EXAM 4 study guide Flashcards
1
Q
In photosynthesis, plants use carbon from __________ to make sugar and other organic molecules.
A
carbon dioxide
2
Q
How does carbon dioxide enter the leaf?
A
Through the stomata
3
Q
In a rosebush, chlorophyll is located in __________.
A
thylakoids, which are in chloroplasts in the mesophyll cells of a leaf
4
Q
Chlorophyll molecules are in which part of the chloroplast?
A
Thylakoid membranes
5
Q
The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from __________.
A
water
6
Q
In photosynthesis, what is the fate of the oxygen atoms present in CO2? They end up __________.
A
in sugar molecules and in water
7
Q
Molecular oxygen is produced during __________.
A
linear electron flow during the light reactions
8
Q
The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why?
A
The Calvin cycle requires products only produced when the photosystems are illuminated.
9
Q
The Calvin cycle occurs in the __________.
A
Stroma
10
Q
What is the role of NADP+ in photosynthesis?
A
It forms NADPH to be used in the Calvin cycle.
11
Q
A photon of which of these colors would carry the most energy?
A
Blue
12
Q
The most important role of pigments in photosynthesis is to __________.
A
capture light energy
13
Q
What is the range of wavelengths of light that are absorbed by the pigments in the thylakoid membranes?
A
Violet-blue and red
14
Q
Based on the work of Engelmann, a plot of photosynthetic activity versus wavelength of light is referred to as __________.
A
an action spectrum
15
Q
When chloroplast pigments absorb light, __________.
A
the pigments’ electrons become excited
16
Q
What structure is formed by the reaction center, light-harvesting complexes, and primary electron acceptors that cluster in the thylakoid membrane?
A
The photosystem
17
Q
Where do the electrons entering photosystem II come from?
A
Water
18
Q
During photosynthesis in chloroplasts, O2 is produced from __________ via a series of reactions associated with __________.
A
H2O; photosystem II
19
Q
Which of the following is cycled in the cyclic variation of the light reactions?
A
Electrons
20
Q
Both mitochondria and chloroplasts __________.
A
use chemiosmosis to produce ATP
21
Q
You could distinguish a thylakoid membrane from an inner mitochondrial membrane because the thylakoid membrane would __________.
A
have photosynthetic pigments
22
Q
During photosynthesis in a eukaryotic cell, an electrochemical gradient is formed across the __________.
A
thylakoid membrane
23
Q
The light reactions of photosynthesis generate high-energy electrons, which end up in __________ through linear electron flow. The light reactions also produce __________ and __________.
A
NADPH; ATP; oxygen
24
Q
The energy used to produce ATP in the light reactions of photosynthesis comes from __________.
A
movement of H+ through a membrane
25
What is the role of NADP+ in photosynthesis?
It is reduced and then carries electrons to the Calvin cycle.
26
CO2 is reduced.
27
Which of the following occurs during the Calvin cycle?
ATP is hydrolyzed, and NADPH is oxidized.
28
Rubisco is __________.
the enzyme in plants that captures CO2 to begin the Calvin cycle
29
In the Calvin cycle, CO2 is combined with __________.
a five-carbon compound to form an unstable six-carbon compound, which decomposes into two three-carbon compounds
30
Glyceraldehyde-3-phosphate (G3P) is produced in the stroma of chloroplasts. Which of the following statements is most accurate regarding this compound?
All of the listed responses are correct.
31
Which of the following statements correctly describes the relationship between the light reactions and the Calvin cycle?
The light reactions produce ATP and NADPH, both of which are used in the Calvin cycle.
32
The use of non-C3 and non-CAM plants as crops may be limited in some regions because on hot, dry days, they close their stomata. What happens as a result of closing their stomata?
All of the listed responses are correct.
33
Why are C4 plants more suited to hot climates than C3 plants?
Unlike C3 plants, they keep fixing carbon dioxide even when the concentration of carbon dioxide in the leaf is low.
34
You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark?
While it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation.
35
The function of the mitotic cell cycle is to produce daughter cells that __________.
are genetically identical to the parent cell (assuming no mutation has occurred)
36
Which of the following is false regarding sister chromatids?
Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
37
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________.
chromatin
38
The region of a chromosome in which the two double strands of replicated DNA are held together is called __________.
a centromere
39
The centromere is a region in which __________.
sister chromatids are attached to one another in prophase
40
How many maternal chromosomes are present in a somatic human cell when it is not engaged in cell division?
