NEET Morphology of Flowering Plants Previous Year Questions with Solutions

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. Its primary adaptive purpose is to orient leaves in a manner that avoids self-shading and maximizes light interception for photosynthesis.

• • There are three primary types of phyllotaxy: Alternate, Opposite, and Whorled.

1. Alternate Phyllotaxy: A single leaf arises at each node in an alternate manner (e.g., China rose, Mustard, Sunflower). 2. Opposite Phyllotaxy: A pair of leaves arise at each node and lie opposite to each other (e.g., Calotropis, Guava). 3. Whorled Phyllotaxy: More than two leaves arise at a node and form a whorl (e.g., Alstonia).

• • All three describe patterns of leaf arrangement.

1. Flowers: The arrangement of flowers on the floral axis is called INFLORESCENCE (Racemose or Cymose). 2. Sepals and Petals: The mode of arrangement of sepals or petals in floral bud with respect to other members is called AESTIVATION (Valvate, Twisted, Imbricate, Vexillary). 3. Fruits: Developed from fertilized ovaries; arrangement is not termed phyllotaxy.

• • Matches Option (1).

In Solanaceae (e.g., Solanum nigrum, Petunia, Datura), flowers are bisexual (hermaphrodite, ⚥) and actinomorphic (radial symmetry, ⊕).

• • Flowers can be divided into equal vertical halves in any radial plane.

Calyx consists of 5 sepals that are united (gamosepalous, $K_{(5)}$), persistent (as seen in brinjal and Physalis), and exhibit valvate aestivation.

• • Statement (b) is an accurate diagnostic feature.

Androecium consists of 5 alternipetalous stamens ($A_5$) whose filaments are adnate/attached to the corolla tube (epipetalous condition, denoted by an arch over $C_{(5)}$ and $A_5$).

• • Anthers are dithecous, dehiscing longitudinally or poricidally.

The gynoecium is bicarpellary, syncarpous, with an obliquely oriented ovary and a swollen placenta bearing many ovules. Most importantly, the flower is hypogynous, meaning the ovary is SUPERIOR ($\underline{G}_{(2)}$), NOT inferior.

• • Inferior ovary (epigynous flower) is found in Asteraceae, Cucurbitaceae, guava, and cucumber, never in Solanaceae.

Statements (a), (b), and (c) are correct, while (d) is incorrect. The matching choice is Option (1).

• • Matches official NTA final answer key Option A / (1).

In marginal placentation, the placenta forms a ridge along the ventral suture of the monocarpellary ovary, and ovules are borne along this ridge in two rows. Canonical example: Pea (Pisum sativum).

• • A pairs with IV.

In axile placentation, the placenta is axial and the ovules are attached to it in a multilocular ovary divided by septa. Canonical examples: Tomato, China rose, Lemon.

• • B pairs with II.

In parietal placentation, ovules develop on the inner wall of the unilocular ovary or on peripheral parts. The ovary becomes two-chambered due to the formation of a false septum (replum). Canonical examples: Mustard, Argemone.

• • C pairs with I.

In free central placentation, ovules are borne on a central axis and septa are completely absent. Canonical examples: Dianthus, Primrose.

• • D pairs with III.

Assembling all pairs gives: A-IV, B-II, C-I, D-III. Looking at the options, this matches Option (4).

• • Matches official NTA final answer key Option D / (4).

Floral symmetry indicates the geometric planes along which a flower can be divided into identical halves:

• • Actinomorphic flowers (e.g., mustard, datura, chilli) can be divided into equal halves in any radial plane passing through the center.
• • Therefore, ⊕ represents actinomorphy, not zygomorphy.

The horizontal line placed relative to the letter G (Gynoecium) designates the position of the ovary relative to the calyx, corolla, and androecium:

• • In a hypogynous flower, sepals, petals, and stamens insert below the ovary, so the line is drawn beneath the letter G (G).
• • In an epigynous flower, floral parts arise above the ovary, so the line is drawn above G (Ḡ).

