From a test construction perspective, that data doesn't tell you very much unless you also know how those percentages break down among students at different levels. Ideally, the best students overall would be the ones getting it right, but it may also be a poorly written question where both high and low scoring students have equal chances of getting it right.
From UWorld's perspective, they will often write "bad" questions with flawed answers because their aim is to teach rather than examine. In this case, tricky and somewhat misleading answer choices combined with vague/incomplete stems may be playing a role, but these are designed to help you learn subtle distinctions that will benefit you later.
In the questions you listed above, without looking at the stems it's still pretty obvious what the stems had to say, so these are not bad questions at all. Biochemistry is generally a weaker area for students overall and thus you often see these sporadic distributions. After describing a pathway or a disease resulting from a pathway defect, I can ask which part of that pathway is defective and simply list A through E with plausible enzymes. Students with strong understanding will select the correct options, but less informed students will be more likely to go for any option that sounds familiar.
In your case, I think it means your biochemistry is weak but you're not alone. Depending on your overall performance thus far, it may or may not be worth investing the time to strengthen this area. For example, if you're averaging 220s right now with weakness across all areas, then biochem is pretty low yield and may not be worth the time. If you're averaging 240s and looking to hit 250s and 260s, then biochem may be worth some additional time.
