ANSC 3040 Midterm Exam with All
Correct Answers 2026-2027 Updated.
is the biological sex of an embryo already determined? - Answer yes because it will always
contain an XX or XY
When do the forming sperm cells go from 2n (XY) to n (X or Y) - Answer the secondary
spermatocyte is the first cell that isn't 2n in the spermatogenesis
what are diploid and haploid cells - Answer diploid = 2n
haploid = n
are somatic and germ cells diploid or haploid cells - Answer diploid
What are totipotent cells - Answer cells capable to differentiate into any type of embryonic
(body) or extra-embryonic (placenta) cells
what are trophectoderm cells - Answer multipotent cells capable to differentiate into any type
of cells within a cell lineage, in this case, placental cells
What are pluripotent cells - Answer cells capable to differentiate into any type of cells in the
embryo
where can you find pluripotent cells - Answer in the inner cell mass of the blastocyst
What are the levels of early embryogenesis? (3) - Answer 1. highly specialized cells - oocyte
and sperm which then gets fertilized
2. totipotent cells which forms the zygote
3. blastocyst cells which contains the inner cell mass and the trophectoderm
what causes cells to become a liver or an intestine if they all contain the same DNA? - Answer
Their epigenetics and the differentiation of markers. Modifications of DNA or transcription of
different areas of the DNA leads to the cell becoming something more specialized
What is gastrulation - Answer the formation of the 3 layers - ectoderm, mesoderm, and
endoderm.
,How does gastrulation work (3) - Answer 1. the inner cell mass contains the epiblast and
hypoblast
2. within the epiblast, a primitive streak will release cells and form a mesoderm
3. the epiblast becomes the ectoderm, the mesoderm was just formed, and the hypoblast
becomes the endoderm
Where will the epiblast cells differentiate in the inner cell mass - Answer the ones that are
attached to the blastocoele
What does the endoderm form - Answer digestive system, lungs, and endocrine system
what does the mesoderm form - Answer Muscle, Skeleton, Cardiovascular system,
reproductive system, urinary system
what does the ectoderm form - Answer nervous system, skin, hair, external parts of the
reproductive tract
What cell type will develop the repro and urinary system - Answer somitic mesoderm
what are the founder cells for the germline in animals as embryos? where are they found? -
Answer Primordial germ cells. located in the hind gut
How and where do the primordial germ cells migrate during embryogenesis? what signal
coordinates this migration? - Answer migrate by amoeboid movement via the dorsal
mesentery of the hindgut to the gonadal ridge
chemotaxis signalling
Why do primordial germ cells go to the gonadal ridge - Answer this is where the primitive sex
cords are formed
what do the Gonads become in embryogenesis - Answer become the testes or the ovaries
what do the metanephros become - Answer kidneys
What gene does the Y chromosome have that the X doesn't - Answer the SRY gene (sex
determining region on the Y chromosome)
, What are the steps of embryogenesis in the male? (6) - Answer 1. Testes determining factor
(TDF)
2. testes develop
3. sertoli cells secretes anti-mullerian hormone (AMH)
4. AMH causes leydig cells to differentiate
5. Testosterone secretion from Leydig cells causes the development of male duct system
6. dihydrotestosterone from the leydig cells causes the development of the penis, scrotum, and
accessory sex glands
What does AMH do in the male (2) - Answer forms Leydig cells
causes degeneration of paramesonephric duct
what are the steps of embryogenesis in the female? (5) - Answer 1. no TDF
2. Ovaries develop
3. No AMH
4. paramesonephric ducts become the oviducts, uterus, cervix, and part of the vagina
5. complete female tract
What are the different things Testosterone and dihydrotestosterone develop in the male -
Answer testosterone - male duct system
dihydrotestosterone - development of penis, scrotum, and accessory sex glands
what do the paramesonephric ducts become in the female (4) - Answer oviducts, uterus,
cervix, and part of the vagina
what do the bipotential gonads become in the male - Answer developing testis
what ducts regress and grow in the male that is opposite for a female? - Answer
paramesonephric duct regresses
mesonephric ducts grows
what does the mesonephric duct become in the male - Answer the epididymus and the ductus
deferens
what do the epithelial cords become in the male - Answer future seminiferous tubules
Correct Answers 2026-2027 Updated.
