Biology/
Biochemistry
Biochemistry
Which of the following biological processes will occur under both aerobic and anaerobic conditions in humans?
a) Krebs cycle
b) Glycolysis
c) Fermentation
d) Citric Acid Cycle
e) All of the above
b) Glycolysis
Alfred is looking through a telescope with one eye closed watching sailboats enter a harbor. He is able to tell that a 20-foot boat has entered before a 30-foot catamaran. Which of the following cues is Alfred NOT able to use to judge relative distance?
a) relative size
b) interposition
c) retinal disparity
d) texture
c) retinal disparity
At standard temperature and pressure, a chemical process is at equilibrium. What is the free energy of reaction (ΔG) for this process?
a) ΔG> 0
b) ΔG< 0
c) ΔG = 0
d) There is not enough information to determine the free energy of the reaction.
c) ΔG = 0
Standard temperature and pressure indicates 0°C and 1 atm. Gibbs free energy is temperature dependent, but if a reaction is at equilibrium, ΔG = 0.
A man walks 30 m east and then 40 m north. What is the difference between his traveled distance and his displacement?
a) 0 m
b) 20 m
c) 50 m
d) 70 m
b) 20 m
Using the Pythagorean theorem, calculate the magnitude of the man’s displacement: 50 m.
His total distance traveled is equal to 30 + 40 = 70 m. Therefore, the difference between these two is 20 m.
Retroactive interference occurs when:
a) old information interferes with learning new material.
b) new material interferes with recalling old material.
c) new information decays over time.
d) old information decays over time.
b) new material interferes with recalling old material.
Retroactive interference is a type of memory interference in which new information interferes with our ability to recall older material (choice B is correct). Proactive interference occurs when old information interferes with learning new material (choice A is wrong). Answer choices C and D refer to memory decay which occurs regardless of intereference (choices C and D are wrong).
During division of a mammalian cell, spindle formation will NOT occur unless there is proper functioning of the:
a) Centrioles
b) Centromeres
c) Cristae
d) Lysosomes
a) Centrioles
Which of the following neurotransmitters could be imbalanced if someone woke up and realized they could not move any muscle?
a) Catecholamine
b) Acetylcholine
c) Frataxin
d) Cortisol
b) Acetylcholine
Acetylcholine is a neurotransmitter. It is released by the neurons. It then synapses at the molecular junctions and provokes the contraction of the skeletal motor cells. It is critical for motor movement. Its absence or blockage would cause paralysis.
What is the highest-energy orbital of elements with valence electrons in the n = 3 shell?
a) s-orbital
b) p-orbital
c) d-orbital
d) f-orbital
c) d-orbital
When n = 3, l = 0, 1, or 2. The highest value for l in this case is 2, which corresponds to the d subshell. Although the 3d block appears to be part of the fourth period, it still has the principal quantum number n = 3. In general, the subshells within an energy shell increase in energy as follows: s < p < d < f (although there is no 3f subshell).
Which of the following relationships is INCORRECT?
a) |sin θ × cos θ| < |sin θ| + |cos θ|
b) sin θ ÷ cos θ = tan θ
c) tan 90° is undefined
d) sin θ = sin (90° – θ)
d) sin θ = sin (90° – θ)
sin θ ≠ sin (90° – θ), although sin θ = cos (90° – θ). The other statements must all be true. Because sine and cosine values are always between –1 and 1, the product of sine and cosine will always have a magnitude less than 1. The sum of the absolute value of sine and the absolute value of cosine, on the other hand, will always be greater than 1. Therefore, choice (A) can be eliminated. Because sine is the ratio of opposite to hypotenuse and cosine is the ratio of adjacent to hypotenuse, the quotient between the two is the ratio of opposite to adjacent, or the tangent of the angle. Therefore, choice (B) can be eliminated. By the same logic, because sin 90° = 1 and cos 90° = 0, tan 90° is undefined, eliminating choice (C).
Based on the reaction mechanism shown below, which of the following statements is correct?
2 NO + O2 → 2 NO2
1) 2 NO → N2O2 (fast)
2) N2O2 + O2 → 2 NO2 (slow)
a) Step 1 is the rate-determining step and the rate of the overall reaction is k[N2O2].
b) Step 1 is the rate-determining step and the rate of the overall reaction is k[NO]2.
c) Step 2 is the rate-determining step and the rate of the overall reaction is k[NO2]2.
d) Step 2 is the rate-determining step and the rate of the overall reaction is k[N2O2][O2].
d) Step 2 is the rate-determining step and the rate of the overall reaction is k[N2O2][O2].
