past paper Qs

Question 1

give two types of molecule from which a ribosome is made

Answer 1

RNA and amino acids/ribosomal protein

Question 2

in a eukaryotic cell, the base sequence of the mRNA might be different from the sequence of pre-mRNA - why?

Answer 2

introns are found in pre-mRNA only

splicing , sections of pre-mRNA are removed

Question 3

during pregnancy, cells lining the uterus are an important source of energy for the embryo.

suggest how glycogen acts as a source of energy.

Answer 3

glycogen is hydrolysed (into glucose)

this glucose is then used in respiration

Question 4

how does an enzyme affect a reaction?

(describe a typical enzyme graph)

Answer 4

an enzyme increases the rate of reaction , by lowering the activation energy - this increase is often non-linear