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Science Mastery Assessments Flashcards

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1
Q

In a neutral solution, most amino acids exist as:

A

Zwitterions

The carboxylic acid is deprotonated and the amine will remain protonated. This dipolar ion is a zwitterion

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2
Q

At pH 7, the charge on a glutamic acid molecule is…

A

-1

Both carboxyl groups are negatively charged and the amino group is positively charged = overall -1 charge

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3
Q

Nonpolar R groups in aqueous solution are…

A

Hydrophobic and found buried with proteins

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4
Q 
Scientists discover a cDNA sequence for an uncharacterized protein. In their initial studies, they use a computer program designed to predict protein structure. Which of the following levels of protein structure can be most accurately predicted?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
A

A. Primary
cDNA is a DNA copy of the mRNA used to generate a protein
A computer program can identify the amino acid that corresponds to each codon and generate a list of these amino acids. This amino acid sequence is the primary structure

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5
Q

How many distinct tripeptides can be formed from one valine molecule, one alanine molecule, and one leucine molecule?

A

6
3 for valine, 2 for alanine, and 1 for leucine: 3x2x1=6
VAL, VLA, ALV, AVL, LVA, and LAV

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6
Q

What happens to the entropy of water and protein during protein folding?

A

Entropy of the water increases and entropy of the protein decreases.
As protein foods, it takes on an organized structure = decrease entropy

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7
Q

An a-helix is most likely to be held together by…

A

Hydrogen bonds between the carboxyl and amino groups

Side chains are too far apart to participate in string interactions

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8
Q

Which of the following is least likely to cause denaturation of proteins?
A. Heating the protein to 100C
B. Adding 8M urea
C. Moving it to a more hypotonic environment
Adding a detergent such as sodium dodecyl sulfate

A

C. Moving it to a more hypotonic environment

High salt concentrations, detergents, and high temps. denature a protein, but a lower solute concentration does not

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9
Q 
A particular a-helix is known to cross the cell membrane. Which of these amino acids is most likely to be found in the transmembrane portion of the helix?
A. Glutamate
B. Lysine
C. Phenylalanine
D. Aspartate
A

C. Phenylalanine
Transmembrane of a-helix will be exposed to a hydrophobic environment, so we need an amino acid with a hydrophobic side chain

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10
Q

Which of these amino acids has a chiral carbon in its side chain?
A. Serine
B. Threonine
C. Isoleucine

A

Threonine and Isoleucine
Every amino acid, except glycine, has a chiral a-carbon, but threonine and isoleucine are the only two that also have a chiral carbon in their side chains

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11
Q

Following translation and folding, many receptor tyrosine kinases exist as monomers in their inactive state on the cell membrane. Upon the binding of a ligand, these proteins dimerize and initiate a signaling cascade. During this process, their highest element of protein structure changes from ___ to ___.

A

Tertiary to quaternary
In their inactive state, tyrosine kinases are fully folded single polypeptide chains and have a tertiary structure. When they dimerize, they become a protein complex and have a quaternary structure.

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12
Q 
Which of these amino acids has a side chain that can become ionized in cells?
A. Histidine
B. Leucine
C. Proline
D. Threonine
A

A. Histidine

The imidazole ring has a nitrogen atom that can be protonated

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13
Q

In lysine, the pKa of the side chain is about 10.5. Assuming that the pKa of the carboxyl and amino groups are 2 and 9, respectively, the pI of lysine is ___.

A

9.75
Lysine has a basic side chain so we ignore the pKa of the carboxyl group. We average the pKa of the amino and side chain groups: (9 + 10.5)/2 = 9.75

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14
Q

Which of the following is a reason for conjugating proteins?
A. To direct their delivery to a particular organelle
B. To direct their delivery to the cell membrane
C. To add a cofactor needed for their activity

A

All of the above
Conjugated proteins can have lipid or carbohydrate “tags” added to them. These tags indicate that the protein should be directed to the cell membrane or to a specific organelle. They can also provided the activity of the protein.

