Problem 12 - Objective Biology for NEET

Question

Why the growth of a plant is unique? (a) The plant retains the capacity of unlimited growth. (b) The plant can regenerate the same characters. (c) There is no change in offspring's characters. (d) None of the above

Step-by-Step Solution

Answer

(a) The plant retains the capacity for unlimited growth.

Step 1: Analyze the Options

Each option can be observed in details. For (a), it is known that most plants possess unlimited growth throughout their life due to the presence of meristematic tissue in certain regions. For (b), 'regeneration of the same characters' could mean consistent structural traits, or self-healing and regrowth capabilities which plants possess. For (c), 'no change in offspring’s characters' could imply that offspring are identical to parent plant, which is not always true as there are variations in offspring due to genetic recombination or mutation.

Step 2: Confirm the Unique Quality

Among these, 'Plant retains the capacity for unlimited growth' is a distinct feature of plants, not seen in animal life cycle, hence making plant growth unique. This is due to their meristematic tissue which animals lack.

Step 3: Make Final Decision

By the process of elimination, and based on the definitions, we deduce that the correct answer is (a), 'The plant retains the capacity for unlimited growth.'

Key Concepts

Unlimited Growth

Plants are fascinating organisms with the unique ability for unlimited growth, which means that they can continue to grow throughout their lifespan without a predetermined limit. This is in stark contrast to most animals, which typically have determinate growth, meaning they grow to a certain size and then stop. There are several factors that enable this continuous growth:

• Plants can keep producing new cells at proper growth regions.
• They can overcome environmental challenges through adaptive growth.
• Their growth is not restricted to a particular period of their life.

Plants can also exhibit growth in multiple dimensions, like height and width. This ability ensures that plants can occupy space and resources efficiently, competing well in diverse ecosystems. Understanding this concept helps explain why plants can achieve large sizes, such as towering trees, or achieve diverse forms, such as sprawling vines.

Meristematic Tissue

The secret behind unlimited plant growth lies in the presence of meristematic tissue. This special tissue consists of undifferentiated cells that have the potential to divide and form new tissues throughout the plant's life. They are found in specific areas known as meristems. Types of meristems include:

• Apical Meristems: Located at the tips of roots and shoots. They are responsible for lengthening these parts.
• Lateral Meristems: Found along the sides of stems and roots. They are responsible for the thickening or lateral growth of the plant.

Meristematic tissues are different from other plant cells because they can continually divide and specialize to form various types of tissues and organs. This enables plants to grow indefinitely, repair themselves when injured, and even replace lost parts. This remarkable feature provides plants with resilience and adaptability in changing environments.

Regeneration in Plants

Plants have an impressive ability to regenerate, which refers to their capacity to regrow or repair parts that are damaged or lost. This ability is linked closely with meristematic tissues, which act as a source of new cells. Regeneration can occur in various forms:

• Regrowth: Such as when a cut stem grows new shoots.
• Healing: Like the sealing of a wounded tree bark.
• Adventitious roots or shoots: Forming from unusual places such as leaves or roots.

This regenerative power allows plants not only to survive wounds like broken branches but also to continue spreading and propagating, even under less than ideal conditions. It helps ensure survival and reproduction by allowing plants to adapt quickly and recover from damage, contributing to their success across a wide range of environments.