Question: David was working in his chemistry lab. He selected two isotopes, sample A and sample B. Sample A had longer half-life, but sample B had shorter half-life. After some time he checked sample A when its one half-life had passed. He noted it as sample A1. Then he came back to see it again when two half-lives had passed. He noted it as sample A2. Would sample A2 have less or more isotopes than sample A1? Hint: Each radioactive isotope has a characteristic decay time periodthe half-lifethat is determined by the amount of time needed for half of a sample to decay. This is an exponential decay process that steadily decreases the proportion of the remaining isotope by 50% every half-life. Hence after two half-lives have passed only 25% of the isotope is present, and so forth.
Answer: less

Question: Dan studied genetic engineering. He was applying his knowledge of genetic engineering to develop better crops. Recently, he had successfully developed a crop, crop A, that was herbicide tolerant. To determine the versatility of the crop he compared it with another crop that was not tolerant of herbicides, crop B. The results of his research would allow his company to market the new crop. Would crop B need less or more number of chemicals than crop A? Hint: In addition to insects, weeds have also been a menace to farmers - just ask anyone with a garden how much they hate weeds. They can quickly compete for water and nutrients needed by other plants. Sure, farmers can use herbicides to kill weeds, but do these chemicals also harm the crops? Can biotechnology help with this issue? Some crops have also been genetically engineered to acquire tolerance to the herbicides - allowing the crops to grow, but killing the weeds. But the lack of cost effective herbicides with a broad range of activity - that do not harm crops - is a problem in weed management. Multiple applications of numerous herbicides are routinely needed to control the wide range of weeds that are harmful to crops. And at times these herbicides are being used as a preventive measure that is, spraying to prevent weeds from developing rather than spraying after weeds form. So these chemicals are being added to crops. This practice is followed by mechanical and/or hand weeding to control weeds that are not controlled by the chemicals. Crops that are tolerant of herbicides would obviously be a tremendous benefit to farmers ( Figure above ). The introduction of herbicide tolerant crops has the potential to reduce the number of chemicals needed during a growing season, thereby increasing crop yield due to improved weed management and decreased harm to the crops.
Answer: more

Question: Berg village and Hill village are renowned for the high number of cyclists living there. Berg village dealt with many traffic casualties because of narrower streets and lanes, While Hill village had wide streets, more traffic signals and a greater number of cyclists. Which village had more traffic casualties? Hint: Turner et al (2006) derived crash prediction models for this report's predecessor and found a pronounced 'safety in numbers' effect in the models. Using the crash prediction model for mid-block locations, generic motorist and cyclist volumes can be used to demonstrate the impacts on the expected crash rate of varying motor vehicle and cycle volumes. As shown in figure 2.20, an increase in the proportion of cyclists to the overall traffic volume causes an increase in expected crashes at mid-block locations, but the crash rate increases at a decreasing rate. That is to say, the crash rate per cyclist goes down as the cycle volume increases.
Answer:
Berg