23
41
A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with __________.
none of the listed numbers of chromosomes
42
"Cytokinesis" refers to __________.
the division of the cytoplasm
43
Chromatids are __________.
identical copies of each other if they are part of the same duplicated chromosome
44
If a cell contains 60 chromatids at the start of mitosis, how many chromosomes will be found in each daughter cell at the completion of the cell cycle?
30
45
A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled __________.
between the G1 and G2 phases
46
A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in one of the grasshopper daughter cells?
100 units
47
During interphase, the genetic material of a typical eukaryotic cell is __________.
dispersed in the nucleus as long strands of chromatin
48
DNA replication occurs in __________.
the S phase of interphase
49
If a human somatic cell is just about to divide, it has __________ chromatids.
92
50
Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present?
94
51
Which of the following does not occur during mitosis?
replication of chromosomes
52
During what phase in the cell cycle would you find the most DNA per cell?
G2
53
In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in __________.
prophase
54
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope?
Telophase
55
Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis?
0
56
In a human skin cell that is going through the cell cycle, when do the centrosomes separate?
Prophase
57
Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess?
Two
58
The phase of mitosis during which the chromosomes move toward separate poles of the cell is __________.
anaphase
59
One event occurring during prophase is __________.
the beginning of the formation of a spindle apparatus
60
Which event or events occur during anaphase?
All of the listed responses are correct.
61
Which of the following represents a mismatch or incorrect description?
Metaphase: the nuclear envelope disappears
62
At what point do sister chromatids separate?
Anaphase
63
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle?
Cytokinesis
64
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?
Metaphase
65
You would know that a dividing cell was a plant cell rather than an animal cell if you saw that __________.
it had formed a cell plate
66
Which of the following processes does not occur in dividing bacteria?
Mitosis
67
During binary fission in a bacterium, __________.
the origins of replication move apart
68
Which of the following is involved in the binary fission of most bacteria?
Distribution of a copy of the single parental chromosome to each daughter cell
69
When a cell in S phase is fused with a cell in G1, __________.
DNA synthesis begins immediately in the original G1 nucleus
70
Tissue culture experiments with PDGF demonstrate that without this substance, __________.
fibroblasts fail to divide
71
You would be ,unlikely to see which of the following human cells dividing?
Nerve cell
72
Which of the following hypotheses is best supported by observing cancer cells in a culture?
The cancer cells do not exhibit density-dependent inhibition.
73
What is the difference between a benign tumor and a malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do.
74
How many genes are present in the human genome?
Tens of thousands
75
What is a locus?
The precise location of a gene on a chromosome
76
Sexual and asexual reproduction are alike in that __________.
they can both occur in multicellular organisms
77
A karyotype is __________.
a photograph of all the chromosomes in a single cell from an individual
78
Fertilization produces __________.
a diploid zygote
79
Which of the following statements is most accurate?
All of the listed responses are correct.
80
Which of the following is part of the life cycle called alternation of generations?
All of the listed responses are correct.
81
The sexual cycle of the diploid, multicellular algal genus Fucus involves __________.
mitosis, meiosis, and fertilization
82
A life cycle in which the only multicellular form is haploid is most typical of __________.
fungi
83
In sexually reproducing species, the chromosome number remains stable over time because __________ and __________ always alternate.
meiosis; fertilization
84
The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?
44
85
In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.
5
86
How many pairs of autosomes do humans have?
22
87
Sister chromatids __________.
are identical copies of each other formed through DNA synthesis
88
Which of the following statements about homologous chromosomes is correct?
They have genes for the same traits at the same loci.
89
When we say that an organism is haploid, we mean that __________.
its cells have a single set of chromosomes
90
Which of the following is a function of mitosis in humans?
Multiplication of body cells
91
Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.
two; diploid
92
Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place __________.
at fertilization, when gametes fuse
93
Spores and gametes are different in that __________.
gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote
94
Humans have 46 chromosomes. This number of chromosomes will be found in __________.
liver cells
95
Which of the following results in cells that contain half the parental chromosome number?
Meiosis
96
At the end of telophase I of meiosis and the first cytokinesis, there are __________.
two haploid cells
97
What is the typical result when a diploid cell has completed meiosis?
Four haploid cells
98
Synapsis occurs during __________.
prophase I
99
Which of the following occurs during anaphase II?
Sister chromatids separate and migrate toward opposite poles.
