#Question id: 5000
#Unit 9. Evolution & Diversity of Life Forms
The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that
#Question id: 5001
#Unit 9. Evolution & Diversity of Life Forms
Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers. If some of these feather-bearing dinosaurs incubated clutches of eggs in carefully constructed nests, this might be evidence supporting the claim that
#Question id: 5002
#Unit 9. Evolution & Diversity of Life Forms
All animals with eyes or eyespots that have been studied so far share a gene in common. When mutated, the gene Pax-6 causes lack of eyes in fruit flies, tiny eyes in mice, and missing irises (and other eye parts) in humans. The sequence of Pax-6 in humans and mice is identical. There are so few sequence differences with fruit fly Pax-6 that the human/mouse version can cause eye formation in eyeless fruit flies, even though vertebrates and invertebrates last shared a common ancestor more than 500 million years ago.
The appearance of Pax-6 in all animals with eyes can be explained in multiple ways. Based on the information above, which explanation is most likely?
#Question id: 5003
#Unit 9. Evolution & Diversity of Life Forms
Fruit fly eyes are of the compound type, structurally very different from the camera-type eyes of mammals. Even the camera-type eyes of mollusks, such as octopi, are structurally quite different from those of mammals. Yet, fruit flies, octopi, and mammals possess very similar versions of Pax-6. The fact that the same gene helps produce very different types of eyes is most likely due to
#Question id: 5004
#Unit 9. Evolution & Diversity of Life Forms
Pax-6 usually causes the production of a type of light-receptor pigments. In vertebrate eyes, though, a different gene (the rh gene family) is responsible for the light-receptor pigments of the retina. The rh gene, like Pax-6, is ancient. In the marine ragworm, for example, the rh gene causes production of c-opsin, which helps regulate the wormʹs biological clock. Which of these most likely accounts for vertebrate vision?
#Question id: 5005
#Unit 9. Evolution & Diversity of Life Forms
Fossilized stromatolites