Cytokinins, Ethylene and ABA — NEET Importance

NEET Importance Analysis

The topic of Cytokinins, Ethylene, and Abscisic Acid (ABA) is of paramount importance for the NEET UG examination in Biology. Plant Growth Regulators (PGRs) as a whole constitute a significant portion of the Plant Physiology unit, which is a high-weightage section in NEET.

Questions on these three specific hormones frequently appear, often testing their individual functions, chemical nature, sites of synthesis, and most importantly, their synergistic or antagonistic interactions with other hormones.

Typically, 2-3 questions can be expected from the entire Plant Growth and Development chapter, with a good chance that at least one will pertain to Cytokinins, Ethylene, or ABA. Question types range from direct recall of functions (e.

g., 'Which hormone promotes fruit ripening?'), to identifying the 'stress hormone,' to more complex questions involving their interactions (e.g., 'What is the effect of auxin-cytokinin ratio in tissue culture?

'). Numerical problems are rare in this specific subtopic, but conceptual understanding and application-based scenarios are common. Students must understand the unique gaseous nature of ethylene, the role of ABA in stress tolerance, and cytokinin's role in cell division and breaking apical dominance.

Misconceptions, such as attributing a function of one hormone to another, are common traps, making a clear and distinct understanding of each hormone's primary roles crucial.

Vyyuha Exam Radar — PYQ Pattern

Analysis of previous year NEET (and AIPMT) questions reveals consistent patterns regarding Cytokinins, Ethylene, and Abscisic Acid. Questions frequently revolve around:

1
Direct Function Recall: — Identifying the primary role of a specific hormone (e.g., 'Which hormone is responsible for the triple response in seedlings?' - Ethylene; 'Which hormone causes stomatal closure?' - ABA). These are often easy to medium difficulty.
2
Chemical Nature/Unique Properties: — Questions about ethylene's gaseous nature or the chemical class of cytokinins (adenine derivatives) or ABA (carotenoid derivative) appear periodically.
3
Antagonistic/Synergistic Interactions: — This is a high-yield area. Questions often test the interplay between hormones, such as the auxin-cytokinin ratio in tissue culture or apical dominance, or the ABA-gibberellin balance in seed dormancy. These tend to be medium to hard difficulty.
4
Specific Effects/Phenomena: — Terms like 'Richmond-Lang effect' (cytokinin and delayed senescence) or 'triple response' (ethylene) are tested to check for detailed knowledge.
5
Stress Response: — ABA's role as a 'stress hormone' is a recurring theme, particularly its function in drought tolerance.

There's a clear trend towards conceptual understanding rather than rote memorization of obscure facts. The difficulty distribution is typically balanced, with a mix of easy, medium, and a few challenging questions that require a deeper understanding of hormonal interactions. Students should expect questions that require differentiating between similar-sounding effects or identifying the hormone responsible for a specific developmental event.