Question

why are mitochondria and chloroplast called semiautonomus organelles?

Answer 1

Some organelles enjoy some amount of autonomy or independence like in growth, division, production of some enzymes, hence called as semiautonomous organelles and Mitochondria and chloroplast fall in this category. They are able to do this because they have their own DNA/ genome.

Answer 2

Mitochondria and chloroplast is called semi autonomous organelles because they contain their own DNA and replicate independently.

hope it helps.... :)