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15
Q 
Collagen consists of 3 helices with carbon backbones that are tightly wrapped around one another in a “triple helix.” Which of these amino acids is most likely to be found in the highest concentration?
A. Proline
B. Glycine
C. Threonine
D. Cysteine
A

B. Glycine
Triple helix means the carbon backbones are close together and steric hindrance is an issue. Glycine has a small side chain that reduces this issue

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16
Q

Hyperbaric oxygen may be used as a treatment for certain types of bacterial infections. In this therapy, the patient is placed in a chamber in which the partial pressure of oxygen is significantly increased, increasing the partial pressure of oxygen in the patient’s tissues. This treatment is most likely used for infections with…

A

Obligate anaerobic bacteria

These can’t survive with oxygen and would be killed by kuscheln therapy

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17
Q

Which of the following does NOT describe connective tissue cells?
A. They account for most cells in muscles, bones, and tendons
B. They secrete substances to form the extracellular matrix
C. In organs, they tend to form the stroma
D. In organs, they provide support for epithelial cells

A

A. They account for most cells in muscles, bones, and tendons
Bones and tendons are predominantly composed of connective tissue, but muscle tissue is different

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18
Q

Which type of nucleic acid could form the genome of a virus?

A

Single-stranded RNA, double-stranded DNA, and single-stranded DNA

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19
Q

The theory of spontaneous generation states that living organisms can arise from nonliving material. In 1859, Pasteur demonstrated that no organisms emerged from sterilized growth media, weakening the theory of spontaneous generation and supporting which tenet of cell theory?

A

Cells arise only from preexisting cells

Sterilization kills all living cells so no growth in this environment supports this tenet

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20
Q

Mitochondrial DNA is ___ and ___.

A

Circular and self-replicating
Mitochondrial DNA evolved from an anaerobic prokaryote engulfing an aerobic prokaryote and establishing a symbiotic relationship, so mDNA is similar to bacterial DNA. Both are organized into a single circular chromosome of double-stranded DNA that can replicate during binary fission

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21
Q 
Which I of the following is NOT a function of the smooth ER?
A. Lipid synthesis
B. Poison detoxification
C. Protein synthesis
D. Transcription of proteins
A

C. Protein synthesis

Protein synthesis is a function of the ribosomes associated with the rough ER

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22
Q

What is the main function of the nucleolus?

A

Ribosomal RNA synthesis

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23
Q 
Which of the following organelles is surrounded by a single membrane?
A. Mitochondria
B. Lysosomes
C. Nuclei
D. Ribosomes
A

B. Lysosomes
Mitochondria and nuclei are surrounded by double membranes. Ribosomes are surrounded by no membranes since they are present in eukaryotes and prokaryotes.

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24
Q

Which of the following is NOT a difference that would allow one to distinguish a prokaryotic and a eukaryotic cell?
A. Ribosomal subunit weight
B. Presence of a nucleus
C. Presence of a membrane on the outside surface of a cell
D. Presence of membrane-bound organelles

A

C. Presence of a membrane on the outside surface of the cell

Both gram- negative bacteria and animal cells share this feature

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25
Q 
Which of the following does NOT contain tubulin?
A. Cilia
B. Flagella
C. Microfilaments
D. Centrioles
A

C. Microfilaments

Microfilaments are composed of actin

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26
Q

Herpes simplex virus (HSV) enters the human body and remains dormant in the nervous system until it produces an outbreak after exposure to heat, radiation, or other stimuli. What statement correctly describes HSV?

A

HSV adds its genetic information to the genetic information of the cell.
In the lysogenic cycle, viral DNA is added to the host cell’s genome, where it can remain dormant for days or years. Either spontaneously or as a result of environmental circumstances, the provirus can reactivate and enter a lytic cycle where the host cell bursts and releases new virions.

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27
Q

Resistance to antibiotics is a well-recognized medical problem. Which methods of bacterial recombination can account for a bacterium’s ability to increase its genetic variability and thus adapt itself to resist different antibiotics?

