#Question id: 4972
#Unit 11. Evolution and Behavior
Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Anatomically, what was true of Lystrosaurus?
#Question id: 12529
#Unit 6. System Physiology – Plant
#Question id: 2668
#Unit 2. Cellular Organization
The toxic shock syndrome toxin is produced by some Salmonella species when there is not sufficient iron present. When iron is present, it prevents transcription of the TSS-toxin gene. Iron therefore serves as __________.
#Question id: 30110
#Unit 1. Molecules and their Interaction Relevant to Biology
The ribose phosphate group of purine nucleotide is taken from which compound?
#Question id: 54
#Unit 1. Molecules and their Interaction Relevant to Biology
About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter?