Morphology of flowering plants is essential to understand for classification. Many plants undergo modifications for purposes such as storage, respiration and support. Here is a collection of all important questions relating to morphology of flowering plants, their adaptations and floral formulas that are crucial for NEET 2023.
1. The root develops from
(a) radicle
(b) plumule
(c) stem
(d) shoot apex
Answer: (a)
Explanation: Root system develops from the radicle of the seed. The root is the part of the plant that generally grows towards the soil and is formed from the radicle of the germinating seed. Plumule gives rise to the shoot system, which includes the stem and grows after the radicle. The shoot apex has meristematic cells that give rise to almost every aerial part of the plant body.
2. Select the correct statement.
I. From the region of elongation, some of the epidermal cells form root hairs.
II. Pneumatophores are seen in Sonneratia.
III. Adventitious roots are seen in banyan trees.
IV. Maize and sugarcane have prop roots.
(a) I and IV
(b) I, III and IV
(c) III and IV
(d) II and III
Answer: (d)
Explanation: The root has four distinct regions – root cap, region of meristematic activity, region of elongation and region of maturation. The region of elongation undergoes rapid elongation and enlargement and is hence responsible for growth of root lengthwise. The region of maturation has fine, delicate, thread-like structures that are called root hairs.
Pneumatophores are respiratory roots that are seen in halophytes such as Sonneratia and Heritiera. These plants grow in soil having high salt content, the pneumatophores rise vertically upwards from the plant to get oxygen for respiration. Prop roots (a type of adventitious root) are seen in banyan trees whereas stilt roots are seen in maize and sugarcane.
3. Axillary buds get modified into
(a) thorns
(b) tendrils
(c) spines
(d) both a and b
Answer: (d)
Explanation: The axillary buds or lateral buds get modified into thorns and tendrils in certain plants. Thorns are seen in Bougainvillaea and they provide protection from grazing animals. Tendrils are seen in cucumber, watermelon and grapes. They are spirally coiled structures that provide support and help in climbing. Spines are modification of leaves seen in plants of arid regions or deserts such as Opuntia.
4. An example of underground stem is
(a) potato
(b) carrot
(c) groundnut
(d) sweet potato
Answer: (a)
Explanation: The edible part of the potato is a modified stem. This edible part grows underground and is known as tuber. Carrot is a modified tap root for storage of food. Sweet potato is a modified adventitious root specialised for food storage. Adventitious roots are the roots that arise from parts of the plant other than radicles. Groundnut is an edible seed.
5. Which of the following is not a part of the leaf?
(a) Lamina
(b) Petiole
(c) Stipules
(d) Node
Answer: (d)
Explanation: The parts of the leaf are leaf base, petiole and leaf lamina. The part of the leaf by which it is attached to the stem is called leaf base. In some plants, the leaf base bears a pair of small leaf-structures called stipules. Anatomically, in a flowering plant, stipules are considered as a part of the leaf. The stalk of the leaf is called petiole. The expanded green part of the leaf is called leaf lamina or leaf blade and has veins and veinlets. Leaf lamina majorly performs photosynthesis.
The stem bears nodes and internodes and hence is not a part of the leaf. The leaves arise from the node of the stem.
6. Swollen leaf bases are called _______ and are found in _____ plants.
(a) sheathing, leguminous
(b) pulvinus, non-leguminous
(c) sheathing, non-leguminous
(d) pulvinus, leguminous
Answer: (d)
Explanation: The leaf base is swollen in certain leguminous plants and is called pulvinus leaf base. Leguminous plants are the plants belonging to the family Fabaceae in which the fruits are legumes. The roots of these plants have nodules that house nitrogen fixing bacteria.
Sheathing leaf base is found in grasses. It is formed when the leaf base expands into a sheath and covers the stem wholly or partially.
7. The leaflets are attached at a common point in
(a) single leaf
(b) pinnately compound leaf
(c) palmately compound leaf
(d) both a and b
Answer: (c)
Explanation: When the leaf lamina divides and forms leaflets, the leaf is said to be compound. Compound leaves are of two types – pinnately compound and palmately compound leaf.
In pinnately compound leaves, the leaflets are present on a common axis, the rachis, which represents the midrib. Example – neem
In palmately compound leaves, the leaflets are attached at a common point i.e at the base of the petiole. Example – silk cotton
8. Which of the following is an incorrect statement?
(a) Dicots have reticulate venation
(b) Monocots have tap root system
(c) Monocots have parallel venation
(d) Dicots have tap root system
Answer: (b)
Explanation: The arrangement of veins and veinlets in a leaf lamina is called venation. It is of two types:
- Reticulate Venation: In this type, the veinlets form a network and are found in dicots.
- Parallel Venation: In this type, the veins run parallel to each other and are found in monocots.
The tap root system is mostly seen in dicots such as mustard whereas monocots are characterised by fibrous roots such as in wheat.
9. Which of the following is not a leaf modification?
(a) Pitcher of Nepenthes
(b) Spines in cactus
(c) Phylloclade
(d) Phyllode
Answer: (c)
Explanation:
- In Nepenthes, the lamina of the leaf is modified to form a pitcher-like structure that helps to trap insects.
- In cactus, the leaves get modified into spines in order to reduce the rate of transpiration.
- Phyllode is the modification of the petiole to carry out photosynthesis. Example: Acacia
- Phylloclade is a stem modified into a flat, fleshy and green leaf- like structure and carries out photosynthesis like leaves.
