Question

Meristems are found in (a) Root apex (b) Shoot apex (c) Both (a) and (b) (d) None of these

Short answer

The answer is (c) Both (a) and (b).

Step-by-step solution

Understand what meristems are

Meristems are a group of plant cells that have the ability to divide. These are the regions of the plant where growth can take place.

Identify where meristems are located

Meristems are typically found at the tips of roots and shoots. This is because these are the areas of a plant where growth can occur in two directions.

Match the locations with the answer choices

Given that meristems are found at both the root apex and shoot apex, the answer is (c) Both (a) and (b).

Key concepts

Plant Growth

Plant growth is a crucial aspect of plant life, allowing them to reach for the sun, delve into the soil for nutrients, and reproduce. One of the primary drivers of this growth is a type of plant tissue known as meristems. These are regions within plants consisting of unspecialized cells capable of continuous division and differentiation.

Meristematic tissue functions similarly to stem cells in animal systems, providing a pool of cells that can develop into various plant tissues and organs. In plants, growth occurs primarily in two ways: through elongation, where cells grow larger, and through cell division, where more cells are produced. Meristems are central to the latter, cell division, and are thus intricately linked to a plant's ability to grow.

Meristematic tissues can be classified into apical meristems situated at the tips of roots and shoots (contributing to primary growth), and lateral meristems, like the cambium and phellogen, which are responsible for the thickening of the plant stems and roots (secondary growth). The continuous activity of these meristems allows plants to adapt and survive in their environments by growing in length and girth over time.

Root Apex

The root apex, or the tip of the root, is an essential structure in a plant's growth and development. Here, the apical meristem is a region of intense activity where cells are continuously dividing. This constant division is the driving force behind the plant's ability to push deeper into the soil.

The primary function of the root apex is facilitating elongation, allowing the root to extend and access untapped water and mineral resources. The cells produced by the meristem undergo specialization to become various parts of the root system, including the root cap that protects the delicate meristematic cells as they make way through the soil. Also, behind the meristem is a region called the zone of elongation, where the newly created cells increase in size, pushing the root tip further into the earth. The root apical meristem is also a sensory region that responds to gravity and various chemical signals in the soil, guiding the root's direction as it grows.

Shoot Apex

Conversely, the shoot apex, found at the tip of a plant's stem, is responsible for upward and outward growth, allowing the plant to maximize its exposure to sunlight and air - essential for photosynthesis and respiration, respectively. The shoot apical meristem includes a dome-shaped bundle of dividing cells that give rise to leaves, stems, and eventually flowers and fruits in some species.

Differentiation of cells in the shoot apex leads to the formation of nodes and internodes, branches, and leaves. This area is highly organized and tightly regulated to maintain the plant's overall growth pattern and shape. Additionally, the shoot apex plays a pivotal role in the formation of secondary metabolites, which are compounds that help protect the plant from herbivores and diseases. Simultaneously, hormones produced by the shoot apical meristem, such as auxins, cytokinins, and gibberellins, act as chemical messengers to coordinate growth and response to environmental cues across the plant.