The answer is b the viral envelopes subdivided to cap some res in some viruses
Answer: E). Acetate enters the citric acid cycle and joins a four-carbon acceptor molecule to form citrate.
Explanation: Acetyl CoA enters the citric acid cycle and combines with oxaloacete (a four carbon acceptor molecule) to form citrate. Citric acid cycle is a cycle of eight enzyme catalyzed reactions in which acetyl CoA from pyruvate is oxidized to generate ATP/GTP, NADH and FADH2. Decarboxylation occurs in citric acid cycle at two steps catalyzed by isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase complex. Substrate level phosphorylation occurs at the step catalyzed by succinyl CoA synthase in which GTP is produced from addition of a phosphoryl group to ADP.
These are some ways how scientists and engineers develop, use and refine models.
1. Imagine. They have to know what exactly trying to model. They have to imagine and brainstorm what are the things to be considered.
2. Reason. Next, they need to answer the questions brought from their brainstorming. They need to be able to reason out.
3. Calculate and Predict. Once they know it, that's the time they can start modelling and calculate - and predict.
If the cell membrane were not selectively permeable, then unwanted substances would transfer through instead of being blocked out. Think of it like this: you have a sifter with various sizes of spice in it. You only want the finer grains of spice in your food, so when you shake the sifter, the larger pieces of spice don't fit through the small holes that only allow fine grains. Then you are left with the small spices in your food and the large ones stuck in the sifter.
Hopefully this helps and I wasn't too confusing :)