heredity Flashcards
1
Q
What is genetics?
A
Genetics is that branch of biology concerned with heredity and variation.
2
Q
What are genes?
A
Hereditary units transmitted from one generation to the next.
3
Q
Where do genes reside?
A
In long molecules of deoxyribonucleic acid (DNA).
4
Q
What structures do DNA form when associated with proteins?
A
Chromosomes.
5
Q
What is a mutation?
A
A change in some part of the DNA code.
6
Q
How can mutations occur?
A
Spontaneously or induced by exposure to mutagenic chemicals or radiation.
7
Q
What may be the result of a mutation?
A
A change in the physical appearance of the individual or a change in some measurable attribute (character or trait).
8
Q
What are alleles?
A
Alternative forms of a gene.
9
Q
What is a gene locus?
A
A specific position on a chromosome where a gene occupies.
10
Q
What are homologous chromosomes?
A
Chromosomes that are genetically similar and carry the same genes at corresponding loci.
11
Q
What is the role of DNA in most organisms?
A
Carries the genetic information.
12
Q
What are prokaryotes?
A
Organisms that lack a nucleus, such as bacteria.
13
Q
What are eukaryotes?
A
Organisms characterized by the presence of a nucleus.
14
Q
What is the smallest unit of life?
A
The cell.
15
Q
What is the diploid number of chromosomes?
A
The total number of chromosomes in somatic cells, inherited from both parents.
16
Q
What are haploid cells?
A
Sex cells that contain half the number of chromosome sets found in somatic cells.
17
Q
What is a genome?
A
The genetic information contained in the chromosomes of a particular species.
18
Q
What is chromatin?
A
The complex of DNA and proteins that can be seen inside cells.
19
Q
What is the function of histones?
A
Help organize the long strands of DNA into a structure known as a nucleosome.
20
Q
What are the different types of chromosomes based on centromere position?
A
- Metacentric
- Submetacentric
- Acrocentric
- Telocentric
21
Q
What are sex chromosomes?
A
Morphologically dissimilar chromosomes associated with sex (e.g., X and Y chromosomes).
22
Q
What are autosomes?
A
All chromosomes excluding the sex chromosomes.
23
Q
What is the function of the plasma membrane?
A
Regulates molecular traffic into and out of the cell.
24
Q
What is the nucleus’s role in the cell?
A
Master control of cellular functions via its genetic material (DNA).
25
What is the nucleolus responsible for?
Ribosomal RNA synthesis.
26
What is the main function of mitochondria?
Production of adenosine triphosphate (ATP).
27
What do chloroplasts do?
Site of photosynthesis in plant cells.
28
What is the function of lysosomes?
Aids in intracellular digestion of bacteria and other foreign particles.
29
What is the role of the Golgi body?
Site where sugars, phosphates, or fatty acids are added to certain proteins.
30
What is the function of the cytoskeleton?
Contributes to shape, division, and motility of the cell.
31
What is the main function of lysosomes?
Aids in intracellular digestion of bacteria and other foreign particles; may cause cell destruction if ruptured
32
What is the role of vacuoles in plant cells?
Storage of water and metabolic products (e.g., amino acids, sugars); creates turgor pressure making the cell turgid
33
What do spindle apparatus poles contribute to during cell division?
Form poles of the spindle apparatus during cell divisions
34
What is the function of the cytoskeleton?
Contributes to shape, division, motility of the cell, and the ability to move and arrange its components
35
What are the components involved in building macromolecular biopolymers?
Nucleic acids, proteins, lipids, and large carbohydrates such as starch and cellulose
36
What is the process called that produces somatic cells in multicellular organisms?
Mitosis
37
What occurs during the S phase of interphase?
DNA molecules of each chromosome are replicated, producing an identical pair of DNA molecules called chromatids
38
What are the three phases of interphase?
G1 (gap 1), S (synthesis), and G2 (gap 2)
39
What happens during the G1 phase?
Cells prepare for DNA synthesis (S phase)
40
What are the four major phases of mitosis?
Prophase, metaphase, anaphase, telophase
41
What is the typical duration of mitosis in an idealized animal cell?
1 hour of an 18-24 hour total cell cycle time
42
What are cell cycle checkpoints?
