EMBRYOLOGY
FERTILISATION EARLY DEVELOPMENT OF EMBRYO AND IMPLANTATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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several million
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a few hundred
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one
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six to ten
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Detailed explanation-1: -Around 300 million sperm are typically released during sex, but only about 200 sperm will reach the egg.
Detailed explanation-2: -Occasionally, two sperm are known to fertilize a single egg; this ‘double fertilization’ is thought to happen in about 1% of human conceptions. An embryo created this way doesn’t usually survive, but a few cases are known to have made it-these children are chimaeras of cells with X and Y chromosomes.
Detailed explanation-3: -An egg fertilized by three sperms receives two extra chromosome sets, resulting in a quadruploid individual with 92 chromosomes. Extra chromosome sets directly harm sex determination. A triploid individual, for instance, has an abnormal combination of sex chromosomes (XXX, XXY or XYY).