A

Conjugation and transduction
Conjugation is sexual mating in bacteria. It is the transfer of genetic material between two bacteria that are temporarily joined. Transduction occurs when fragments of the bacterial chromosome accidentally become packaged into viral progeny produced during a viral infection and are introduced into another bacterium by the viral vector. Both increase bacterial genetic variability.

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28
Q

A bacterial cell is noted to be resistant to penicillin. The bacterium is transferred to a colony that lacks the fertility factor, and the rest of the colony does not become resistent to penicillin. However, the penicillin-resistant cell has also started to exhibit other phenotypic characteristics, including secretion of a novel protein. Which method of bacterial recombination is NOT likely to account for this change?

A

Conjugation
A bacterial cell that does not rapidly cause a phenotypic change in the rest of the colony is likely not F+, meaning that this cell is not able to form a sex pilus for conjugation.

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29
Q

In Alzheimer’s disease, a protein called the amyloid precursor protein (APP) is cleaved to form a protein called B-amyloid. This protein has a B-pleated sheet structure and precipitates to form plaques in the brain. This mechanism of disease is most similar to which pathogen?

A

Prions
Prions are infectious proteins that cause misfolding of other proteins. Prions generally cause a shift toward B-pleated sheet conformations, causing decreased solubility and increased resistance to degradation, leading to disease.

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30
Q

After infection of a cell, a viral particle must transport itself to the nucleus in order to produce viral proteins. What is the likely genomic content of this virus?

A

Double-stranded DNA
A virus that requires transport to the nucleus in order to produce viral proteins likely requires use of nuclear RNA polymerase in order to create mRNA that can be translated to protein. Therefore, only DNA viruses need to be transported to the nucleus to produce viral proteins.

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31
Q

What are the common names for ethanal, methanal, and ethanol?

A

Acetaldehyde, formaldehyde, and ethyl alcohol, respectively

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32
Q

Which of the following are considered terminal functional groups?
A. Aldehydes
B. Ketones
C. Carboxylic acids

A

Aldehydes and carboxylic acids
Aldehydes and carboxylic acids are terminal and the carbon they are attached to is usually designated carbon 1
Ketones are found in the middle of a carbon chain

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33
Q

Look at Science Mastery OChem 1 notecard

A

Carboxyl group provides the suffix

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34
Q

Look at Science Mastery OChem 2 notecard

A

Anhydride takes priority over the carbonyl

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35
Q

Look at Science Mastery OChem 3 notecard

A

Carboxylic acid has highest-priority and provides the suffix

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36
Q

Look at Science Mastery OChem 4 notecard

A

Find longest carbon chain

Alkyl groups get lowest numbers on parent chain

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37
Q

Look at Science Mastery OChem 5 notecard

A

Tartaric acid

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38
Q

Look at Science Mastery OChem 6 notecard

A

2,5-dimethylheptane

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39
Q

Look at Science Mastery OChem 7 notecard

A

3-ethyl-2,2,5-trimethylhexane

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40
Q

Look at Science Mastery OChem 8 notecard

A

Hydroxyl group has highest priority and provides the suffix NOT the prefix

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41
Q

Look at Science Mastery OChem 9 notecard

A

Acetylformic acid is an acetyl group directly attached to formic acid

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42
Q

The common names for the aldehydes and carboxylic acids that contain only one carbon start with what prefix?

A

Form-

43
Q

NADH is a coenzyme that releases high-energy electrons into the electron transport chain. It is known as nicotinamide adenine dinucleotide or diphosphopyridine nucleotide. Which of the following functional groups exist in this molecule?
A. Phosphate
B. Amide
C. Anhydride

A

Phosphate and amide
“-amide” indicates an amide group
“diphospho-“ indicates two phosphate groups

44
Q

Which of the following are common names for carboxylic acid derivatives?
A. Acetic anhydride
B. Formic acid
C. Methyl formate

A

Acetic anhydride and methyl formate
Acetic anhydride = enthanoic anhydirde
Methyl formate = methyl methanoate
Formic acid = methanoic acid which is a carboxylic acid, not a derivative

45
Q

Consider the name 2,3-diethylpentane. Based on the structure implied by this name, what is the correct IUPAC name for this molecule?

