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heredity Flashcards

1
Q

What is genetics?

A

Genetics is that branch of biology concerned with heredity and variation.

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2
Q

What are genes?

A

Hereditary units transmitted from one generation to the next.

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3
Q

Where do genes reside?

A

In long molecules of deoxyribonucleic acid (DNA).

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4
Q

What structures do DNA form when associated with proteins?

A

Chromosomes.

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5
Q

What is a mutation?

A

A change in some part of the DNA code.

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6
Q

How can mutations occur?

A

Spontaneously or induced by exposure to mutagenic chemicals or radiation.

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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).

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8
Q

What are alleles?

A

Alternative forms of a gene.

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9
Q

What is a gene locus?

A

A specific position on a chromosome where a gene occupies.

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10
Q

What are homologous chromosomes?

A

Chromosomes that are genetically similar and carry the same genes at corresponding loci.

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11
Q

What is the role of DNA in most organisms?

A

Carries the genetic information.

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12
Q

What are prokaryotes?

A

Organisms that lack a nucleus, such as bacteria.

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13
Q

What are eukaryotes?

A

Organisms characterized by the presence of a nucleus.

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14
Q

What is the smallest unit of life?

A

The cell.

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15
Q

What is the diploid number of chromosomes?

A

The total number of chromosomes in somatic cells, inherited from both parents.

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16
Q

What are haploid cells?

A

Sex cells that contain half the number of chromosome sets found in somatic cells.

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17
Q

What is a genome?

A

The genetic information contained in the chromosomes of a particular species.

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18
Q

What is chromatin?

A

The complex of DNA and proteins that can be seen inside cells.

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19
Q

What is the function of histones?

A

Help organize the long strands of DNA into a structure known as a nucleosome.

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20
Q

What are the different types of chromosomes based on centromere position?

A
  • Metacentric
  • Submetacentric
  • Acrocentric
  • Telocentric
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21
Q

What are sex chromosomes?

A

Morphologically dissimilar chromosomes associated with sex (e.g., X and Y chromosomes).

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22
Q

What are autosomes?

A

All chromosomes excluding the sex chromosomes.

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23
Q

What is the function of the plasma membrane?

A

Regulates molecular traffic into and out of the cell.

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24
Q

What is the nucleus’s role in the cell?

A

Master control of cellular functions via its genetic material (DNA).

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25
Q

What is the nucleolus responsible for?

A

Ribosomal RNA synthesis.

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26
Q

What is the main function of mitochondria?

A

Production of adenosine triphosphate (ATP).

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27
Q

What do chloroplasts do?

A

Site of photosynthesis in plant cells.

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28
Q

What is the function of lysosomes?

A

Aids in intracellular digestion of bacteria and other foreign particles.

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29
Q

What is the role of the Golgi body?

A

Site where sugars, phosphates, or fatty acids are added to certain proteins.

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30
Q

What is the function of the cytoskeleton?

A

Contributes to shape, division, and motility of the cell.

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31
Q

What is the main function of lysosomes?

A

Aids in intracellular digestion of bacteria and other foreign particles; may cause cell destruction if ruptured

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32
Q

What is the role of vacuoles in plant cells?

A

Storage of water and metabolic products (e.g., amino acids, sugars); creates turgor pressure making the cell turgid

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33
Q

What do spindle apparatus poles contribute to during cell division?

A

Form poles of the spindle apparatus during cell divisions

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34
Q

What is the function of the cytoskeleton?

A

Contributes to shape, division, motility of the cell, and the ability to move and arrange its components

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35
Q

What are the components involved in building macromolecular biopolymers?

A

Nucleic acids, proteins, lipids, and large carbohydrates such as starch and cellulose

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36
Q

What is the process called that produces somatic cells in multicellular organisms?

A

Mitosis

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37
Q

What occurs during the S phase of interphase?

A

DNA molecules of each chromosome are replicated, producing an identical pair of DNA molecules called chromatids

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38
Q

What are the three phases of interphase?

A

G1 (gap 1), S (synthesis), and G2 (gap 2)

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39
Q

What happens during the G1 phase?

A

Cells prepare for DNA synthesis (S phase)

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40
Q

What are the four major phases of mitosis?

A

Prophase, metaphase, anaphase, telophase

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41
Q

What is the typical duration of mitosis in an idealized animal cell?

