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MCAT > Bio: Ch 8, 12 > Flashcards

Bio: Ch 8, 12 Flashcards

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1
Q

immune system can be divided into

A

innate and adaptive immunity

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2
Q

innate immunity

A

aka nonspecific immunity

always active against infection but

cannot target a specific invader and cannot maintain immunologic memory

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3
Q

adaptive immunity

A

aka specific immunity

target specific invader and can maintain immunological memory

takes time to activate

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4
Q

immune cells come from

A

bone marrow

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5
Q

sites where immune responses can be mounted

and in which b cells are activated

A

spleen and lymph nodes

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6
Q

site of t cell maturation

A

thymus

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7
Q

thymus

A

site of t cell maturation

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8
Q

gut-associated lymphoid tissue (GALT)

A

includes tonsils and adenoids

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9
Q

spleen

A

location of blood storage and activation of b cells

recycling center for red blood cells

filter of blood and lymph for immune system

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10
Q

B-cells turn into ___ to…

A

plasma cells to produce antibodies as part of adaptive immunity

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11
Q

agents of cell mediated immunity

A

t cells

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12
Q

monocytes

A

agranulocytes

phagocytic cells in blood stream

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13
Q

monocytes become

A

macrophages

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14
Q

macrophages in CNS are called

A

microglia

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15
Q

macrophages in skin are called

A

langerhans cells

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16
Q

macrophages in bone are called

A

osteoclasts

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17
Q

specific immune system can be divided into

A

humoral immunity and cell mediated immunity

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18
Q

humoral immunity

A

type of specific immunity

driven by B cells and antibodies

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19
Q

cell mediated immunity

A

type of specific immunity

driven by t cells

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20
Q
A
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21
Q

innate defenses

noncellular and cellular

A
  • noncellular
    • skin
    • mucus
    • lysozyme
    • stomach
    • complement system
    • interferons
  • cellular
    • macrophages (MHC, cytokines)
    • dendritic cells
    • natural killer cells
    • granulocytes
    • neutrophils, eosinophils, basophils
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22
Q

immune system

skin

A

innate immune system

physical barrier

secretes antimicrobial compounds such as defensins

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23
Q

mucus

A

innate immune system

traps pathogens

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24
Q

lysozyme

A

innate immune system

in tears and saliva

antibacterial compound

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25
Q

immune system

stomach

A

innate immune system

produces acid, killing most pathogens

colonization of gut helps prevent overgrowth by pathogenic bacteria through competition

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26
Q

complement system

A

innate immune system

punch holes in cell walls of bacteria, making them osmotically unstable

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27
Q

interferons

A

innate immune system

given off by virally infected cells

help prevent viral replication and dispersion to nearby cells

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28
Q

macrophages

A

innate immune system

ingest pathogens and present them on MHC molecules

secrete cytokines

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29
Q

MHC class I (MHC-I)

A

innate immune system

present in all nucleated cells

displays endogenous antigen to cytotoxic t cells (CD8+ cells)

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30
Q

endogenous antigen

A

proteins from within the cell

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31
Q

MHC class II (MHC-II)

A

innate immune system

present in professional antigen-presenting cells (macrophages, dendritic cells, some b cells, certain activated epithelial cells)

displays exogenous antigen to helper t cells (CD4+ cells)

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32
Q

exogenous antigen

A

proteins from outside the cell

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33
Q

dendritic cells

A

innate immune system

antigen presenting cells in skin

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34
Q

natural killer cells

A

innate immune system

attack cells not presenting MHC molecules, including virally infected cells and cancer cells –> induce apoptosis

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35
Q

granulocytes

include

A

innate immune system

include neutrophils, eosinophils, and basophils

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36
Q

neutrophils

A

innate immune system

ingest bacteria, particularly opsonized bacteria (those marked with antibodies)}

can follow bacteria using chemotaxis

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37
Q

eosinophils

A

innate immune system

used in allergic reactions and invasive parasitic infections

release histamine

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38
Q

basophils

A

innate immune system

used in allergic reactions

release histamine

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39
Q

mast cells

A

innate immune system

cells found in skin

release histamine

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40
Q

opsonnized

A

marked with antibody from b cell

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41
Q

antibodies

A

target particular antigen

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42
Q

antibody structure

A

contain two heavy chains and two light chains

have a constant region and variable region

tip = antigen binding region

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43
Q

what happens when antibodies are activated?

