Question

How many statements are incorrect amongst the following?
a. Microfilaments help in the formation of a cleavage furrow during cell division.
b. Microtubules present in the cytoplasm are highly liable.
c. The nuclear lamina is a network of acidic proteins and intermediate filaments.
d. Microtubules control the orientation of microfibrils in a cell wall.

A. One
B. Three
C. Four
D. Two
E. None

Answer 1

Hint: Cytoplasmic division is also termed as cytokinesis which happens at the end of mitosis or meiosis. As a result of this, two daughter cells are separated. Microtubules as the name suggests, are tubular structures which can further aggregate to form complex structures. Nuclear lamina can be found near to the inner side of the nuclear membrane and on peripheral chromatin.

Complete answer:
Each statement is described below in detail.
a. The cleavage furrow is formed by the fungi, amoeba and animal cells at the end of cell division which is cytokinesis. It forms in the plasma membrane. The microfilaments do not help in their formation. There is a contractile ring that has actin and myosin which are assembled together at the site of cleavage furrow. So this statement is wrong.

b. The microtubules are present in the cytoplasm, they are a part of the cytoskeleton. They are like rigid hollow rods. They mainly provide mechanical support and organization of cytoplasm. They also help in locomotory processes. Hence, this statement is also discarded.

c. The nuclear lamina is thought to be a nuclear meshwork having nuclear lamins. It is a fibrillar network that is made up of structural proteins that helps in lining of inner membranes of eukaryotic cells. It is not composed of acidic proteins and intermediate filaments. This statement is incorrect.

d. It is false. Microtubules don’t control the orientation of microfibrils in a cell wall.

Note: Microtubules function as conveyor belts. They are important for various cellular processes. They give proper shape to the cells. They are also important for movement which is due to the contraction of muscle cells. In the cell division process, their contribution is important for mitotic spindle formation. They are also good transporters within the cells to move mitochondria, organelles and vesicles.