Which one of the following tissues is known as basic packing tissue and found in xylem and phloem ?
- A.Collenchyma
- B.Parenchyma
- C.Sclerenchyma
- D.Vessels
Correct answer
Explanation
The correct answer is B, Parenchyma. Parenchyma is the basic packing tissue of plants, and it is also present in both xylem (xylem parenchyma) and phloem (phloem parenchyma).
Parenchyma is a simple permanent tissue of living, thin-walled cells with large vacuoles and often loose spaces between them. It fills the soft parts of stems, roots, leaves and fruits, stores food, and when it has chloroplasts (chlorenchyma) it makes food. In the complex tissues, xylem parenchyma stores food and helps sideways movement of water, while phloem parenchyma stores food and other materials.
A is wrong because collenchyma, with walls thickened at the corners, gives flexibility and mechanical support to young stems and leaf stalks. C is wrong because sclerenchyma is made of dead, lignified cells that give hardness, as in coconut husk. D is wrong because vessels are tube-like water-conducting elements of xylem, not a packing tissue.
Exam tip: parenchyma packs and stores, collenchyma bends, sclerenchyma stiffens.
Practice Questions
View allWhich one of the following features is an indication for modification of stem of a plant?
- A.Presence of 'eye' on potato
- B.'Scale' found in onion
- C.'Tendril' found in pea
- D.'Hair' present in carrot
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The eyes of a potato are nodes with buds, and only a stem bears nodes and buds, so they prove that the potato is a modified stem.
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- A.Tungsten
- B.Copper
- C.Rubidium
- D.Aluminium
Show answer
Rubidium, an alkali metal like caesium, gives off electrons easily when light falls on it, so it is used in photoelectric cells.
Read the full explanation →Tooth enamel is made up of which one of the following calcium compounds ?
- A.Calcium carbonate
- B.Calcium sulphate
- C.Calcium hydroxide
- D.Calcium phosphate
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Tooth enamel is made mainly of calcium phosphate in the form of a hard crystal called hydroxyapatite. Enamel is the hardest substance in the human body, harder even than bone.
Read the full explanation →Which one of the following viruses used to be responsible for highly infectious disease Smallpox ?
- A.Adenovirus
- B.Variola virus
- C.Aichi virus
- D.Coxsackie virus
Show answer
Smallpox was caused by the variola virus, a large DNA virus of the pox family that spread from person to person through the air.
Read the full explanation →After fertilization, the fruit and the seed are produced by
- A.ovule and ovary, respectively
- B.ovary and ovule, respectively
- C.ovary, no ovule required
- D.ovule, no ovary required
Show answer
After fertilisation the ovary of the flower grows into the fruit, and each ovule inside it develops into a seed.
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