Control points that ensure proper progress is being made before proceeding to the next stage
43
What is the role of cyclin-dependent kinases (CDKs) in the cell cycle?
Control key events of the cell cycle by adding phosphate groups to other proteins
44
What happens during prophase of mitosis?
Chromosomes condense and become thicker, nuclear membrane disappears, spindle fibers form
45
Fill in the blank: The structure that organizes microtubules during prophase is called the _______.
mitotic spindle
46
What occurs during metaphase?
Chromosomes align at the metaphase plate due to the tension from kinetochore fibers
47
What is the process called when sister chromatids separate during mitosis?
Anaphase
48
What occurs during telophase?
Chromatids uncoil, nuclear membrane reforms, and cytoplasm divides (cytokinesis)
49
What is cytokinesis in animal cells?
Formation of a cleavage furrow that deepens and eventually 'pinches' the cell in two
50
What is the primary function of meiosis?
To reduce the chromosome number by half from diploid (2n) to haploid (n)
51
What is gametogenesis?
The production of gametes
52
What are the two divisions involved in meiosis?
Meiosis I (reductional division) and Meiosis II (equational division)
53
What is synapsis in meiosis?
The pairing of homologous chromosomes during prophase I
54
What is crossing over?
The exchange of genetic material between nonsister chromatids during prophase I
55
List the five stages of prophase I in meiosis.
* Leptotene
* Zygotene
* Pachytene
* Diplotene
* Diakinesis
56
What is a bivalent in meiosis?
A pair of homologous chromosomes
57
What is a tetrad?
A structure consisting of four chromatids formed during synapsis
58
What is the outcome of crossing over in meiosis?
It results in genetic recombination between homologous chromosomes
## Footnote
Crossing over is usually inferred from breeding experiments and leads to non-parental type chromatids.
59
What occurs during the diplotene stage of meiosis?
The synaptonemal complex begins to disappear, allowing individual chromatids and chiasmata to be seen
## Footnote
Chiasmata are still visible during this stage.
60
What happens during diakinesis in meiosis?
Chromosomes reach maximal condensation and the nuclear membrane disappears
## Footnote
The spindle apparatus begins to form during this stage.
61
What is the result of telophase I in meiosis?
The nuclear membrane reforms and the chromosome number is reduced from diploid (2n) to haploid (n)
## Footnote
This occurs after the homologous pairs of chromosomes have separated.
62
What is interkinesis?
The period between the first and second meiotic divisions
## Footnote
No DNA synthesis occurs during interkinesis.
63
What distinguishes meiosis II from meiosis I?
Meiosis II is an equational division where sister chromatids separate
## Footnote
Meiosis I is a reductional division separating homologous chromosomes.
64
What genetic condition results from nondisjunction during meiosis?
Trisomy
## Footnote
Most trisomies are lethal; however, trisomy 21 (Down syndrome) is an exception.
65
What are the key differences between mitosis and meiosis?
Mitosis produces 2 identical daughter cells; meiosis produces 4 genetically diverse gametes
## Footnote
Mitosis occurs in somatic cells, while meiosis occurs in specialized germ line cells.
66
What is the principle of segregation?
Only one of the two alleles for a trait is transmitted through a gamete
## Footnote
This principle was established by Gregor Mendel's studies on pea plants.
67
What does the principle of independent assortment state?
The segregation of one gene pair occurs independently of any other gene pair
## Footnote
This applies to unlinked genes on nonhomologous chromosomes.
68
What is gametogenesis?
The process of producing mature gametes or spores
## Footnote
Meiosis is a crucial part of gametogenesis.
69
What is spermatogenesis?
The process of gametogenesis in males, producing sperm cells
## Footnote
It begins in the germinal epithelium of the seminiferous tubules.
70
What is oogenesis?
The process of gametogenesis in females, producing ova
## Footnote
It involves unequal cytokinesis during meiotic divisions.
71
What happens during fertilization?
The sperm and egg unite to reestablish the diploid number in the zygote
## Footnote
The sperm's tail degenerates and does not enter the egg.
72
What is microsporogenesis?
