Question

According to Wikipedia the oldest human was Jeanne Clament (122.5 years), and the oldest cat was Crème Puff (38 years). The oldest organism in North America is often cited to be a bristlecone pine in California dated at 5065 years by ring count.. Still others claim that the oldest plant is actually a creosote bush in the Mojave desert, called King Clone, that is shaped as a ring that is 67 feet in diameter. Its age is estimated at 11,700 years. Others dispute this by stating that the oldest cells in these trees and shrubs are no more than a few years old. Explain how a plant can be so old but only have young cells. How old to you think the oldest cells in Jeanne Clament were?

Answer 1

It is because of indeterminate growth and natural regeneration of cells in plants is faster than animals. Certain plants have indeterminate growth and animals have determinate growth. Indeterminate growth means a plant is able grow and reproduce if conditions are favouravle. Cells of the apical meristem in plants are capable of dividing and producing new cells. Therefore in plants we can see cells which are no more than a few years old. However, in an animal, after completely forming the genetically pre determined size and shape, the  growth stops, therefore the oldest cells an animal will be as old as the animal. Therefore the oldest cells in Jeanne Clament will be as old as Jeanne Clament ie 122.5 years. However, natural regeneration of cells of tissues in humans occurs. Example- Visual cortex will stop its growth and replacement of cells when we are born.Some other cells such as hippocampal neurons are replaced in every 20-30 years.