Q53. Which of the following cellular component(s) is/are NOT part(s) of
cytoskeleton in Angiosperms?
(A) Microtubules
(B) Microfilaments
(C) Intermediate filaments
(D) Centrioles
Centrioles are not part of the cytoskeleton in angiosperms. The cytoskeleton in plant cells, including angiosperms, primarily consists of microtubules and microfilaments, while centrioles are absent and intermediate filaments are not considered standard components.
Option Analysis
(A) Microtubules: These form hollow tubes from tubulin dimers and organize arrays like cortical microtubules and the preprophase band in angiosperm cells, essential for cell wall deposition and division. They are core cytoskeleton parts.
(B) Microfilaments: Also called actin filaments, these drive cytoplasmic streaming, organelle movement, and vesicle transport in plant cells. They are integral to the plant cytoskeleton.
(C) Intermediate filaments: Animal cells use these for mechanical strength, but in angiosperms, while some IF-like proteins exist, they lack defined intermediate filaments as standard cytoskeleton elements like microtubules and microfilaments. Standard references list only the latter two for plants.
(D) Centrioles: These microtubule-based organelles organize spindles in animal cells but are absent in all angiosperm cells, which use decentralized microtubule organizers for division. Thus, they are not part of the cytoskeleton.
Correct Answer
(D) Centrioles. This fits CSIR NET-level questions on plant cell differences from animals.
The cytoskeleton in angiosperms forms a dynamic network vital for cell shape, division, and intracellular transport, differing from animal cells. Unlike animals, angiosperm cells rely on specific components without centrioles.
Core Components
Microtubules guide cellulose deposition and form spindles/phragmoplasts during mitosis. Microfilaments enable streaming and support growth. These two dominate plant cytoskeletal functions.
Absent Elements
Centrioles, crucial in animals for centrosomes, do not exist in angiosperm cells; plants use alternative organizers. Intermediate filaments, prominent in animals for strength, are not standard in plants despite some protein homologs.
Exam Relevance
For CSIR NET, recognize microtubules (A) and microfilaments (B) as parts, but centrioles (D) as the clear non-component in angiosperm cytoskeleton.
