Question

1. 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:

To solve this, we use the base - pair rules in DNA: Adenine (A) pairs with Thymine (T), so \( \%A=\%T \); Guanine (G) pairs with Cytosine (C), so \( \%G = \%C \). Also, the sum of all base percentages is \( 100\% \), i.e., \( \%A+\%T+\%G+\%C = 100\% \), which can be simplified using the base - pair rules to \( 2(\%A+\%G)=100\% \) or \( \%A+\%G = 50\% \) (and similarly \( \%T+\%C = 50\% \)).

Step 1: Human

• We know that \( \%A = 31 \) and \( \%C=19 \).
• Since \( \%A=\%T \), then \( \%T = 31 \).
• Since \( \%G=\%C \), then \( \%G = 19 \).
• We can also verify using \( \%A+\%G+\%C+\%T=31 + 19+19 + 31=100 \), which is correct.

Step 2: Cow

• Given \( \%A = 28 \) and \( \%G = 22 \).
• Since \( \%A=\%T \), \( \%T = 28 \).
• Since \( \%G=\%C \), \( \%C = 22 \).
• Verify: \( 28+22 + 22+28=100 \), which is correct.

Step 3: Salmon

• Given \( \%T = 29 \) and \( \%C = 21 \).
• Since \( \%A=\%T \), \( \%A = 29 \).
• Since \( \%G=\%C \), \( \%G = 21 \).
• Verify: \( 29+21+21 + 29=100 \), which is correct.

Step 4: Wheat

• Given \( \%A = 27 \).
• Since \( \%A+\%G=50\% \) (because \( \%A+\%T+\%G+\%C = 100 \) and \( \%A=\%T,\%G=\%C \)), then \( \%G=50 - 27=23 \).
• Since \( \%G=\%C \), \( \%C = 23 \).
• Since \( \%A=\%T \), \( \%T = 27 \).
• Verify: \( 27+23+23 + 27=100 \), which is correct.

Step 5: Yeast

• Given \( \%A = 31 \) and \( \%G = 19 \).
• Since \( \%A=\%T \), \( \%T = 31 \).
• Since \( \%G=\%C \), \( \%C = 19 \).
• Verify: \( 31+19+19 + 31=100 \), which is correct.

Now we can fill the table:

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

Answer:

The completed table is as shown above. For each organism, the percentages are calculated using the base - pair rules (\( \%A=\%T,\%G = \%C \)) and the fact that the sum of all base percentages is \( 100\% \).