問題一覧
1
What does the basic animal life cycle consist of?
Fertilization, cleavage, gastrulation, germ layer formation, organogenesis, metamorphosis, adulthood, and senescence
2
What happens during gametogenesis?
All of the choices are correct.
3
What is epigenesis?
The creation of organisms from the disordered cytoplasm of the egg.
4
What is preformation?
The genetic instructions that instruct the formation of anatomical structures.
5
What does the ectoderm give rise to?
The epidermis, nervous system, and pigment cells
6
What does Karl von Baer's principles state?
The general features of a large group of animals appear earlier in the embryo than do the specialized features of a smaller group.
7
What do migratory cells include?
All of the choices are correct.
8
What does the phrase “Community of embryonic structure reveals community of descent” mean according to Charles Darwin?
Similar embryonic structures indicate a common ancestry.
9
What are homologous structures?
Organs whose similarity is due to sharing a common ancestral structure.
10
What can cause congenital anomalies?
Both genetic factors and environmental agents
11
What are teratogens?
Environmental compounds that can alter development.
12
What is cell differentiation?
The process by which a cell acquires the structural and functional properties unique to a given cell type.
13
What is the term used to describe the process of maturation that a cell goes through from an undifferentiated state to a postmitotic differentiated cell type?
Commitment
14
When is a cell considered specified toward a given fate?
When it maintains its developmental maturation toward that cell type even in isolation.
15
What is the term used to describe a cell that is committed or determined to a given fate?
Committed cell
16
How many modes of cell specification are there?
Three
17
What is autonomous specification?
Cells that possess cytoplasmic determinants and mature into their determined cell types even when isolated.
18
Who first observed the yellow crescent in the tunicate embryo and showed that cells with this yellow crescent give rise to muscle?
Conklin
19
What is conditional specification?
The acquisition of a given cell identity based on its position or interactions with other cells and molecules.
20
Do most species have cells that develop via autonomous specification or conditional specification?
Both autonomous specification and conditional specification.
21
What is syncytial specification?
The process of specifying cell fate in a syncytium of nuclei.
22
What maintains the positioning of nuclei in a syncytium, enabling specification of these nuclei by opposing morphogen gradients?
Cytoskeletal arrangements
23
What genetic technique allows scientists to follow the developmental history of individual cells?
Brainbow
24
What is responsible for the sorting out of one cell type from another?
Inductive interactions
25
Which membrane structures are often involved in cell sorting out?
Cadherin proteins
26
How can cadherins cause cells to sort out?
By changing the surface tension properties of the cells
27
What determines the specific response to an inducer in inductive interactions?
The competence of the responding cells
28
What type of interactions occur when a cell or tissue secretes proteins that induce changes in neighboring cells?
Paracrine interactions
29
What are paracrine factors and how do they affect competent responding cells?
Secreted proteins that bind to cell membrane receptors and activate signal transduction pathways
30
What are morphogens and how do they affect gene expression?
Secreted signaling molecules that affect gene expression differently at different concentrations
31
How do signal transduction pathways begin?
With a conformational change in the cell membrane receptor caused by a paracrine or juxtacrine factor
32
How can the differentiated state of cells be maintained?
Through positive feedback loops involving transcription factors, autocrine factors, or paracrine factors
33
What is the role of the extracellular matrix in cell differentiation and migration?
It serves as a source of signals and modifies how signals are secreted across cells
34
11. What is the epithelial-mesenchymal transition (EMT) and when does it occur?
A series of transformations involved in wound healing and cancer metastasis
35
How is the cell surface involved in cell signaling?
All of the choices are correct
36
What are juxtacrine signaling interactions?
Local protein interactions between receptors on adjacent cells or between a cell membrane and an extracellular matrix
37
Which signaling pathway influences organ size?
Hippo signaling
38
In mammals, primary sex determination is a function of:
The sex chromosomes
39
Which combination of sex chromosomes is typically associated with females in mammals?
XX
40
What role does the mammalian Y chromosome play in male sex determination?
It plays a key role in the development of the male gonads
41
In XY animals, which cells differentiate and enclose the germ cells within testis cords?
Sertoli cells
42
In XX mammals, the germ cells become surrounded by:
Granulosa cells
43
In humans, the SRY gene encodes:
The testis-determining factor
44
7. What is the function of the SOX9 gene in testis formation?
It initiates testis formation
45
Which proteins have a positive feedback loop that activates testicular development and suppresses ovarian development?
Fgf9 and Sox9 proteins
46
What proteins are involved in mammalian ovary formation?
Wnt4 and Rspo1 proteins
47
What transcription factor is required for ovary formation in mammals?
Foxl2
48
What happens to the Müllerian duct in male mammals?
It is destroyed by anti-Müllerian hormone (AMH) produced by the Sertoli cells
49
What enables the differentiation of the penis, scrotum, and prostate gland in mammals?
Conversion of testosterone to dihydrotestosterone
50
In Drosophila, sex is determined by:
The number of X chromosomes in the cell
51
What role does the Drosophila Sex-lethal gene play in sex determination?
It activates the expression of the transformer gene in females
52
What is the function of the Sxl protein in Drosophila sex determination?