The rate-determining step (RDS) of a reaction mechanism is the slowest step of that mechanism, eliminating choices A and B. The rate law of an elementary step can be determined from the coefficients of the reactants in the elementary step. Because Step 2 is the RDS, the overall rate law will be equivalent to the rate law for the RDS. Therefore, rate = k[N2O2][O2].
In eukaryotes, the enzymes that catalyze the reactions of the Krebs cycle are located in the:
a) cytosol
b) endoplasmic reticulum
c) mitochondria
d) nucleus
c) mitochondria
The Krebs cycle takes place in the cell mitochondria, where the enzymes that catalyze the reaction are located. Before the Krebs cycle can take place, pyruvate must first be transported to the cytosol into the mitochondria.
Thomas Malthus assumed that food production grows at an arithmetic rate while population grown exponentially, a state affairs that eventually culminating in the population's:
a) growth
b) stability
c) decline
d) normal distribution
c) decline
Malthus assumed that while food production only grew at an arithmetic rate, the population would grow at an exponential rate and therefore outgrow food production in the long run, which would lead to famine, mortality, and population's decline.
Which of the following actions does NOT affect the equilibrium position of a reaction?
a) Adding or removing heat.
b) Adding or removing a catalyst.
c) Increasing or decreasing concentrations of reactants.
d) Increasing or decreasing volumes of reactants.
b) Adding or removing a catalyst.
The equilibrium of a reaction can be changed by several factors. Adding or subtracting heat, choice (A), would shift the equilibrium based on the enthalpy change of the reaction. Increasing reactant concentrations would shift the equilibrium in the direction of the product, and the opposite would occur if reactant concentrations were decreased, eliminating choice (C). Changing the volume of a reactant would affect any reaction with gaseous reactants or products, eliminating choice (D). While adding or removing a catalyst would change the reaction rates, it would not change where the equilibrium lies.
A charge of 2 μC flows from the positive terminal of a 6 V battery, through a 100 Ω resistor, and back through the battery to the positive terminal. What is the total potential difference experienced by the charge?
a) 0 V
b) 0.002 V
c) 0.2 V
d) 6 V
a) 0 V
Kirchhoff's loop rule states that the total potential difference around any closed loop of a circuit is 0 V. Another way of saying this is that the voltage gained in the battery (6 V) will be used up through the resistors. Because this charge both started and ended at the positive terminal, its total potential difference is therefore 0 V. 6 V, choice (D), is the voltage gained in the battery as well as the voltage drop in the resistors—creating a net sum of 0 V.
Middle-aged men require a base level of 900 Calories per day plus an additional 12 Calories per kilogram of body mass per day. Young adult women require a base level of 500 Calories per day, plus 15 Calories per kilogram of body mass per day. At what mass do middle-aged men and young adult women have the same caloric needs?
a) 26 kg
b) 67 kg
c) 133 kg
d) 266 kg
c) 133 kg
This is a system of equations couched in data. From this information, we can construct two equations: C= 900 + 12m and C = 500 + 15m. These equations can be solved by setting them equal: 900 + 12m = 500 + 15m, 400 = 3m, 133 kg = m.
In chemiosmosis, hydrogen ions (protons) release their energy to produce ATP as they pass across the inner mitochondrial membrane. This process involves the use of:
a) ATP synthase
b) ATP dehydrogenase
c) ATP decarboxylase
d) electron carriers
a) ATP synthase
What is the best definition of proprioception? It consists of the ability to:
a) detect changes in motion
b) sense relative location of body parts
c) move and maintain momentum
d) maintain balance and equilibrium
b) sense relative locations of body parts
Every option holds some truth, however, proprioception is generally defined as the ability to sense the relative locations of body parts.
Consider (E)-2-butene and (Z)-2-butene. This is a pair of what type(s) of isomers?
I. Cis–trans isomers
II. Diastereomers
III. Enantiomers
a) I only
b) II only
c) I and II only
d) I and III only
c) I and II only
(E)-2-butene can also be called trans-2-butene; (Z)-2-butene can also be called cis-2-butene. As such, they are cis–transisomers. Remember that cis–trans isomers are a subtype of diastereomers in which the position of substituents differs about an immovable bond. Diastereomers are molecules that are non-mirror-image stereoisomers (molecules with the same atomic connectivity). These are not enantiomers because they are not mirror images of each other.