A

3-ethyl-4-methylhexane
Draw it out— the longest carbon chain with the substituents at the lowest possible carbon numbers is different from the one chosen in the original name

46
Q 
A researcher deletes a gene from an organism to determine the gene’s function. This approach is most analogous to the work of which of the following scientists?
A. Paul Broca
B. Pierre Fluorens
C. Franz Gall
D. Sir Charles Sherrington
A

B. Pierre Fluorens

Used ablation/extirpation to show that specific parts of the brain served particular functions

47
Q 
Which component of the nervous system is NOT involved in the initial reflexive response to pain?
A. Spinal cord
B. Cerebral cortex
C. Interneuron
D. Motor neuron
A

B. Cerebral cortex
Sensory receptors send information to interneurons in the spinal cord, which stimulate a motor neuron to allow quick withdrawal

48
Q

A child has experienced nervous system damage and can no longer coordinate the movements to dribble a basketball, although she can still walk in an uncoordinated fashion. Which region of the CNS was most likely affected?

A

Hindbrain

Responsible for balance and motor coordination

49
Q

The temporal lobe deals with what functions?

A 
Sound processing (auditory cortex)
Speech perception (Wernicke’s area)
Memory and emotion (limbic system)
50
Q

Which part of the brain deals with both homeostasis and emotions?

A

Hypothalamus

51
Q 
Which of the following activities would most likely be completed by the right hemisphere of a left-handed person?
A. Finding a car in a parking lot
B. Learning a new language
C. Reading a book for pleasure
D. Jumping rope with friends
A

A. Finding a car in a parking lot

Right hemisphere is usually the nondominant hemisphere. Sense of direction is an ability of the nondominant hemisphere.

52
Q

Which of the following is/are true with regard to neuralation?
A. The neural tube differentiates from endoderm
B. The neural tube becomes the peripheral nervous system
C. Neural crest cells migrate from their original site

A

C. Neural crest cells migrate from their original site
Neurulation occurs occurs when the notochord causes differentiation of overlaying ectoderm into the neural tube and neural crest cells. The neural tube ultimately becomes the CNS (brain and spinal cord), and neural crest cells migrate to other sites in the body of differentiate into a number of different tissues

53
Q 
Which of the following neurotransmitters is NOT classified as a catecholamine?
A. Epinephrine
B. Norepinephrine
C. Dopamine
D. Acetylcholine
A

D. Acetylcholine
Catecholamines are hormones produced by adrenal glands during the flight-or-fight response
Acetylcholine is produced by cholinergic neurons

54
Q

If the amount of acetylcholinesterase, an enzyme that breaks down acetylcholine, is increased, what would be the likely result?

A

Weakness of muscle movements

Low levels of acetylcholine would result in weakness or paralysis of muscles

55
Q

What is the function of adrenal glands?

A

Produces stress responses via cortisol
Produces both hormones and neurotransmitters
Releases estrogen in males and testosterone in females

56
Q

A disorder of the pineal gland would most likely result in what disorder?

A

Insomnia

Pineal gland produces melatonin which controls the body’s circadian rhythm

57
Q

Which of the following conclusions would William James most likely support?
A. Mental processes help individuals adapt to their environments
B. Psychological attributes could be measured by feeling the skull
C. Specific functional impairments can be linked to specific lesions in the brain
D. Synaptic transmission is an electrical process

A

A. Mental processes help individuals adapt to their environments
William James studied how the mind adapts to the environment and formed the foundation of functionalism

58
Q

A scientist designs a study to determine if different regions of the brain are activated when a person speaks their native language vs. a second language. Which method would the scientist most likely choose?

