IGCSE Biology Paper-2: Specimen Questions with Answers 143 - 144 of 203

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Explanation

• The Foetus and embryo develop within the uterus, an organ that sits within the pelvis of the mother. The process the mother experiences whilst carrying the Foetus or embryo is referred to as pregnancy.
• The placenta connects the developing Foetus to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother’s blood supply; to fight against internal infection; and to produce hormones, which support pregnancy.
• The placenta provides oxygen and nutrients to growing fetuses and removes waste products from the fetus’s blood. The placenta attaches to the wall of the uterus, and the fetus’s umbilical cord develops from the placenta.

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Answer

Explanation

Fertilization

• Definition: fertilization The fusion of the haploid male gamete (the sperm) and the haploid female gamete (the ovum) to form a diploid zygote is called .
• In human beings, fertilization takes place mostly in the ampulla of the oviduct. After insemination (i. e. discharge of semen in the female vagina close to the cervix), the sperms travel all the way up towards the uterus but only a few thousand find their way into the openings of the fallopian tubes.
• Primarily the contractions of the uterus and the fallopian tubes assist the sperm in movement but later on, they move by their own motility. Sperms swim in the fluid medium at the rate of 1.5 to 3 mm per min to reach the site. In the meantime, the leucocytes of the vaginal epithelium also engulf millions of the sperms.

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