The process of gametogenesis in the male part of flowering plants, resulting in pollen grains
## Footnote
A diploid microspore mother cell undergoes meiosis to form haploid microspores.
73
What is the product of the first karyokinesis in the process described?
A cell containing two identical haploid nuclei.
74
What happens to one of the haploid nuclei during the germination of the pollen tube?
It becomes a generative nucleus and divides again by mitosis without cytokinesis.
75
What does the other nucleus that does not divide become?
The tube nucleus.
76
How many nuclei are present in the mature embryo sac after megasporogenesis?
Eight haploid nuclei.
77
What are the three nuclei that orient themselves near the micropylar end of the embryo sac?
Two synergids and one egg nucleus.
78
What is the fate of the three haploid megaspores produced after meiosis?
Three of the megaspores degenerate.
79
What is the end result of the fertilization process described?
Formation of a diploid zygote and a triploid nucleus.
80
What is the term used for the process involving two sperm nuclei during fertilization?
Double fertilization.
81
What do the two sperm nuclei fuse with during fertilization?
* One fuses with the egg nucleus to form a diploid zygote
* The other fuses with the fusion nucleus to form a triploid nucleus.
82
What is the function of the triploid nucleus formed during fertilization?
It forms a starchy nutritive tissue called endosperm.
83
What are genetic model systems?
Organisms that can be easily grown and manipulated in laboratory settings to explore various genetic and developmental effects.
84
List some examples of genetic model systems.
* Escherichia coli
* Saccharomyces cerevisiae
* Arabidopsis thaliana
* Caenorhabditis elegans
* Drosophila melanogaster
* Mus musculus
85
What is the diploid number of chromosomes in a horse?
64 chromosomes.
86
What is the diploid number of chromosomes in an ass?
62 chromosomes.
87
How many chromosomes does a mule have?
63 chromosomes.
88
Why are mules usually sterile?
The haploid set of chromosomes from the horse and the ass are too dissimilar for meiosis to proceed.
89
What chromosomal type is expected in the embryo from a plant of chromosomal type aa pollinating a plant of type AA?
Aa.
90
What chromosomal type is expected in the endosperm from the same pollination?
AAa.
91
How many different kinds of meiotic products can an individual with three pairs of homologous chromosomes produce?
Eight different chromosomal combinations.
92
What is the formula to calculate the number of possible combinations of meiotic products?
2^n where n is the number of loci.
93
How many chromosomes does a mouse receive from its father?
20 chromosomes.
94
How many autosomes are present in a mouse gamete?
19 autosomes.
95
How many sex chromosomes are there in a mouse ovum?
One sex chromosome.
96
How many autosomes are present in somatic cells of a female mouse?
38 autosomes.
97
What corresponds to the three megaspores that degenerate following meiosis in plants?
Animal polar bodies.
98
What plant cell corresponds functionally to the primary spermatocyte?
Megasporocyte.
99
What is the probability of a sperm cell containing only replicas of the centromeres received from the mother?
1/8.
100
How many chromosomes are found in a secondary spermatocyte of humans?
23 chromosomes.
101
How many chromosomes are found in a spermatid of humans?
23 chromosomes.
102
How many chromosomes are found in a spermatozoan of humans?
23 chromosomes.
103
How many chromosomes are found in a spermatogonium of humans?
46 chromosomes.
104
How many chromosomes are found in a primary spermatocyte of humans?
46 chromosomes.
105
How many egg cells are produced by an oogonium?
One egg cell.
106
How many egg cells are produced by a primary oocyte?
One egg cell.
107
How many egg cells are produced by an ootid?
One egg cell.
108
How many chromosomes are produced by a polar body?
23 chromosomes.
109
How many chromosomes would be expected in a meiotic product of corn?
10 chromosomes.
110
What is the chromosomal number for a polar nucleus in corn?
10 chromosomes.
111
How many chromosomes are in a sperm nucleus of corn?
10 chromosomes.
112
What is the chromosomal number for a microspore mother cell in corn?
20 chromosomes.
113
What is the chromosomal number for a leaf cell in corn?
20 chromosomes.
114
How many chromosomes are in a mature embryo sac after degeneration of nonfunctional nuclei?
8 chromosomes.
