Question

Killer whales are an endangered species. The decline in the whales’ numbers has been linked to poor nutrition, resulting in the inability to maintain a pregnancy. This risk to developing whale embryos is most likely a result of

(1) an environmental factor not associated with the embryo’s genes
(2) an infection caused by the embryo’s exposure to a pathogen
(3) faults in the genes of the embryo itself
(4) toxins that are introduced into the mother
from the embryo’s blood

Answer 1

Answer: The risk to developing whale embryos, resulting in the decline of killer whale numbers, is most likely a result of toxins that are introduced into the mother from the embryo's blood. Therefore, option (4) "toxins that are introduced into the mother from the embryo's blood" is the most likely cause.

Toxins can accumulate in the mother's body through various mechanisms such as bioaccumulation or biomagnification in the food chain. When the mother killer whale is exposed to toxins, they can be transferred to the developing embryo through the placenta and the mother's blood circulation, potentially causing harm to the embryo's development.

These toxins can have adverse effects on the embryo's health and development, including poor nutrition, compromised immune system, and reproductive issues. In the case of killer whales, the poor nutrition resulting from exposure to toxins can lead to difficulties in maintaining a pregnancy and ultimately contribute to the decline in whale numbers.