It splices an inhibitory exon from the transformer (tra) transcript
53
The Tra protein acts as an RNA splicing factor to splice exons from the doublesex (dsx) transcript. The dsx gene is transcribed in both XX and XY cells, but its pre-mRNA is processed to form different mRNAs, depending on whether the Tra protein is present. What is the role of the proteins translated from both dsx messages?
They activate or inhibit transcription of sexually dimorphic genes.
54
In Drosophila, Tra proteins also activate the fruitless gene in males (but not in females). What is the role of the fruitless gene?
It activates brain sexual differentiation.
55
In turtles and alligators, sex is often determined by the temperature experienced by the embryo during the time of gonad determination. What enzyme is involved in distinguishing male from female patterns of gonadal differentiation?
Aromatase
56
In most species, the precursors of the gametes are the primordial germ cells (PGCs). Where do the PGCs form in most species?
Outside the gonads
57
The cytoplasm of the PGCs in many species contains inhibitors of transcription and translation, making them translationally and transcriptionally silent. What is the purpose of this inhibition?
To prevent the activation of sexually dimorphic genes
58
In most organisms studied, the coordination of germline sex (sperm/egg) is coordinated to somatic sex (male/female) by signals coming from the gonad. What is the role of these signals?
To coordinate the development of germline and somatic sex
59
In humans and mice, germ cells entering ovaries initiate meiosis while in the embryo, while germ cells entering testes do not initiate meiosis until puberty. What is the significance of this difference?
It determines the timing of meiosis initiation in germ cells
60
What is the purpose of the first division of meiosis?
To separate the homologous chromosomes
61
What is the purpose of the second division of meiosis?
To separate the chromatids
62
Which type of meiosis is characterized by the production of four gametes per meiosis and the absence of meiotic arrest?
Spermatogenic meiosis in male mammals
63
Which type of meiosis is characterized by the production of one gamete per meiosis and a prolonged first meiotic prophase?
Oogenic meiosis in female mammals
64
In male mammals, what do the primordial germ cells (PGCs) generate?
Stem cells that last for the life of the organism
65
In female mammals, what do the germ cells do during the first meiotic prophase (dictyate stage)?
Synthesize mRNAs and proteins
66
In some species, what is modified in meiosis to form a diploid egg?
The first division of meiosis
67
What is the purpose of the prolonged first meiotic prophase in female mammals?
To allow the egg to grow
68
In which stage of meiosis are germ cells retained until ovulation in female mammals?
First meiotic prophase
69
What do germ cells in the dictyate stage synthesize in female mammals?
mRNAs and proteins
70
In which type of meiosis do PGCs become germ stem cells in the ovaries?
Spermatogenic meiosis in female mammals
71
What is the purpose of the signals coming from the gonad in coordinating germline and somatic sex in most organisms?
To coordinate the development of germline and somatic sex
72
What is the significance of the difference in meiosis initiation timing in germ cells in male and female mammals?
It determines the timing of meiosis initiation in germ cells
73
In which stage of meiosis are germ cells translationally and transcriptionally silent?
First meiotic prophase
74
What is the term used to describe the process of producing a new generation without fertilization?
Parthenogenesis
75
What are the two separate activities accomplished by fertilization?
Sex and reproduction
76
2. Which of the following is NOT an event of fertilization?
Activation of egg metabolism to start development
77
What is the function of the acrosome in the sperm head?
Contains enzymes needed to digest extracellular coats surrounding the egg
78
4. What is the female gamete called in an earlier stage of development?
Oocyte
79
What is the extracellular layer surrounding the egg cell membrane called in mammals?
Zona pellucida
80
Which of the following statements is true about the activation of the egg and sperm?
Both activations involve calcium ions and membrane fusions
81
What do eggs secrete to attract and activate sperm in many organisms?
Diffusible molecules
82
What are the chemotactic molecules secreted by the egg called?
Resact and speract
83
What initiates the acrosome reaction in sea urchin sperm?
Egg jelly compounds
84
How is fusion between sperm and egg likely mediated?
By protein molecules with hydrophobic groups
85
What is the process by which the sperm penetrates the egg called?
Acrosome reaction
86
What is the term for the early stage of development when the zygote undergoes rapid cell division?
Cleavage
87
What is the name of the solid ball of cells that forms during early embryonic development?
Morula
88
What is the process by which the blastocyst attaches to the uterine wall?
Implantation
89
What is the outer layer of cells in the blastocyst called?
Trophoblast
90
What is the term for the process by which cells become specialized and take on specific functions?
Differentiation
91
What is the name of the structure that forms from the inner cell mass during embryonic development?
Embryo
92
What is the term for the process by which the three germ layers form during embryonic development?
Gastrulation
93
What are the three germ layers that form during gastrulation?
Ectoderm, mesoderm, endoderm
94
What is the outermost germ layer that gives rise to the skin and nervous system?
Ectoderm
95
What is the middle germ layer that gives rise to muscles, bones, and blood vessels?
Mesoderm
96
What is the innermost germ layer that gives rise to the digestive system and respiratory system?
Endoderm
97
Polyspermy occurs when:
Two or more sperm fertilize an egg.
98
The fast block to polyspermy is mediated by the influx of:
Sodium ions
99
The slow block to polyspermy is mediated by the release of:
Calcium ions
100
The cortical granule reaction causes the:
Hardening of the vitelline envelope into the fertilization envelope.