Biology Regents Practice Exam

Which of the following is a function of the placenta in mammals?

1. Support the development of the ovary.

2. Transport nutrients and waste between mother and fetus.

3. Produce hormones for sexual reproduction.

4. Facilitate breathing for the fetus.

The correct answer is: Transport nutrients and waste between mother and fetus.

The function of the placenta in mammals primarily includes the transport of nutrients and waste between the mother and the fetus. This organ acts as an interface, allowing for the exchange of essential substances such as oxygen and nutrients from the mother’s bloodstream to the developing fetus while simultaneously removing waste products from fetal blood, which are then eliminated by the mother’s body. This nutrient and waste exchange is crucial for fetal development, as the fetus relies entirely on the placenta for hydration, nourishment, and elimination of waste throughout the gestation period. The placenta also plays a critical role in protecting the fetus from harmful substances and bacteria that may be present in the mother's circulation. Other options might describe processes that are not direct functions of the placenta. For example, supporting the development of the ovary or producing hormones specifically for sexual reproduction does not pertain to the placenta’s role in supporting the embryo and fetus. Additionally, while the fetus does receive oxygen, it does so via the placenta's mediation rather than through direct breathing, which is not a function of this organ. Thus, the emphasis on the placenta's role in nutrient and waste transport clearly highlights its fundamental importance in mammalian reproduction.