Which 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
Correct answer
Explanation
The correct answer is A, Presence of 'eye' on potato. 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. The potato is a stem tuber: the tip of an underground stem that swells with stored starch. Each eye holds an axillary bud in the axil of a tiny scale leaf, and when a piece of potato with an eye is planted, the bud grows into a new shoot; this is how farmers propagate potatoes vegetatively. Option B is wrong because the fleshy scales of an onion are modified leaves; the true stem of the onion bulb is the small disc at its base. Option C is wrong because the tendrils of the pea are modified leaflets, unlike the stem tendrils of cucumber and grapevine. Option D is wrong because the hairs on a carrot are root hairs, and the carrot itself is a modified tap root. Exam tip: potato, ginger and turmeric are stems; carrot, radish and sweet potato are roots.
Practice Questions
View allWhich one of the following metals is used in the filaments of photo-electric cells that convert light energy into electric energy ?
- 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
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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.
Read the full explanation →Which among the following statements with respect to carbon is/are correct?
1. Carbon forms the basis for all living organisms and many things we use
2. Carbon shows tetra-valency and the property of catenation
3. Carbon forms covalent bonds with itself and other elements
4. Carbon forms compounds containing triple and tetra bonds between carbon atoms
Select the correct answer using the code given below :
- A.1 only
- B.1 and 2 only
- C.1, 2 and 3
- D.2 and 4
Show answer
Statements 1, 2 and 3 are true, but carbon never forms a quadruple, or tetra, bond between two carbon atoms.
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