When eukaryotes make mRNA, they add a 5' cap and a poly-A tail to protect the mRNA from being destroyed by ribonucleases (enzymes that break down RNA). But why do cell have ribonucleases to begin with? Why would cells to break down the mRNA it went through all the trouble to make? Use an example to explain your answer.

Which of the following is not a benefit of green revolution? a) new crop varieties b) increased crop yields c) cost effective d) new crops may require larger amonts of water than the previous ones.

Math focus 4. calculate a map has index contours at 250 m, 500 m, and 750 m. what is the contour interval?

You will create a molecular clock model for an arthropod gene. follow these guidelines to make your model: . your timeline will span from 90 million years ago to the present. the common ancestor in your model is an arthropod that lived 90 million years ago. the gene that you'll track codes for a protein in the species venom . the dna sequence youll track contains 10 nitrogen bases. you can choose the order of the bases and where the mutations occur. this gene mutates at a rate of approximately 0.76 base pairs every 17.1 million years. to build your model,/ calculate the estimated time period it takes for 1 base pair to mutate. the first time period will only show the common ancestor. at the beginning of the second time period, three lineages will diverge from the common ancestor, each with a different mutation in their gene sequences. the first and third descendant species will survive for the rest of the timeline. the second descendant species was extinct 50 million years ago. calculate how long it will take for one full base pair mutation to occur. explain your reasoning by constructing a mathematical equation