A

humoral immunity

  1. activated by b cell
  2. antigen binding region undergoes hypermutation to improve the specificity of antibody produced
  3. cells may be given signals to switch isotypes of antibody
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44
Q

cell surface antibodies

A

humoral immunity

can activate immune cells or mediate allergic reactions

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45
Q

memory b cells

A

humoral immunity

wait for second exposure to a pathogen and can mount a more rapid and vigorous response (secondary response)

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46
Q

t cells under goe maturation in the ___ through…

A

thymus

positive selection and negative selection

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47
Q

positive selection

A

only selecting for t cells that can react to antigen presented on MHC

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48
Q

negative selection

A

causing apoptosis in self reactive t cells

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49
Q

helper t-cells (CD4+)

A

cell mediated (cytotoxic) immunity

  • respond to antigen on MHC-II and coordinate rest of immune system
    • secrete lymphokines to activate other arms
    • Th1 cells
    • Th2 cells
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50
Q

Th1 cells

A

cell mediated (cytotoxic) immunity

secrete interferon gamma, which activates macrophages

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51
Q

Th2 cells

A

cell mediated (cytotoxic) immunity

activate B cells, primarily in parasitic infections

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52
Q

cytotoxic t-cell (CD8+)

A

cell mediated (cytotoxic) immunity

repond to antigen on MHC-I and kill virally infected cells

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53
Q

suppressor (regulatory) t cells

A

cell mediated (cytotoxic) immunity

tone down the immune response after an infection

promote self tolerance

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54
Q

memory T cells

A

cell mediated (cytotoxic) immunity

remember and can mount faster immune response

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55
Q

autoimmune conditions

A

self antigen is identified as foreign

immune system attacks the body’s own cells

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56
Q

allergic reaction

A

nonthreatening exposures incite an inflammatory resposne

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57
Q

active immunity

A

activation of B cells that produce antibodies to an antigen

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58
Q

immunization

A

induces active immunity prior to exposure to a particular pathogen

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59
Q

passive immunity

A

transfer of antibodies to an individual

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60
Q

lymphatic system

A

circulatory system that consists of one way vessels with intermittent lymph nodes

  • equalizes fluid distribution
  • transports fats and fat soluble compounds in chylomicrons
  • provides sites for mounting immune response
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61
Q

lymphatic system connects to cardiovascular system via

A

thoracic duct in posterior chest

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62
Q

HIV

A

loss of helper t cells

prevents immune system from mounting an adequate response to infection

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63
Q

degranulation

A

when antigen binds to antibodies on surface of mast cell and exocytosis of granule contents happens

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64
Q

primary response

A

initial activation of memory cells

can take several days

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65
Q

lymphokines

A

recruit other immmune cells and increase their activity

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66
Q

self tolerance

A

when suppressor t cells turn off self reactive lymphocytes to prevent autoimmune diseases

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67
Q

what are the 3 main effects circulating antibodies can have on a pathogen

A
  1. mark a pathogen for destruction by phagocytic cells
  2. cause agglutination of pathogen into insoluble complexes that can be taken up by phagocytic cells
  3. neutralize pathogen by preventing it from invading tissues
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68
Q

how do antibodies become specific for a given antigen?

A
  • b cells that mature in bone marrow have some specificity
  • antibodies that can respond to a given antigen undergo hypermutation
    • only those b cells have the highest affinity for the antigen survive and proliferate, increasing the specificity for the antigen over time
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69
Q

a t cell appropriately passes through positive selection, but then inappropriately passes through negative selection. what will this t cell be reactive toward?