A

1 hour of an 18-24 hour total cell cycle time

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42
Q

What are cell cycle checkpoints?

A

Control points that ensure proper progress is being made before proceeding to the next stage

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43
Q

What is the role of cyclin-dependent kinases (CDKs) in the cell cycle?

A

Control key events of the cell cycle by adding phosphate groups to other proteins

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44
Q

What happens during prophase of mitosis?

A

Chromosomes condense and become thicker, nuclear membrane disappears, spindle fibers form

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45
Q

Fill in the blank: The structure that organizes microtubules during prophase is called the _______.

A

mitotic spindle

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46
Q

What occurs during metaphase?

A

Chromosomes align at the metaphase plate due to the tension from kinetochore fibers

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47
Q

What is the process called when sister chromatids separate during mitosis?

A

Anaphase

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48
Q

What occurs during telophase?

A

Chromatids uncoil, nuclear membrane reforms, and cytoplasm divides (cytokinesis)

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49
Q

What is cytokinesis in animal cells?

A

Formation of a cleavage furrow that deepens and eventually ‘pinches’ the cell in two

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50
Q

What is the primary function of meiosis?

A

To reduce the chromosome number by half from diploid (2n) to haploid (n)

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51
Q

What is gametogenesis?

A

The production of gametes

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52
Q

What are the two divisions involved in meiosis?

A

Meiosis I (reductional division) and Meiosis II (equational division)

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53
Q

What is synapsis in meiosis?

A

The pairing of homologous chromosomes during prophase I

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54
Q

What is crossing over?

A

The exchange of genetic material between nonsister chromatids during prophase I

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55
Q

List the five stages of prophase I in meiosis.

A
  • Leptotene
  • Zygotene
  • Pachytene
  • Diplotene
  • Diakinesis
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56
Q

What is a bivalent in meiosis?

A

A pair of homologous chromosomes

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57
Q

What is a tetrad?

A

A structure consisting of four chromatids formed during synapsis

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58
Q

What is the outcome of crossing over in meiosis?

A

It results in genetic recombination between homologous chromosomes

Crossing over is usually inferred from breeding experiments and leads to non-parental type chromatids.

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59
Q

What occurs during the diplotene stage of meiosis?

A

The synaptonemal complex begins to disappear, allowing individual chromatids and chiasmata to be seen

Chiasmata are still visible during this stage.

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60
Q

What happens during diakinesis in meiosis?

A

Chromosomes reach maximal condensation and the nuclear membrane disappears

The spindle apparatus begins to form during this stage.

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61
Q

What is the result of telophase I in meiosis?

A

The nuclear membrane reforms and the chromosome number is reduced from diploid (2n) to haploid (n)

This occurs after the homologous pairs of chromosomes have separated.

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62
Q

What is interkinesis?

A

The period between the first and second meiotic divisions

No DNA synthesis occurs during interkinesis.

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63
Q

What distinguishes meiosis II from meiosis I?

A

Meiosis II is an equational division where sister chromatids separate

Meiosis I is a reductional division separating homologous chromosomes.

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64
Q

What genetic condition results from nondisjunction during meiosis?

A

Trisomy

Most trisomies are lethal; however, trisomy 21 (Down syndrome) is an exception.

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65
Q

What are the key differences between mitosis and meiosis?

A

Mitosis produces 2 identical daughter cells; meiosis produces 4 genetically diverse gametes

Mitosis occurs in somatic cells, while meiosis occurs in specialized germ line cells.

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66
Q

What is the principle of segregation?

A

Only one of the two alleles for a trait is transmitted through a gamete

This principle was established by Gregor Mendel’s studies on pea plants.

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67
Q

What does the principle of independent assortment state?

A

The segregation of one gene pair occurs independently of any other gene pair

This applies to unlinked genes on nonhomologous chromosomes.

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68
Q

What is gametogenesis?

A

The process of producing mature gametes or spores

Meiosis is a crucial part of gametogenesis.

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69
Q

What is spermatogenesis?

A

The process of gametogenesis in males, producing sperm cells

It begins in the germinal epithelium of the seminiferous tubules.

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70
Q

What is oogenesis?

A

The process of gametogenesis in females, producing ova

It involves unequal cytokinesis during meiotic divisions.

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71
Q

What happens during fertilization?