Compare with the statements presented:

• • Statement I is incorrect and Statement II is correct, matching Option (4).

Cereal grains (such as maize, wheat, barley, and rice) are single-seeded fruits (caryopsis) where the seed coat is membranous and generally fused with the fruit wall (pericarp):

• • The seed is divided into two unequal regions: a large storage endosperm and a small laterally placed embryo.
• • The outer covering of the endosperm differentiates into a specialized protein-rich peripheral layer termed the aleurone layer.
• • The aleurone layer synthesizes hydrolytic enzymes (such as $\alpha$-amylase induced by gibberellins) during seed germination to mobilize stored starch from the endosperm to the developing embryo.

Distinguishing protective coverings of the monocot embryo:

• • Coleoptile: A conical protective foliar sheath enclosing the plumule (shoot tip).
• • Coleorhiza: An undifferentiated protective sheath enclosing the radicle and root cap.
• • Integument: The diploid maternal layer enveloping the ovule that matures into the seed coat (testa and tegmen).

The protein-rich boundary layer separating the endosperm from the embryo is the Aleurone layer.

Floral symmetry is a primary taxonomic character in angiosperm classification:

• • A flower is zygomorphic (bilaterally symmetrical) when it can be divided into two equal and similar halves along only one single vertical median longitudinal plane.
• • In floral diagrams and formulas, zygomorphic symmetry is denoted by the percentage sign ($\%$).

Classifying the provided options based on NCERT examples:

• • 1. Petunia: Belongs to family Solanaceae; flowers are actinomorphic (radial symmetry, $\oplus$).
• • 2. Datura: Belongs to family Solanaceae; flowers are actinomorphic (radial symmetry, $\oplus$).
• • 3. Pea (*Pisum sativum*): Belongs to family Fabaceae; flowers have vexillary (papilionaceous) aestivation with standard, wings, and keel, making them distinctly zygomorphic ($\%, C_{1+2+(2)}$).
• • 4. Chilli (*Capsicum annuum*): Belongs to family Solanaceae; flowers are actinomorphic (radial symmetry, $\oplus$).

Among the choices, Pea is the definitive example of a zygomorphic flower.

Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, flowers are described as hypogynous, perigynous and epigynous.

If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous. The ovary here is said to be half inferior (e.g., plum, rose, peach). NCERT illustrates two complementary section diagrams of perigynous arrangements demonstrating variation in thalamus cup depth.

Both figures depict the gynoecium situated centrally with floral appendages attached along the elevated thalamus rim at the same horizontal plane—both are perigynous flowers.

When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic (radial symmetry).

NCERT provides specific examples: Mustard, Datura, and Chilli are actinomorphic. Pea, Gulmohur, Bean, and Cassia are zygomorphic (can be divided into two similar halves only in one particular vertical plane).

Datura possesses actinomorphic floral symmetry.

Rose possesses perigynous flowers where the rim of the thalamus bears floral organs at the level of the half-inferior ovary (A -> II). Pea exhibits marginal placentation along the ventral suture of the monocarpellary ovary (B -> IV).

Cotton belongs to Malvaceae, showing twisted aestivation where one margin of an appendage overlaps that of the next (C -> I). Mango fruit develops from a monocarpellary superior ovary as a drupe with stony endocarp (D -> III).

The corresponding combination is A-II, B-IV, C-I, D-III, matching Option (3).

The stamens may be united into one bunch or one bundle (monoadelphous) as in China rose, or into two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus.

When stamens are attached to the perianth, as in the flowers of lily, they are described as epiphyllous (in contrast to epipetalous when attached to petals, as in brinjal).

A-IV, B-II, C-I, D-III correctly represents all conditions, matching Option (3).

Analyzing the androecium of the three canonical NCERT angiosperm families:

Epiphyllous stamens (adnate to perianth) are unique to Liliaceae. Epipetalous stamens (adnate to corolla) characterize Solanaceae. Monadelphous monothecous stamens characterize Malvaceae (China rose).