A

reactive to self antigens

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70
Q

True or False? The lymphatic vessels are special in that they create a closed loop.

A

False. The lymphatic vessels DO NOT create a closed loop. It is connected to the systemic circulatory system.

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71
Q

As we move from an oxygenated capillary to the deoxygenated capillary, is there an increase or decrease in pressure?

A

There is a decrease in pressure.

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72
Q

Do blood vessels or lymph have a higher percentage of protein? Why is this important?

A

Blood vessels. This is because so much fluid gets out from blood vessels, making lymph very diluted. Having a higher concentration of protein in the blood makes it more osmotically active, pulling water back into the blood stream, preventing edema (swelling).

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73
Q

As we move down a capillary, the blood is more osmotically active. Does this cause fluid to enter or leave the capillary?

A

Because there is a higher osmotic pressure inside the capillary, this causes fluid to re-enter the capillary.

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74
Q

Which of the following are antibacterial enzymes found in the skin?

(A) Sweat
(B) Defensins
(C) Integrins
(D) Langerhans

A

(B) Defensins

Defensins are antibacterial enzymes found in the skin. Sweat is not an enzyme, but it does have microbial properties!

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75
Q

Which acts faster? Non-specific/Innate Immunity or Adaptive/Specific Immunity?

A

Innate Immunity acts faster as Adaptive Immunity requires time to recognize and prepare defenses against invaders. Think about how B and T Cells need to replicate and divide in order to prepare for a certain invader.

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76
Q

True or false? The main actors of the specific immune system are lymphocytes.

A

True. The main actors of the specific immune system are lymphocytes such as B and T Cells.

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77
Q

Which of the following are different types of phagocytes in the body?

I. Neutrophils
II. Macrophages
III. Dendritic Cells

(A) III only
(B) III and I only
(C) I and II only
(D) I, II, and III

A

(D) I, II, and III.

Neutrophils, Macrophages and Dendritic Cells are all different types of phagocytes found in the body.

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78
Q

True or false? Macrophages are the fast and abundant phagocytes.

A

False. Neutrophils are the fast and abundant type of phagocytes.

Macrophages are the the most versatile but not as abundant as neutrophils.

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79
Q

CRB Compare the Complement System and Interferons, which are two other parts of the nonspecific Immune Response.

A

The complement system is based off many proteins in the blood, and will punch holes in bacterial cell membranes in the blood.
Interferons are proteins that prevent viral replication and dispersion, and will be produced by cells that have been already infected by viruses.

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80
Q

True or false? The humoral response of the B-lymphocytes comes into play if the cell has been colonized by a virus or bacteria

A

False. Humoral response comes into the picture if the bacterial/virus cells are floating around in the humoral fluid and haven’t colonized a cell yet.

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81
Q

B Cells have receptors presented on their membranes that recognize the proteins of invaders. We might think of these receptors as:

(A) Membrane-bound Antigens
(B) Membrane-bound Antibodies
(C) Membrane-bound MHC I
(D) Membrane-bound MHC II

A

(B) Membrane-bound Antibodies

Each B-lymphocytes have membrane-bound antibodies (aka Immunoglobulins) on their surfaces. Antigens refer to the proteins that are recognized by antibodies.

82
Q

Antibodies have various mechanisms of action, including Opsonization, Neutralization, and Agglutination. Describe each of these three mechanisms.

A

Opsonization - tags pathogens for phagocytosis by other white blood cells.

Neutralization - masks dangerous parts of the pathogen, making them no longer pathogenic.

Agglutination - Multiple pathogens are bound up together, making them easier for digestion/phagocytosis.

83
Q

Which of the following are examples of Professional (MHC II) Antigen Presenting Cells (APCs)?

