Class 12 Biology, Chapter 3 (NCERT). 15 questions by concept. Open “Show answer” for the answer and why.
How to teach this chapter · Common misconceptions & worked visual for this chapter
Which is a proper medical use of amniocentesis?
(b) Prenatal detection of certain fetal abnormalities
Amniotic fluid and fetal cells can support prenatal diagnosis; sex-selective misuse is prohibited.
Fetal cells from amniotic fluid are cultured to examine chromosomes after a suspected disorder. How should the procedure be classified?
(b) Diagnostic prenatal testing
The described analysis investigates a medical abnormality rather than selecting sex.
Death rate and infant mortality fall rapidly while birth rate remains high. What is the expected short-term effect?
(b) Population grows more rapidly
More individuals survive while additions by birth remain high.
A region improves survival but initially retains large-family norms. Which observation is most consistent?
(c) A growing excess of births over deaths
Population change depends on both additions and losses, not death rate alone.
Which statement about natural contraception is accurate?
(b) Its success depends strongly on correct timing and consistent behaviour
Natural methods avoid devices and hormones but are user- and physiology-dependent.
A fully breastfeeding woman has no periods for several weeks after birth. Which conclusion is safest?
(d) Ovulation may be suppressed temporarily, but protection is limited in duration and conditions
Lactational amenorrhea is conditional and mainly useful during an early postpartum interval.
Which method both reduces sperm entry and meaningfully lowers many STI risks?
(c) Condom
A condom reduces direct exchange of genital fluids as well as acting as contraception.
A cervical cap is correctly placed with spermicide. What is its main action?
(a) Covering the cervix to reduce sperm passage
Cervical barriers chiefly prevent sperm from reaching the uterus.
When is emergency contraception intended to be used?
(a) Soon after exceptional unprotected intercourse or contraceptive failure
Emergency methods are time-sensitive pregnancy prevention, not routine infection control.
A condom breaks during intercourse. Which response matches the intended role of an emergency contraceptive?
(a) Prompt use according to medical guidance to reduce pregnancy risk
The indication is an unexpected contraceptive failure and requires timely action.
Which structure is interrupted in tubectomy?
(c) Oviduct
Tubectomy cuts and ties a segment of each fallopian tube.
Which prenatal finding can provide a medical reason for considering MTP after appropriate assessment?
(b) A severe fetal abnormality
A severe fetal abnormality may warrant consideration of MTP after appropriate medical assessment. Fetal sex alone is not a medical reason for termination.
Can a person without obvious symptoms transmit an STI?
(a) Yes, some infections are asymptomatic yet can be passed on
Many STIs have silent early phases, so testing and prevention matter.
What happens in ICSI?
(a) One sperm is injected directly into an ovum
Intracytoplasmic sperm injection directly delivers a single sperm into the oocyte cytoplasm.
What is the appropriate first principle when evaluating an infertile couple?
(d) Assess both partners because male, female, combined, or unexplained factors may occur
Infertility is a couple-level clinical issue with multiple possible sources.
Wrong
Any method that prevents pregnancy also reduces the chance of a sexually transmitted infection.
Why it feels right. I am applying the pregnancy protection to a second outcome.
Right
Pregnancy prevention and STI risk reduction depend on different mechanisms.
Worked example
