CBSE 2025 · Region 2 · Set 2 · Q31 · 5 marks
Student to attempt either option (A) or (B).(i)Draw a diagrammatic sectional view of human seminiferous tubule (enlarged) and label the following :(a)cell that undergoes spermiogenesis(b)cell that nourish male gametes(c)cell which undergoes meiosis I and meiosis II.(ii)State what is seminal plasma. Mention two constituents of seminal plasma. How is it different from semen ?(i)Mention the event that induces the completion of the meiotic division of the secondary oocyte in humans.(ii)Trace the journey of the zygote until its implantation inside the uterus.
Student to attempt either option (A) or (B).
(i)
Draw a diagrammatic sectional view of human seminiferous tubule (enlarged) and label the following :
(a)
cell that undergoes spermiogenesis
(b)
cell that nourish male gametes
(c)
cell which undergoes meiosis I and meiosis II.
(ii)
State what is seminal plasma. Mention two constituents of seminal plasma. How is it different from semen ?
(i)
Mention the event that induces the completion of the meiotic division of the secondary oocyte in humans.
(ii)
Trace the journey of the zygote until its implantation inside the uterus.
Marking-scheme solution
(i)
(ii)
$\displaystyle \star$ Secretions of male accessory glands (prostate, bulbourethral glands and seminal vesicles) constitute the seminal plasma.
$\displaystyle \star$ Seminal plasma is rich in fructose, calcium and, certain enzymes
$\displaystyle \star$ Seminal plasma along with sperms constitutes the semen.
(i)
Entry of sperm into the cytoplasm of the ovum induces the completion of second meiotic division of the secondary oocyte.
(ii)
As the zygote moves through the fallopian tube the mitotic divisions (cleavage) start, it results into $\displaystyle 2$ -$\displaystyle 16$ daughter cells called blastomeres , Embryo with $\displaystyle 8$ to $\displaystyle 16$ blastomeres is called morula , Morula continues to divided and form Blastocyst which moves further into uterus, The blastomeres in the blastocyst are arranged into an outer layer trophoblast and an inner group of cells called the inner cell mass, the trophoblast gets attached to the endometrium, and the inner cell mass gets differentiated as the embryo, the uterine cells divide rapidly to cover blastocyst which gets embedded in the endometrium and this is called as implantation
Human ReproductionThe Male Reproductive SystemApplylong_answermedium
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CBSE Class 12 Biology past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.