A

fMRI
Activity in different regions of the brain is assumed to positively correlate with blood flow. Changes in blood flow can be measured with fMRI

59
Q

During a physical examination, a physician brushes the bottom of the foot of a 50 year old patient with multiple sclerosis. Her toes are observed to curl toward the bottom of her foot, with no fanning of the toes. This response is…

A

Normal and evidence that she is not exhibiting a primitive reflex

60
Q

Which of the following fine motor tasks would one expect to see first in an infant?
A. Grasping for objects with 2 fingers
B. Following objects with the eyes
C. Scribbling with a crayon
D. Moving a toy from one hand to the other

A

B. Following objects with the eyes

Motor skills develop from the core to the periphery

61
Q

What is the correct sequence of the development of a mature sperm cell?

A 
Spermatogonium —> 1 spermatocyte —> 2 spermatocyte —> spermatid —> spermatozoan
Diploid cells (spermatogonia) differentiate into primary spermatocytes, which undergo the first meiotic division to yield two haploid secondary spermatocytes. These undergo a second meiotic division to become immature spermatids. The spermatids then undergo a series of changes leading to the production of mature sperm, or spermatozoa.
62
Q 
Which of the following correcttly pairs the stage of development of an egg with the relevent point in a woman’s life cycle?
A. From birth to menarche — prophase II
B. At ovulation — metaphase I
C. At ovulation — metaphase II
D. At fertilization — prophase II
A

C. At ovulation — metaphase II
At ovulation, the egg cell has completed meiosis I and is now rested in metaphase II as a haploid cell called a secondary oocyte

63
Q

Some studies suggest that in patients with Alzheimer’s disease, there is a defect in the way the spindle apparatus attaches to the kinetochore fibers. At which stage of mitotic division would one first expect to be able to visualize this problem?

A

Prophase

The spindle apparatus first interacts with the kinetochore fibers near the end of prophase

64
Q

A researcher wishes to incorporate a radiolabeled deoxyadenine into the genome of one of the two daughter cells that would arise as a result of mitosis. What is the latest stage of cellular development during which the radiolabeled deoxyadenine could be added to achieve this?

A

S phase
It has to be inserted into the nucelotide before DNA replication is completed. Replication occurs during S phase, so that is the latest point in which the nucleotide could be added

65
Q

Certain ovarian tumors called granulosa cell tumors are known to produce excessive levels of estrogen. A physician who diagnoses a granulosa cell tumor should look for a secondary cancer in which part of the reproductive tract?

A

Endometrium
Estrogen is known to cause groeth of the endometrial lining during the follicular phase of the menstural cycle. Excessive levels of estrogen may provide a strong enough signal for cell growth to promote tumor formation or even cancer

66
Q

Upon ovulation, the oocyte is released into the…

A

Abdominal cavity

The ruptured ovarian follicle releases an oocyte into the abdominal cavity, close to the entrance of the fallopian tube

67
Q

Cancer cells are cells in which mitosis occurs continuously, without regard to quality or quantity of the cells produced. For this reason, most chemotherapies attack rapidly dividing cells. At which point(s) in the cell cycle could chemotherapy effectively prevent cancer cell division?

A

S phase, prophase, and metaphase
Prevent DNA synthesis in the S phase
Prevent the mitotic cycle from forming altogether in prophase by preventing spindle apparatus formation, preventing the nuclear membrane from dissolving
Interfere with the mitotic phase in metaphase

68
Q

Which of the following INCORRECTLY pairs a structure of the male reproductive system with a feature of the structure?
A. Seminal vesicles — produce alkaline fructose-containing secretions
B. Prostate gland — surrounded by muscle to raise and lower the testes
C. Vas deferens — tube connecting the epididymis to the ejaculatory duct
D. Cowper’s glands — produce a fluid to clear traces of urine in the urethra

A

B. Prostate gland — surrounded by muscle to raise and lower the testes
The prostate gland secretes seminal fluid that combines with sperm to produce semen

69
Q

What is the last point in the meiotic cycle in which the cell has a diploid number of chromoses?