100
Which of the following occurs during anaphase I?
Homologs separate and migrate toward opposite poles.
101
Cytokinesis is the __________.
division of the cytoplasm to create two cells
102
What is the function of meiosis?
To make cells with a haploid (half that of the parents) number of chromosomes
103
prophase I
104
Regions of chromosomes where nonsister chromatids cross over are called __________.
chiasmata
105
The synaptonemal complex __________.
physically connects homologous chromosomes during prophase I
106
An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis?
4
107
Which event occurs only during prophase I of the first meiotic division?
Synapsis of homologous pairs occurs.
108
Which of the following occurs in meiosis but not mitosis?
Homologous chromosomes separate.
109
Which function makes meiosis lengthier and more complex than mitosis?
All of the listed responses are correct.
110
Ignoring crossover events, how many kinds of gametes can be produced by an organism with a diploid number of 8?
16
111
Which of the following contributes to genetic variation in sexually reproducing species?
Random fertilization, independent assortment, crossing over
112
The diploid number of chromosomes in a certain animal is 8 (2n = 8). How do the four pairs of homologous chromosomes align and separate during meiosis?
They align and assort independently to form any of 16 different combinations.
113
In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal), and the other comes from the mother (maternal). If 2n = 6, what is the probability that a particular gamete will contain only paternal chromosomes?
1/8
114
The major contribution of sex to evolution is that __________.
it provides a method to increase genetic variation
115
Which of the following answers is neither involved with crossing over nor an outcome of crossing over?
Independent assortment results from the random alignment of homologous pairs of chromosomes at metaphase I.
116
Which of the following statements reflects an advantage that sexual reproduction likely provides over asexual reproduction?
Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment.
117
Although __________ is nearly universal among animals, bdelloid rotifers __________.
sexual reproduction; reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers
118
If a plant variety is true-breeding for a dominant trait, then __________.
if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait
119
Assume that there is a gene in apples that determines fruit color and a second gene that determines fruit size. Let A represent the dominant allele for big apples and a represent the recessive allele for small apples. Similarly, let R represent the dominant allele for red apples and r represent the recessive allele for yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents?
AArr and aaRr
120
Assume tall (T) is completely dominant to dwarf (t) in a certain species of plant. If a homozygous dominant individual is crossed with a homozygous dwarf, the offspring will __________.
all be tall
121
The F1 generation differed from the F2 in Mendel's experiments in that __________.
all of the F1 showed the dominant phenotype, but only three-quarters of the F2 did
122
Physically, what are different alleles?
Different alleles are different DNA sequences found at the same locus on homologous chromosomes.
123
In a certain plant, the alleles A, B, and C are completely dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as a plant with the genotype __________.
AaBBcc
124
Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous?
The ratio of tall offspring to short offspring is 1:1.
125
What is indicated when a single-character testcross yields offspring that all have the dominant phenotype?
The parent with the dominant phenotype was homozygous.
126
If an organism that is homozygous dominant is crossed with a heterozygote for that trait, the offspring will be __________.
all of the dominant phenotype
127
In Mendel's monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation had the __________ phenotype because their genotype was __________ at the flower-color locus.
purple-flowered; heterozygous
128
If the two traits that Mendel looked at in his dihybrid cross of smooth yellow peas with wrinkled green peas had been controlled by genes that were located near each other on the same chromosome, then the F2 generation __________.
would have deviated from the 9:3:3:1 phenotypic ratio that is predicted by the law of independent assortment
129
Which of the following properties were present in the characters that Mendel examined in his breeding experiments?
All of the listed responses are correct.
130
The law of independent assortment __________.
The first, second, and third answers are correct.
131
Homologous pairs of chromosomes often __________.
contain different alleles
132
If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce?
10,000
133
Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr × PpRr will have white flowers and wrinkled seeds?
1/16
134
An AABbccDdEeFF individual is crossed with an individual with the genotype AaBBCCDdEeff. What is the probability that their offspring will have the genotype AaBBCcddEEFf?
1/64
135
If a heterozygous plant is allowed to self-pollinate, what proportion of the offspring will also be heterozygous?
1/2
136
An individual with the genotype AABbCcDD can make how many different kinds of gametes?
4
137
A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of genes that are __________.
codominant
138
Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, the progeny plants will be __________.
25% red, 50% pink, and 25% white
139
Which choice below describes the expression of Tay-Sachs disease in humans at the biochemical level?
