Question

When a plant undergo senescence,the nutrients may be ______
A) Accumulated
B) Bound to the cell wall
C) Translocation
D) None of these

Answer 1

Hint: The process in which the plant loses its power of cell division and growth is called senescence. It is the final stage of the plant development and can be triggered by various factors like hormones, environmental factors like season change, drought, etc.

Complete answer:
In senescence, the cells never permanently die, but stop division and growth. Plant senescence happens due to induced stress and age-related issues. During ageing the leaves, stems, organs or the whole plant change. Vessels like xylem are formed after the death of cells and their differentiation. They will carry out conduction after senescence. Organs like leaves will wither after a certain period. Some plants will die after reproduction.

The death of plant organs is considered to be programmable or adaptive. It starts with the degeneration of leaves in relation to the accumulation of degenerative products. Respiration is plants will also decrease during the period of senescence. This process senescence is also seasonal where certain parts of palest will deteriorate during the winter or autumn. Plants also lose their chlorophyll during senescence and turn yellow.

Cytokinin is the plant hormone that keeps the plant healthy and young. Failure to absorb this hormone will also lead to senescence. Exposure to hormone-like ethylene will also lead to senescence in plants. Along with the leaves, Turing yellow loss of RNA and protein and transport of nutrients and abscission is also observed in plants during senescence.

The nutrient also undergoes a lot of changes during senescence. As the cells are dying these nutrients will not be able to reach other parts of plants if it stays there. So the nutrient resources like minerals and carbohydrates will be trans located or shifted away into other parts of plants that are actively dividing and growing form the senescent part. Nutrients are transported into a new location or trans located during senescence.

Hence the correct answer is option ‘C’.

Note: During senescence as the plants lose its chlorophyll it will lead to the release or revealing of carotenoid such xanthophyll and anthocyanin. This is the reason for the autumn yellow colour of leaves in the deciduous plants.