The lack of access to the healthy food has caused the growth of Sebastian to slow down. In the case healthy food is provided to him, he can grow into the size he was genetically suited to. This process is known as the canalization. Canalization term is used as the measure of the ability of any given genotype to result in the same phenotype in-spite of the environmental variability.
The answers are the following:
- composed of DNA: Both
- blue eye trait: Recessive
- takes precedence over the other: Dominant
- codes for physical traits: Both
- brown eye trait: Dominant
- expressed only when present in both parents: Recessive
Chromatids are only called as chromatids when they are sister chromatids, meaning that when chromosome have two double stranded DNA attached together, each of the double stranded DNA is a sister chromatid, and while the whole thing (the two sister chromatids that are attached together) is called a chromosome.
So after the DNA has been replicated, the chromosome consist of 2 sister chromatids, attached to each other at their centromere.
Overall, sister chromatid is one of the two double stranded DNA in a replicated chromosome, and chromosome is the whole "X" shape that we see. For example, in humans, after the S phase of interphase in the cell cycle, we have 46 chromosomes, with 92 chromatids, since each chromosome is an "X" shape, by having two sister chromatids.
Hope this helps!