Multiple choice

Which of the following is NOT membrane-bound?

  1. Nucleus

  2. Mitochondria

  3. 70S Ribosomes

  4. Chloroplast

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ribosomes (such as 70S ribosomes in prokaryotes, mitochondria, and chloroplasts) are macromolecular complexes of RNA and proteins and do not possess a surrounding lipid membrane. The nucleus, mitochondria, and chloroplasts are all bound by double membranes.