ZOO3603C Exam 3 Questions And Answers (Verified And Updated)

ZOO3603C Exam 3 Questions And Answers (Verified And Updated) Trigger for Limb Development - answerDecreasing food, decreasing reproductive opportunities, more competition From which group of fish did tetrapods arise from? - answerRay-finned fishes (actinopterygii) and lobe-finned fishes (sarcopterygii) Which ancient fish limbs is more likely to have evolved into tetrapod limbs? - answerCoelacanth fin strucutre (homologous elements) What digit limb evolved first? - answerFive digit limbs (not a basal trait of all tetrapods) Pentadactyl limbs - answerBetter weight bearing (fin with a wrist) Where do digits come from? - answerLepidotrichia lost at the same time as new autopods evolved (lose and gain digits at the same time) Tetrapod limb is made up of two independent parts Hox genes involved in autopod appearance - answeras you knock out genes of the Hoxd13 group you decrease the length and lose digits How did limbs evolve? - answerSecond domain of Hoxd expression Zebrafish limb development - answerNo second domain and the genome duplicates again to create 8 Hox genes What does Hox13 knockout do in zebrafish? - answerDeletes lepidotrichia What does double and triple knockout of Hoxa and Hoxd do? - answerreduces or deletes autopod and fin rays What do alternating enhancers do? - answerChange limbs (not genes) Are lepidotrichia homologous to digits? - answerTrue Python gene expression and what is it caused by? - answerLow Shh expression = reduced hindlimbs Caused by a change in the enchancer known as ZRS