A

The sperm and egg unite to reestablish the diploid number in the zygote

The sperm’s tail degenerates and does not enter the egg.

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72
Q

What is microsporogenesis?

A

The process of gametogenesis in the male part of flowering plants, resulting in pollen grains

A diploid microspore mother cell undergoes meiosis to form haploid microspores.

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73
Q

What is the product of the first karyokinesis in the process described?

A

A cell containing two identical haploid nuclei.

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74
Q

What happens to one of the haploid nuclei during the germination of the pollen tube?

A

It becomes a generative nucleus and divides again by mitosis without cytokinesis.

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75
Q

What does the other nucleus that does not divide become?

A

The tube nucleus.

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76
Q

How many nuclei are present in the mature embryo sac after megasporogenesis?

A

Eight haploid nuclei.

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77
Q

What are the three nuclei that orient themselves near the micropylar end of the embryo sac?

A

Two synergids and one egg nucleus.

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78
Q

What is the fate of the three haploid megaspores produced after meiosis?

A

Three of the megaspores degenerate.

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79
Q

What is the end result of the fertilization process described?

A

Formation of a diploid zygote and a triploid nucleus.

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80
Q

What is the term used for the process involving two sperm nuclei during fertilization?

A

Double fertilization.

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81
Q

What do the two sperm nuclei fuse with during fertilization?

A
  • One fuses with the egg nucleus to form a diploid zygote
  • The other fuses with the fusion nucleus to form a triploid nucleus.
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82
Q

What is the function of the triploid nucleus formed during fertilization?

A

It forms a starchy nutritive tissue called endosperm.

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83
Q

What are genetic model systems?

A

Organisms that can be easily grown and manipulated in laboratory settings to explore various genetic and developmental effects.

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84
Q

List some examples of genetic model systems.

A
  • Escherichia coli
  • Saccharomyces cerevisiae
  • Arabidopsis thaliana
  • Caenorhabditis elegans
  • Drosophila melanogaster
  • Mus musculus
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85
Q

What is the diploid number of chromosomes in a horse?

A

64 chromosomes.

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86
Q

What is the diploid number of chromosomes in an ass?

A

62 chromosomes.

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87
Q

How many chromosomes does a mule have?

A

63 chromosomes.

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88
Q

Why are mules usually sterile?

A

The haploid set of chromosomes from the horse and the ass are too dissimilar for meiosis to proceed.

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89
Q

What chromosomal type is expected in the embryo from a plant of chromosomal type aa pollinating a plant of type AA?

A

Aa.

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90
Q

What chromosomal type is expected in the endosperm from the same pollination?

A

AAa.

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91
Q

How many different kinds of meiotic products can an individual with three pairs of homologous chromosomes produce?

A

Eight different chromosomal combinations.

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92
Q

What is the formula to calculate the number of possible combinations of meiotic products?

A

2^n where n is the number of loci.

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93
Q

How many chromosomes does a mouse receive from its father?

A

20 chromosomes.

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94
Q

How many autosomes are present in a mouse gamete?

A

19 autosomes.

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95
Q

How many sex chromosomes are there in a mouse ovum?

A

One sex chromosome.

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96
Q

How many autosomes are present in somatic cells of a female mouse?

A

38 autosomes.

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97
Q

What corresponds to the three megaspores that degenerate following meiosis in plants?

A

Animal polar bodies.

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98
Q

What plant cell corresponds functionally to the primary spermatocyte?

A

Megasporocyte.

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99
Q

What is the probability of a sperm cell containing only replicas of the centromeres received from the mother?

A

1/8.

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100
Q

How many chromosomes are found in a secondary spermatocyte of humans?

A

23 chromosomes.

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101
Q

How many chromosomes are found in a spermatid of humans?

A

23 chromosomes.

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102
Q

How many chromosomes are found in a spermatozoan of humans?

A

23 chromosomes.

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103
Q

How many chromosomes are found in a spermatogonium of humans?

A

46 chromosomes.

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104
Q

How many chromosomes are found in a primary spermatocyte of humans?

A

46 chromosomes.

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105
Q

How many egg cells are produced by an oogonium?

A

One egg cell.

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106
Q

How many egg cells are produced by a primary oocyte?

A

One egg cell.

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107
Q

How many egg cells are produced by an ootid?

A

One egg cell.

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108
Q

How many chromosomes are produced by a polar body?

A

23 chromosomes.

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109
Q

How many chromosomes would be expected in a meiotic product of corn?

A

10 chromosomes.

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110
Q

What is the chromosomal number for a polar nucleus in corn?

A

10 chromosomes.

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111
Q

How many chromosomes are in a sperm nucleus of corn?

A

10 chromosomes.

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112
Q

What is the chromosomal number for a microspore mother cell in corn?

A

20 chromosomes.

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113
Q

What is the chromosomal number for a leaf cell in corn?

A

20 chromosomes.

114
Q

How many chromosomes are in a mature embryo sac after degeneration of nonfunctional nuclei?

A

8 chromosomes.

115
Q

What is the chromosomal number for an egg nucleus in corn?

A

10 chromosomes.

116
Q

How many chromosomes are in an endosperm cell of corn?

A

30 chromosomes.

117
Q

How many chromosomes are in a cell of the embryo in corn?

A

20 chromosomes.

118
Q

How many chromosomes are in a cell of the pericarp in corn?

A

20 chromosomes.

119
Q

How many chromosomes are in an aleurone cell of corn?

A

20 chromosomes.

120
Q

What is the term for any chromosome other than a sex chromosome?

121
Q

What is the site on a chromosome to which spindle fibers attach called?

A

centromere or kinetochore

122
Q

What adjective describes a chromosome with arms of about equal length?

A

metacentric

123
Q

What adjective refers to the number of chromosomes in a gamete?

124
Q

What is the specialized cell division process consisting of a reductional and an equational division?

125
Q

What is the term for the division of the cytoplasm?

A

cytokinesis

126
Q

What is the first phase of mitosis?

127
Q

What is the cytological structure on paired chromosomes with which genetic exchange (crossing over) is correlated?

A

chiasma or recombination nodule

128
Q

What are chromosomes that contain enough similar genetic material to pair in meiosis called?

A

homologues

129
Q

What is the period between mitotic division cycles known as?

A

interphase

130
Q

Which organelle is involved in major ATP synthesis?

A

Mitochondria

131
Q

Which organelle establishes the polar region?

A

Centrioles

132
Q

What is the site of protein synthesis in the cell?

133
Q

Where are genes located in a cell?

134
Q

What organelle contains linear chromosomes?

A

Chromosome

135
Q

What is the RNA-rich region in the nucleus called?

136
Q

What organelle is involved in protein modification and subcellular localization?

A

Golgi body

137
Q

What is the function of the vacuole in a cell?

A

Storage of excess water and other metabolic products

138
Q

Fill in the blank: During meiosis, synapsis occurs in the __________ phase.

139
Q

True or False: A centriole is present in plant cells.

140
Q

How many autosomes would be expected in a kidney cell?

141
Q

A locus is best defined as __________.

A

the position of a gene on a chromosome

142
Q

The different forms of a gene are called __________.

143
Q

Which of the following cells is normally diploid? (a) primary polar body (b) spermatid (c) primary spermato- cyte (d) spermatozoan (e) secondary polar body

A

primary spermato- cyte

144
Q

Upon which two major features of chromosomes does their cytological identification depend?

A

length of chromosome and position of centromere

145
Q

In oogenesis, the cell that corresponds to a spermatid is called a __________.

A

secondary polar body

146
Q

What is the significance of sex in organisms?

A

It provides genetic variability essential for natural selection.

147
Q

What term is used for an organism with both male and female reproductive organs?

A

Hermaphrodite.

148
Q

What is a monoecious plant?

A

A plant that has both staminate (male) and pistillate (female) flowers on the same individual.

149
Q

What is the term for plants that have male and female elements in separate individuals?

A

Dioecious.

150
Q

What is the sex ratio?

A

The proportion of males to females in a population.

151
Q

What are the two types of sex chromosomes in most mammals?

A

X and Y chromosomes.

152
Q

In mammals, what determines maleness?

A

The presence of the Y chromosome.

153
Q

What is the XY method of sex determination?

A

A system where males are heterogametic (XY) and females are homogametic (XX).

154
Q

What gene is responsible for male sex determination in humans?

A

SRY (sex-determining region Y).

155
Q

What does the XO method of sex determination involve?

A

Males have a single X chromosome (X0), and females have two X chromosomes (XX).