I. Macrophages
II. Basophils
III. T Cells

(A) I Only
(B) II Only
(C) I and II Only
(D) I and III Only

A

(A) I Only

Examples of Antigen Presenting Cells (APCs) include Macrophages, Dendtritic Cells and B Cells.

84
Q

What is the primary difference between the role of B Cells vs. T Cells?

A

B Cells produce antibodies.

T Cells recognize and destroy invaders and infected cells.

85
Q

When a pathogen binds to a receptor on a B-Cell, the B-Cell will form both Memory B Cells and Effector B Cells. What is the difference between these two B Cell types?

A

Memory B Cells are basically copies of the original B Cell. Their purpose is to recognize future invaders of the same type hence the name “memory”.

Effector B Cells are Antibody producing “factories” with the sole purpose of producing tons of antibodies.

86
Q

There are two major types of T Cells: Helper T Cells (Th) and Cytotoxic T Cells (Tc). What is the difference between these two?

A

Cytotoxic T Cells will recognize cells that are infiltrated by an invader and destroy those infected cells.

Helper T Cells will recognize cells that are presenting an antigen via MHC II. Upon binding they will divide into Memory and Effector Th Cells.

87
Q

Which of the following is not an effect that Antibodies can have on pathogens?

(A) Binding to a specific antigen on the pathogen and attract other leukocytes.
(B) Bind and cause Degranulation, where the granules in the cell undergo exocytosis.
(C) Bind and cause pathogens to Agglutinate, or clump together, so they can be phagocytosed.
(D) Block the ability of pathogens to invade tissues.

A

(B) Bind and cause Degranulation, where the granules in the cell undergo exocytosis.

Antibodies actually cause Degranulation in Mast Cells, which leads to the mass release of Histamine and inflammation.

88
Q

Which of the following terms best describes how B cells can change the type of antibody they produce (between IgM, IgG, etc.)?

(A) Clonal Selection
(B) Natural Selection
(C) Isotope Switching
(D) Isotype Switching

A

(D) Isotype Switching

Isotype Switching is when B cells can change the type of Antibody they produce.

89
Q

True or False. B Cell receptors can bind both directly to invaders or to MHC complexes that are presenting part of that invader.

A

False. B Cell receptors do not bind to MHCs.

90
Q

What happens if a bacteria gets into your bone marrow and binds to a B Cell?

A

The B Cells that recognize that antigen will be destroyed, leaving you susceptible to infection!

91
Q

How do Autoimmune diseases relate to these ideas?

A

When you have B or T Cells that recognize self-antigens, that is known as an Autoimmune Disease.

92
Q

What is the function of a Neutrophil?

A

Neutrophils function by phagocytosing invaders and then dying. They are like suicide bombers. After they die they make up what we call “pus”.

93
Q

chromosome

A

contain genes in linear sequences

94
Q

alleles

A

alternative forms of genes

95
Q

dominant allele

A

requires only one copy to be expressed

96
Q

recessive allele

A

requires two copies to be expressed

97
Q

genotype

A

combination of alleles one has at a given genetic locus

98
Q

homozygous

A

having two of the same allele

99
Q

heterozygous

A

having two different alleles

100
Q

hemizygous

A

having only one allele

(ex male sex chromosomes)

101
Q

phenotype

A

observable manifestation of a genotype

102
Q

complete dominance

A

effect of one allele completely masks the effect of another

103
Q

codominance

A

has more than one dominant allele

104
Q

incomplete dominance

A

has no dominant alleles

heterozygotes express a phenotype that is intermediate between the two homozygous genotypes

105
Q

penetrance

A

proportion of a population with a given genotype who express the phenotype

106
Q

expressivity

A

the different manifestations of the same genotype across the population

107
Q

mendel’s first law

A

of segregation

an organism has two alleles for each gene, which segregate during meiosis, resulting in gametes carrying only one allele for a trait

