What is the difference between apical and lateral meristems?

• A. Apical meristems enable secondary (girth) growth; lateral meristems enable primary (length) growth
• B. Apical meristems enable primary (length) growth; lateral meristems enable secondary (girth) growth
• C. Apical meristems are found only in roots; lateral meristems only in stems
• D. Lateral meristems produce chloroplasts

Answer: (D)

Growth in plants happens in two main ways: lengthening at tips and thickening around the stem and roots. Apical meristems, located at the tips of shoots and roots, drive primary growth, which increases the plant’s length and the development of primary tissues like epidermis, cortex, and primary vascular tissues. Lateral meristems run along the sides of stems and roots and drive secondary growth, which adds girth by producing secondary xylem and phloem and forming the periderm.

Chloroplasts are organelles inside differentiated photosynthetic cells, not something that meristems produce. Meristems generate many new cells that then differentiate into various tissues, but they don’t specialize to create chloroplasts themselves. So the idea that lateral meristems produce chloroplasts isn’t accurate.

In short, apical meristems enable lengthening (primary growth), while lateral meristems enable thickening (secondary growth).