Answer:
The text needs commas in the following lines
* Which includes the outermost layer, the inner layer, and the smallest part of the grain.
* Together, they make a whole grain.
* Are not as nutritionally powerful, for they lack the vitamins and fiber that the two outer layers of grain provide.
* A general recommended daily intake of grains amounts to about one cup of cereal at breakfast, two slices of whole-grain bread at lunch, and one cup of pasta or rice at dinner.
Explanation:
The added commas in the first and fourth sentences are examples of elements making a list which have to be connected by commas one after each one until the last one that adds the word and. The comma in the second sentence is used as the rule for connectors at the beginning of a sentence, and finally, the last example follows the rule of a comma before because since for has the same use in this example.