10. Name the part of the seed that provides nutrition for the growing dicot seedlings.
(a) Plumule
(b) Micropyle
(c) Aleurone Layer
(d) Cotyledon
Answer: (d)
Explanation: The cotyledons of the seed in several dicots provide nutrition for the growing seedlings or the embryo. In dicots, the cotyledons have endosperms that provide nourishment only in the young seeds and are absent in mature seeds.
Monocotyledonous seeds are endospermic and provide nutrition to the embryo. Plumule is a part of the embryonic axis that grows into the shoot. Micropyle is a small opening that is found in the seed and is part of the ovule. It helps in the absorption of water at the time of germination.
The Aleurone layer is the outermost layer of the endosperm in a monocot seed and is proteinaceous in nature. It provides nourishment to the growing embryo of the seed.
11. Flowers in which only one set of essential organ is present are said to be
(a) bisexual
(b) staminate
(c) pistillate
(d) both b and c
Answer: (d)
Explanation: Flowers that have only set of essential organs are called unisexual flowers. They can either be pistillate ( possessing carpels) or staminate (possessing stamens). Flowers that have both carpels and stamens in them are called bisexual flowers.
12. Radial symmetry is found in the flower of
(a) Cassia
(b) Brassica
(c) Trifolium
(d) Pisum
Answer: (b)
Explanation:
- Actinomorphic: Flowers that can be cut in any plane to get equal halves, i.e., are radially symmetrical. Example: Brassica
- Zygomorphic: Flowers that can be cut in only one one plane, i.e., are bilaterally symmetrical. Example: Pisum, Trifolium, Cassia
- Asymmetrical: Flowers that cannot be divided into two equal halves in any plane.
13. Out of 5 petals of a flower bud, the standard petal overlaps the two wing petals which in turn overlaps two smaller keel petals. This type of aestivation is called
(a) Twisted
(b) Valvate
(c) Vexillary
(d) Imbricate
Answer: (c)
Explanation: The mode of arrangement of sepals and petals in the flower is called aestivation. If the largest petal (standard) overlaps the two lateral petals (wings) which in turn overlaps two smaller anterior petals (keels), then the aestivation is known as vexillary or papilionaceous. Example: pea and bean flower.
14. The perinath is the term used when
(a) androecium and gynoecium are not distinguishable
(b) androecium and calyx are not distinguishable
(c) corolla and gynoecium are not distinguishable
(d) calyx and corolla are not distinguishable
Answer: (d)
Explanation: If there is no distinction between calyx and corolla, then it is called perianth. Perianth is the collective term of the non-essential floral organ called tepal. Example – lilium, tulip
15. Tetradynamous condition is seen in _______
(a) potato family
(b) lily family
(c) mustard family
(d) cotton family
Answer: (c)
Explanation: Tetradynamous condition refers to the presence of 6 stamens in a flower, out of which, 4 are long and 2 are short. This is a characteristic feature of Brassicaceae (mustard family).
16. In a unilocular ovary, the ovules develop on the inner wall of the ovary. This type of placentation is called
(a) basal
(b) axile
(c) parietal
(d) free central
Answer: (c)
Explanation: The arrangement of ovules in the ovary is called placentation. The ovary is made up of chambers called locules in which the ovules are attached. The five types of placentation are:
- Axile: The placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, as in china rose.
- Parietal: The ovules develop on the inner walls of the ovary or on peripheral parts, such as Cucurbita.
- Free central: The ovules are borne on the central axis and septa are absent. It is seen in primrose and Dianthus.
- Basal: One or few ovules develop at the base of a simple or compound ovary as seen in tomatoes.
- Marginal: The ovules are arranged in two rows on the margins of the ovary as seen in sweet peas.
17. What do you call a fruit that develops from inflorescence?
(a) Simple fruit
(b) False fruit
(c) Aggregate fruit
(d) Composite fruit
Answer: (d)
Explanation:
- Composite Fruit: A fruit that develops from an inflorescence. E.g., pineapple
- Simple Fruit: A fruit that develops from a single flower which has a monocarpellary or multicarpellary syncarpous superior gynoecium. E.g., Pea
- False Fruit: A fruit that develops from any other part of the flower other than the ovary. E.g., Apple
- Aggregate Fruit: A fruit that develops from a multicarpellary apocarpous gynoecium of a single flower. E.g., Raspberry
18. Which among the following is not represented in a floral formula?
(a) Position of ovary
(b) Symmetry of flower
(c) Number of sepals
(d) Placentation
Answer: (d)
Explanation: Floral formula uses symbols, alphabets and numbers to describe a flower. The floral formula gives information about:
- Symmetry of the flower
- Sexuality of the flower
- Numbers of petals and sepals and whether they are free or fused
- Number of stamens (free or fused)
- Number of carpels (free or fused)
- Position of ovary
Placentation is the arrangement of ovules in the ovary and is not represented in a floral formula.
19. Which among the following families shows the following floral formula?
(a) Fabaceae
(b) Solanaceae
(c) Brassicaceae
(d) Liliaceae
Answer: (c)
Explanation: The floral formula tells us that the brassicaceae flowers are ebracteate, actinomorphic, bisexual, have four sepals in two whorls, four petals, six stamens in tetradynamous condition and are syncarpour, bicarpellate with superior ovary.
20. Persistent calyx is observed in the family ______
(a) Fabaceae
(b) Solanaceae
(c) Liliaceae
(d) Brassicaceae
Answer: (b)
Explanation: Persistent calyx is characteristic of the family Solanaceae. After fertilisation, when the ovary transforms into a fruit, all floral parts wither away. But in the family of Solanaceae, sepals persist even after fruit formation. Such a calyx is said to be persistent.
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