skeptical problems from "KAPLAN PCAT"

[cimdy]

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Hi,
😱I come across a very questionable question in KAPLAN PCAT 2008-2009:
1.Nucleotides are linked by
A. Hydrongen bonds
B. phosphotediester bonds
C. covalent bonds
D. van der Waals bonds

What's your choices?
Thanks in advance

 

[DrPavoreal]

A. hydrogen bonds

3 bonds link G to C and 2 bonds link A to T

 

[halekulani]

well it depends
it doesn't specify between two bases

technically it could be phosphodiester bonds

 

[hmmmmm]

diphosphoester bonds aka B

simple 🙂

 

[ChubbyChaser]

The way the question is worded i would say phosphodiester bonds, if it had said on two different strands of DNA or whatnot, it would be hydrogen,

 

[cimdy]

I think so, but the answer is in fact A.

 

[fiteOFFurDEMONS]

Hi,
😱I come across a very questionable question in KAPLAN PCAT 2008-2009:
1.Nucleotides are linked by
A. Hydrongen bonds
B. phosphotediester bonds
C. covalent bonds
D. van der Waals bonds

What's your choices?
Thanks in advance

I'm pretty sure that the answer is A) hydrogen bonds
Aren't the nucleotides in DNA such as Adenine/Thymine and Guanine/Cytosine attached by hydrogen bonds?
Phosphodiester bonds exist between the phosphate group and ribose / deoxyribose sugar.

 

[dt30]

It's an ambiguous question and both A and B are correct.

Hydrogen bonding between base pairs between either RNA or DNA strands.

Phosphodiester bonding between nucleotides on the same strand (i.e. forming the strand backbone).


This type of question almost always seems to show up on biology standardized tests (i.e. GRE subject; PCAT, etc.), and they are usually trying to figure out if you know that its hydrogen bonding between pairs, it was just worded poorly here.

Hope that helps!

 

[nerv12345]

the answer is B (phosphodiester bond)

if it was asking what the NUCLEOTIDE BASES were connected by...it would be A (hydrogen bonds)

 

[hmmmmm]

i just opened up my kaplan

and cmidy is right

kaplan says its A

their reasoning:

"Nucleotides are linked by hydrogen bonds. A always binds to T with 2 H bonds, whereas C and G with 3 H bonds. Note that the phosphodiester bonds are covalent bonds"

don't really get why they included the little note for...

that is totally petarded

EDIT:

are there many ambiguous questions like these on the real pcat?

 

[spicedmanna]

Moving to PCAT forum...

 

[hmmmmm]

the OP double posted

i think you should merge threads

theres already one asking the exact same question

 

[manutdmax]

yeah it will be aswome if someone will provide us with more of these questions that resemble PCAT or a website to exam ourselves..the answer is A

 

[SGPharmD]

I asked my biology professor and she said the answer is B. phosphotediester bonds. Just the base pairs A-T, G-C are held together by hydrogen bonds. She also said that many practice books for PCAT, MCAT, etc. have lots of mistakes in them.