156
Q

In the ZW method of sex determination, which sex is heterogametic?

A

Females (ZW).

157
Q

What determines sex in Drosophila?

A

The ratio of X chromosomes to haploid sets of autosomes.

158
Q

What is the X:A ratio for a normal female in Drosophila?

A

2X:2A, or 1.0.

159
Q

What happens when the X:A ratio is above 1.0 in Drosophila?

A

It produces sterile metafemales.

160
Q

What is haplodiploidy?

A

A sex determination system where males are haploid and females are diploid.

161
Q

What determines whether a female bee becomes a worker or a queen?

A

The quantity and quality of food available to the diploid larva.

162
Q

What is complementary sex determination (CSD)?

A

A mechanism where males develop from homozygous alleles at a single-gene locus.

163
Q

In microorganisms, what controls sex?

A

A single gene at the mating-type locus.

164
Q

What are isogametes?

A

Morphologically indistinguishable gametes from haploid individuals.

165
Q

What happens when haploid cells with opposite alleles fuse?

A

They form a diploid zygote.

166
Q

Fill in the blank: In the XO method of sex determination, males are _______ and females are _______.

167
Q

True or False: In the ZW method of sex determination, males are heterogametic.

168
Q

What is a zygote?

A

A diploid nonmotile cell formed by the fusion of two haploid cells

Zygotes are resistant to unfavorable growth conditions.

169
Q

What are zoo-spores?

A

Motile haploid daughter cells formed by the meiosis of a zygote

Two zoo-spores are of plus mating type and two are of minus mating type.

170
Q

What does it mean for a gene to be sex-linked?

A

A gene located on the X chromosome or the Z chromosome in birds

The first sex-linked gene discovered was the recessive white-eye mutation in Drosophila.

171
Q

What are reciprocal crosses?

A

Mating a male of one phenotype with a female of another phenotype and reversing the sexes in a second cross

Example: black fur coat male crossed with white fur coat female, then white male with black female.

172
Q

What is hemizygous?

A

A condition where males carry only one allele for sex-linked traits

This contrasts with homozygous or heterozygous conditions in females.

173
Q

What is the expected phenotypic ratio in the F₂ generation if F₁ individuals mate among themselves?

A

1 red: 1 white phenotypic ratio in males

All F₂ females are phenotypically wild type.

174
Q

What is a characteristic of sex-linked recessive traits?

A

They are usually more frequent in males than in females

These traits fail to appear in females unless they also appear in the paternal parent.

175
Q

What is a characteristic of sex-linked dominant traits?

A

They are found more frequently in females than in males

All female offspring of a male showing the trait will express it.

176
Q

What are completely sex-linked genes?

A

Genes on the nonhomologous segment of the X chromosome that exhibit unique inheritance patterns

These genes are expressed only in males and transmitted from father to son.

177
Q

What are holandric genes?

A

Completely Y-linked genes expressed only in males

These genes reside in the nonrecombining region of the Y chromosome.

178
Q

What are sex-influenced traits?

A

Traits whose expression is affected by the sex of the individual

The dominance or recessiveness of alleles can differ between males and females.

179
Q

Provide an example of a sex-influenced trait.

A

Pattern baldness in humans

Dominance in men but acts recessively in women.

180
Q

What are sex-limited traits?

A

Traits that come to expression in only one sex

Example: milk production genes in bulls, which are not expressed in males.

181
Q

What happens during sex reversal in chickens?

A

Female chickens can develop male characteristics and even testes

This can occur due to disease destroying ovarian tissue.

182
Q

What is dioecism in plants?

A

A condition where some flowering plants have separate male and female individuals

The Y chromosome can determine maleness in some plant species.

183
Q

What is self-fertilization in plants?

A

The ability of gametes produced by the same individual to unite and produce viable offspring

Common in many flowering plants, but some have mechanisms to prevent it.

184
Q

What is the expected sex ratio from a cross involving a recessive gene tra in Drosophila?

A

3 males: 1 female in the F₁ generation

Transformed males are sterile and do not contribute to the F₂ generation.

185
Q

What is the expected outcome of a cross between a homozygous barred male and a nonbarred female chicken?

A

All offspring will exhibit the barred trait

The trait is sex-linked and will be expressed in the offspring.

186
Q

What is the genotype of a hemophilic male?

A

hY

The hemophilic allele is recessive and located on the X chromosome.

