Blog
Chemistry question bank now live Free
The Chemistry question bank (qBank) is now up and running on this site. Information on how to access it can be found in Using student access. It contains brand new multiple choice type questions and...
Blog
How precious metals were first formed Free
In the week when the price of the precious metal palladium reached $1000 per ounce it was interesting to see that the problem as to how precious metals such as gold, silver, platinum and palladium were...
eBook
Nucleic acids answers
1. (a) Hydrogen bonding (b) Show two bonds between thymine and adenine and three bonds between cytosine and guanine in the correct positions. (c) A sugar (deoxyribose) and a phosphate group. (d) The...
eBook
Stereochemistry in biomolecules questions
1. (a) Draw 3-D representations of the two enantiomers of cysteine that show clearly that they are mirror images of each other. (b) Identify, with a reason, which of the two configurations you have drawn...
eBook
Stereochemistry in biomolecules answers
1. (a) (b) The one on the left is the D- isomer and the one of the right, the L-configuration, is the one that occurs in proteins. (c) Glycine (0), isoleucine (2), threonine (2) 2. (a) Cis/trans isomerisation...
eBook
Biological pigments questions
1. Cyanidin is an anthocyanin found in berries and other fruits. The diagram below shows the structure of cyanidin in acidic solution and in alkaline solution. (a) Explain why cyanidin is coloured in...
eBook
Biological pigments answers
1. (a) In both acidic and alkaline solution cyanidin contains extensive conjugation. The delocalised pi electrons absorbs energy in the visible region of the spectrum as they are excited (to an empty...
eBook
Nucleic acids questions
1. Two strands of nucleotides bond together to form the double helix structure of DNA. This bonding is caused by the pairing of particular nitrogen-containing bases. The diagram shows the two different...
eBook
Proteins & enzymes (HL) questions
1. The graph below shows how the rate of an enzyme-catalysed reaction varies with the concentration of substrate when there is no inhibitor present, when there is a competitive inhibitor present and in...
eBook
Biochemistry & the environment questions
1. DDT was used extensively as an insecticide against malaria until its use was banned in many countries. One of the reasons for the ban was the effect it had on wildlife – particularly certain birds...