NCERT Solution for Class 10 Science Chapter 8
How do Organisms Reproduce?
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Intext Questions
Page No-133
Questions No-3
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
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Simple organisms such as Hydra and Planaria are capable of producing new individuals
through the process of regeneration. The process of regeneration involves the formation
of new organisms from its body parts. Simple organisms can utilize this method of
reproduction as their entire body is made of similar kind of cells in which any part of their
body can be formed by growth and development.
However, complex organisms have organ-system level of organization. All the organ
systems of their body work together as an interconnected unit. They can regenerate their
lost body parts such as skin, muscles, blood, etc. However, they cannot give rise to new
individuals through regeneration.
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Complex organisms are not simply a random collection of cells where specialized cells are organised as tissues, and tissues ale organised into organs which then have to be placed at definite positions in the body. In such a carefully organised situation, it is not easy to develoP organism through regeneration.
Higher complex organisms cannot give rise to new individuals through regeneration because complex organisms have organ-system level of organization. All the organ systems of their body work together as an interconnected unit. They can regenerate their lost body parts such as skin, muscles, blood, etc. However, they cannot give rise to new individuals through regeneration.
Complex organisms have highly differentiated tissues and organs and not a single cell of a tissue is able to produce another type of tissue. For example, a dog is a complex multicellular organism and if we cut dog into two parts, then the cells of one part are not able to produce cells of other body part to produce a complete dog but in case of hydra (simple organism), regeneration takes place because cells in the cut body part are able to produce cells of other body parts.
Complex organism have division of labour in their body, to avoid duplication of efforts. Thus they have specialised organs to perform specific functions. Through regeneration, it will not always be possible to differentiate in all types of cells. Thus, more complex organisms use more complex ways of reproduction.
Regeneration is the process by which organisms replace or restore damaged or lost body parts, and it is more commonly observed in less complex organisms such as certain invertebrates, amphibians, and plants. While some complex organisms, like certain amphibians and reptiles, do exhibit limited regeneration capabilities, it is not as widespread or efficient as in simpler organisms. There are several reasons why more complex organisms may face challenges in achieving regeneration comparable to less complex ones:
1. Specialization of Cells and Tissues: In complex organisms, cells and tissues often become highly specialized for specific functions. This specialization may limit the ability of cells to dedifferentiate and give rise to various cell types needed for regeneration. In contrast, many simpler organisms have a greater degree of cellular plasticity.
2. Complex Body Plans: More complex organisms typically have intricate body plans with specialized organs and structures. Regenerating complex structures with specific functions requires precise spatial and temporal control of cell differentiation, a challenge that is more pronounced in organisms with sophisticated body plans.
3. Developmental Constraints: The development of complex organisms involves intricate signaling pathways and genetic regulation. The same pathways that guide development may impose constraints on the ability of cells to regenerate or differentiate properly in response to injury.
4. Energy Requirements: Regeneration can be an energetically costly process. More complex organisms may allocate their energy resources toward growth, maintenance, and reproduction, limiting the amount of energy available for regenerative processes.
5. Longer Generation Times: Complex organisms often have longer generation times compared to simpler ones. This longer time frame for reproduction may reduce the selective pressure for efficient regeneration, as the organism’s primary strategy for passing on its genes may be through sexual reproduction rather than through the regeneration of damaged body parts.
6. Immune System Responses: The immune system of complex organisms is more sophisticated and may play a role in limiting the regenerative capacity. In some cases, the immune system may recognize regenerating tissues as foreign or abnormal, triggering immune responses that interfere with the regeneration process.
7. Evolutionary Trade-offs: Evolutionary trade-offs occur when certain traits or capabilities are favored over others due to natural selection. In complex organisms, the evolution of sophisticated physiological processes and structures may have come at the cost of efficient regeneration.
While regeneration is more limited in complex organisms, it’s essential to note that some exceptions exist, such as the regenerative abilities observed in certain amphibians and certain tissues in mammals. Researchers are actively studying regenerative processes in various organisms to understand the underlying mechanisms and explore potential applications in medicine and biotechnology.