusion

channel proteins

The sodium-potassium pump establishes and maintains both concentrations and electrical gradients across the plasma membrane. Which statement best explains the difference between sodium’s and potassium’s respective gradients in the cell?

Sodiums electrochemical gradient drives Na+ into the cell because both the electrical and concentration forces favor its entry, while potassium concentration gradient drives K+ out of thecell despite an opposing electrical gradient

ATP is relatively _____, allowing it to undergo hydrolysis which ____ energy, which then forms ADP

Unstable, releases

Which of the following is true of enzymes

The same enzyme can speed up the same reaction over a thousand times

Lactose —> Glucose + Galactose; catabolic or anabolic

catabolic

Lactose —> Glucose + Galactose; positive or negative ΔG

negative ΔG

using facilitated diffusion?

Large, Polar, Charged

what type of molecules cross the membrane using simple diffusion?

small, nonpolar, uncharged

what type of molecules cross the membrane using active transport?

against concentration gradient

Would you expect the molecule below to cross the membrane down its concentration gradient via diffusion, facilitated diffusion, or active transport?

facilitated diffusion

What is the first law of thermodynamics?

energy cannot be created or destroyed, but only transferred or transformed

Briefly and concisely explain how the events illustrated in the figure above demonstrate the first law of thermo dynamics.

for the H+ to be pumped across the membrane ATP is required as it is moving against its concentration gradient. This allows the secondary transporter to take that energy and pump H+ down its concentration gradient and sucrose against its concentration gradient

What is the second law of thermodynamics? Briefly and concisely explain how the events illustrated in the figure above demonstrate the second law.

The second law of thermodynamics states that the total entropy of the universe increases. In the figure, ATP hydrolysis drives the pumping of H⁺ against its gradient and the cotransport of sucrose against its gradient, which decreases entropy locally by creating order. However, the entropy increase from ATP hydrolysis in the surroundings is greater than the entropy decrease in the system, so the total entropy of the universe increases.

When ATP is broken down to release energy, it forms:

ADP and one phosphate

During the second half glycolysis, what occurs?

ATP is made

What is the main transformation that occurs during glycolysis?

Glycolysis produces ATP, pyruvate, and NADH by oxidizing glucose

Which product of pyruvate oxidation enters the Citric-Acid Cycle

Acetyl-CoA

Select the true statement about fermentation

results in the formation of lactic acid or alcohol

How many ATP is generated from oxidizing all 10 NADH during oxidative phosphorylation?

25 ATP

Which of the following process(es) generate NADH?

Glycolysis, pyruvate oxidation and citric acid cycle

ATP synthase during the oxidative phosphorylation consists of two primary components, the proton channel (F0) and the ATP synthesis enzyme (F1). Which of the following best describes the roles of these components and the overall process of ATP synthesis?

F0 creates a proton gradient, while F1 uses the energy from the gradient to phosphorylate ADP, forming ATP

Which of the following processes will be impacted by low NAD+ and FAD levels?

All of the above

how to know highest oxidation state?

highest H:O, low C:H ex. carbon dioxide is highly oxidized while methane is not

Identify the oxidized and reduced products in the following reaction: Cr⁺+Sn⁴⁺ —> Cr³⁺ +Sn ²⁺

Cr3+: oxidized; Sn2+:reduced

Oxidized form of NAD

NAD+

Reduced form of NAD

NADH