187
Q

If a carrier female marries a normal male, what is the chance of their first child being a hemophilic boy?

A

1/8

The chance combines the probability of being a carrier (1/2) and the probability of producing a hemophilic boy (1/4).

188
Q

What is the probability that a carrier female’s second child, after having one hemophilic child, will also be a hemophilic boy?

A

1/4

The first child being hemophilic confirms the mother is a carrier.

189
Q

If II3 marries a hemophilic man, what is the probability that their first child will be normal?

A

3/4

II3 has a 50% chance of being a carrier, and any child has a 50% chance of being normal.

190
Q

What phenotype must the father of a hemophilic daughter (hh) possess?

A

Normal (HY)

The father must have at least one dominant normal allele to produce a normal daughter.

191
Q

What is the expected phenotypic ratio in the F₂ generation when bobbed females are crossed with heterozygous males?

A

1/2 bobbed females, 1/2 wild-type females, 1/2 bobbed males, 1/2 wild-type males

This assumes an incompletely sex-linked gene interaction.

192
Q

In the context of sex-influenced traits, what is the phenotype of a heterozygous bald man with a long index finger?

A

Bald, long-fingered

Baldness is dominant in men, while the index finger length is not influenced by the same dominance.

193
Q

What are the genotypes of the three parental females producing 15 hen-feathered males, 18 hen-feathered females, and 3 cock-feathered males?

A

2 HH, 1 Hh

This combination produces the observed ratio of hen-feathered to cock-feathered males.

194
Q

What are the expected phenotypic proportions in the F₂ generation when a barred female is crossed with a nonbarred female?

A

3 barred males, 2 females (half barred, half nonbarred)

This reflects the sex-linked inheritance in the ZW system.

195
Q

What does the recessive gene ‘tassel-seed’ (ts) produce when homozygous?

A

Only seeds where the tassel normally appears

It results in functional reduction to a single sex, female.

196
Q

Fill in the blank: The hemophilia gene is ______.

A

recessive sex-linked

This gene influences blood clotting and is carried on the X chromosome.

197
Q

True or False: A cock-feathered male can be produced from a cross of two hen-feathered females.

A

False

Hen-feathered females can only produce hen-feathered males.

198
Q

What is the genotype of corn plants that produce only seeds where the tassel normally appears?

A

ts/ts

The gene is called ‘tassel-seed’ (ts) and is recessive.

199
Q

What is the effect of the recessive gene ‘silkless’ (sk) when homozygous in corn?

A

Produces ears with no pistils (silks)

Without silks, these ears cannot produce seeds.

200
Q

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)?

A

1 male:1 female

Subsequent generations will continue to exhibit a 1:1 sex ratio.

201
Q

True or False: The recessive gene for tassel-seed is epistatic to the silkless locus.

A

True

This means that the presence of the tassel-seed gene affects the expression of the silkless gene.

202
Q

In the context of self-incompatibility in plants, what happens to pollen tubes containing the same self-incompatibility allele?

A

They grow slowly and cannot fertilize before the flower withers

This prevents fertilization in self-compatible plants.

203
Q

What are the possible genotypes for the six varieties of plants with four self-sterility alleles?

A

S’s³, s’s, S’s², s²s, S²s, ss

None can be homozygous for self-incompatibility alleles.

204
Q

Fill in the blank: A sex-linked recessive gene c produces ______ in humans.

A

red-green color blindness

This condition is inherited in a specific manner due to its linkage to sex chromosomes.

205
Q

What is the expected percentage of color-blind girls produced by a normal woman whose father was color-blind and a color-blind man?

A

0%

Color-blindness is a recessive trait linked to the X chromosome.

206
Q

How many chromosomes do grasshoppers have according to the XO method?

A

23 chromosomes

This number indicates the diploid state for the grasshopper.

207
Q

In chickens, what color is associated with the dominant sex-linked gene S?

A

Silver-colored plumage

The recessive allele s produces gold-colored plumage.

208
Q

What happens to the progeny of a barred creeper female and a non-barred creeper male?

A

Progeny will display both barred and non-barred plumage

The exact ratios depend on the specific genotypes of the parents.

209
Q

What is the sex index in Drosophila for diploid males?

A

0.5

This is calculated as the ratio of X chromosomes to autosome sets.

