Which one of the following plant tissues has dead cells?
- (a)Epidermis
- (b)Parenchyma
- (c)Collenchyma
- (d)Sclerenchyma
Correct — D, Sclerenchyma. Sclerenchyma is a supporting tissue whose cells (fibres and sclereids) develop thick, lignified walls and lose their living contents, so they are dead at maturity. This gives plants rigidity and mechanical strength. The other three tissues listed are made of living cells.
- (a)Epidermis — The epidermis is the living, usually single-layered protective covering of the plant body; its cells are alive (often with a waxy cuticle on the outside).
- (b)Parenchyma — Parenchyma consists of living, thin-walled cells that carry out photosynthesis, storage and other active functions; it is the most metabolically alive tissue.
- (c)Collenchyma — Collenchyma is made of living cells with unevenly thickened walls that provide flexible support to young, growing parts; the cells remain alive.
Simple permanent plant tissues include parenchyma, collenchyma and sclerenchyma. Parenchyma and collenchyma are living; sclerenchyma cells become dead at maturity, with thick lignified walls that stiffen the plant. Among the options, only sclerenchyma is a dead tissue (xylem also contains dead conducting cells, but it is not listed).
Group the tissues by whether their cells stay alive. Three options (epidermis, parenchyma, collenchyma) are living tissues; sclerenchyma stands out as the one made of dead, lignified cells.
- Sclerenchyma cells (fibres and sclereids) are dead at maturity with thick, lignified walls.
- Sclerenchyma provides mechanical strength and rigidity to the plant.
- Parenchyma (living, thin-walled) handles storage and photosynthesis.
- Collenchyma (living, unevenly thickened) gives flexible support to growing parts.
Only sclerenchyma is composed of dead cells at maturity.
- Confusing collenchyma (living, flexible support) with sclerenchyma (dead, rigid support).
- Forgetting that some xylem cells are also dead — but xylem is not among the options here.
Asked as 'which tissue has dead cells / provides mechanical support' — sort living from dead tissues.
No directly related past PYQ was found.
- practice — not a real PYQ
Mechanical support and rigidity in mature plant parts is provided mainly by
- (a)parenchyma
- (b)collenchyma
- (c)sclerenchyma
- (d)epidermis
Answer(c) sclerenchyma — its dead, thick-walled cells stiffen the plant.
- practice — not a real PYQ
Which plant tissue is made of living cells with unevenly thickened walls that give flexible support?
- (a)Sclerenchyma
- (b)Collenchyma
- (c)Parenchyma
- (d)Xylem
Answer(b) Collenchyma — living cells with corner-thickened walls, common in young stems and leaf stalks.