It is known to all that the technological and scientific advances have made greater changes to the range and quality of our food. Some people regard it as an improvement while others believe that the change is harmful. Discuss both views and give your own opinion.
Recent years have witnessed the(删) great changes in the range and quality of our food due to the(删) advancements(advances或者advancement) in technology and science. When it comes to the effects of these changes on people's life, some people regard it a huge step of human beings while others worry that these changes may have negative effects on people’s lives. It is true that both of the views have their reasons.
第二句显得啰嗦，不如直接说：some people regard these changes as a huge step forward for the mankind while others worry that they may have negative effects on people’s lives.
第三句，改为：in my opinion, both views have their own validity.(注意，在表达你的观点时，要表达出“这是我的观点”，而不是随随便便地用上你的原话中it is true…)
On the one hand, it is undeniable that people's quality of life is (has)improved dramatically since the remarkable development in technology and science indeed helps in dealing with several well-known problems that we human beings are faced with. One of the most important one(problems)may be the(删 )food shortage. Unlike decades before, many countries have gotten rid of this problem successfully due to the outcome(applications)of genetic engineering. Besides, scientific developments also bring people better ways to store grains and other food properly. This is fairly vital because fewer people would be under threat of eating decayed food, especially in impoverished countries.
评：首句过长。雅思写作潜规则：写作句子长度一般不要超过30。更重要的是，该topic sentence也稍有跑题，要知道本文话题是“changes to food brought by S&T是好还是坏”而不是“development in S&T是好还是坏”。建议修改，比如：On the one hand, the world can better feed itself since some major food problems are being effectively tackled by advanced science and technology in agriculture and other fields.
On the other hand, many people worry that these changes may have influenced their lives in a negative way. For example, modifying the gene of grains is still a heated debate nowadays since some of the scientists argue that this may lead to some uncertain ends, to some extent, even to be destructive. What is more, as it turns out that some precious animals and disgusting insects own abundant nutrition, many of them are becoming dishes nowadays while in past decades most of them would never be cooked. This may be a challenge to traditions and cultures in many counties.
评: 这一段的论证较为孱弱。食品科技的不良影响，1.转基因食品(genetically-modified food)的长期影响还未可期。2.大量反季节食品的安全性存疑(anti-season food)。3.零食的大爆炸(explosive increase of snack category)应当是现在肥胖问题的一个原因。文中提到的unconventional foods对传统文化造成冲击，这个可以说主观性太强，与话题也无关(科技带来的食物变化!难道，在科技不发展的年代，人们不会吃这些东西?)。并且，你用上了“disgusting”，这种强烈色彩的词慎用!如果，考官正好是一个喜欢昆虫食物的人，你就完蛋了。
From my personal perspective, the advantages outweigh the disadvantages. Although there tends to be some uncertainty in such changes, the progress of technology and science already give people a(删) great means to tackle a variety of urgent problems and I believe such changes will make more contribution to people's lives in the long term.
评：从结论看到，你chose a side，那么为何在导入段没有表明你的这个立场呢，这很让人费解。