1 Which of the following statements about DNA is false a DNA

1. Which of the following statements about DNA is false?

a) DNA contains deoxyribose as its sugar

b) DNA contains the base thymine

c) DNA is double-stranded

d) DNA exists as an alpha-helix

e) None of the above

2. If glucose needs to enter a cell:

a) it will most likely do so by simple diffusion down its concentration gradient.

b) it will most likely require ATP to enter a cell.

c) it will most likely use a protein carrier to cross the lipid bilayer.

d) it will most likely use a hydrophilic pore to cross the lipid bilayer.

e) glucose doesn’t enter cells; they manufacture it.

Solution

Answer :

Question number 1 : The correct answer is D (DNA exists as an alpha-helix). Alpha helix is one of the secondary structures found in proteins. In an alpha-helix, the protein chain is coiled like a loosely-coiled spring. The polypeptide backbone is coiled up like a very tight clockwise screw thread or the cord of a telephone.

Features of alpha helix.

Question number 2 : The correct answer is C (it will most likely use a protein carrier to cross the lipid bilayer.)

Supplementary information : Glucose transport in to the cells occurs by facilitated diffusion which is kind of passive transport.Facilitated diffusion transport across the membrane if facilitated by specific permeases in the membrane.Example: Glucose transporter through erythrocyte plasma membrane