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Plant Life Cycle Questions and Answers

  • Botany
  • In this plant life cycle questions and answers post we have briefly explained about annuals, biennial, perennials, monocarpic, polycarpic plants, genetics and environmental conditions.

Plant Life Cycle Questions and Answers

  • The time from the start of development until the end that a plant experiences is referred to as its life duration (Plant Life Spans). The life cycle on other on the other hand is the series of stages that a plant through from the time of seed germination until the seed production of maturing plants. Certain plants, such as annuals, need only some weeks to grow to produce seeds and die. Others, like bristlecone pines, last for many thousands of years. Some bristlecone trees have been recorded to have an age of 4500 years.
  • Although some regions of the plant, for instance, areas with meristematic tissues (the zone of active plant growth composed of cells that are not differentiated capable of division), continue to expand, certain parts are subject to programmed cells dying (apoptosis). The cork on the stems and the water-conducting tissue that forms part of the xylem, for instance, is made up of dead cells.
Plant Life Spans

Plant life spans: The bristlecone pine, shown here in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California, has been known to live for 4,500 years.

Annuals, Biennial, and Perennials

  • Plant species that finish their lives in one season are called annuals. An example can be found in Arabidopsis, also known as mouse-ear cress. Biennials, including carrots, can complete their cycles in two different seasons. In the initial season of a biennial, it is in a vegetative phase, and in the second season, it is finished with its reproduction phase. 

  • Commercial cultivators harvest the roots of carrots in the initial year of growth, and they don’t allow the plants to bloom. Perennials, like magnolia, finish their life span in two or more years.

Monocarpic and Polycarpic Plants

  • Another classification is dependent on the frequency of their monocarpic flowering plants bloom once during their lives. The monocarpic species include yucca and bamboo. In the vegetative phase of their lives (which can be up to 120 years for some bamboo species), these plants can reproduce sexually, creating plenty of food matter which will be needed for their once-in-a-lifetime flowering and the establishment of seeds following fertilization. After flowering, the plants will die. 

  • Polycarpic plants bloom several times throughout their lives. Like the orange and apple trees, fruit trees are polycarpic and bloom each year. Other polycarpic species like perennials bloom several times throughout their lives. However, they do not bloom every year. In this way, the plant doesn’t require all of its nutritional resources to go into flowers every year.

Genetics and Environmental Conditions

  • As with every living thing, Genetics and environmental conditions are a factor in determining the length of time plants will last. The susceptibility to illness, changes in conditions in the environment, drought, cold and the competing for nutrients are just a few aspects that affect the life span. The plants continue to grow even when there is dead tissue, for example, cork. The individual parts of plants, like flowers and leaves, are different in their survival rate. 
  • In many trees, older leaves become too yellow and fall off the tree. The fall of leaves is caused by causes such as the decrease in the efficiency of photosynthetic processes due to shading of upper leaves or damage resulting from photosynthesis reactions. Plants reuse the elements in the portion to be removed for other processes, including the creation of seeds or storage. This is known as the recycling of nutrients. However, the complicated processes in nutrient recycling inside the plant aren’t fully comprehended.
  • The process of ageing plants and the related processes is called senescence. A variety of intricate biochemical changes characterizes this. One of the features of senescence can be seen as the loss of chloroplasts. It is evident in the leaves turning yellow. 
  • Chloroplasts have parts of the machinery for photosynthetic production, including proteins and membranes. Chloroplasts also have DNA. Certain enzymes degrade the proteins, lipids, and nucleic acids into smaller molecules. They are then recovered by plants to aid in developing different plant tissue. Hormones have been identified to be involved in the process of senescence. The use of cytokinins and ethylene can delay or stop the cycle of senescence. On the other hand, abscisic acids trigger the early beginning of senescence.
Plant Life Spans

 Plant senescence: The autumn color of these Oregon Grape leaves is an example of programmed plant senescence.

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