Question

Mitochondria and chloroplast are:
a) Semi-autonomous organelles
b) Formed by a division of pre-existing organelles and they contain DNA but lack protein-synthesis machinery.
Which one of the following options is correct?
A. Both (a) and (b) are correct
B. (b) is true but (a) is false
C. (a) is true but (b) is false
D. Both (a) and (b) are false

Answer 1

Hint:Mitochondria are capable of self-duplication as they have genetic material DNA, self-transcribed RNAs, protein machinery (ribosomes) etc. Chloroplasts also show autonomy as they can manufacture some proteins with the help of their DNA, RNAs etc.

Complete answer:
>Mitochondria and chloroplasts are double membrane cell organelles present in the cytoplasm. Both multiply by fission, both form ATP. Both are semi-autonomous organelles.
>Mitochondria are semi-autonomous organelles. They are capable of replication. For replication they have genetic material DNA, self-transcribed RNAs (rRNA, tRNA and mRNA), protein making machinery (ribosome), energy producing mechanism (respiratory enzymes), structural proteins. They get other protein from cytoplasm formed by the directions of nuclear DNA. Since the mitochondria are capable of replication, some scientists think they were once independent organisms (bacteria) which later got trapped in larger eukaryotic cells and changed over time.
>Chloroplasts like mitochondria are also semi-autonomous organelles. They manufacture some of their proteins with the help of their DNA, RNAs, enzymes and ribosomes and get others from cytoplasm. >Chloroplasts multiply and increase their number. Some scientists believed that earlier they were photosynthetic prokaryotic cells and got trapped into eukaryotic cells. Both live in symbiotic relationships and with time phototrophs changed into chloroplasts protein.
>Both mitochondria and chloroplasts are self-replicating and have protein synthesis machinery.

Therefore, we can conclude that statement a is true and statement b is false. Thus, the correct option is C.

Note:Both mitochondria and chloroplast show similarities with prokaryotes as they have similar ribosomes i.e. 70S type, similar DNA i.e. circular and similar mode of division. Mitochondria are known as “powerhouse” of the cell and chloroplast are known as “food factories” of plant cells.