Q.65 In the context of plant development, which of the following statements are CORRECT?
- P. Cell migration is absent
- Q. Apoptosis plays a major role
- R. Pattern formation continues throughout life
- S. Homeotic changes are caused by mutations in non-homeodomain proteins
Options:
(A) P, Q, R
(B) Q, R, S
(C) P, Q, S
(D) P, R, S
P is correct: Unlike animals, plant cells are encased in rigid cellulose walls, preventing cell migration during development.
Q is correct: Programmed cell death (PCD), often likened to apoptosis, plays a major role in plant development, such as in tracheary element formation and root cap sloughing.
R is correct: Plants exhibit indeterminate growth via meristems, allowing pattern formation (e.g., new organs) to continue throughout life.
S is incorrect: Homeotic changes in plants (e.g., floral organ identity defects) are primarily caused by mutations in homeodomain-containing MADS-box transcription factors like those in ABC model genes, not non-homeodomain proteins.
Correct option: (A) P, Q, R
Plant development cell migration apoptosis pattern formation processes differ fundamentally from animals, making them crucial for GATE Life Sciences preparation. This article breaks down a key MCQ on these features, explaining each statement with evidence for competitive exam success.
Statement P: Cell Migration Absent
Plant cells cannot migrate due to rigid cell walls that fix them in position post-division. Development relies on localized divisions and expansions instead. This contrasts with animal gastrulation and is a hallmark of plant morphogenesis.
Statement Q: Apoptosis Major Role
Apoptosis-like programmed cell death (PCD) sculpts plant tissues, forming xylem vessels, aerenchyma, and shedding root caps. DNA fragmentation and apoptotic bodies occur, conserved from animal paradigms but adapted to plant vacuolar clearance.
Statement R: Pattern Formation Continues
Meristems enable indeterminate growth, sustaining pattern formation (e.g., phyllotaxy, floral patterning) lifelong, unlike fixed animal body plans. Environmental cues perpetually refine organogenesis.
Statement S: Homeotic Changes
False—homeotic mutations (e.g., leafy conversions) arise mainly from homeodomain proteins like MADS-box genes (APETALA, AGAMOUS). Non-homeodomain proteins rarely cause them.
MCQ Solution Table
| Statement | Correct? | Reason |
|---|---|---|
| P | Yes | Rigid walls prevent migration |
| Q | Yes | PCD essential for differentiation |
| R | Yes | Meristems allow lifelong patterning |
| S | No | Homeotic mutations in homeodomains |
Answer: (A) P, Q, R – Ideal for GATE XL PYQ review. Focus on these for plant developmental biology scoring.
