Mitosis - class-XI

Ageing is the process where there is a continuous decline in the metabolism of the body. The hearing power also declines after the age of 40 years. Presbycusis is the term which is generally used for hearing impairment due to old age. It is mainly caused due to degeneration of the cochlea or associated structures of the inner ear or auditory nerves.

Pleomorphic organisms, such as certain bacteria like Mycoplasma, lack a rigid cell wall and can readily alter their size and shape in response to environmental conditions. Spirilla are rigid spiral-shaped bacteria, while symbionts and gram negative refer to ecological relationships or cell wall staining properties.

Brain cells (neurons) have very limited capacity for regeneration compared to other tissues like bone or muscle. This is why injuries to the central nervous system are often permanent.

Maleic hydrazide : It is a growth retardant which checks cell division. So during seed storage this is applied for checking sprouting of potato tubers so that the importance of potato may not be lowered down.

Glucose and amino acids are absorbed through the epithelial cells (enterocytes) of the villi in the small intestine. From there, they pass into the blood capillaries.

The human body replaces approximately 1 billion (1 x 10^9) cells daily, primarily through processes like cell turnover in the skin and gut lining.

All epithelia are separated from their underlying tissues by an extracellular basement membrane which is fibrous in nature. The basement membrane is the fusion of two lamina namely, the basal lamina and the reticular lamina. The lamina reticularis is attached to the basal lamina with collagen anchoring fibrils and fibrillin microfibrils. The two layers together are collectively referred to as the basement membrane.

Calcium is an essential mineral required by all living cells for various signaling processes, membrane stability, and enzymatic functions.

Division of the nucleus is called karyokinesis. The process of partition of a cell's nucleus into the daughter cells during cell division is called karyokinesis. All the changes in a nucleus that occur during cell division are collectively termed as karyokinesis. It has four stages prophase, metaphase, anaphase, and telophase.

All nuclear changes (Prophase, metaphase, anaphase, and telophase) that occurs during mitotic cell division are collectively called as karyokinesis. Mitotic cell division consists of two steps. The first step is karyokinesis where nuclear division takes place which is followed by cytokinesis i.e the division of cytoplasm takes place and individual daughter cells are formed. So, the correct answer is 'Karyokinesis'.

Epithelial tissues rest on a specialized extracellular matrix called the basal lamina, which separates them from the underlying connective tissues. Other options like lamina propria are connective tissue layers rather than the immediate separating boundary.