Fig. 1 shows a fetus in the uterus at about 20 weeks of pregnancy. A midwife uses a similar diagram to explain the exchange between the pregnant person's bl...
Question 1 Report
Fig. 1 shows a fetus in the uterus at about 20 weeks of pregnancy. A midwife uses a similar diagram to explain the exchange between the pregnant person's blood and the fetus. The placenta has a large surface area and contains blood vessels from both the fetus and the mother. In a normal pregnancy, the two blood supplies remain separate. The umbilical cord carries blood between the fetus and the placenta. The fetus needs oxygen and glucose for respiration and growth, while carbon dioxide must be removed from its body.
(a) What is structure X? [1]
(b) Give two substances that move from the mother's blood into the fetal blood at Y. [2]
(c) Describe how carbon dioxide made by fetal cells is removed from the fetus. [2]
(d) Explain why the maternal and fetal blood do not normally mix directly. [2]
(e) When does implantation occur during human reproduction? [1]
(f) Give two health choices during pregnancy that reduce risks to fetal development. [2]
Answer Details
(a) Structure X is the placenta. [1]
(b) Accept any two substances moving from maternal to fetal blood at the placenta: oxygen, glucose, amino acids, or antibodies. [2]
(c) Carbon dioxide travels in fetal blood along the umbilical cord to the placenta [1]. It diffuses into the mother's blood and is removed by her lungs [1].
(d) The blood supplies do not normally mix directly because this prevents direct mixing of different blood groups [1], which could trigger an immune reaction or damage blood cells [1].
(e) Implantation occurs when the embryo attaches to or embeds in the lining of the uterus. [1]
(f) Accept any two: avoid alcohol; do not smoke; eat a balanced diet; attend antenatal appointments; avoid non-prescribed drugs. [2]
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