A

Telophase I
The first meiotic division pulls homologous chromosomes to opposite poles of the cell during anaphase I. Near the end of telophase I, cytokinesis occurs, resulting in 2 haploid daughter cells. The cell is diploid during interphase, but remains diploid up until the end of telophase I

70
Q

Which of the following does NOT likely contribute to genetic variability?
A. Random fertilization of an egg by a sperm
B. Random segregation of homologous chromosomes
C. Crossing over between homologous chromosomes during meiosis
D. Replication of the DNA during S phase

A

D. Replication of the DNA during S phase
DNA is copied precisely, without error, in S phase. Since both strands should be identical, this would not lead to genetic variability

71
Q

What is a key difference between mitosis and meiosis?

A

During metaphase of mitosis, centromeres are present directly on the metaphase plate. During metaphase of meiosis I, there are no centromeres on the metaphase plate

72
Q

Which of the following is true regarding prophase?
A. The chromosomes separate and move to opposite poles of the cell
B. The spindle apparatus disappears
C. The chromosomes uncoil
D. The nucleoli disappear

A

D. The nucleoli disappear
In prophase, the chromatin condenses into chromosomes, the spindle apparatus forms, and the nucleoli and nuclear membrane disappear

73
Q

An individual who is phenotypically female is found to have only one copy of a disease-carrying recessive allele on the X chromosome, yet she demonstrates all of the classic symptoms of the disease. Geneticists determine she has a genotype that likely arose from nondisjunction in one of her parents. What is the likely genotype of this individual?

A

45,X
Nondisjunction refers to thr incorrect segregation of homologous chromosomes during anaphase I, or of sister chromatids during anaphase II. One daughter cell end up with 2 copies of relsted genetic material, while the other recieves 0

74
Q

During which phase of the menstural cycle does progesterone concentration peak?

A

Luteal phase

Proesterone peaks during the lutesl phase because it supports the endometrium for potential implantation of a blastula.

75
Q

Which of the following would NOT be seen during pregnancy?
A. High levels of hCG in the first trimester
B. High levels of progesterone throughout the pregnancy
C. Low levels of FSH in the first trimester
D. High levels of GnRH throughout the pregnancy

A

D. High levels of GnRH throughout the pregnancy
During the first trimester of pregnancy, the corpus luteum is preserved by hCG. During the second trimester, hCG levels decline, but progesterone levels rise because the hormone is now secreted by the placenta itself. High levels of progesterone and estrogen inhibit GnRH secretion, thus preventing FSH and LH secretion and the onset of a new menstrual cycle

76
Q

A man walks 30m east and then 40m north. What is the difference between his traveled distance and his displacement?

A

Total distance traveled: 30m + 40m = 70m
Magnitude of displacement: sqrt(30^2 + 40^2) = 50m
Difference: 70m - 50m = 20m

77
Q

A 1000kg rocket ship, travelling at 100m/s, is acted upon by an average force of 20kN applied in the direction of its motion for 8s. What is the change in velocity of the rocket?

A 
a = v/t —> v = at = Ft/m
(20*10^3N)(8s)/1000kg = 160m/s
78
Q

A car is traveling at 40km/hr and the driver puts on the brakes, bringing the car to rest in a time of 6s. What is the magnitude of the average acceleration of the car?

A 
6s = 1/600hr
a = v/t
a = (-40km/hr)/(1/600hr) = -24,000km/hr^2
Magnitude = 24,000km/hr^2
79
Q

An elevator is designed to carry a maximum weight of 9800N (including its own weight), and to move upward at a speed of 5m/s after an initial period of acceleration. What is the relationship between the maximum tension in the elevator cab,e and the maximum weight of the elevator while the elevator is accelerating upward?

