Describe two different methods used for measuring the expression of very large number (thousands) of genes . Compare the two methods and comment on...

1. Describe two different methods used for measuring the expression of very large number (thousands) of genes. Compare the two methods and comment on advantages of one over the other. 

2. All mRNAs are present at the same level in all tissues irrespective of the condition or the type of tissue. Is this statement true or false? Explain!