Incompletely dominant
140
Human blood groups are governed by three alleles: IA, IB, and i. IA and IB are codominant and i is recessive to both. A man who has type B blood and a woman who has type A blood could have children of which of the following phenotypes?
A, B, AB, or O
141
Which of the following matings cannot produce a child with blood type O? The letters refer to blood types (phenotypes).
O × AB
142
A woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood?
50%
143
A single genetic locus that controls more than one trait is said to be __________.
pleiotropic
144
Color in squash is controlled by epistatic interactions in which color is recessive to no color. At the first locus, white squash (W) is dominant to colored squash (w). At the second locus, yellow (Y) is dominant to green (y). What is the phenotype of a squash with the genotype wwYy?
Yellow
145
Tail length in a certain species of armadillo falls along a continuum; a plot of tail length versus frequency displays a normal distribution. Assuming that environmental factors do not play an important role in determining tail length, this type of variation probably reflects __________.
polygenic inheritance
146
Mendel's theory of inheritance __________.
can explain inheritance patterns for virtually every sexually reproducing organism but does not explain multifactorial characters
147
Tay-Sachs disease runs in Rebecca's family. On a family pedigree, she saw a shaded circle. This represented a __________.
female with Tay-Sachs
148
A man has a pointed frontal hairline known as a widow's peak. This trait is thought to be controlled by a dominant allele. His wife lacks a widow's peak, and their son has a widow's peak. (W: widow's peak; w: no widow's peak). The son is curious about whether his father is homozygous or heterozygous for the widow's peak trait. Which of the following facts would allow him to know?
His father's mother lacks a widow's peak.
149
Michelle and Keith are apparently healthy, but their daughter was born with alkaptonuria, an inherited metabolic disorder. If alkaptonuria is like most other human hereditary disorders, the probability of their next child being born with alkaptonuria is __________.
1/4
150
Tom's brother suffers from phenylketonuria (PKU), a recessive disorder. Tom and the brother's parents do not have PKU. What are the chances that Tom is a carrier of the recessive PKU allele?
2/3
151
A couple, both descended from eastern European (Ashkenazic) Jews, visit a genetic counselor before trying to have children. In view of their ethnic background, the counselor recommends that they be tested to see if they are carriers for __________.
Tay-Sachs disease
152
Cystic fibrosis, which is usually lethal before the age of reproduction, is a homozygous recessive trait. Why do cases continue to arise, even though people with the disease rarely live to reproduce?
The harmful allele "hides" within heterozygous individuals, and one-fourth of the offspring of two heterozygotes would be afflicted.
153
The genetic disease cystic fibrosis is caused by a defective allele that __________.
encodes a defective chloride-channel membrane transport protein
154
In people with sickle-cell disease, red blood cells break down, clump, and clog the blood vessels. The blood vessels and the broken cells accumulate in the spleen. These events lead to physical weakness, heart failure, joint pain, and brain damage. Such a suite of symptoms can be explained by __________.
the pleiotropic effects of the sickle-cell allele
155
When two average-height parents give birth to a child exhibiting achondroplasia, it is most likely due to a new mutation. This is because __________.
achondroplasia is caused by an allele that is always expressed; therefore, the parents must not have the allele
156
It is far more common to find human genetic disease caused by __________ alleles than by __________ alleles because __________.
recessive; dominant; harmful recessive alleles can survive in the heterozygote without any selection pressure against them
157
Huntington's disease is an example of a genetic disorder caused by __________.
a lethal dominant allele that afflicts an individual later in life
158
Heart disease, diabetes, cancer, alcoholism, and many mental illnesses can best be described as __________.
multifactorial disorders with a possible polygenic component
159
Fetal cells may be removed along with fluid from the womb by a process known as __________.
amniocentesis
160
In which genetic testing procedure would a physician remove a small tissue sample from a membrane of fetal genetic origin?
Chorionic villus sampling
161
How does codominance at the molecular level help to explain why evolutionary processes haven't resulted in the elimination of the sickle-cell allele among people of African descent?
Individuals with normal and sickle-cell hemoglobin in their red blood cells are usually healthy and, when infected by the malaria parasite, have lower parasite densities and, thus, reduced malaria symptoms.
162
What kind of protection does the Genetic Information Nondiscrimination Act of 2008 provide the public with regard to the use of genetic information?
The law prohibits the use of genetic test information to deny insurance coverage or employment to individuals.