A

The tension is great than 9800N
For the elveator to accelerate upwards, the tension in the cable will have to be greater thwn the maximum weight so thst there is a net force directed upwards

80
Q 
A student must lift a mass of 4kg a distance of 0.5m. The ambient temperature is 298K and the student must lift the mass in 30s. Which of the following values is NOT necessary to calculate power?
A. Mass
B. Distance
C. Temperature
D. Time
A

C. Temperature
The unit of power is the watt which breaks down to:
(kg*m^2)/s^2

81
Q

A firefighter jumps horizontally from a burning building with an initial speed of 1.5m/s. At what time is the angle between his velocity and acceleration vectors the greatest?

A

The instant he jumps
His acceleration is always downwards, but his velocity starts out horizontal and gradually rotates downwards. As time progresses, the angle between his velocity and acceleration decreases, so the maximum angle occurs at the instant he jumps

82
Q

A 10kg wagon rests on an inclined plane. The plane makes an angle of 30 with the horizontal. Approximately how large is the force required to keep the wagon from slifing down the plane? (sin30 = 0.5, cos30 = 0.866)

A

(10kg)(9.8m/s^2)(sin30) = 49N

83
Q

What are the correct SI base units for each of the variables in the formula below?
m/\v = F/\t

A

m: kg
/\v: m/s
F: kg m/s^2
t: s

84
Q 
Which of the following quantities is NOT a vector?
A. Velocity
B. Force
C. Displacement
D. Distance
A

D. Distance

85
Q

A 30kg girl sits on a seesaw at a distance of 2m from the fulcrum. Where must her father sit to the balance the seesaw if he has a mass of 90kg?

A 
r(g)F(g)sin@(g) = r(f)F(f)sin@(f)
r(g)m(g)gsin90 = r(f)m(f)gsin90
(2m)(30kg) = r(f)(90kg)
r(f) = 0.67m = 67cm from the fulcrum
86
Q

A physics major builds a potsto gun and tests it in an open field. He launches a potato with a velocity of 12m/s at an angle of 30. The potato is found 60m from the launch site. What is the maximum height achieved by the potato? (cos60 = 0.86)

A 
v(f) = 12(sin30) = 6m/s
v(f)^2 = v(i)^2 + 2ax
0 = 36 - 20x
20x = 36
x = 1.8m
87
Q

A rock (m = 2kg) is shot up vertically at the same time that a ball (m = 0.5kg) is projected horizontally. If both start from the same height…

A

The ball will reach the ground first
The rock begins with an upward component of velocity and will take time to reach a maximum height before falling back toward the ground. The rock’s free fall starts higher and later than the ball’s.

88
Q

Centrifugal force is an apparent outward force during circular motion. It has been described as a reaction force according to Newton’s third law. What is true regarding centrifugal force?

A

Centrifugal force always acts antiparallel to the centripetal force vector
Centrifugal force is a reaction to centripetal force. According to Newton’s third law, these forces must have equal magnitudes and opposite directions

89
Q

Which of the following statements in true of movement on a plane with friction?
A. Acceleration is a function of applied force only
B. More force is needed to accelerate a stationary object than an identical moving object
C. The force of friction is independent of the mass of objects

A

B. More force is needed to accelerate a stationary object than an identical moving object
Static friction opposes the movement of stationary objects and is greater than the force of kinetic friction

90
Q

What is the electron configuration of Zn2+?

A

1s(2)2s(2)2p(6)3s(2)3p(6)4s(0)3d(10)

91
Q 
Which of the following quantum number sets is possible?
A. n=2, l=2, m(l)=1, m(s)=+1/2
B. n=2, l=1, m(l)=-1, m(s)=+1/2
C. n=2, l=0, m(l)=-1, m(s)=-1/2
D. n=2, l=0, m(l)=1, m(s)=-1/2
A

B. n=2, l=1, m(l)=-1, m(s)=+1/2

l cannot be higher than n-1; m(l) can only be an integer between -l and l

92
Q

What is the maximum number of electrons allowed in a single atomic energy level in terms of the principal quantum number n?

A

2n^2

Two electrons per orbital

93
Q

What is the maximum number of electrons that can fill a subshell in terms of l?