210
Q

What results from a cross between heterozygous females and yellow-green males in Melandrium?

A

Predicted phenotypic ratio in the progeny

This is influenced by the lethality of the sex-linked gene when homozygous in females.

211
Q

Fill in the blank: The homozygous dominant genotype CC in chickens is ______.

A

lethal

This means that individuals with this genotype do not survive.

212
Q

What sex index values give rise to intersexes?

A

Values between 0.5 and 1.0

Values over 1.0 or under 0.5 produce weak and inviable flies called ‘superfemales’ (metafemales) and ‘supermales’ (metamales), respectively.

213
Q

What is the diploid number of chromosomes in honey bees?

214
Q

How many chromosomes are found in the somatic cells of a drone (male) honey bee?

215
Q

How many bivalents are seen during gametogenesis in male honey bees?

216
Q

How many bivalents are seen during gametogenesis in female honey bees?

217
Q

What are the seven eye colors known in honey bees produced by recessive genes?

A
  • brick (bk)
  • chartreuse (ch)
  • ivory
  • cream (cr)
  • snow (S)
  • pearl (pe)
  • garnet (g)
218
Q

What percentage of drone offspring is expected to be brick-eyed when a heterozygous queen is inseminated by mutant drones?

219
Q

What percentage of worker offspring is expected to be brick-eyed?

220
Q

In Chlamydomonas, how many mating types are there?

A

Two: (+) and (-)

221
Q

Does the fusion of (+) and (-) gametes in Chlamydomonas produce a diploid zygote?

222
Q

Is there a morphological distinction between the (+) and (-) sexes in Chlamydomonas?

223
Q

What is a recessive gene called in wasps that assort independently of sex alleles?

A

veinless (v)

224
Q

What is the expected phenotypic ratio of progeny when crossing two heterozygous veinless wasps?

A

1 haploid male: 1 diploid male: 2 females

225
Q

What is the trait of ‘porcupine man’ likely to be?

A

A sex-limited trait

226
Q

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?

227
Q

What is a holandric gene?

A

A gene located on the Y chromosome

228
Q

What percentage of sons would be expected to have hairy ears if their father has the trait?

229
Q

What proportion of daughters is expected to show the trait if the father has hairy ears?

230
Q

What is the expected genetic ratio of hairy-eared to normal children from a hairy-eared father?

231
Q

What does the white forelock in humans represent?

A

A sex-influenced gene

232
Q

What kind of genetic dominance does the presence of horns in sheep exhibit?

A

Dominance in males, recessiveness in females

233
Q

What is the expected phenotypic ratio in the F1 generation from a cross between horned and polled sheep?

A

1 horned: 1 polled

234
Q

What is the expected phenotypic ratio in the F2 generation from the same cross?

A

3 horned: 1 polled

235
Q

What is the sex-linked gene that governs the barred plumage pattern in chickens?

236
Q

What is the expected phenotype of progeny from a cross between a barred hen-feathered male and a non-barred hen-feathered female?

A

All progeny will be hen-feathered

237
Q

What is the expected sex ratio among seedlings grown early in the year from crosses between XY males and XY females?

238
Q

What type of flower is produced by the recessive genotype nn in castor bean plants?

A

Completely pistillate (female) flower

239
Q

What is the expected sex ratio among the F1 generation from selfing an exceptional staminate-seed plant of genotype Pp?

240
Q

What kind of mating gives a 1:1 sex ratio in asparagus plants?

241
Q

What is the expected phenotypic result from crossing homozygous broad-leaf pollen with narrow-leaf seed parents?

A

All broad-leaf offspring

242
Q

In the clover butterfly, what are the expected phenotypic proportions from the cross Yy x Yy?

A

3 yellow: 1 white

243
Q

What is a form of reproduction involving the union of haploid gametes to form a diploid zygote?

A

Fertilization

244
Q

What is an animal that has both male and female reproductive organs called?

A

Hermaphrodite

245
Q

What is a flower having female but no male reproductive parts called?

A

Pistillate flower

246
Q

What adjective is applicable to the sex that produces gametes bearing structurally different sex chromosomes?

A

Heterogametic

247
Q

What are the two symbols that represent the sex chromosomes of female chickens?

248
Q

What is the mode of sex determination for Drosophila?

A

Genic balance

249
Q

What is the mode of sex determination for bees?

