Morphology of Flowering Plants – The Stem: NEET MCQs with Answers

15 free questions on Morphology of Flowering Plants – The Stem for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: The Stem

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Question 1

Previous-year question
In Bougainvillea, thorns are the modifications of [NEET 2017]
  1. Adventitious root
  2. Stem
  3. Leaf
  4. Stipules
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Answer: (B) Stem
Explanation: In Bougainvillea and Citrus the axillary buds become modified into woody, straight and pointed thorns, so the thorns are stem modifications serving to protect the plant.

Question 2

Previous-year question
Stems modified into flat green organs performing the functions of leaves are known as [NEET 2016]
  1. Cladodes
  2. Phyllodes
  3. Phylloclades
  4. Scales
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Answer: (C) Phylloclades
Explanation: Phylloclades are flattened or fleshy green stems of unlimited growth which take over photosynthesis in xerophytes such as Opuntia, while the leaves are reduced to spines. Cladodes are phylloclades of limited growth (one or two internodes).

Question 3

Previous-year question
Which of the following pairs is NOT correctly matched? [AIPMT 2015] Mode of reproduction – Example
  1. Rhizome – Banana
  2. Binary fission – Sargassum
  3. Conidia – Penicillium
  4. Offset – Water hyacinth
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Answer: (B) Binary fission – Sargassum
Explanation: Sargassum is a brown alga that reproduces vegetatively by FRAGMENTATION and sexually by oogamy — not by binary fission, which is a mode of division in unicellular organisms.

Question 4

Previous-year question
An example of an edible underground stem is [AIPMT 2014]
  1. Carrot
  2. Groundnut
  3. Sweet potato
  4. Potato
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Answer: (D) Potato
Explanation: The potato is a stem tuber — an underground stem swollen with stored starch and bearing 'eyes', which are nodes with axillary buds. Carrot is a tap root and sweet potato a tuberous adventitious root.

Question 5

Previous-year question
Vegetative propagation in mint takes place by means of [AIPMT 2009]
  1. Runner
  2. Offset
  3. Rhizome
  4. Sucker
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Answer: (D) Sucker
Explanation: In mint (Mentha arvensis), vegetative propagation occurs through suckers. A sucker is a non-green, specialised underground stem that develops from the underground base of an erect shoot or crown, grows obliquely upwards and forms a new leafy shoot.

Question 6

Previous-year question
Which one of the following is a xerophytic plant in which the stem is modified into a flat, green and succulent structure? [AIPMT 2010]
  1. Opuntia
  2. Casuarina
  3. Hydrilla
  4. Acacia
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Answer: (A) Opuntia
Explanation: In Opuntia, a xerophyte of dry habitats, the stem becomes flattened, green, thick and succulent (a phylloclade) and carries out photosynthesis, while the leaves are reduced to spines to check transpiration. Hydrilla is a submerged hydrophyte and Casuarina has cylindrical green stems.

Question 7

Previous-year question
The structures known as the 'eyes' of a potato tuber are [AIPMT 2011]
  1. Flower buds
  2. Shoot buds
  3. Axillary buds
  4. Root buds
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Answer: (C) Axillary buds
Explanation: The eyes of the potato tuber are spirally arranged depressions, each representing a node bearing one to three axillary buds in the axil of a small scaly leaf. Their presence confirms that the potato is a modified stem and enables vegetative propagation.
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Question 8

Previous-year question
Which one of the following is NOT a modification of the stem? [NEET 2016]
  1. Thorns of Citrus
  2. Tendrils of cucumber
  3. Flattened structures of Opuntia
  4. Pitcher of Nepenthes
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Answer: (D) Pitcher of Nepenthes
Explanation: The pitcher of Nepenthes is a modified leaf lamina; the petiole becomes the tendril and the leaf apex forms the lid. It traps insects in insectivorous plants. Thorns of Citrus, tendrils of cucumber (axillary buds) and the flat phylloclade of Opuntia are all stem modifications.

Question 9

Previous-year question
Stems modified into flat, green organs that carry out the functions of leaves are termed [NEET 2016]
  1. Phyllodes
  2. Phylloclades
  3. Scales
  4. Cladodes
Show answer
Answer: (B) Phylloclades
Explanation: A phylloclade is a flattened or cylindrical, green, fleshy stem of unlimited growth that takes over photosynthesis while the leaves are reduced to spines, e.g. Opuntia. A cladode is a phylloclade consisting of only one or two internodes (e.g. Asparagus), and a phyllode is a flattened green petiole (Australian Acacia).

Question 10

Previous-year question
In Bougainvillea, the thorns represent modifications of the [NEET 2017]
  1. Stipules
  2. Adventitious root
  3. Stem
  4. Leaf
Show answer
Answer: (C) Stem
Explanation: In Bougainvillea and Citrus, the axillary bud loses its growing point, becomes hard, stiff and pointed and is converted into a thorn. Since axillary buds are stem structures, the thorns are stem modifications. Spines, on the other hand, are leaf modifications (e.g. Opuntia).

Question 11

Previous-year question
Identify the correct set of statements given below. I. The leaflets are modified into pointed hard thorns in Citrus and Bougainvillea. II. Axillary buds form slender and spirally coiled tendrils in cucumber and pumpkin. III. Stem is flattened and fleshy in Opuntia and is modified to perform the function of leaves. IV. Rhizophora shows vertically upward growing roots that help to get oxygen for respiration. V. Subaerially growing stems in grasses and strawberry help in vegetative propagation. [NEET 2022]
  1. I and IV
  2. II, III, IV and V
  3. I, II, IV and V
  4. II and III
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Answer: (B) II, III, IV and V
Explanation: Statements II, III, IV and V are correct. Statement I is wrong: in Citrus and Bougainvillea it is the axillary bud of the stem, not the leaflet, that is modified into a woody, straight and pointed thorn. Such thorns protect the plant from browsing animals and also reduce transpiration.

Question 12

Previous-year question
The eye of a potato is a [2001]
  1. adventitious bud
  2. axillary bud
  3. apical bud
  4. accessory bud
Show answer
Answer: (B) axillary bud
Explanation: The potato tuber is a modified underground stem, and each 'eye' on it is a node bearing an axillary bud in the axil of a scale leaf. These buds sprout into new shoots, proving the tuber is a stem.

Question 13

Previous-year question
Vegetative reproduction in Agave takes place through [1990]
  1. bulbils
  2. rhizomes
  3. suckers
  4. stolons
Show answer
Answer: (A) bulbils
Explanation: In Agave many of the flowers of the inflorescence fail to develop and are replaced by fleshy multicellular vegetative buds called bulbils, which fall to the ground and grow into new plants. Oxalis and Dioscorea propagate similarly, whereas rhizomes, suckers and stolons are modified stems of other kinds.

Question 14

Previous-year question
New banana plants develop from a [1990]
  1. stolon
  2. rhizome
  3. seed
  4. sucker
Show answer
Answer: (D) sucker
Explanation: A sucker is a lateral branch that arises from the basal underground portion of the stem, grows obliquely upward and produces a new aerial shoot. Banana, pineapple and chrysanthemum multiply in this way. Cultivated bananas are triploid and seedless, so seed propagation is not possible.

Question 15

Previous-year question
Stems modified into flat green organs performing the functions of leaves are [NEET-I 2016]
  1. Cladodes
  2. Phyllodes
  3. Phylloclades
  4. Scales
Show answer
Answer: (C) Phylloclades
Explanation: Flattened green photosynthetic stems are phylloclades (e.g., Opuntia).

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