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Biology · 2026 · 5 marks
CBSE 2026 · Region 2 · Set 3 · Q31
(a) In the given diagram - 'A' is an embryonic stage that gets transformed into 'B', which in turn gets implanted in the endometrium of human female.…
In the given diagram - 'A' is an embryonic stage that gets transformed into 'B', which in turn gets implanted in the endometrium of human female.
(i)(1)
Identify A, B, C and D.
(2)
State the fate of 'C' immediately after implantation.
(3)
Name the special cells found in 'C' and their function.
(ii)
What is the role of oxytocin during parturition ? Where is it released from ?
Sexually transmitted infections are a major threat to our society. So it is said that "Prevention is better than cure".
(i)
Write the three simple principles to be followed to prevent such infections.
(ii)
How can sex education programs in schools help in improving reproductive health ? ($\displaystyle 4$ points)
Marking-scheme solution
(a)
(i)
(1)
A- Morula, B- Blastocyst, C-Inner Cell Mass, D-Trophoblast
(2)
Inner cell mass get differentiated into an embryo.
(3)
Stem cells, they have the potency to give rise to all tissues and organs.
(ii)
It acts on uterine muscles and causes strong uterine contractions, Oxytocin is
released from maternal Pituitary.
(i)
Avoid sex with unknown partners / multiple partners.
Use condoms during coitus.
In case of doubt, one should go to a qualified doctor for early detection and get complete treatment if diagnosed with infection
(ii)
Discourage children from believing in myths and having misconception about sex related problems.
Proper information of reproductive organs.
Safe and hygienic sexual practices
Proper information of sexually transmitted diseases/STDs
Information about AIDS would help those in adolescent age group to lead a reproductively healthy life.
All Human Reproduction questions2026 question paperNCERT solutions: Human ReproductionPractice Human Reproduction →
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CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.