Question

Both whales and humans have mammary glands. This trait can be considered:

1) are a synapomorphy for these species and other mammals
2) are homologous traits
3) were likely present in the most recent common ancestor of humans and whales
4) all are correct
5) none are correct

Answer 1

Mammary glands are synapomorphic, homologous traits that were present in the most recent common ancestor of humans, whales, and other mammals.

Step-by-step explanation:

The trait of having mammary glands can be considered a synapomorphy for whales, humans, and other mammals, as these traits fulfill several criteria. First, mammary glands are homologous traits since they are derived from a common ancestor that all mammalian species share. Secondly, they are indeed a synapomorphy because this trait is shared by all mammals, which helps to define the class Mammalia and distinguish mammals from other vertebrates. Finally, it is reasonable to infer that the presence of mammary glands was likely present in the most recent common ancestor of humans and whales, given that all modern mammals possess these glands. Therefore, the correct answer to the student's question is all are correct.