Q4. An embryo formed in the laboratory has reached the 16-cell stage. Into which organ would it be transferred, and what is the technique called?
In NCERT’s comparison, the uterus by IUT, because 16 exceeds 8 (page 48). Modern uterine embryo transfer also includes earlier cleavage stages; this threshold is not an absolute clinical rule.
Q5. Which technique helps a female who cannot produce ova but can provide a suitable environment for fertilisation, and what is transferred?
NCERT illustrates donor-ovum GIFT (page 48). More generally, GIFT transfers eggs and sperm into a tube for fertilisation in the body.
Q6. Why are assisted reproductive technologies available to only a limited number of people?
They need extremely high precision handling by specialised professionals and expensive instrumentation, so cost and access can limit use; emotional, religious and social factors also deter their use (NCERT page 48).
Q7. A clinic transfers an eight-cell embryo into the uterus. Does NCERT’s eight-cell comparison make this biologically impossible?
No. Modern IVF includes uterine transfer of cleavage-stage embryos. NCERT contrasts ZIFT and IUT using cell numbers, but this is not a universal clinical cutoff.