Question

The following features belong to I. Cells are thick at corner due to the deposition of cellulose, hemicelluloses and pectin. II. Cells may contain chloroplast and gets assimilated. III. Intercellular spaces are absent. IV. Provide mechanical support to growing parts of the plant such as young stem and petiole of leaf. (a) Collenchyma (b) Parenchyma (c) Xylem (d) Sclerenchyma

Short answer

The given characteristics belong to the Collenchyma cells. So, the correct answer is (a) Collenchyma.

Step-by-step solution

Analyze the given statements

The four statements given all describe a type of plant cell that is thick at the corner due to cellulose deposits (I), can contain chloroplast and get assimilated (II), has no intercellular spaces (III), and provides mechanical support to young growing parts of the plant (IV).

Review properties of cell types

Let's review the characteristic of each cell type option: \n\n- Collenchyma: These are living cells that provide support to the plant and are usually found where growth is ongoing. They are characterized by unevenly thick cell walls.\n\n- Parenchyma: These are also living cells that have the capacity for total cellular activities. They can have the capability of photosynthesis when they contain chloroplasts.\n\n- Xylem: These are non-living conductive cells. They are responsible for carrying water and minerals from roots to leaves.\n\n- Sclerenchyma: These are also non-living cells, they provide mechanical support to the plant and have thick cell walls.

Match the statements with the correct cell type

The cellular properties from the statements provided in the exercise match with the definition and characteristics of Collenchyma cells. They are thick at the corners, can contain chloroplast (meaning they can also photosynthesize), absence of intercellular spaces (usually) and provides support to the young growing parts of the plant.

Key concepts

Plant Cell Structure

The structure of a plant cell can be compared to a city where each component plays a crucial role in its overall function. One such component is the collenchyma cell, recognized for its unique properties in the plant's growth and structure. Collenchyma cells are living cells found in regions of new growth, such as the young stem and petiole of a leaf. Unlike other plant cells, collenchymas have thicker cell walls at their corners due to the deposition of cellulose, hemicelluloses, and pectin. This characteristic enables them to provide mechanical support while still allowing the plant to grow. Because they are living cells, they may also contain chloroplasts for photosynthesis. A distinctive aspect of collenchyma cells is the absence of intercellular spaces, which means the cells are tightly packed together, forming a sturdy, yet flexible structure for the young plant parts.

Cell Wall Composition

In discussing the composition of plant cell walls, it's vital to focus on the materials that provide plants with both strength and flexibility. The cell walls of collenchyma cells are uniquely adapted for support without restraining growth. This is due to the composition of their cell walls, which include cellulose, hemicelluloses, and pectin. Cellulose is a carbohydrate polymer that serves as the primary skeletal substance of the plant cell wall, giving it rigidity. Hemicelluloses are a group of polysaccharides that work alongside cellulose to fortify the cell wall, while pectin, another class of polysaccharides, is responsible for the 'glue' that holds cells together and adds flexibility. This combination allows the plant to grow while still being supported by collenchyma cells, which is essential in the developing areas of the plant.

Photosynthesis in Cells

Photosynthesis is a vital process for plant growth and survival, and certain plant cells are distinctively involved in this process. Collenchyma cells, as mentioned earlier, may contain chloroplasts - the site of photosynthesis. These cellular structures contain chlorophyll, the green pigment that captures light energy. The chloroplasts use this light energy to convert carbon dioxide and water into glucose and oxygen - the fundamental reaction of photosynthesis. This capability is significant for collenchyma cells because it means they not only provide structural support for the plant but also help in energy production. This dual role is particularly important in the young parts of plants where rapid growth and development occur, and a high demand for energy is present.