115
What is the chromosomal number for an egg nucleus in corn?
10 chromosomes.
116
How many chromosomes are in an endosperm cell of corn?
30 chromosomes.
117
How many chromosomes are in a cell of the embryo in corn?
20 chromosomes.
118
How many chromosomes are in a cell of the pericarp in corn?
20 chromosomes.
119
How many chromosomes are in an aleurone cell of corn?
20 chromosomes.
120
What is the term for any chromosome other than a sex chromosome?
autosome
121
What is the site on a chromosome to which spindle fibers attach called?
centromere or kinetochore
122
What adjective describes a chromosome with arms of about equal length?
metacentric
123
What adjective refers to the number of chromosomes in a gamete?
haploid
124
What is the specialized cell division process consisting of a reductional and an equational division?
meiosis
125
What is the term for the division of the cytoplasm?
cytokinesis
126
What is the first phase of mitosis?
prophase
127
What is the cytological structure on paired chromosomes with which genetic exchange (crossing over) is correlated?
chiasma or recombination nodule
128
What are chromosomes that contain enough similar genetic material to pair in meiosis called?
homologues
129
What is the period between mitotic division cycles known as?
interphase
130
Which organelle is involved in major ATP synthesis?
Mitochondria
131
Which organelle establishes the polar region?
Centrioles
132
What is the site of protein synthesis in the cell?
Ribosome
133
Where are genes located in a cell?
Nucleus
134
What organelle contains linear chromosomes?
Chromosome
135
What is the RNA-rich region in the nucleus called?
Nucleolus
136
What organelle is involved in protein modification and subcellular localization?
Golgi body
137
What is the function of the vacuole in a cell?
Storage of excess water and other metabolic products
138
Fill in the blank: During meiosis, synapsis occurs in the __________ phase.
prophase
139
True or False: A centriole is present in plant cells.
False
140
How many autosomes would be expected in a kidney cell?
44
141
A locus is best defined as __________.
the position of a gene on a chromosome
142
The different forms of a gene are called __________.
alleles
143
Which of the following cells is normally diploid? (a) primary polar body (b) spermatid (c) primary spermato- cyte (d) spermatozoan (e) secondary polar body
primary spermato- cyte
144
Upon which two major features of chromosomes does their cytological identification depend?
length of chromosome and position of centromere
145
In oogenesis, the cell that corresponds to a spermatid is called a __________.
secondary polar body
146
What is the significance of sex in organisms?
It provides genetic variability essential for natural selection.
147
What term is used for an organism with both male and female reproductive organs?
Hermaphrodite.
148
What is a monoecious plant?
A plant that has both staminate (male) and pistillate (female) flowers on the same individual.
149
What is the term for plants that have male and female elements in separate individuals?
Dioecious.
150
What is the sex ratio?
The proportion of males to females in a population.
151
What are the two types of sex chromosomes in most mammals?
X and Y chromosomes.
152
In mammals, what determines maleness?
The presence of the Y chromosome.
153
What is the XY method of sex determination?
A system where males are heterogametic (XY) and females are homogametic (XX).
154
What gene is responsible for male sex determination in humans?
SRY (sex-determining region Y).
155
What does the XO method of sex determination involve?
Males have a single X chromosome (X0), and females have two X chromosomes (XX).
156
In the ZW method of sex determination, which sex is heterogametic?
Females (ZW).
157
What determines sex in Drosophila?
The ratio of X chromosomes to haploid sets of autosomes.
158
What is the X:A ratio for a normal female in Drosophila?
2X:2A, or 1.0.
159
What happens when the X:A ratio is above 1.0 in Drosophila?
It produces sterile metafemales.
160
What is haplodiploidy?
A sex determination system where males are haploid and females are diploid.
161
What determines whether a female bee becomes a worker or a queen?
The quantity and quality of food available to the diploid larva.
162
What is complementary sex determination (CSD)?
A mechanism where males develop from homozygous alleles at a single-gene locus.
163
In microorganisms, what controls sex?
A single gene at the mating-type locus.
164
What are isogametes?
Morphologically indistinguishable gametes from haploid individuals.
165
What happens when haploid cells with opposite alleles fuse?
