Where do the lipids and proteins constituting cell membranes get synthesized?
a) Smooth endoplasmic reticulum (SER) and ribosome respectively
b) Ribosomes and SER respectively
c) Mitochondria and lysosome respectively
d) None of the above

Hint: An endoplasmic reticulum that does not bear ribosomes on their surface so they appear smooth and named as smooth endoplasmic reticulum, instead if ribosome is found on the surface, they are rough endoplasmic reticulum. Mitochondria is metabolic energy production while lysosome is the defence unit of the cell.

Complete answer:
Smooth endoplasmic reticulum surface appears smooth. This is because it doesn’t bear ribosomes on its surface. Hence it derives its name Smooth endoplasmic reticulum. Its primary role is to synthesize lipids. Later on, they are packed, transported by the Golgi apparatus to the cell membrane. The rough endoplasmic reticulum is an association of endoplasmic reticulum with ribosomes. So, its surface appears rough and gets their name as the rough endoplasmic reticulum. The rough endoplasmic reticulum is found in association with the nucleus of the cell. So, they are involved in protein synthesis. Mitochondria is a double membranous organelle that generates ATP while. So, they are called the Powerhouse of the cell. Lysosomes are unit membrane organelle. They secrete & store digestive enzymes. Sometimes it bursts & kills an entire cell. They are called the suicidal bag of the cell.
Hence, the correct answer is (A) Smooth endoplasmic reticulum (SER) and ribosome respectively.

Note: Lipids and protein are macro biomolecules that are synthesized by the endoplasmic reticulum. The SER synthesizes lipids while RER makes protein. Lysosome defends cells against pathogens & protects it. They release the digesting enzymes & digests the pathogen. Mitochondria generate energy in the form of ATP molecules. ATP is the energy currency of the cell.