Which of the following statement is correct regarding DNA?

a. Differences among organisms reflect different nucleotide sequences in their DNA.


b. Genes are proteins that produce DNA.


c. Each DNA molecule is a single strand of nucleotides.


d. Each organism has its own unique DNA code.


e. DNA relies upon five different building blocks as the alphabet of inheritance.





I have ruled out b, c, and e. I am stuck between a and d. d throws me off because if you are a twin you would have the same DNA code as your twin. Can you please tell me which one is right and why the other statement would be wrong. Thank you in advance.

Which of the following statement is correct regarding DNA?
The answer is A.





B is incorrect because DNA codes for proteins to be made. so DNA produces proteins not the other way around.





C is incorrect because it is a double helix (two strands of nucleotides). RNA is a single stand of nucleotides.





D is incorrect because organisms that reproduce by binary fission have the same DNA. Also monozygotic twins have identical DNA.





E is incorrect because DNA relies on 4 bases (building blocks). they are adenine (A), cytosine (C), guanine (G) and thymine(T) not five. Uracil (U) is not part of DNA Uracil takes the place of Thymine is RNA.
Reply:a
Reply:Tricky question. All of the answers are incorrect. As for answer A, two organisms can have the same DNA sequence, but due to environmental factors you will often see differences. As an extreme example, imagine two twins, one of which is fed well and the other mal-nourished. As such, the two will have significant differences in height and weight, among other measurable traits and will look different.





The reasons against answers b, c and e have been discussed above.





Answer d is very close to correct, but there are cases where two organisms share the same DNA code, as you mentioned in your question and Olive mentioned. The reason against d is that each organism has its own DNA code, but it is not necessarily different from another organism's, so it isn't true that each organism has its own unique DNA code.





So, having to pick an answer, we have to go back to answer A and look at it again. The answer has to be A, but in order for it to be correct, it has to be argued that, instead of the word differences, the teacher meant to use the word variations. Variations is a term in genetics that indicates different nucleotide sequences. "Differences" is a little too generic and in this case caused a lot of confusion.
Reply:It all depends upon which police department you are dealing with. They will take anything and everything which will prove that their prime suspect is the perp.
Reply:Hi there,


A is correct. Not only does it change according to our species/organism, it changes towards to individual as well (which is why we are all different)





B is correct. Genes code for proteins in a process called Translation and Transcription.





C in incorrect. A DNA molecule is two strands of nucleotides joined together in a double helix.





D is correct; for the same reason in A. Twins are an exception to the rule, but in essence, they are clones! However, differences in environment lead to personality differences and differences in interest. You were right to ask though; impressive thinking!





E is correct. The different building blocks are Adenine, Guanine, Cytosine, Thymin and Uracil





Hope this helps,


Tom
Reply:I agree with "Oliveyou2" except for the explanation for "d." I assumed that "d" meant that each different TYPE of organism has its own unique DNA code, which is correct (frogs versus humans versus E. coli have different DNA codes). If "d" means that each individual has it own unique DNA code, then it is incorrect for the reason given by Olive.

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