A

Haplodiploidy

250
Q

What adjective is applied to genes on the differential segment of the Y chromosome?

251
Q

What class of traits is governed by autosomal alleles whose dominance relationships are reversed in the two sexes?

A

Sex-influenced traits

252
Q

What class of autosomal traits has phenotypic variability in a population in only one sex?

A

Sex-limited traits

253
Q

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?

A

26 in males

254
Q

If a pink-eyed queen mates with a brown-eyed drone in bees, what would their offspring most likely be?

A

Wild-type workers and pink-eyed drones

255
Q

In a guinea pig pedigree involving sex-linked inheritance, can III1 exhibit the dominant trait?

256
Q

What is the fraction of the F1 expected to be polled when mated between polled males and horned females?

257
Q

In the clover butterfly, what is expected in the F1 generation from matings between heterozygotes?

A

3/4 yellow: 1/4 white

258
Q

What is expected among adult progeny when a long-tailed male undergoes primary sex reversal and is mated to a short-tailed male?

A

2/3 of males long-tailed

259
Q

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.

260
Q

How much of the pollen is compatible in the crosses involving self-incompatibility?

A

Varies by cross; specific ratios depend on alleles

261
Q

What genotype do all thrum plants possess in the genus Primula?

A

S/S or S/s

262
Q

What is the expected genotypic ratio if both pin and thrum are heterozygous for an independently segregating allelic pair Aa?

263
Q

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?

A

1 S’s: 1 Ss

264
Q

What percentage of haploid males are wild type veinless?

A

0%

Reflects the genetic distribution in the given population.

265
Q

Can a sex chromosome mechanism operate without a morphological difference in the chromosomes, gametes, or spores?

A

Yes

Indicates that sex determination can occur through genetic mechanisms even without observable differences.

266
Q

What is the genotype for males if ‘w’ is dominant in men?

A

WW, Ww, W’w’

Represents the possible genotypes based on inheritance patterns.

267
Q

In a cross of horned males and polled females, what would be the phenotype ratio for males?

A

3/4 horned : 1/4 polled

Illustrates the expected outcome of phenotypic ratios in offspring.

268
Q

What is the expected phenotype ratio for females in the same cross?

A

1/4 horned : 3/4 polled

Shows the phenotypic ratios for female offspring based on genetic inheritance.

269
Q

True or False: All males are short and all females are long in a certain genetic cross.

A

True

Indicates a complete dominance scenario for the trait in question.

270
Q

In a genetic cross, what does a holandric gene refer to?

A

Y-linked

Refers to genes located on the Y chromosome, typically expressed in males.

271
Q

What is the expected ratio of yellow to white in a certain phenotype?

A

5/8 yellow: 3/8 white

Reflects the phenotypic ratios based on genetic inheritance patterns.

272
Q

Fill in the blank: A gene that is dominant in males and recessive in females is referred to as a _______ gene.

A

sex-influenced

Describes a type of inheritance where the phenotype expression differs by sex.

273
Q

What is the expected ratio of staminate to pistillate flowers in a certain genetic cross?

A

3/4 staminate: 1/4 pistillate

Illustrates the distribution of flower types based on genetic inheritance.

274
Q

What does ‘haplodiploidy’ refer to?

A

A form of sexual reproduction

Involves different ploidy levels for males and females, common in some insects.

275
Q

What is the phenotype ratio for bald males with normal vision?

A

1/8 daughters, 3/8 sons

Indicates the distribution of phenotypes among offspring based on genetic traits.

276
Q

What does the term ‘genic balance’ refer to?

A

A genetic concept related to sex determination

It describes how the ratio of sex chromosomes to autosomes influences sexual development.

277
Q

What percentage of the progeny would be expected to be nonbald and color blind?

A

3/8

This reflects the outcome based on the genetic crosses analyzed.

278
Q

What is the expected male to female ratio in a specific genetic cross?

A

2 males: 1 female

Represents the expected offspring ratio based on inheritance patterns.

279
Q

What are the genotypes for females if ‘w’ is dominant in men?

A

w’w, ww’

Indicates the possible combinations for female offspring based on male genotypes.

280
Q

True or False: All progeny from a specific genetic cross will exhibit the same phenotype.

A

False

Different combinations of alleles can lead to various phenotypes.

bio 101 exams practice (5 decks)

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