Which of the following structures is NOT seen in cells of angiosperms?
1. Centrioles
2. Peroxisome
3. Mitochondria
4. Golgi Complex

Centrioles in Angiosperms: Understanding Their Absence

Introduction

Angiosperms, or flowering plants, have unique cellular structures that differ from those in animal cells. While they contain essential organelles such as the nucleus, mitochondria, peroxisomes, and Golgi complex, centrioles are absent in most angiosperm cells. This distinction is crucial in understanding plant cell division and microtubule organization.

Key Phrase: Centrioles in Angiosperms

Question and Answer

Question:
Which of the following structures is NOT seen in the cells of angiosperms?

1. Centrioles (Correct Answer)
2. Peroxisome
3. Mitochondria
4. Golgi Complex

Explanation of the Correct Answer: Centrioles

What Are Centrioles?

Centrioles are cylindrical microtubule structures found in animal cells and some lower plant cells. They play a key role in organizing spindle fibers during mitosis and meiosis, ensuring proper chromosome segregation.

Why Are Centrioles Absent in Angiosperms?

Most angiosperm cells do not have centrioles because they utilize alternative mechanisms for spindle formation during cell division. Instead, they rely on:

• Microtubule Organizing Centers (MTOCs) – These help form spindle fibers without centrioles.
• Polar Caps – Structures that direct microtubule assembly in plant cells.

Unlike animal cells, which depend on centrioles to organize microtubules, angiosperms have evolved independent systems for cell division.

Explanation of Incorrect Options

Peroxisomes

Peroxisomes are present in angiosperms and are involved in:

• Breaking down fatty acids.
• Detoxifying hydrogen peroxide.
• Playing a role in photorespiration.

Mitochondria

Mitochondria are essential organelles in all eukaryotic cells, including angiosperms. They generate ATP through cellular respiration, supporting plant growth and metabolism.

Golgi Complex

The Golgi complex (Golgi apparatus) is involved in:

• Processing and packaging proteins and lipids.
• Synthesizing components for the plant cell wall.
• Transporting cellular materials.

How Do Angiosperms Perform Cell Division Without Centrioles?

Angiosperms use alternative structures to manage mitotic spindle formation:

• Microtubule Organizing Centers (MTOCs) – Replace centrioles in spindle formation.
• Phragmoplast – A plant-specific structure that aids in cytokinesis by forming the new cell wall.
• Spindle Fibers – Self-organized microtubules direct chromosome movement during mitosis.

This system allows plants to divide efficiently without the need for centrioles.

Importance of This Topic in CSIR NET & Other Exams

The study of plant cell structures is crucial for competitive exams such as CSIR NET Life Science, DBT JRF, GATE Biotechnology, and IIT JAM. Understanding why certain organelles are absent or function differently in plant cells can help answer exam questions accurately.

Summary of Key Points

• Centrioles are absent in angiosperms.
• Microtubule Organizing Centers (MTOCs) replace centrioles for spindle formation.
• Peroxisomes, mitochondria, and Golgi complex are present in angiosperms.
• Plant cell division is regulated by alternative mechanisms such as the phragmoplast.