  1. genes exist in alternative forms (allele)
  2. an organsim has two alleles for each gene, one inherited from each parent
  3. two alleles segregate during meiosis
  4. full dominance
108
Q

mendel’s second law

A

of independent assortment

inheritance of one allele does not influence the probability of inheriting an allele for a different trait

109
Q

Griffith experiment

A

demonstrated transforming principle

converting nonvirulent live bacteria into virulent bacteria by exposure to heat killed virulent bacteria

injected different live/virulent strains of pneumonia into mice to see if they died

110
Q

avery-maclead-mccarty experiment

A

demonstrated that DNA is the genetic material

bc degradation of DNA led to a cessation of bacterial transformation

111
Q

hershey-chase experiment

A

demonstrated that DNA is genetic material

only radiolabeled DNA could be found in bacteriophage-infected bacteria

112
Q

locus

A

location on a specific chromosome

113
Q

if expressivity is constant…

A

all individuals with a given genotype express the same phenotype

114
Q

if expressivity is variable…

A

individuals with the same genotype may have different phenotypes

115
Q

transforming principle

A

live nonvirulent bacteria acquired the ability to form smooth capsules from dead virulent bacteria

116
Q

which phase of meiosis does mendel’s first law most closely correlate?

A

segregation

anaphase I of meiosis

117
Q

which phase of meiosis does mendel’s second law most closely correlate?

A

of independent assortment

prophase I of meiosis

118
Q

gene pool

A

all of the alleles in a given population

119
Q

mutations

A

changes in the DNA sequence

120
Q

point mutation

A

substituting of one nucleotide for another

121
Q

frameshift mutation

A

moving the three letter transcriptional reading frame

122
Q

silent mutation

A

has no effect on the protein

123
Q

missense mutation

A

substitution of one amino acid for another

124
Q

nonsense mutation

A

substitution of stop codon for an amino acid

125
Q

insertions and deletions result in

A

shift in reading frame

126
Q

deletion mutation

A

large segment of DNA is lost

127
Q

duplication mutation

A

segment of DNA is copied multiple times

128
Q

inversion mutation

A

segment of DNA is reversed

129
Q

insertion mutation

A

segment of DNA is moved from one chromosome to another

130
Q

translocation mutation

A

segment of DNA is swapped with a segment of DNA from another chromosome

131
Q

genetic leakage

A

flow of genes between species through hybrid offspring

132
Q

genetic drift

A

occurs when composition of gene pool changes as a result of chance

133
Q

founder effect

A

extreme case of genetic drift in which small population finds itself in reproductive isolation from other populations

results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes

134
Q

codons

A

3 letter sequences in DNA

135
Q

inbreeding depression

A

loss of genetic variation that cuases reduced fitness of the population

136
Q

outbreeding/outcrossing

A

introduction of unrelated individuals into a breeding group

137
Q

monohybrid

A

cross in which only one trait is being studied

138
Q

parent generation

A

P

individuals being crossed

139
Q

filial generation

A

F

offspring of the parents that are being crossed

140
Q

dihybrid cross

A

studying two genes

141
Q

punnet ratio

2 heterozygotes

A

1:2:1

PP:Pp:pp

142
Q

test cross

A

used to determine unknown genotype

143
Q

punnet ratio

dihybrid cross - 2 plants that are heterozygous for both traits

A

9:3:3:1

144
Q

recombination frequency

A

θ

likelihood of two alleles being separating during crossing over in meiosis

145
Q

genetic maps

A

can be made using recombination frequency as scale

146
Q

hardy-weinberg principle

A

if a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant

147
Q

allele frequency

A

how often an allele appears in a population

148
Q

5 criteria for hardy weinberg equilibirum

A
  1. population is very large (no genetic drift)
  2. no mutations that affect gene pool
  3. mating between individuals is random (no sexual selection)
  4. no migration of individuals into or out of the population
  5. genes in population are all equally successful at being reproduced
149
Q

hardy weinberg eqs

A

p + q = 1

p2 + 2pq +q2 = 1

p = freq of dominant allele

q = freq of recessive allele

150
Q

natural selection

A

chance variations exist between individuals

advantageous variations afford the most opportunities for reproductive success

151
Q

modern synthesis model

A

neo darwinism

accounts for mutation and recombination as mechanisms of variation

considers differential reproduction to be the mechanism for reproductive success

152
Q

inclusive fitness

A

considers an organism’s success to be based on the number of offspring, success in supporting offspring, and the ability of the offspring to then support others

survival of offspring or relatives ensures appearance of genes in subsequent generations

