Structure of the Flower Practice Questions
20 free Structure of the Flower practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
A flower is a modified shoot where the shoot apical meristem changes to floral meristem. In this transition, which of the following occurs?
- A Internodes elongate significantly
- B The floral axis becomes condensed
- C Leaves transform into roots
- D Nodes produce only axillary buds
Correct answer: The floral axis becomes condensed
When the shoot apical meristem transforms into a floral meristem, the internodes do not elongate and the axis becomes condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves.
The swollen end of the stalk or pedicel on which the four whorls of a flower are arranged is called the:
- A Petiole of the leaf
- B Perianth of the flower
- C Stigma of the carpel
- D Thalamus or Receptacle
Correct answer: Thalamus or Receptacle
The thalamus or receptacle is the enlarged tip of the flower stalk (pedicel) that supports the floral organs. It serves as the base for the calyx, corolla, androecium, and gynoecium.
In which type of symmetry can a flower be divided into two similar halves only in one particular vertical plane?
- A Actinomorphic
- B Asymmetric
- C Radial
- D Zygomorphic
Correct answer: Zygomorphic
Zygomorphic symmetry (bilateral symmetry) occurs when a flower can be divided into two similar halves through only one specific vertical plane. Examples include pea, gulmohur, bean, and Cassia.
A flower is described as 'Epigynous' when:
- A The gynoecium occupies the highest position on a prominently raised thalamus
- B The ovary is half-inferior with respect to the surrounding thalamus
- C The margin of thalamus grows upward enclosing the ovary completely
- D The calyx and corolla are completely absent from the entire flower
Correct answer: The margin of thalamus grows upward enclosing the ovary completely
In epigynous flowers, the thalamus grows upward to enclose the ovary completely and fuses with it, making the ovary inferior. Other floral parts arise above the ovary, as seen in guava and cucumber.
What is the term used when the calyx and corolla are not distinct, as seen in Lily?
- A Corolla
- B Androecium
- C Gamosepalous
- D Perianth
Correct answer: Perianth
In some flowers like Lily, the sepals and petals are not differentiated into two distinct whorls. This combined whorl is referred to as the perianth.
In the floral formula, the symbol '⊕' represents which of the following?
- A Zygomorphic (bilateral) symmetry
- B Bisexual flower type
- C Superior ovary type
- D Actinomorphic symmetry
Correct answer: Actinomorphic symmetry
The circle with a cross inside (⊕) is the standard botanical symbol for actinomorphic or radial symmetry. Zygomorphic symmetry is represented by a percentage sign (%) or a vertical line with dots.
The mode of arrangement of sepals or petals in a floral bud with respect to other members of the same whorl is known as:
- A Placentation
- B Phyllotaxy
- C Aestivation
- D Inflorescence
Correct answer: Aestivation
Aestivation refers to the arrangement of accessory whorls (sepals or petals) in the bud stage. Common types include valvate, twisted, imbricate, and vexillary.
In 'Vexillary' aestivation, the largest petal that overlaps the two lateral petals is called the:
- A Keel
- B Wing petal
- C Standard
- D Corona
Correct answer: Standard
Vexillary aestivation is characteristic of the pea and bean family. It consists of a large posterior petal called the standard, two lateral wings, and two smallest anterior petals called the keel.
Sterile stamens that do not produce fertile pollen are called:
- A Pistillodes
- B Synandrous
- C Epipetalous
- D Staminodes
Correct answer: Staminodes
A staminode is an underdeveloped or sterile stamen that is incapable of producing pollen. They are often found in flowers that have transitioned toward specific pollination syndromes.
When stamens are attached to the petals, they are described as:
- A Epiphyllous
- B Monadelphous
- C Polyadelphous
- D Epipetalous
Correct answer: Epipetalous
Stamens are epipetalous when they are fused with the petals, a feature common in Brinjal. If they are attached to the perianth (as in Lily), they are called epiphyllous.
In a floral diagram, the 'Mother Axis' is represented by a dot at the top. This represents the _______ of the flower.
- A Anterior side
- B Lateral sides
- C Posterior end
- D Ventral side
Correct answer: Posterior end
The position of the mother axis with respect to the flower is represented by a dot on the top of the floral diagram. This dot denotes the posterior side of the flower.
The fusion of carpels in a gynoecium is termed as:
- A Apocarpous
- B Monocarpellary
- C Syncarpous
- D Polycarpellary
Correct answer: Syncarpous
When more than one carpel is present and they are fused together, the condition is called syncarpous, as seen in mustard and tomato. If they are free, they are called apocarpous.
The arrangement of ovules within the ovary is known as:
- A Placentation
- B Aestivation
- C Ovulation
- D Parthenocarpy
Correct answer: Placentation
Placentation refers to the specific pattern in which ovules are attached to the placenta within the ovary. Types include marginal, axile, parietal, free central, and basal.
Which type of placentation is found in members of the family Fabaceae (e.g., Pea)?
- A Axile
- B Basal
- C Marginal
- D Parietal
Correct answer: Marginal
In marginal placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge in two rows. This is characteristic of the pea plant.
In 'Basal' placentation, the placenta develops at the base of the ovary and a single ovule is attached to it. This is found in:
- A Sunflower
- B Mustard
- C Lemon
- D Groundnut
Correct answer: Sunflower
Basal placentation is typically found in plants belonging to the Asteraceae family, such as sunflower and marigold. It features a single ovule at the base of a unilocular ovary.
In the floral formula of Solanaceae, 'K(5)' indicates which of the following?
- A Five fused sepals
- B Five free sepals
- C Five free petals
- D Five fused petals
Correct answer: Five fused sepals
In floral formulas, 'K' stands for Calyx (sepals). Brackets surrounding the number indicate that the members of that whorl are fused (gamosepalous).
The symbol 'G' with a line drawn below it (G) in a floral formula represents a/an:
- A Superior ovary
- B Inferior ovary
- C Half-inferior ovary
- D Absent gynoecium
Correct answer: Superior ovary
A line below the 'G' signifies that the gynoecium is superior (hypogynous flower). If the line is above the 'G', it represents an inferior ovary.
The term 'Diadelphous' refers to a condition where stamens are united into:
- A Two bundles
- B One bundle
- C Many bundles
- D No bundles (free)
Correct answer: Two bundles
In the diadelphous condition, stamens are united into two groups or bundles. This is famously seen in Pea plants where the arrangement is (9) + 1.
Which whorl of the flower is primarily responsible for attracting insects for pollination?
- A Corolla
- B Calyx
- C Androecium
- D Gynoecium
Correct answer: Corolla
The corolla is composed of petals, which are usually brightly colored. Their primary function is to attract insects or birds for the process of pollination.
In the floral diagram of Mustard (Brassicaceae), the number of stamens and their arrangement is shown as:
- A 2 + 4
- B 2 + 2
- C 5 + 5
- D Infinite
Correct answer: 2 + 4
Mustard exhibits a tetradynamous condition where there are six stamens in two whorls. The formula 'A 2+4' represents two short outer stamens and four long inner stamens.