31 Years NEET Previous Year Questions: Morphology of Flowering - 1 - NEET MCQ

The correct answer is: Option A: A-IV, B-II, C-I, D-III
Monoadelphous: Stamens united into a single bundle by their filaments. Example: China rose
Diadelphous: Stamens united into two bundles by their filaments. Example: Pea
Polyadelphous: Stamens united into more than two bundles by their filaments. Example: Citrus
Epiphyllous: Stamens arise from the perianth (sepals and petals) rather than from the receptacle. Example: Lily

The radicle is the part of the seed that will develop into the root when the seed germinates.
In the provided diagram, 'C' represents the radicle.
Topic in NCERT: Structure of a Dicotyledonous Seed
Line in NCERT: "The embryo is made up of a radicle, an embryonal axis and one (as in wheat, maize) or two cotyledons (as in gram and pea)."

Rose has a half-inferior ovary, thus it is a Perigynous flower.
Pea: The placenta forms a ridge along the ventral suture of the ovary, and ovules are borne on this ridge forming two rows.
Cotton: Twisted aestivation is present.
Mango: The fruit is a drupe.

An actinomorphic flower is one that can be divided into two equal halves along any plane passing through its center. This is also known as radial symmetry.
Datura flowers exhibit radial symmetry, as their petals are arranged in a circular pattern around the center.

The other options are incorrect:

• Cassia: Zygomorphic (bilateral symmetry)
• Pisum: Zygomorphic (bilateral symmetry)
• Sesbania: Zygomorphic (bilateral symmetry)

Topic in NCERT: Flower Symmetry

Line in NCERT: "it is said to be actinomorphic, e.g., mustard, datura, chilli."

If the gynoecium is situated in the center and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous.
Both diagrams show the perigynous condition.

Topic in NCERT: THE FLOWER

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

Fabaceae: Diadelphous and dithecous anthers.
Solanaceae: Polyandrous, epipetalous, and dithecous anthers.
Liliaceae: Polyandrous, epiphyllous, and dithecous anthers.

Statement A is true. A flower is indeed a modified shoot wherein the shoot apical meristem changes to a floral meristem.
Statement R is also true and is the correct explanation of Statement A. The internodes of the shoot get condensed, and instead of leaves, different floral appendages (such as sepals, petals, stamens, and carpels) are produced laterally at successive nodes, leading to flower formation.

Topic in NCERT: THE FLOWER

Line in NCERT: "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 given figure is of a false unit. False fruit develops from other floral parts and thalamus alongwith the development of ovary wall.

When a flower can be divided into two similar halves only in one particular vertical plane, it is zygomorphic for e.g. pea, gulmohar, bean, Cassia. Mustard, Datura and Chilly show actinomorphic flowers.
Topic in NCERT: THE FLOWER
Line in NCERT: "When it can be divided into two similar halves only in one particular vertical plane, it is zygomorphic, e.g., pea, gulmohur, bean, Cassia."

• Vexillary aestivation and diadelphous stamens are the characteristic features of family Fabaceae.
• Pisum sativum (garden pea) belongs to family Fabaceae.
• Allium cepa (onion) and Colchicum autumnale (colchicine) belong to family Liliaceae.
• Solanum nigrum belongs to Solanaceae.

Topic in NCERT: Aestivation
Line in NCERT: "In pea and bean flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous."

The floral diagram given in the question represents Brassicaceae family. It can be easily identified by looking on its parietal placentation
Topic in NCERT: floral formula
Line in NCERT: "The floral diagram and floral formula in Figure 5.16 represents the mustard plant (Family: Brassicaceae)."

Imbricate aestivation is found in Cassia
Valvate aestivation is found in Calotropis
Vexillary aestivation is found in Bean
Twisted aestivation is found in Cotton

The floral formula of

So, a(iii), b(iv), c(ii), d(i) is correct matching.

The stamens may be united into one bunch or one bundle (monoadelphous) as in china rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus.
Line in NCERT: The stamens may be united into one bunch or one bundle (monoadelphous) as in china rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus. There may be a variation in the length of filaments within a flower, as in Salvia and mustard.

Ray floret have inferior ovary. Ray floret is condition in flower where any of a number of strap-shaped and typically sterile florets that form the ray e.g., Sunflower Epigynous flower are formed in family Asteraceae.

Parietal placentation is found in compound or syncarpous ovary. There are two or more longitudinal placentae or files of ovules attached to the ovary wall. The ovary is usually unilocular but becomes falsely two or more locular due to ingrowth of placentae or formation of false septa.

Topic in NCERT: placentation

Line in NCERT: "In parietal placentation, the ovules develop on the inner wall of the ovary or on peripheral part."

Line in NCERT : In coconut which is also a drupe, the mesocarp is fibrous.

Papilionaceous flowers are flowers with the characteristic irregular and butterfly-like corolla. A single, large upper petal is known as the banner or vexillum and the name has been derived from an ancient military standard. 

Topic in NCERT: Aestivation

Line in NCERT: "In pea and bean flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous."

The Liliaceae are a huge variety, comprising about 280 genera and 4000 species of perennial herbs mostly. It includes starchy rhizomes, corms or bulbs, characterized by alternate leaves which are whorled. The flowers are often showy, mostly bisexual and actinomorphic. Also, they exhibit tricarpellary syncarpous gynoecium. Example of such a class is the Erythronium montanum, the alpine fawn lily. 

The proximal end is attached to the thalamus and the distal end bears the anthers.

The cotyledons are known as seed leaves, they are attached to the embryonic axis. Dicotyledons typically have two cotyledons and monocotyledons have only one cotyledon. The single shield-shaped cotyledon in grains known as scutellum.

Topic in NCERT: Structure of Monocotyledonous Seed

Line in NCERT: "The embryo is small and situated in a groove at one end of the endosperm. It consists of one large and shield shaped cotyledon known as scutellum and a short axis with a plumule and a radicle."

Ovary is half superior and half inferior in perigynous flower. Among the lists of options, rose is the peri-gynous flower.
This characterisation is based on the position of the ovary in the flowers. In this case, all sepals, petals and stamens are fused together in a cup like structure which is usually around the ovary called hypanthium.These flowers are termed as perigynous.

Topic in NCERT: Position of floral parts on thalamus

Line in NCERT: "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."

Superior ovary is found in china rose, mustard brinjal, potato, onion and tulip. Guava and cucumber have inferior ovary. 

Topic in NCERT: Position of floral parts on thalamus

Line in NCERT: "The ovary in such flowers is said to be superior, e.g., mustard, china rose and brinjal."

Axile placentation occurs in syncarpous pistils. The ovary is partitioned into two or more chambers. Placentae occur in the central region where the septa meet so that an axile column bearing ovules is formed e.g., shoe flower (pentalocular), lemon (multilocular), etc.

Topic in NCERT: placentation

Line in NCERT: "When 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, tomato and lemon."

In sweetpea (Pisum sativum), the placentation is marginal, in which the placenta develops along the junction of two carpels, in a unilocular ovary. In basal placentation, the ovules are few or reduced to one and are borne at the base of ovary.