They form a diploid zygote.
166
Fill in the blank: In the XO method of sex determination, males are _______ and females are _______.
X0; XX.
167
True or False: In the ZW method of sex determination, males are heterogametic.
False.
168
What is a zygote?
A diploid nonmotile cell formed by the fusion of two haploid cells
## Footnote
Zygotes are resistant to unfavorable growth conditions.
169
What are zoo-spores?
Motile haploid daughter cells formed by the meiosis of a zygote
## Footnote
Two zoo-spores are of plus mating type and two are of minus mating type.
170
What does it mean for a gene to be sex-linked?
A gene located on the X chromosome or the Z chromosome in birds
## Footnote
The first sex-linked gene discovered was the recessive white-eye mutation in Drosophila.
171
What are reciprocal crosses?
Mating a male of one phenotype with a female of another phenotype and reversing the sexes in a second cross
## Footnote
Example: black fur coat male crossed with white fur coat female, then white male with black female.
172
What is hemizygous?
A condition where males carry only one allele for sex-linked traits
## Footnote
This contrasts with homozygous or heterozygous conditions in females.
173
What is the expected phenotypic ratio in the F₂ generation if F₁ individuals mate among themselves?
1 red: 1 white phenotypic ratio in males
## Footnote
All F₂ females are phenotypically wild type.
174
What is a characteristic of sex-linked recessive traits?
They are usually more frequent in males than in females
## Footnote
These traits fail to appear in females unless they also appear in the paternal parent.
175
What is a characteristic of sex-linked dominant traits?
They are found more frequently in females than in males
## Footnote
All female offspring of a male showing the trait will express it.
176
What are completely sex-linked genes?
Genes on the nonhomologous segment of the X chromosome that exhibit unique inheritance patterns
## Footnote
These genes are expressed only in males and transmitted from father to son.
177
What are holandric genes?
Completely Y-linked genes expressed only in males
## Footnote
These genes reside in the nonrecombining region of the Y chromosome.
178
What are sex-influenced traits?
Traits whose expression is affected by the sex of the individual
## Footnote
The dominance or recessiveness of alleles can differ between males and females.
179
Provide an example of a sex-influenced trait.
Pattern baldness in humans
## Footnote
Dominance in men but acts recessively in women.
180
What are sex-limited traits?
Traits that come to expression in only one sex
## Footnote
Example: milk production genes in bulls, which are not expressed in males.
181
What happens during sex reversal in chickens?
Female chickens can develop male characteristics and even testes
## Footnote
This can occur due to disease destroying ovarian tissue.
182
What is dioecism in plants?
A condition where some flowering plants have separate male and female individuals
## Footnote
The Y chromosome can determine maleness in some plant species.
183
What is self-fertilization in plants?
The ability of gametes produced by the same individual to unite and produce viable offspring
## Footnote
Common in many flowering plants, but some have mechanisms to prevent it.
184
What is the expected sex ratio from a cross involving a recessive gene tra in Drosophila?
3 males: 1 female in the F₁ generation
## Footnote
Transformed males are sterile and do not contribute to the F₂ generation.
185
What is the expected outcome of a cross between a homozygous barred male and a nonbarred female chicken?
All offspring will exhibit the barred trait
## Footnote
The trait is sex-linked and will be expressed in the offspring.
186
What is the genotype of a hemophilic male?
hY
## Footnote
The hemophilic allele is recessive and located on the X chromosome.
187
If a carrier female marries a normal male, what is the chance of their first child being a hemophilic boy?
1/8
## Footnote
The chance combines the probability of being a carrier (1/2) and the probability of producing a hemophilic boy (1/4).
188
What is the probability that a carrier female's second child, after having one hemophilic child, will also be a hemophilic boy?
1/4
## Footnote
The first child being hemophilic confirms the mother is a carrier.
189
If II3 marries a hemophilic man, what is the probability that their first child will be normal?
3/4
## Footnote
II3 has a 50% chance of being a carrier, and any child has a 50% chance of being normal.
190
What phenotype must the father of a hemophilic daughter (hh) possess?
Normal (HY)
## Footnote
The father must have at least one dominant normal allele to produce a normal daughter.
