Question

Senescence in plants leads to ______ of cells.
(a) Increase in size
(b) Increase in number
(c) Death
(d) Differentiate

Answer 1

The growth activity of the plants depends on the activity of meristems which is always embryonic. This could mean it can grow forever but the plant parts, however, age and this is not always an accident or environmental stress but of physiological decline i.e. senescence.

Complete answer:
The natural process of aging of the cells of the plant is known as senescence. The cells undergo differentiation to make new cells and it ultimately leads to the death of cells. The cells characterize features the onset of senescence-like changes related to the accumulation of breaking of products. Metabolic changes accompany these changes in the cell. The respiration rate in the plants may increase for a while and later on reduce as the cellular apparatus degenerates. The synthesis of proteins and nucleic acids almost stops. Many different ways of physiological senescence and death occur in the cells of the plant. This may affect cells, tissues, organs, or the entire plant. For the formation of the vessels of the xylem, the cells differentiate by dying and their walls are given to the conducting tissue. The leaf senescence recycles nutrients mostly which is nitrogen and this is given to the growing and storage of the plant parts. The plants continuously form new organs for the functioning of the body and the older organs maximize nutrient export by undergoing a highly regulated senescence.
So, the correct answer is ‘(c) Death’.

Note: Ageing and senescence are related but they both are not the same. The degenerative changes that occur in all individuals without talking about death are known as aging whereas senescence talks about the developmental stages which are close to death symptoms. Sometimes senescence can be said to be reversible when it becomes phenotypically and functionally similar to the older state of the plant which doesn’t contain any DNA damage.