153
Q

punctuated equilibrium

A

considers evolution to be a very slow process with intermittent rapid bursts of evolutionary activity

154
Q

stabilizing selection

A

keeps phenotypes in a narrow range, excluding extremes

155
Q

directional selection

A

moves average phenotype toward one extreme

156
Q

disruptive selection

A

moves the population toward two different phenotypes at the extremes

can lead to speciation

157
Q

adaptive radiation

A

rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche

158
Q

species

A

largest group of organisms capable of breeding to form fertile offspring

159
Q

species are reproductively isolated from each other by

A

pre or post zygotic mechanisms

160
Q

divergent evolution

A

occurs when two species sharing a common ancestor become more different

161
Q

parallel evolution

A

occurs when two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures

162
Q

convergent evolution

A

occurs when two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures

163
Q

molecular clock model

A

degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor

164
Q

fitness

A

related to relative genetic contribution of indivdiual to the next generation

165
Q

polymorphisms

A

naturally occurring differences in form between members of the same population

166
Q

niche

A

specific environment, including habitat, available resources, and predators, for which a species is specifically adapted

167
Q

prezygotic mechanisms

A

prevent formation of zygote completely

includes: temporal isolation, ecological isolation, behavioral isolation, reproductive isolation, gametic isolation

168
Q

postzygotic mechanisms

A

allow for gamete fusion but yield either nonviable or sterile offspring

includes: hybrid inviability, hybrid sterility, hybrid breakdown

169
Q

temporal isolation

A

breeding at different times

170
Q

behavioral isolation

A

lack of attraction between members due to differences in pheromones, courtship displays, etc)

171
Q

reproductive isolation

A

incompatible reproductive anatomy

172
Q

gametic isolation

A

intercourse can occur, but fertilization cannot

173
Q

hybrid inviability

A

formation of a zygote that cannot develop to term

174
Q

hybrid sterility

A

forming hybrid offspring that cannot reproduce

175
Q

hybrid breakdown

A

forming first generation hybrid offspring that are viable and fertile, but second gen hybrid offspring are inviable and infertile

176
Q

Mutations are only a serious issue if they occur on the level of:

(A) DNA
(B) mRNA
(C) tRNA
(D) Protein

A

(A) DNA

A mutation in DNA will result in ALL future proteins being mutated.

177
Q

DNA mutations may be inherited or they may occur spontaneously. Spontaneous mutations may result from:

I. DNA replication errors.
II. DNA transcription errors.
III. Environmental factors.

(A) I Only
(B) I and II Only
(C) I and III Only
(D) I, II, and III

A

(C) I and III Only

Spontaneous mutations may result from:

(1) DNA replication errors.
(2) Completely random events.
(3) Environmental factors.

178
Q

The bottom part of Chromosome 7 switches places with the top part of Chromosome 7. This is an example of a(n):

(A) Inversion
(B) Translocation
(C) Insertion
(D) Deletion

A

(A) Inversion

An Inversion is a mutation in which two genes of the same Chromosome switch places.

179
Q

True or false? Crossing over occurs at Tetrads, when there are two sister chromatids attached at by a Centromere (X in appearance).

A

False. Crossing over occurs at Tetrads, where the homologous chromosomes, each with two sister chromatids attached by Centromeres, are close enough to exchange genetic material (XX in appearance).

180
Q

Compare the term Allele with the term Gene. Give an example.

