Question

Consider the following statements:

$\left(a\right)$ In prokaryotic cell, an outgrowth of plasma membrane into cell is called polysome.
$\left(b\right)$ $\text{SER}$ is major site for glycoprotein synthesis.
$\left(c\right)\text{RuBisCO}$ is most abundant protein of biosphere.
$\left(d\right)$ Mitochondria, chloroplasts and peroxisomes are not part of endomembrance system.

Of the above statements:

• A. $c$ and $b$ alone are correct
• B. $b$ and $a$ alone are correct
• C. $c$ and $d$ alone are correct
• D. $a$ and $d$ alone are correct

Answer 1

The correct option is C $c$ and $d$ alone are correct

Statement $a$

Statement: In prokaryotic cell, an outgrowth of plasma membrane into cell is called polysome.

Elaboration: During prokaryotic translation, multiple ribosomes are associated with a single mRNA molecule. Therefore, multiple peptides are formed simultaneously from a single mRNA molecule.

There is a bead on string structure with multiple ribosomes associated with a single mRNA and this structure is called a polyribosome or polysome. Hence, statement $\left(a\right)$ is wrong.

Statement $b$

Statement : $\text{SER}$ is major site for glycoprotein synthesis.

Elaboration: Glycoprotein synthesis occurs in the rough endoplasmic reticulum and golgi apparatus sequentially. Lipid and glycogen synthesis occurs in the smooth endoplasmic reticulum. Hence, statement$\left(b\right)$ is wrong.

Statement $c$

Statement : $\text{RuBisCO}$ is most abundant protein of biosphere.

Elaboration: $\text{RuBisCO}$ plays an important role in carbon fixation during photosynthesis and it is the most abundant protein in the biosphere. It helps maintian the carbon cycle. Hence, statement $\left(c\right)$ is true.

Statement $d$

Statement : Mitochondria, chloroplasts and peroxisomes are not part of endomembrane system.

Elaboration: The endomembrane system includes the endoplasmic reticulum, Golgi apparatus, Lysosome and vacuoles. Mitochomdria, chloroplasts and peroxisomes are not part of this system. Hence, statement $\left(d\right)$ is true.

Final answer: a. c and d alone are correct.