The combination of diadelphous stamens and dithecous anthers uniquely differentiates Fabaceae from Solanaceae and Liliaceae.

When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is termed axile:

Reviewing canonical plant examples classified by placentation:

Option (1) contains China rose (Malvaceae), Petunia (Solanaceae), and Lemon (Rutaceae)—all of which possess multilocular ovaries with axile placentation.

In plant morphology (Goethe's foliar theory), a flower is fundamentally a determinate, modified reproductive shoot:

NCERT states under The Inflorescence: "A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem. Internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves."

The shoot nature of the flower is proven by the presence of nodes and condensed internodes on the thalamus, and the lateral appendages (sepals, petals, stamens, carpels) being homologous to modified leaves. Therefore, Reason R directly explains Assertion A.

When the filaments of stamens are fused together while anthers remain free, the condition is termed adelphy:

In the pea flower (*Pisum sativum*, family Fabaceae), there are 10 stamens. Nine stamens fuse by their filaments into a common sheath enclosing the ovary, while the tenth posterior stamen remains free. This configuration is denoted in the floral formula as $\mathbf{A_{(9)+1}}$, representing the classic diadelphous condition.

Each angiosperm family in the NCERT syllabus possesses unambiguous diagnostic floral characteristics:

Matching (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i) directly and exclusively points to Option (1).

Flowering plants exhibit three fundamental types of root systems based on their ontogeny and developmental origin: 1. Tap Root System: In dicots (e.g. mustard), direct elongation of the embryonic radicle forms the persistent primary root, which bears lateral roots of several orders (secondary, tertiary roots). 2. Fibrous Root System: In monocotyledonous plants (e.g. wheat, maize), the primary root is short-lived. It is quickly replaced by a large cluster of thin, thread-like roots that originate from the base of the stem. 3. Adventitious Roots: Roots that arise from any organ of the plant other than the embryonic radicle (e.g. *Monstera*, banyan tree prop roots, stilt roots of sugarcane).

- Primary roots: Direct downward continuation of the embryonic radicle. - Prop roots: Pillar-like massive adventitious roots hanging down from horizontal aerial tree branches (e.g. banyan tree) to provide columnar support. - Lateral roots: Endogenous branch roots originating from the pericycle of the primary root.

Based on the spatial insertion of calyx, corolla, and androecium relative to the gynoecium on the thalamus: - 1. Hypogynous Flower (Superior Ovary): Gynoecium occupies the highest position on the convex/conical thalamus while other floral whorls arise below it (e.g. mustard, China rose, brinjal). - 2. Perigynous Flower (Half-Inferior Ovary): Gynoecium is situated in the centre of a cup-shaped thalamus, and other parts arise on the rim of the thalamus at the same level (e.g. plum, rose, peach). - 3. Epigynous Flower (Inferior Ovary): The margin of the hollowed cup-shaped thalamus grows completely upward, enclosing and fusing with the ovary wall. The sepals, petals, and stamens arise above the top of the ovary. The ovary is consequently inferior. - NCERT explicitly provides three canonical examples of epigynous flowers with inferior ovaries: guava, cucumber, and the ray florets of sunflower.

In the composite head (capitulum) of sunflower (*Helianthus annuus*), the marginal zygomorphic strap-shaped ray florets are pistillate or sterile and strictly epigynous, with the ovary situated inferior to the attached ligulate petal tube.

Based on the position of calyx, corolla, and androecium in respect of the ovary on thalamus, flowers are described as hypogynous, perigynous, and epigynous.

If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous. The ovary here is said to be half inferior.

The canonical NCERT examples of perigynous flowers with half inferior ovaries are Plum, Rose, and Peach.

Brinjal and Mustard have hypogynous flowers with superior ovaries. Sunflower ray florets have epigynous flowers with inferior ovaries.