191
What is the expected phenotypic ratio in the F₂ generation when bobbed females are crossed with heterozygous males?
1/2 bobbed females, 1/2 wild-type females, 1/2 bobbed males, 1/2 wild-type males
## Footnote
This assumes an incompletely sex-linked gene interaction.
192
In the context of sex-influenced traits, what is the phenotype of a heterozygous bald man with a long index finger?
Bald, long-fingered
## Footnote
Baldness is dominant in men, while the index finger length is not influenced by the same dominance.
193
What are the genotypes of the three parental females producing 15 hen-feathered males, 18 hen-feathered females, and 3 cock-feathered males?
2 HH, 1 Hh
## Footnote
This combination produces the observed ratio of hen-feathered to cock-feathered males.
194
What are the expected phenotypic proportions in the F₂ generation when a barred female is crossed with a nonbarred female?
3 barred males, 2 females (half barred, half nonbarred)
## Footnote
This reflects the sex-linked inheritance in the ZW system.
195
What does the recessive gene 'tassel-seed' (ts) produce when homozygous?
Only seeds where the tassel normally appears
## Footnote
It results in functional reduction to a single sex, female.
196
Fill in the blank: The hemophilia gene is ______.
recessive sex-linked
## Footnote
This gene influences blood clotting and is carried on the X chromosome.
197
True or False: A cock-feathered male can be produced from a cross of two hen-feathered females.
False
## Footnote
Hen-feathered females can only produce hen-feathered males.
198
What is the genotype of corn plants that produce only seeds where the tassel normally appears?
ts/ts
## Footnote
The gene is called 'tassel-seed' (ts) and is recessive.
199
What is the effect of the recessive gene 'silkless' (sk) when homozygous in corn?
Produces ears with no pistils (silks)
## Footnote
Without silks, these ears cannot produce seeds.
200
What is the expected sex ratio in the F₁ and F₂ generations from the cross ts/ts, sk+/sk+ (female) × ts+/ts+, sk/sk (male)?
1 male:1 female
## Footnote
Subsequent generations will continue to exhibit a 1:1 sex ratio.
201
True or False: The recessive gene for tassel-seed is epistatic to the silkless locus.
True
## Footnote
This means that the presence of the tassel-seed gene affects the expression of the silkless gene.
202
In the context of self-incompatibility in plants, what happens to pollen tubes containing the same self-incompatibility allele?
They grow slowly and cannot fertilize before the flower withers
## Footnote
This prevents fertilization in self-compatible plants.
203
What are the possible genotypes for the six varieties of plants with four self-sterility alleles?
S's³, s's, S's², s²s, S²s, ss
## Footnote
None can be homozygous for self-incompatibility alleles.
204
Fill in the blank: A sex-linked recessive gene c produces ______ in humans.
red-green color blindness
## Footnote
This condition is inherited in a specific manner due to its linkage to sex chromosomes.
205
What is the expected percentage of color-blind girls produced by a normal woman whose father was color-blind and a color-blind man?
0%
## Footnote
Color-blindness is a recessive trait linked to the X chromosome.
206
How many chromosomes do grasshoppers have according to the XO method?
23 chromosomes
## Footnote
This number indicates the diploid state for the grasshopper.
207
In chickens, what color is associated with the dominant sex-linked gene S?
Silver-colored plumage
## Footnote
The recessive allele s produces gold-colored plumage.
208
What happens to the progeny of a barred creeper female and a non-barred creeper male?
Progeny will display both barred and non-barred plumage
## Footnote
The exact ratios depend on the specific genotypes of the parents.
209
What is the sex index in Drosophila for diploid males?
0.5
## Footnote
This is calculated as the ratio of X chromosomes to autosome sets.
210
What results from a cross between heterozygous females and yellow-green males in Melandrium?
Predicted phenotypic ratio in the progeny
## Footnote
This is influenced by the lethality of the sex-linked gene when homozygous in females.
211
Fill in the blank: The homozygous dominant genotype CC in chickens is ______.
lethal
## Footnote
This means that individuals with this genotype do not survive.
212
What sex index values give rise to intersexes?
