In aquatic plants, large air sacs give them buoyancy effects. These sacs are surrounded by which one of the following types of tissues?
- (a)Parenchyma
- (b)Collenchyma
- (c)Sclerenchyma
- (d)Complex tissue
Correct — A, Parenchyma. The buoyancy-giving air sacs of aquatic plants lie within aerenchyma, a modified form of parenchyma with large air-filled spaces. So the tissue surrounding these air sacs is parenchyma.
- (b)Collenchyma — Collenchyma is a living support tissue with corner-thickened walls, found in young stems and leaf stalks; it does not form the air-filled buoyancy tissue of aquatic plants.
- (c)Sclerenchyma — Sclerenchyma is made of dead, thick-walled cells that provide mechanical strength (as in husks and nut shells); it is rigid, not the light, air-storing tissue needed for floating.
- (d)Complex tissue — Complex tissues (xylem and phloem) conduct water and food; they are not the aerating tissue that gives aquatic plants their buoyancy.
Parenchyma is the basic, thin-walled living tissue of plants. In aquatic (hydrophytic) plants it is modified into aerenchyma, which contains large intercellular air spaces. These air-filled spaces lower the plant's density and provide buoyancy, letting it float while also supplying oxygen to submerged parts.
Buoyancy comes from stored air, and only the soft, thin-walled parenchyma (as aerenchyma) forms such air spaces. The support tissues collenchyma and sclerenchyma add rigidity, not buoyancy, so they are wrong.
- Parenchyma is thin-walled living tissue that forms the ground tissue of plants.
- Aerenchyma is parenchyma with large air spaces, giving aquatic plants buoyancy.
- Collenchyma (living) and sclerenchyma (dead) are the supporting simple tissues.
- Sclerenchyma cells are dead with thick lignified walls; parenchyma cells stay living.
- Choosing a support tissue (collenchyma or sclerenchyma) for a buoyancy function.
- Forgetting that aerenchyma is a modified form of parenchyma.
A 'which tissue…' recall linking parenchyma/aerenchyma to buoyancy in aquatic plants.
No directly related past PYQ was found.
- practice — not a real PYQ
The air-storing tissue that provides buoyancy to aquatic plants is a modified
- (a)parenchyma
- (b)collenchyma
- (c)sclerenchyma
- (d)phloem
Answer(a) parenchyma — specifically aerenchyma, parenchyma with large air spaces.
- practice — not a real PYQ
Which plant tissue is composed of dead, thick-walled cells?
- (a)parenchyma
- (b)collenchyma
- (c)sclerenchyma
- (d)epidermis
Answer(c) sclerenchyma — dead cells with lignified walls that provide mechanical support.