Question

one argument that is commonly cited to support the idea that birds lack a sense of smell is that some birds olfactory bulbs are relatively small. as a result, many scientists concluded that these creatures gave up smell in favor of improved eyesight. this notion became so pervasive that it once was repeated to avian expert danielle whittaker as fact by a prominent neurobiologist.
4 mark for review
which finding, if true, would most undermine the neurobiologist’s statement?
a an analysis of avian genomes revealed the presence of proteins that bind to odors and relay a signal to the brain.
b the number of olfactory neurons is much smaller in birds than in most other animals.
c the odors that birds depend on for food and social relationships are quickly dispersed in the wind.
d birds sometimes overlook strongly scented prey in favor of animals that are more visually striking.

Explanation:

The neurobiologist's statement is that birds lack a sense of smell (supported by small olfactory bulbs). To undermine this, we need evidence showing birds do have a sense of smell. Option A shows avian genomes have proteins for odor detection and signal relay, indicating a sense of smell. Option B (fewer olfactory neurons) and D (overlook scented prey) support the idea birds lack smell, and C (odors disperse) is irrelevant to whether they can smell.

Answer:

A. An analysis of avian genomes revealed the presence of proteins that bind to odors and relay a signal to the brain.