Question

1. dna molecules can be tens of thousands of base pairs in length. mistakes in dna replication lead to mutations, which may or may not be harmful to an organism. how does semi - conservative replication help prevent mutations during dna replication?
2. the proportions of the bases are consistent within a species; however they do vary between species. using the base - pair rules, complete the following table to show the percentage of each type of base in the five different organisms.

organism	percentage of each type of base
human	31		19
cow	28	22
salmon			21	29
wheat	27
yeast	31	19

Explanation:

Step1: Recall base - pair rules

In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). So, the percentage of A = T and the percentage of G = C.

Step2: Calculate missing values for Human

Since A = 31%, then T = 31%. Since C = 19%, then G = 19%.

Step3: Calculate missing values for Cow

Since A = 28%, then T = 28%. Since G = 22%, then C = 22%.

Step4: Calculate missing values for Salmon

Since C = 21%, then G = 21%. Since T = 29%, then A = 29%.

Step5: Calculate missing values for Wheat

Since A = 27%, then T = 27%. Since G+C = 100-(27 + 27)=46%, then G = C = 23%.

Step6: Calculate missing values for Yeast

Since A = 31%, then T = 31%. Since G = 19%, then C = 19%.

Answer:

Organism	Adenine	Guanine	Cytosine	Thymine
Cow	28	22	22	28
Salmon	29	21	21	29
Wheat	27	23	23	27
Yeast	31	19	19	31