A

A Gene is a portion of DNA that results in a certain trait.

An Allele is a version of a gene.

For instance, you may have a gene for hair color. The three alleles for this gene might be brown, black, or blonde hair.

181
Q

A cross between a blue bird and a white bird produces only offspring that are light blue (they only have light blue pigments). The color of birds is determined by just two alleles. What are the genotypes of the parent birds in the original cross? Is this an example of incomplete dominance or codominance?

A

Since the parents produced offspring that are only light blue we must be dealing with incomplete dominance, thus the genotype of the blue bird parent is homozygous blue (BB) and the white bird parent is homozygous white (WW).

182
Q

Which of the following are forms of Genetic Drift?

I. The Bottleneck Effect
II. The Founder’s Effect
III. Outbreeding

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(B) I and II only

The Bottleneck Effect and Founder’s Effect are both forms of Genetic Drift.

183
Q

CRB Compare the Bottleneck effect and the Founder’s Effect.

A

The Bottleneck Effect is whenever a population is drastically reduced, which typically decreases genetic variance. This can occur from a variety of natural disasters.
The Founder’s Effect is a subtype of the Bottleneck Effect, where a small subset of a population will move and find itself in reproductive isolation, again decreasing genetic variance.

184
Q

p² refers to what?
2pq refers to what?
q² refers to what?

A

p² refers to the frequency of AA in a given population.

2pq refers to the frequency of Aa in a given population.

q² refers to the frequency of aa in a given population.

185
Q

What was the conclusion of the Avery-MacLeod-McCarty experiment?

A

The Avery-MacLeod-McCarty experiment determined that the inheritable disease was passed along by DNA and only DNA, indicating it is the molecule of heritability.

186
Q

What are autosomal chromosomes?

A

Autosomal chromosomes are the 22 pairs of homologous chromosomes found similarly in both males and females.

187
Q

True or false? Autosomal Dominant or Autosomal Recessive genes should have no preference for either sex.

A

True. Autosomal Dominant or Autosomal Recessive genes should have no preference for either sex.

188
Q

Crossing Over is the process by which:

I. Genetic Information is transferred from one Homologous Chromosome to another.
II. DNA physically moves from one Homologous Chromosome to the another.
III. Genetic Recombination occurs.

(A) I Only
(B) I and III Only
(C) II and III Only
(D) I, II, and III

A

(D) I, II, and III

Crossing Over (aka Genetic Recombination) is the process by which Genetic Information is transferred from one Homologous Chromosome to another as DNA physically moves from one Homologous Chromosome to the another.

189
Q

Which of the following principles was NOT part of Darwin’s original theory of evolution by natural selection?

(A) Evolution is a gradual process that occurs over long periods of time.
(B) Variation occurs among individuals in a population.
(C) Mutations are the ultimate source of genetic variation.
(D) Individuals that possess the most favorable variations have the best chance of reproducing.

A

(C) Mutations are the ultimate source of genetic variation.

This was not part of Darwin’s original theory of evolution.

190
Q

CRB Define Differential Reproduction. Does it relate more to Darwinism or Neo-Darwinism?

A

The term Differential Reproduction describes Mutations or Recombinations that lead to advantageous phenotypes (typically meant as increasing reproductive success) are more likely to be passed on to future generations.
Since this term accounts for genetics, it is more closely related to Neo-Darwinism.

191
Q

An organism’s relative fitness is measured by fecundity. What does this mean?

A

An organism’s relative fitness is measured by fecundity, which is basically the ability of one to survive and reproduce offspring. In other words, fitness is measured by the contribution to the gene pool of the next generation.

192
Q

Which of the following are other modes of Natural Selection?

I. Sexual Selection, where mates are chosen for certain traits/phenotypes, which will be more likely to be seen in future generations.
II. Kin selection, where one animal will sacrifice itself to save its genetically-similar family members or pack.
III. Visual Selection, where only the most physically appealing specimens will reproduce and have their traits seen in future generations.

