The excretory system allows animals to remove metabolic waste their bodies. Many of these substances are potentially toxic. in Mammals nitrogenous toxins like urea are expelled through liquid urine while in reptiles and birds the nitrogenous compounds are expelled as a solid. This allows birds and reptiles to use less water in the processes of metabolism.
To transcribe the mRNA to make the DNA, we use genetic codes called codons. These are composed of three amino acids clumped together. It could be Adenine(A), Guanine(G), Uracil(U) and Cytosine (C). The difference is that first thread contains GUG, while the second one contains AGU. GUG is for Histidine while AGU is for Serine.
I would answer with A. cell membrane
I know it's not B. ribosome for a fact
descriptive statistics sum of all numbers divided by the total number of scores; the average = mean
the number that occurs the most often in a given set of number = mode
relationship between two variables = correlation
the middle number in a set of ordered numbers = median