Question
In Bougainvillea thorns are the modifications of [NEET 2017]
(a) stipules
(b) adventitious root
(c) stem
(d) lea
Answer/Explanation
Ans. (c)
In Bougainvillea, thorns are the modifications of stem. They are stiff, sharp structures, which have lost their growing point and become hard. They reduce transpiration as well as browsing by animals.
Question
Stems modified into flat green organs performing the functions of leaves are known as [NEET 2016, Phase I]
(a) phyllodes
(b) phylloclades
(c) scales
(d) cladodes
Answer/Explanation
Ans. (b)
Phylloclades are aerial modified stem, in which stem becomes thick, fleshy succulent, green and perform the function of photosynthesis. The leaves are reduced to spines in this.
Question
Which of the following is not a stem modification? [NEET 2016, Phase I]
(a) Thorns of Citrus
(b) Tendrils of cucumber
(c) Flattened structures of Opuntia
(d) Pitcher of Nepenthes
Answer/Explanation
Ans. (d)
Pitcher of Nepenthes is modified leaf. It. helps to trap insects, in insectivorous plants.
Question
An example of edible underground stem is [CBSE AIPMT 2014]
(a) carrot
(b) groundnut
(c) sweet potato
(d) potato
Answer/Explanation
Ans. (d)
Potato (Solanum tuberosum) is an edible underground stem which become fleshy and tuberous as a result of food storage.
Question
The ‘eyes’ of the potato tuber are [CBSE AIPMT 2011, 01]
(a) flower buds
(b) shoot buds
(c) axillary buds
(d) root buds
Answer/Explanation
Ans. (c)
Eyes of potato tubers are axillary buds. As tuber is oval or spherical swollen underground modified stem lacking adventitious roots.
It possesses a number of spirally arranged depressions called eyes. Each eye represents node and consists of 1-3 axillary buds in the axil of small scally leaves.
Question
Vegetative propagation in mint occurs by [CBSE AIPMT 2009]
(a) runner
(b) offset
(c) rhizome
(d) sucker
Answer/Explanation
Ans. (d)
The vegetative propagation in mint (Mentha arvensis) occurs by sucker.
Sucker is a non-green underground specialised stem developing from the underground base of an erect shoot or crown.
Question
Vegetative reproduction of Agave occurs through [CBSE AIPMT 1991]
(a) rhizome
(b) stolon
(c) bulbils
(d) sucker
Answer/Explanation
Ans. (c)
Bulbil is a condensed axillary bud meant for vegetative propagation, e.g. Dioscorea and Agove. In ananas, bulbils are associated with flowers and fruits.
Tiny secondary bulb that forms in the angle between a leaf and stem or in place of flowers. in certain plants.
Bulbills are called offsets when full-sized, fall or are removed and planted to produce new plants.
Question
New banana plants develop from [CBSE AIPMT 1990]
(a) rhizome
(b) sucker
(c) stolon
(d) seed
Answer/Explanation
Ans. (b)
Sucker is the subaerial modification of stem, which originates from the basal and underground portion of the main stem but it grows obliquely upwards and give rise to leafy shoot or a new plant, e.g. Musa (banana). Chrysanthemum, mint.