NATS 1675 EXAM 2025 QUESTIONS
AND ANSWERS
Flagellum (flagella) - ....ANSWER ...-the tail of the sperm which enables
them to swim to the egg
Fertilization - ....ANSWER ...--After ovulation the egg can last from 6- 24
hours,
-After ejaculation sperm can for 24-28 hours,
-Ovulation takes place in the uterine tubes, and moves through tubes to the uterus
to be fertilized,
-Spermatozoa mature as they pass through the epididymis (10-14 days),
-At ovulation cervical secretions are watery and less acidic (better for sperm),
-Cervical crypts are reservoirs for escaping sperm
1% of less of sperm make it to uterus (only 20-30 out of 150-200 million),
-One sperm fertilizes egg and sperm head binds with zona pellucida,
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,-The union of sperm and the egg is called a zygote, the first cell of that new
individual/baby,
Middle Sperm - ....ANSWER ...-contains energy producing mitochondria
Sperm Head - ....ANSWER ...-contains a nucleus sapped by a membrane
bound acrosome
Acrosome - ....ANSWER ...--contains digestive enzymes with penetrates
zona pellucida,
-chemical changes to plasma membrane and zona pellucida prevents other sperm
from binding
zona pellucida - ....ANSWER ...-extra cellular outer membrane of the egg
cortical granules - ....ANSWER ...-release enzymes that convert the zona
pellucida into a fertilized membrane (hardens)
corona radiata - ....ANSWER ...-follicular cells that surround zona pellucida
Week 1 - ....ANSWER ...--Ovulation and fertilization in uterine tubes,
-Zygote travels to uterus,
-Cleavage- after fertilization zygote divides (2,4,6,8,12) all with full pair of
chromosome genes,
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
, -Formation of morula (ball of cells),
-Formation of blastocyst (inner cell mass),
Week 2 - ....ANSWER ...--Implantation occurs and implantation of
blastocyst marks beginning of embryonic period,
-Zona pellucida prevents blastocyst from implanting before reaching uterus,
-Amnion and Yolk Sac appear, embryo has tissues, placenta begins to form,
Trophoblast - ....ANSWER ...--Gives rise to tissues for placenta,
-Digests part of endometrium,
-Secretes human chorionic gonadotropin (HCG),
-Acts like LH,
-Clinical marker for pregnancy,
-Preserves corpus luteum and keeps lining intact,
Inner Cell Mass - ....ANSWER ...--Gives rise to the embryo,
-Starts with 8 cells,
-About 4 for the body,
-About 4 for the yolk sac and the amnion,
-Gastrulation turns inner cell mass into embryonic disk (ex. morphogenesis)
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 3
AND ANSWERS
Flagellum (flagella) - ....ANSWER ...-the tail of the sperm which enables
them to swim to the egg
Fertilization - ....ANSWER ...--After ovulation the egg can last from 6- 24
hours,
-After ejaculation sperm can for 24-28 hours,
-Ovulation takes place in the uterine tubes, and moves through tubes to the uterus
to be fertilized,
-Spermatozoa mature as they pass through the epididymis (10-14 days),
-At ovulation cervical secretions are watery and less acidic (better for sperm),
-Cervical crypts are reservoirs for escaping sperm
1% of less of sperm make it to uterus (only 20-30 out of 150-200 million),
-One sperm fertilizes egg and sperm head binds with zona pellucida,
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,-The union of sperm and the egg is called a zygote, the first cell of that new
individual/baby,
Middle Sperm - ....ANSWER ...-contains energy producing mitochondria
Sperm Head - ....ANSWER ...-contains a nucleus sapped by a membrane
bound acrosome
Acrosome - ....ANSWER ...--contains digestive enzymes with penetrates
zona pellucida,
-chemical changes to plasma membrane and zona pellucida prevents other sperm
from binding
zona pellucida - ....ANSWER ...-extra cellular outer membrane of the egg
cortical granules - ....ANSWER ...-release enzymes that convert the zona
pellucida into a fertilized membrane (hardens)
corona radiata - ....ANSWER ...-follicular cells that surround zona pellucida
Week 1 - ....ANSWER ...--Ovulation and fertilization in uterine tubes,
-Zygote travels to uterus,
-Cleavage- after fertilization zygote divides (2,4,6,8,12) all with full pair of
chromosome genes,
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
, -Formation of morula (ball of cells),
-Formation of blastocyst (inner cell mass),
Week 2 - ....ANSWER ...--Implantation occurs and implantation of
blastocyst marks beginning of embryonic period,
-Zona pellucida prevents blastocyst from implanting before reaching uterus,
-Amnion and Yolk Sac appear, embryo has tissues, placenta begins to form,
Trophoblast - ....ANSWER ...--Gives rise to tissues for placenta,
-Digests part of endometrium,
-Secretes human chorionic gonadotropin (HCG),
-Acts like LH,
-Clinical marker for pregnancy,
-Preserves corpus luteum and keeps lining intact,
Inner Cell Mass - ....ANSWER ...--Gives rise to the embryo,
-Starts with 8 cells,
-About 4 for the body,
-About 4 for the yolk sac and the amnion,
-Gastrulation turns inner cell mass into embryonic disk (ex. morphogenesis)
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 3