is the biological sex of an embryo already determined? - Answer yes because it will always
contain an XX or XY
When do the forming sperm cells go from 2n (XY) to n (X or Y) - Answer the secondary
spermatocyte is the first cell that isn't 2n in the spermatogenesis
what are diploid and haploid cells - Answer diploid = 2n
haploid = n
are somatic and germ cells diploid or haploid cells - Answer diploid
What are totipotent cells - Answer cells capable to differentiate into any type of embryonic
(body) or extra-embryonic (placenta) cells
what are trophectoderm cells - Answer multipotent cells capable to differentiate into any type
of cells within a cell lineage, in this case, placental cells
What are pluripotent cells - Answer cells capable to differentiate into any type of cells in the
embryo
where can you find pluripotent cells - Answer in the inner cell mass of the blastocyst
What are the levels of early embryogenesis? (3) - Answer 1. highly specialized cells - oocyte
and sperm which then gets fertilized
2. totipotent cells which forms the zygote
3. blastocyst cells which contains the inner cell mass and the trophectoderm
what causes cells to become a liver or an intestine if they all contain the same DNA? - Answer
Their epigenetics and the differentiation of markers. Modifications of DNA or transcription of
different areas of the DNA leads to the cell becoming something more specialized
What is gastrulation - Answer the formation of the 3 layers - ectoderm, mesoderm, and
endoderm.
,How does gastrulation work (3) - Answer 1. the inner cell mass contains the epiblast and
hypoblast
2. within the epiblast, a primitive streak will release cells and form a mesoderm
3. the epiblast becomes the ectoderm, the mesoderm was just formed, and the hypoblast
becomes the endoderm
Where will the epiblast cells differentiate in the inner cell mass - Answer the ones that are
attached to the blastocoele
What does the endoderm form - Answer digestive system, lungs, and endocrine system
what does the mesoderm form - Answer Muscle, Skeleton, Cardiovascular system,
reproductive system, urinary system
what does the ectoderm form - Answer nervous system, skin, hair, external parts of the
reproductive tract
What cell type will develop the repro and urinary system - Answer somitic mesoderm
what are the founder cells for the germline in animals as embryos? where are they found? -
Answer Primordial germ cells. located in the hind gut
How and where do the primordial germ cells migrate during embryogenesis? what signal
coordinates this migration? - Answer migrate by amoeboid movement via the dorsal
mesentery of the hindgut to the gonadal ridge
chemotaxis signalling
Why do primordial germ cells go to the gonadal ridge - Answer this is where the primitive sex
cords are formed
what do the Gonads become in embryogenesis - Answer become the testes or the ovaries
what do the metanephros become - Answer kidneys
What gene does the Y chromosome have that the X doesn't - Answer the SRY gene (sex
determining region on the Y chromosome)
, What are the steps of embryogenesis in the male? (6) - Answer 1. Testes determining factor
(TDF)
2. testes develop
3. sertoli cells secretes anti-mullerian hormone (AMH)
4. AMH causes leydig cells to differentiate
5. Testosterone secretion from Leydig cells causes the development of male duct system
6. dihydrotestosterone from the leydig cells causes the development of the penis, scrotum, and
accessory sex glands
What does AMH do in the male (2) - Answer forms Leydig cells
causes degeneration of paramesonephric duct
what are the steps of embryogenesis in the female? (5) - Answer 1. no TDF
2. Ovaries develop
3. No AMH
4. paramesonephric ducts become the oviducts, uterus, cervix, and part of the vagina
5. complete female tract
What are the different things Testosterone and dihydrotestosterone develop in the male -
Answer testosterone - male duct system
dihydrotestosterone - development of penis, scrotum, and accessory sex glands
what do the paramesonephric ducts become in the female (4) - Answer oviducts, uterus,
cervix, and part of the vagina
what do the bipotential gonads become in the male - Answer developing testis
what ducts regress and grow in the male that is opposite for a female? - Answer
paramesonephric duct regresses
mesonephric ducts grows
what does the mesonephric duct become in the male - Answer the epididymus and the ductus
deferens
what do the epithelial cords become in the male - Answer future seminiferous tubules