Values between 0.5 and 1.0
## Footnote
Values over 1.0 or under 0.5 produce weak and inviable flies called 'superfemales' (metafemales) and 'supermales' (metamales), respectively.
213
What is the diploid number of chromosomes in honey bees?
16
214
How many chromosomes are found in the somatic cells of a drone (male) honey bee?
8
215
How many bivalents are seen during gametogenesis in male honey bees?
4
216
How many bivalents are seen during gametogenesis in female honey bees?
8
217
What are the seven eye colors known in honey bees produced by recessive genes?
* brick (bk)
* chartreuse (ch)
* ivory
* cream (cr)
* snow (S)
* pearl (pe)
* garnet (g)
218
What percentage of drone offspring is expected to be brick-eyed when a heterozygous queen is inseminated by mutant drones?
12.5%
219
What percentage of worker offspring is expected to be brick-eyed?
25%
220
In Chlamydomonas, how many mating types are there?
Two: (+) and (-)
221
Does the fusion of (+) and (-) gametes in Chlamydomonas produce a diploid zygote?
Yes
222
Is there a morphological distinction between the (+) and (-) sexes in Chlamydomonas?
No
223
What is a recessive gene called in wasps that assort independently of sex alleles?
veinless (v)
224
What is the expected phenotypic ratio of progeny when crossing two heterozygous veinless wasps?
1 haploid male: 1 diploid male: 2 females
225
What is the trait of 'porcupine man' likely to be?
A sex-limited trait
226
Could a recessive mutant gene in humans be located on the X chromosome if a woman exhibiting the recessive trait and a normal man had a normal son?
No
227
What is a holandric gene?
A gene located on the Y chromosome
228
What percentage of sons would be expected to have hairy ears if their father has the trait?
100%
229
What proportion of daughters is expected to show the trait if the father has hairy ears?
0%
230
What is the expected genetic ratio of hairy-eared to normal children from a hairy-eared father?
1:1
231
What does the white forelock in humans represent?
A sex-influenced gene
232
What kind of genetic dominance does the presence of horns in sheep exhibit?
Dominance in males, recessiveness in females
233
What is the expected phenotypic ratio in the F1 generation from a cross between horned and polled sheep?
1 horned: 1 polled
234
What is the expected phenotypic ratio in the F2 generation from the same cross?
3 horned: 1 polled
235
What is the sex-linked gene that governs the barred plumage pattern in chickens?
B
236
What is the expected phenotype of progeny from a cross between a barred hen-feathered male and a non-barred hen-feathered female?
All progeny will be hen-feathered
237
What is the expected sex ratio among seedlings grown early in the year from crosses between XY males and XY females?
1:1
238
What type of flower is produced by the recessive genotype nn in castor bean plants?
Completely pistillate (female) flower
239
What is the expected sex ratio among the F1 generation from selfing an exceptional staminate-seed plant of genotype Pp?
1:1
240
What kind of mating gives a 1:1 sex ratio in asparagus plants?
Pp x pp
241
What is the expected phenotypic result from crossing homozygous broad-leaf pollen with narrow-leaf seed parents?
All broad-leaf offspring
242
In the clover butterfly, what are the expected phenotypic proportions from the cross Yy x Yy?
3 yellow: 1 white
243
What is a form of reproduction involving the union of haploid gametes to form a diploid zygote?
Fertilization
244
What is an animal that has both male and female reproductive organs called?
Hermaphrodite
245
What is a flower having female but no male reproductive parts called?
Pistillate flower
246
What adjective is applicable to the sex that produces gametes bearing structurally different sex chromosomes?
Heterogametic
247
What are the two symbols that represent the sex chromosomes of female chickens?
Z and W
248
What is the mode of sex determination for Drosophila?
Genic balance
249
What is the mode of sex determination for bees?
Haplodiploidy
250
What adjective is applied to genes on the differential segment of the Y chromosome?
Holandric
251
What class of traits is governed by autosomal alleles whose dominance relationships are reversed in the two sexes?
Sex-influenced traits
252
What class of autosomal traits has phenotypic variability in a population in only one sex?
Sex-limited traits
253
In an animal with the XO method of sex determination, which of the following could be the normal number of chromosomes in its somatic cells?