If an object with an initial temperature of 300 K increases its temperature by 1°C every minute, by how many degrees Fahrenheit will its temperature have increased in 10 minutes?
a) 6°F
b) 10°F
c) 18°F
d) 30°C
c) 18°F
The kelvin unit and Celsius degree are the same size; that is, a change of 10 K is equal to a change of 10°C. One degree Celsius is equal to 1.8 degrees Fahrenheit; therefore, 10°C = 18°F.
A scientist discovers a new hormone that is relatively large in size and triggers the conversion of ATP to cAMP. Which of the following best describes the type of hormone that was discovered?
a) Amino acid-derivative hormone
b) Peptide hormone
c) Steroid hormone
d) Tropic hormone
b) Peptide hormone
The question stem indicates that the newly discovered hormone functions as a first messenger, stimulating the conversion of ATP to cAMP; cAMP functions as a second messenger, triggering a signaling cascade in the cell. Hormones that act via secondary messengers and are relatively large in size (short peptides or complex polypeptides) are peptide hormones. This hormone could be a tropic hormone, but it is also entirely possible for it to be a direct hormone; thus, choice (D) can be eliminated.
During an asthma attack, patients experience difficult breathing due to a sudden onset of bronchoconstriction caused by the contraction of muscle fibers surrounding the bronchioles. These muscle fibers are most likely:
a) cardiac muscle
b) Type I skeletal muscle
c) Type II skeletal muscle
d) smooth muscle
d) smooth muscle
Smooth muscle is found throughout the respiratory tract as well as the walls of blood vessels and hollow visceral organs including the gastrointestinal tract. And like cardiac muscle, smooth muscle's contractions are inherent, involuntary, and rhythmic.
A group of men and women are going to be rated on their driving abilities. The role of gender is emphasized in the experiment and the women perform worse than the men. In another experiment, the role of gender is not mentioned and the ratings are comparable between the two groups. Which principle do these results support?
a) institutional discrimination
b) stereotype threat
c) prejudice
d) the just-world hypothesis
b) stereotype threat
Stereotype threat refers to the concept of people being concerned or anxious about confirming a negative stereotype of their social group. Stereotype threat can hinder performance, creating a self-fulfilling prophecy.
All of the following are true with respect to carbonyls EXCEPT:
a) the carbonyl carbon is electrophilic.
b) the carbonyl oxygen is electron-withdrawing.
c) a resonance structure of the functional group places a positive charge on the carbonyl carbon.
d) the π electrons are mobile and are pulled toward the carbonyl carbon.
d) the π electrons are mobile and are pulled toward the carbonyl carbon.
The reactivity of the carbonyl can be attributed to the difference in electronegativity between the carbon and oxygen atoms. The more electronegative oxygen atom attracts the bonding electrons and is therefore electron-withdrawing. Thus, the carbonyl carbon is electrophilic. One resonance structure of the carbonyl pushes the π electrons onto the oxygen, resulting in a positively charged carbonyl carbon.
A tractor pulls a log with a mass of 500 kg along the ground for 100 m. The rope (between the tractor and the log) makes an angle of 30° with the ground and is acted on by a tensile force of 5000 N. How much work does the tractor perform in this scenario? (Note: sin 30° = 0.5, cos 30° = 0.866, tan 30° = 0.577)
a) 250 kJ
b) 289 kJ
c) 433 kJ
d) 500 kJ
c) 433 kJ
The work done by the tractor can be calculated from the equation
W = Fd cos θ = (5000 N)(100 m)(cos 30°) = (5000)(100)(0.866) ≈ 5000 × 80 = 400,000 J = 400 kJ.
Hemiacetals and hemiketals usually keep reacting to form acetals and ketals. Why is it difficult to isolate hemiacetals and hemiketals?
I. These molecules are unstable.
II. The hydroxyl group is rapidly protonated and lost as water under acidic conditions, leaving behind a reactive carbocation.
III. The molecules are extremely basic and react rapidly with one another.
a) I only
b) I and II only
c) II and III only
d) I, II, and III
b) I and II only
Hemiacetals and hemiketals are usually short-lived because the –OH group will rapidly become protonated in acidic conditions and is lost as water, leaving behind a carbocation that is very susceptible to attack by an alcohol. Once the alcohol has been added, the acetal or ketal becomes more stable because the newly added group is less likely to become protonated and leave as compared to –OH.