Question

In humans, fertilization usually occurs ________ after intercourse, if an egg is present.

1) 24-48 hours
2) 3-6 days
3) 6-24 hours
4) 7-10 days
5) 10-12 days

Answer 1

Fertilization in humans typically occurs 6-24 hours after intercourse, given that an egg is available, with sperm being able to survive in the uterine tubes for 3-5 days.

Step-by-step explanation:

In humans, fertilization usually occurs 6-24 hours after intercourse if an oocyte (egg) is present. After ejaculation, millions of sperm are released into the vagina, but due to the acidity of the vaginal environment and other barriers, only a few thousand might make it to the uterine tubes where fertilization typically occurs. Sperm can survive in the uterine tubes for 3-5 days post-intercourse, giving them some time to meet an egg, whereas the oocyte can survive for about 24 hours after ovulation. This means intercourse more than a day after ovulation is not likely to lead to fertilization. Implantation of the fertilized egg then occurs eight or nine days later.