26 in males
254
If a pink-eyed queen mates with a brown-eyed drone in bees, what would their offspring most likely be?
Wild-type workers and pink-eyed drones
255
In a guinea pig pedigree involving sex-linked inheritance, can III1 exhibit the dominant trait?
Yes
256
What is the fraction of the F1 expected to be polled when mated between polled males and horned females?
1/2
257
In the clover butterfly, what is expected in the F1 generation from matings between heterozygotes?
3/4 yellow: 1/4 white
258
What is expected among adult progeny when a long-tailed male undergoes primary sex reversal and is mated to a short-tailed male?
2/3 of males long-tailed
259
Fill in the blank: A pair of codominant sex-linked alleles in a mammal produce red pigment when homozygous or hemizygous for A1, colorless when homozygous or hemizygous for A2, and _______ when heterozygous.
pink
260
How much of the pollen is compatible in the crosses involving self-incompatibility?
Varies by cross; specific ratios depend on alleles
261
What genotype do all thrum plants possess in the genus Primula?
S/S or S/s
262
What is the expected genotypic ratio if both pin and thrum are heterozygous for an independently segregating allelic pair Aa?
1:2:1
263
In a cross between two self-sterile plants, S's²x Ss, if all F1 progeny are pollinated by plants of genotype S's, what genotypic proportions are expected in the F2?
1 S's: 1 Ss
264
What percentage of haploid males are wild type veinless?
0%
## Footnote
Reflects the genetic distribution in the given population.
265
Can a sex chromosome mechanism operate without a morphological difference in the chromosomes, gametes, or spores?
Yes
## Footnote
Indicates that sex determination can occur through genetic mechanisms even without observable differences.
266
What is the genotype for males if 'w' is dominant in men?
WW, Ww, W'w'
## Footnote
Represents the possible genotypes based on inheritance patterns.
267
In a cross of horned males and polled females, what would be the phenotype ratio for males?
3/4 horned : 1/4 polled
## Footnote
Illustrates the expected outcome of phenotypic ratios in offspring.
268
What is the expected phenotype ratio for females in the same cross?
1/4 horned : 3/4 polled
## Footnote
Shows the phenotypic ratios for female offspring based on genetic inheritance.
269
True or False: All males are short and all females are long in a certain genetic cross.
True
## Footnote
Indicates a complete dominance scenario for the trait in question.
270
In a genetic cross, what does a holandric gene refer to?
Y-linked
## Footnote
Refers to genes located on the Y chromosome, typically expressed in males.
271
What is the expected ratio of yellow to white in a certain phenotype?
5/8 yellow: 3/8 white
## Footnote
Reflects the phenotypic ratios based on genetic inheritance patterns.
272
Fill in the blank: A gene that is dominant in males and recessive in females is referred to as a _______ gene.
sex-influenced
## Footnote
Describes a type of inheritance where the phenotype expression differs by sex.
273
What is the expected ratio of staminate to pistillate flowers in a certain genetic cross?
3/4 staminate: 1/4 pistillate
## Footnote
Illustrates the distribution of flower types based on genetic inheritance.
274
What does 'haplodiploidy' refer to?
A form of sexual reproduction
## Footnote
Involves different ploidy levels for males and females, common in some insects.
275
What is the phenotype ratio for bald males with normal vision?
1/8 daughters, 3/8 sons
## Footnote
Indicates the distribution of phenotypes among offspring based on genetic traits.
276
What does the term 'genic balance' refer to?
A genetic concept related to sex determination
## Footnote
It describes how the ratio of sex chromosomes to autosomes influences sexual development.
277
What percentage of the progeny would be expected to be nonbald and color blind?
3/8
## Footnote
This reflects the outcome based on the genetic crosses analyzed.
278
What is the expected male to female ratio in a specific genetic cross?
2 males: 1 female
## Footnote
Represents the expected offspring ratio based on inheritance patterns.
279
What are the genotypes for females if 'w' is dominant in men?
w'w, ww'
## Footnote
Indicates the possible combinations for female offspring based on male genotypes.
280
True or False: All progeny from a specific genetic cross will exhibit the same phenotype.
False
## Footnote
Different combinations of alleles can lead to various phenotypes.