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(B) I and II only

Each of the following are modes of Natural Selection:

I. Sexual Selection, where mates are chosen for certain traits/phenotypes, which will be more likely to be seen in future generations.
II. Kin selection, where one animal will sacrifice itself to save its genetically-similar family members or pack.

193
Q

What is the difference between natural selection vs group selection vs artificial selection?

A

Natural selection is favoring some individual organisms over others, and leading to the evolution of traits that benefit individuals themselves.

Group selection is the idea that genetic traits that benefit the population as a whole will be selected even if it does not increase the fitness of the individual with the trait.

Artificial selection is a result of the whim of man, thus we may prefer to choose a characteristic which would have never been selected by nature.

194
Q

The studies of changes between black and light color in populations of the Peppered moth show which of the following:

(A) Natural selection can quickly change allele frequencies and common phenotypes in a population
(B) Species can always adapt to environmental changes
(C) Predators prefer light colored moths
(D) Dark colored moths are physiologically superior to light colored moths

A

(A) Natural selection can quickly change allele frequencies and common phenotypes in a population.

The studies of changes between black and light color in populations of the moth show that natural selection can quickly change allele frequencies and common phenotypes in a population.

195
Q

Genetic drift will increase or decrease genetic diversity in dynamic population?

A

Genetic diversity is decreased through genetic drift.

196
Q

Imagine that aliens were found on another planet filled with water, and their life forms looked a whole lot like Earth’s fish. Which type of evolution would this most be like?

(A) Divergent Evolution
(B) Parallel Evolution
(C) Convergent Evolution
(D) I will go read about the 3 main patterns of evolution and come back!

A

(C) Convergent Evolution

There is no reason to assume that these aliens and Earth’s fish are related, so the fact that they have evolved similar characteristics should be chalked up to Convergent Evolution.

197
Q

Gene flow will increase or decrease genetic diversity in dynamic population?

A

Genetic diversity is restored by gene flow.

198
Q

Which of the following is most likely to result in the loss of rare alleles?

(A) Founder Effect
(B) Genetic Drift
(C) Gene Flow
(D) Bottleneck Effect

A

(B) Genetic Drift

Genetic drift is most likely to result the loss of rare alleles because if an allele has a high frequency of at baseline, the chance of it being passed down to subsequent generations is higher than alleles at a lower frequency. The Founder Effect and Bottleneck Effect are specific examples of genetic drift.

199
Q

Describe the relationship between Evolution and Natural Selection.

A

Natural Selection is one mechanism that Evolution can occur through, but Evolution can occur through other mechanisms too. This means that Natural Selection and Evolution are NOT synonymous.

200
Q

A gene seeks only to be passed along to offspring if there are other copies of the gene in other individuals and the success of other individuals to reproduce. What does this concept illustrate?

(A) Natural Selection
(B) Group Selection
(C) Artificial Selection
(D) Inclusive Fitness

A

(D) Inclusive Fitness

This concept illustrates concept of inclusive fitness: a theory suggesting that the genetic success of an organism is dependent upon cooperation with other individuals in a population. A gene will be more prevalent in future generations if all individuals who carry that gene are successful at reproducing, rather than just one individual with that gene.

201
Q

Eldrige and Gould had their own theory of evolution, based on fossil records showing little change over long periods, followed by short periods with lots of increased diversity and evolutionary changes. Which of the following is the name of their theory?

(A) Differential Evolution
(B) Epochal Evolution
(C) Punctuated Equilibrium
(D) Differential Equilibrium

A

Eldrige and Gould had their own theory of evolution, based on fossil records showing little change over long periods, followed by short periods with lots of increased diversity and evolutionary changes. Which of the following is the name of their theory?

(A) Differential Evolution
(B) Epochal Evolution
(C) Punctuated Equilibrium
(D) Differential Equilibrium

MCAT (26 decks)

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