Question | Answer |
At the time the of implantation, the human embryo is called ________. | Blastocyst |
Which of the following is (are) involved in embryonic development? | All of the answers are correct; cell division, cell differentiation, and morphogenesis |
Eukaryotic cells control gene expression by which of the following mechanisms? | All of the answers are correct; DNA methylation, histones acetylation, nucleosomes, and enzyme modification of chromatin structure |
Changes in the shape of the cell usually involves the reorganization of the ________. | Cytoskeleton |
The embryonic precursor to the human spinal cord is the ______. | Neutral tube |
For a repressible operon to be transcribed, which of the following must be true? | RNA polymerase must bind to the promoter and the repressor must be inactive |
Which of the following events is (are) nessicary for the production of a malignant tumor? | Both activation of an oncogene in the cell and the inactivation of tumor-suppressor genes with the cells |
Transcription of the structural genes in an inducible operon ________. | Starts when the pathway's substrate is present |
A(n) ________ can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA. | Repressor |
The outer-to-inner sequence of tissue layers in post-gastrulation vertebrate embryo is _______. | Ectoderm - mesoderm - endoderm |
Which of the following correctly displays the sequence of developmental milestones? | Cleavage - morula - blastula - gastula |
Genomic imprinting, DNA methylation,and histone acetylation are all examples of ______. | Epigenetic inheritance |
In a nucleosome,what is the DNA wrapped around? | Histones |
The earliest developmental stage among these choices is ________. | Morula |
The tryptophan operon is a repressible operon that is ________. | Turned off whenever tryptophan is added to the growth medium |
What is the term for the physical processes that give rise to the shape of an organism? | Morphogenesis |
As an embryo develops, new cells are produced as a result of ________. | Cell division |
Animal cells that are present only for a brief developmental phase will, following completion of that phase, undergo _______. | Apotosis |
From earliest to latest, the overall sequence of early development proceeds in which of the following sequences? | Cleavage - gasturlation - organogenesis |
A human zygote undergoes its first cell division _______. | 24 hours after fertilization |
A(n) _______ is a site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3’ end of the transcript. | Terminator |
In mammalian eggs, the receptors for sperm are found in the _______. | Zona pellucid |
Contact of a sperm with signal molecules in the coat of an eg cause the sperm to undergo _____. | The acrosomal reaction |
. Uterine implantation due to enzymatic digestion of the endometrium is initiated by the _____. | Trophoblast |
In humans, identical twins are possible because ________. | The gray crescent divides the dorsal-ventral axis into new cells. |
To meet a zygote’s metabolic and developmental requirements ___________. | Maternal RNA and maternal proteins must be present. |
Fertilization normally __________. | reinstates diploidy |
Cells move to new positions as an embryo establishes its three germ tissue layers during _______. | Gastrulation |
A(n) _______ binds to a site in the DNA far from the promoter to stimulate transcription. | The longer we live, the more mutations accumulate |
An open space within the gastrula is the ________. | Archenteron |
During fertilization, the acrosomal contents _______. | Digest the protective jelly coat on the surface of the egg. |
Gases are exchanged in the mammalian embryo in the _______. | Chorion |
The cortical reaction functions directly in the _______. | Formation of a fertilization envelope. |