A

4l+2
l= 0, …, n-1
s=0, p=1, d=2, f=3

94
Q 
Which of the following atoms only has paired electrons in its ground state?
A. Sodium
B. Iron
C. Cobalt
D. Helium
A

D. Helium
Elements that come at the end of a block (group IIA, the group containing Zn, and the noble gases) have only paired electrons

95
Q

An electron returns from an excited state to its ground state, emitting a photon at wavelength = 500 nm. What would be the magnitude of the energy change if one mole of these photons were emitted? (h = 6.626 x 10^-34 J*s; N(A) = 6.02 x 10^23 mol^-1)

A

E=hc/(wavelength)
c = 3.00 x 10^8 m/s (speed of light)
wavelength = 500 nm = 500x10^-9 m
E = ((6.626x10^-34)(3.00x10^8))/(500x10^-9) = 3.9756x10^-19
(3.9756x10^-19)(6.02x10^23) = 2.39x10^5 J

96
Q 
Suppose an electron falls from n = 4 to its ground state, n = 1. Which of the following effects is most likely?
A. A photon is absorbed
B. A photon is emitted
C. The electron moves into a p-orbital
D. The electron moves into a d-orbital
A

B. A photon is emitted
Since the electron is moving into the n = 1 shell, the only subshell available is the 1s subshell. There will be some energy change, however, as the electron must lose energy to return to the minimum-energy ground state. That will require emitting radiation in the form of a photon

97
Q 
Which of the following carbon isotopes is LEAST likely to be found in nature?
A. 6C
B. 12C
C. 13C
D. 14C
A

A. 6C

6C would mean that there are 6 protons and 0 neutrons which is unlikely

98
Q

According to the Heisenberg uncertainty principle why is there an inability to measure position and momentum exactly and simultaneously?

A

Error in one variable is increased by attempts to messure the other.
If a particle is moving, it has momentum, but trying to measure that momentum necessarily creates uncertainty in the position.

99
Q 
Which of the following electronic transitions would result in the greatest gain in energy for a single hydrogen electron?
A. An electron moves from n = 6 to n = 2
B. An electron moves from n = 2 to n = 6
C. An electron moves from n = 3 to n = 4
D. An electron moves from n = 4 to n = 3
A

B. An electron moves from n = 2 to n = 6
For the electron to gain energy it must absorb energy from photons to jump up to a higher energy level. There is a bigger jump between n = 2 and n = 6 than there is between n = 3 and n = 4

100
Q

Suppose an atom fills its orbitals as shown:
/\ | /\ /\ /\
| \/ | | |
3s 3p
Such an electron configuration most clearly illustrates which law of atomic physics?

A

Hund’s rule
This element, phosphorus, is often used to demonstrate Hund’s rule because it contains a half-filled p subshell. Hund’s rule explains that electrons fill empty orbitals first before doubling up electrons in the same orbital

101
Q

How many electrons are in a 133Cs cation?

A

54
There are 55 protons in Cs. Neutral Cs would have 55 electrons, but a stable Cs carion would have a +1 charge and only 54 electrons

102
Q

The atomic weight of hydrogen is 1.008 amu. What is the percent composition of hydrogen by isotope, assuming that hydrogen’s only isotopes are 1H and 2D?

A

99.2% H, 0.8% D
H + D = 1
1H + 2D = 1.008
(1-D) + 2D = 1.008

103
Q 
Consider the two sets of quantum numbers shown below, which describe two different electrons in the same atom.
n       l       m(l)       m(s)
2       1        1         +1/2
3       1       -1         +1/2
Which of the following terms best describes these two electrons?
A. Parallel
B. Opposite
C. Antiparallel
D. Paired
A

A. Parallel

m(s) = +1/2 for both, which means they spin the same direction

104
Q

Which of the following species is represented by the electron configuration 1s(2)2s(2)2p(6)3s(2)3p(6)4s(1)3d(5)?
A. Cr
B. Mn+
C. Fe2+

A

A and B. Cr and Mn+

MCAT Prep (8 decks)

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