- Of all the possible amino acids, all living organisms make use of only the same 20 amino acids. This supports the idea that only a limited number of DNA mutations are possible. only 20 amino acids exist on Earth. bacteria, animals, and plants developed independently. natural selection drives evolution. all living things are derived from a single common ancestor.
- The common edible frog of Europe is a hybrid between two named species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia.Both male and female hybrids exist, but when they mate among themselves they rarely produce offspring Which of the following statements is the best inference about the two Rana species? They are different species and postrygotic isolation exists between the two frog species. Prezygotic isolation exists between the two frog species. The hybrids form a separate species under the biological species concept. The two species are likely in the process of fusing back into one species.
- 6. Identify the endocrine organ described by each of the following statements. __ 1. located in the anterior neck; produces key hormones for metabolism __ 2. produces the hormones that are stored in the posterior pituitary __ 3. a mixed gland, located behind the stomach and close to the small intestine __ 4. paired glands suspended in the scrotum __ 5. bilobed gland located ir the sella turcica __ 6. found in the pelvic cavity of the female concerned with ova and female hormone production __ 7. found in the upper thorax overlying the heart;large during youth __ 8. found in the roof of the third ventricle of the brain
- Two juniper trees (Juniperus scopulorum and J. monosperma)have overlapping geographic ranges Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells)of the other species.Which of the following isolating mechanisms keeps the two species separate? gametic isolation habitat isolation temporal isolation behavioral isolation
- Which of the following provides an example of a mechanical isolation as a prezygotic barrier? two snails have shells that spiral in different directions two species mate at different times two species share courtship activities D two species live in different habitats
