BIO 211 - EXAM 4 QUESTIONS &
VERIFIED CORRECT ANSWERS
LATEST VERSION
the oocyte is viable for... - correct answer ✔✔12 to 24 hours
sperm is viable for... - correct answer ✔✔24 hours to 48 hours after ejaculation
fertilization - correct answer ✔✔when the sperm's chromosomes combine with those of a
secondary oocyte to form a zygote (fertilized egg)
for fertilization to occur, coitus must occur no more than... - correct answer ✔✔- 2 days before
ovulation
- 24 hours after ovulation
ejaculation sperm..... - correct answer ✔✔- leak out of the vagina immediately after deposition
- are destroyed by the acidic vaginal environment
- fail to makie it through the cervix
- are dispersed in the uterine cavity or destroyed by phagocytes
- few (100 to a few thousand) reach the uterine tubes
in order to accomplish fertilization the sperm must.... - correct answer ✔✔- become motile
- be capacitated before they can penetrate the oocyte (secretions of the female tract weaken
acrosome membrane)
,acrosomal reaction and sperm penetration.... - correct answer ✔✔1) sperm must breach oocyte
coverings (corona radiata and zona pellucida)
2) sperm binds to the zona pellucida and undergoes the acromosal reaction
--- enzymes are released to digest holes in the zona pellucida
--- hundreds of acrosomes release their enzymes to digest the zona pellucida
3) sperm head approaches the oocyte
4) an acromosome process forms and binds to receptors
5) oocyte and sperm membranes fuse
6) only one sperm is allowed to penetrate the oocyte (monospermy)
Polyspermy is prevented by...... - correct answer ✔✔- upon entry of a sperm, Ca2+ surge from
the ER causes the cortical reaction
--- cortical granules release enzymes (zonal inhibiting proteins, or ZIPs)
--- ZIPs destroy sperm receptors
--- spilled fluid binds water and swells, detaching other sperm (slow block to polyspermy)
Zygote - correct answer ✔✔chromosomes of the pronuclei intermix...fertilization is
accomplished...then, the DNA replicates in preparation for the first cleavage division
cleavage - correct answer ✔✔- mitotic divisions of zygote
- first cleavage at 36 hours--2 daughter cells (blastomeres)
- at 72 hours--morula (16 or more cells)
- there is virtually NO GROWTH in SIZE during cleavage
blastocyst - correct answer ✔✔fluid-filled hollow sphere
trophoblast cells - correct answer ✔✔- display factors that are immunosuppressive
, - participate in placenta formation
inner cell mass - correct answer ✔✔becomes the embryonic disc----embryo and 3 of the
embryonic membranes
implantation.... - correct answer ✔✔- blastocyst floats for 2-3 days
- implantation begins 6-7 days after ovulation
---trophocytes adheres to a site with the proper receptors and chemical signals
---inflammatory-like response occurs in the endometrium
during implantation trophoblasts proliferate and form 2 distinct layers... - correct answer ✔✔1)
Cytotrophoblast (cellular trophoblast)--inner layer of cells
2) Syncytiotrophoblast--cells in the outer layer lose their plasma membranes, invade and digest
the endometrium
the implanted blastocyte is covered over by... - correct answer ✔✔endometrial cells
implantation is completed by the... - correct answer ✔✔12th day after ovulation
Human chorionic gonadotropin (hCG) - correct answer ✔✔- secreted by trophoblast cells, later
the chorion
- prompts corpus luteum to continue secretion of progesterone and estrogen
- hCG levels rise until the end of the 2nd month, then decline as the placenta begins to secrete
progesterone and estrogen
placenta is fully formed and functional by the.. - correct answer ✔✔end of the 3rd month
placenta secretes.... - correct answer ✔✔1) human placental lactogen
VERIFIED CORRECT ANSWERS
LATEST VERSION
the oocyte is viable for... - correct answer ✔✔12 to 24 hours
sperm is viable for... - correct answer ✔✔24 hours to 48 hours after ejaculation
fertilization - correct answer ✔✔when the sperm's chromosomes combine with those of a
secondary oocyte to form a zygote (fertilized egg)
for fertilization to occur, coitus must occur no more than... - correct answer ✔✔- 2 days before
ovulation
- 24 hours after ovulation
ejaculation sperm..... - correct answer ✔✔- leak out of the vagina immediately after deposition
- are destroyed by the acidic vaginal environment
- fail to makie it through the cervix
- are dispersed in the uterine cavity or destroyed by phagocytes
- few (100 to a few thousand) reach the uterine tubes
in order to accomplish fertilization the sperm must.... - correct answer ✔✔- become motile
- be capacitated before they can penetrate the oocyte (secretions of the female tract weaken
acrosome membrane)
,acrosomal reaction and sperm penetration.... - correct answer ✔✔1) sperm must breach oocyte
coverings (corona radiata and zona pellucida)
2) sperm binds to the zona pellucida and undergoes the acromosal reaction
--- enzymes are released to digest holes in the zona pellucida
--- hundreds of acrosomes release their enzymes to digest the zona pellucida
3) sperm head approaches the oocyte
4) an acromosome process forms and binds to receptors
5) oocyte and sperm membranes fuse
6) only one sperm is allowed to penetrate the oocyte (monospermy)
Polyspermy is prevented by...... - correct answer ✔✔- upon entry of a sperm, Ca2+ surge from
the ER causes the cortical reaction
--- cortical granules release enzymes (zonal inhibiting proteins, or ZIPs)
--- ZIPs destroy sperm receptors
--- spilled fluid binds water and swells, detaching other sperm (slow block to polyspermy)
Zygote - correct answer ✔✔chromosomes of the pronuclei intermix...fertilization is
accomplished...then, the DNA replicates in preparation for the first cleavage division
cleavage - correct answer ✔✔- mitotic divisions of zygote
- first cleavage at 36 hours--2 daughter cells (blastomeres)
- at 72 hours--morula (16 or more cells)
- there is virtually NO GROWTH in SIZE during cleavage
blastocyst - correct answer ✔✔fluid-filled hollow sphere
trophoblast cells - correct answer ✔✔- display factors that are immunosuppressive
, - participate in placenta formation
inner cell mass - correct answer ✔✔becomes the embryonic disc----embryo and 3 of the
embryonic membranes
implantation.... - correct answer ✔✔- blastocyst floats for 2-3 days
- implantation begins 6-7 days after ovulation
---trophocytes adheres to a site with the proper receptors and chemical signals
---inflammatory-like response occurs in the endometrium
during implantation trophoblasts proliferate and form 2 distinct layers... - correct answer ✔✔1)
Cytotrophoblast (cellular trophoblast)--inner layer of cells
2) Syncytiotrophoblast--cells in the outer layer lose their plasma membranes, invade and digest
the endometrium
the implanted blastocyte is covered over by... - correct answer ✔✔endometrial cells
implantation is completed by the... - correct answer ✔✔12th day after ovulation
Human chorionic gonadotropin (hCG) - correct answer ✔✔- secreted by trophoblast cells, later
the chorion
- prompts corpus luteum to continue secretion of progesterone and estrogen
- hCG levels rise until the end of the 2nd month, then decline as the placenta begins to secrete
progesterone and estrogen
placenta is fully formed and functional by the.. - correct answer ✔✔end of the 3rd month
placenta secretes.... - correct answer ✔✔1) human placental lactogen
