Biology · Anatomy of Flowering Plants · NEET
Parenchyma is a LIVING tissue. Its cells have thin cellulose walls, living protoplasm, a nucleus and usually a large central vacuole. Because the cells are alive, parenchyma can do active jobs like photosynthesis, storage of food and water, and healing of wounds. Only sclerenchyma is dead at maturity, not parenchyma.
Collenchyma is also LIVING. This is the point NEET tries to trip you on. Its cells stay alive at maturity but have cell walls that are extra thick at the corners because of deposits of cellulose and pectin. Being alive, collenchyma can stretch, so it gives flexible mechanical support to growing young stems and leaves.
Both are living simple tissues, but the wall and the job differ. Parenchyma has thin, even cellulose walls and does storage, photosynthesis and repair. Collenchyma has walls that are thickened at the corners (cellulose plus pectin) and gives mechanical support and flexibility to young growing parts. Collenchyma often has no or few intercellular spaces; parenchyma usually has clear intercellular spaces.
Sclerenchyma is the dead one. At maturity its cells lose their protoplasm and are left with thick, lignified walls and a narrow lumen (its fibres and sclereids are dead). Parenchyma and collenchyma both stay living. So if an exam statement says 'collenchyma is dead,' it is FALSE.
Because it does two things at once: it is made of living cells AND it gives mechanical strength. Sclerenchyma also gives strength but is dead. So collenchyma is special as the living support tissue of young, still-growing organs, where it can support and still allow stretching during growth.
Statement I: Parenchyma is living but collenchyma is dead tissue. Statement II: Gymnosperms lack xylem vessels but presence of xylem vessels is the characteristic of angiosperms. In the light of the above statements, choose the correct answer.
Match List-I with List-II. (a) Cells with active cell division capacity (b) Tissue having all cells similar in structure and function (c) Tissue having different type of cells (d) Dead cells with highly thickened walls and narrow lumen | (i) Vascular Tissues (ii) Meristematic tissues (iii) Sclereids (iv) Simple Tissue
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. Mark parenchyma as living. It has thin cellulose walls, living protoplasm and a nucleus, and it does storage, photosynthesis and wound healing.
Yes, both are living. Among the three simple permanent tissues, parenchyma and collenchyma are living, and sclerenchyma is dead at maturity.
Collenchyma has extra wall thickening at the corners of the cells, made of cellulose and pectin (and some hemicellulose). This lets it support young stems while still being able to stretch.
Yes. Because parenchyma cells stay living and can divide again, they can turn into meristem-like cells and help in repair, regeneration and secondary growth (for example, forming vascular cambium in dicot roots).
Sclerenchyma. Its fibres and sclereids lose their protoplasm at maturity and keep only thick, lignified walls with a narrow lumen.
