In the 1950s, christian anfinsen demonstrated the renaturation of the protein ribonuclease (rnase) in vitro. after reduction (to reduce the disulfide links) and the addition of urea (to denature the protein), the protein was in an unfolded state. after removing the urea and the reducing agent, the protein refolded, with greater than 90% activity. if the urea were removed after oxidation occurred, the protein had less than 5% activity. why would the protein not refold correctly if the urea were removed after the reducing agent was removed? (in other words, what would happen if the urea were removed after oxidation? ) choose the best answer. a. disulfide bonds are not positioned correctly unless weak bonding interactions are present. b. urea would participate in weak bonding interactions with rnase, preventing oxidation of cys. c. contaminants in the rnase preparation would form covalent bonds with the protein, d. the protein would not fully unfold (denature). preventing reactivation.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.