Tag: division for growth and reproduction

According to immunity theory, the immune system is programmed to decline its functions over time, and this fact is the main cause of aging. Thymic involution (shrinking of the thymus with age) is believed to be the main age-related change in the immune system, and this alteration begins after puberty.

So, the correct option is ‘Degeneration of thymus’.

• Ageing is a complex process that varies as to how it affects different people and even different organs. Most gerontologists (people who study aging) feel that aging is due to the interaction of many lifelong influences. These influences include heredity, environment, culture, diet, exercise and leisure, past illnesses, and many other factors.
• Lipofuscin (age pigment) is a brown-yellow, electron-dense, autofluorescent material that accumulates progressively over time in lysosomes of postmitotic cells, such as neurons and cardiac myocytes. It causes ageing by the degradation of phospholipid of the plasma membrane.
  
• So, the correct answer is 'degradation of phospholipid of plasma membrane'.

• The thymus gland secretes a peptide hormone called Thymosin. Thymosin plays a major role in the differentiation of T-lymphocytes, which provide cell-mediated immunity. In addition, thymosins also promote the production of antibodies to provide humoral immunity.
• The thymus gland is degenerated in old individuals resulting in a decreased production of thymosins. As a result, the immune responses of old persons become weak.
• Hence Thymosin hormone controls the biological clock of ageing by promoting immunity in adult and by degeneration in older individuals.
  
• So, the correct answer is 'Thymosin'.

• Scab is a collection of dried blood cells and serum and sits on top of the skin surface.
• The outermost layer of our skin is composed of epithelial cells. As wounds heal, epithelial cells regenerate across the wound surface from the edges to close the wound. 
  
• The Epidermal growth factor induces the epithelial cells below the scab to undergo mitosis and facilitates closure of the wound.
• So, the correct answer is 'Epidermal growth factor'.

When ageing is progressing in the human body, different types of oxidising enzymes activity increases because of decreased rate of metabolism.

So, the correct option is ‘Malate dehydrogenase’.

A. Actin - plays an important role in embryogenesis, the healing of wounds and the invasivity of cancer cells.

B. Myosin – plays an important role in muscle contractions and  a variety of movements of nonmuscle cells, including cell division,

C. Collagen – plays a significant role in ageing.

D. Elastin - plays an important role in the biomechanical function of vital body tissues and organs such as the heart, lungs, skin and the vocal folds.

So, the correct option is ‘Collagen’.

A. Somatic mutation theory - posits that the accumulation of mutations in the genetic material of somatic cells as a function of time results in a decrease in cellular function.

B. Programmed senescence theory - refers to the idea that senescence in humans and other organisms is purposely caused by evolved biological mechanisms in order to obtain an evolutionary advantage.

C. wear and tear theory - asserts that the effects of ageing are caused by progressive damage to cells and body systems over time. Essentially, our bodies "wear out" due to use. Once they wear out, they can no longer function correctly.

D. Immunological theory - asserts that the process of human ageing is, in fact, a mild and generalized form of the prolonged auto-immune phenomenon.

So, the correct option is ‘Programmed senescence theory’.

Ageing starts with the disappearance of thymus according to immunity theory . Thymic involution (shrinking of the thymus with age) is believed to be the main age-related change in the immune system, and this alteration begins after puberty.

So, the correct option is ‘thymus gland’.

Increase in the age of the persons is called ageing. In this, loss or decrease of physical, physiological, behavioural activities takes place. The decrease in wear and tear, neurohormonal changes, the rate of metabolism, somatic mutations take place. Replacement of organs does not take place in ageing.

So, the correct option is ‘Epimorphosis’.

Immunity theory is the widely accepted theory for ageing. The immune system is programmed to decline its functions over time, and this fact is the main cause of aging. Thymic involution (shrinking of the thymus with age) is believed to be the main age-related change in the immune system, and this alteration begins after puberty.

So, the correct option is ‘Non functioning of thymus gland’.