Which of the following is not true ?

Question

Accepted Answer

The correct option is 3: Aleuroplasts stores starch in a cell.

This statement is not true, which is why it is the correct answer to the question "Which of the following is not true?". Aleuroplasts are a specialized type of non-pigmented plastid, known as leucoplasts, found within plant cells. Their primary and defining function is the storage of **proteins**, often in the form of amorphous or crystalline inclusions. For this reason, they are also correctly termed **proteinoplasts** or **proteoplasts**. The plastids that are actually responsible for the synthesis and storage of starch (an important carbohydrate reserve) are called **amyloplasts**. Amyloplasts convert glucose into starch, which accumulates as starch grains inside the plastid. Since aleuroplasts store protein, not starch, the statement is factually incorrect.

The incorrect option is 1: The stain used to visualize mitochondria is Janus green-B.

This is a true statement in cell biology. Janus green-B is a classic, selective stain used for the vital staining of mitochondria, meaning it can be used to observe these organelles in living cells without immediately killing them. The dye specifically targets the mitochondria because it is actively accumulated and retained within the organelle, where it is oxidized by the electron transport chain, turning it a characteristic blue or blue-green color. Its ability to distinguish mitochondria in a living state makes it an invaluable tool for microscopic study.

The incorrect option is 2: Mitochondria without outer membrane are called mitoplast.

This is a true statement. The term 'mitoplast' is used by cell biologists and biochemists to describe a mitochondrion that has been stripped of its outer membrane, usually as part of an isolation procedure in a laboratory experiment. This organelle remnant retains the inner mitochondrial membrane, the cristae, and the matrix—the key structures involved in cellular respiration. The preparation of mitoplasts allows researchers to study the function of the inner membrane and its associated enzymes in isolation from the outer membrane's influence.

The incorrect option is 4: Lysosome is a part of endomembrane system.

This is a true statement. The endomembrane system is a functional and physical network of internal membranes and organelles in eukaryotic cells, which includes the endoplasmic reticulum (ER), the Golgi apparatus, and the vesicles that bud off from them, such as lysosomes and vacuoles. Lysosomes are formed when hydrolytic enzymes, synthesized in the rough ER, are processed and packaged by the Golgi apparatus. They bud off the *trans* face of the Golgi to perform their function as the cell's main digestive and waste disposal system. Therefore, the process of their formation and their role in cellular trafficking confirms the lysosome's position as a crucial component of the endomembrane system.