Is each of these statements true for chloroplasts or mitochondrial genomes, both or neither?

a. contain tRNA genes
b. encode proteins that participate in electron transport pathways
c. all genes necessary for function of the organelle are present
d. vary greatly in size from organism to organism

The correct answers are:

a. both

b. both

c. neither

d. only mitochondrial genomes.

Explanation:

Chloroplast and mitochondria are two organelles that have very similar characteristics and are present in plants and eukaryotic cells, respectively. Among the characteristics that both share are that both contain tRNA genes (which play a pivotal role in the inner organelle functions), both encode proteins that participate in electron transport pathways (since both organelles perform electron transport pathway for cellular respiration) and neither have all the genes necessary for function of the organelle are present (they need genomic DNA for this purpose). On the other hand, only mitochondrial genomes vary greatly in size from organism to organism, since chloroplast genome is very consistent, having 120 to 130 genes in total.