Assertion–Reason Questions

🧬 Flower Structure | Class 12 Biology

Directions (CBSE Pattern):

For each question, choose the correct option:

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true but Reason is NOT the correct explanation of Assertion
C. Assertion is true but Reason is false
D. Assertion is false but Reason is true

Question 1

Assertion (A): Flower is considered a modified shoot. Reason (R): The floral meristem produces nodes, internodes and leaves.

✅ C Answer: C Explanation: Flower is a modified shoot, but nodes and internodes are suppressed, not produced.

Question 2

Assertion: Thalamus bears all the floral whorls.

Reason: Thalamus is the swollen end of the pedicel.

✅ C Answer: A Explanation: Swollen pedicel (receptacle) supports all whorls.

Question 3

Assertion: Sepals are green in colour in most flowers.

Reason: Sepals protect the flower in the bud stage.

✅ C Answer: A Explanation: Green colour aids protection and photosynthesis.

Question 4

Assertion: Petals are brightly coloured.

Reason: Bright colour helps in attracting pollinators.

✅ C Answer: A

Question 5

Assertion: Androecium is the male reproductive whorl.

Reason: It consists of carpels. Answer: C Explanation: Androecium consists of stamens, not carpels.

Question 6

Assertion: Pollen grains are produced inside microsporangia.

Reason: Microsporangia are present in the anther.

✅ C Answer: A

Question 7

Assertion: A bisexual flower can undergo self-pollination.

Reason: Presence of both androecium and gynoecium allows it.

✅ C Answer: A

Question 8

Assertion: Papaya plants bear unisexual flowers.

Reason: Papaya is a dioecious plant.

✅ C Answer: A

Question 9

Assertion: Actinomorphic flowers can be cut into two equal halves in only one plane.

Reason: They show bilateral symmetry.

✅ C Answer: D Explanation: Actinomorphic flowers have radial symmetry.

Question 10

Assertion: Pea flower is zygomorphic.

Reason: It can be divided into two equal halves only in one vertical plane.

✅ C Answer: A

Question 11

Assertion: In hypogynous flowers, ovary is superior.

Reason: Other floral parts are borne above the ovary.

✅ C Answer: C Explanation: Other parts are below the ovary.

Question 12

Assertion: Mustard flower shows hypogynous condition.

Reason: Ovary occupies the highest position.

✅ C Answer: A

Question 13

Assertion: Sunflower has inferior ovary.

Reason: Sunflower flower is epigynous.

✅ C Answer: A

Question 14

Assertion: Perianth is found mostly in monocot flowers.

Reason: Sepals and petals are indistinguishable in monocots.

✅ C Answer: A

Question 15

Assertion: Aestivation refers to arrangement of petals in a flower.

Reason: It is studied when the flower is in bud stage.

✅ C Answer: B Explanation: Definition is correct, but it includes sepals too.

Question 16

Assertion: Valvate aestivation shows overlapping margins.

Reason: Margins of sepals or petals just touch each other.

✅ C Answer: D

Question 17

Assertion: Twisted aestivation is seen in China rose.

Reason: Each petal overlaps the next one in one direction.

✅ C Answer: A

Question 18

Assertion: Vexillary aestivation is characteristic of Papilionaceae.

Reason: Standard petal overlaps the wings and keel. Answer: A

Question 19

Assertion: In diadelphous condition, stamens are united into two bundles.

Reason: Seen in pea plant.

✅ C Answer: A

Question 20

Assertion: Tetradynamous condition is found in Brassica.

Reason: It has four long and two short stamens.

✅ C Answer: A

Question 21

Assertion: China rose shows monadelphous stamens.

Reason: Filaments are united into one bundle.

✅ C Answer: A

Question 22

Assertion: Syngenesious condition involves fusion of filaments.

Reason: Anthers are united while filaments are free.

✅ C Answer: D

Question 23

Assertion: Placentation refers to arrangement of ovules inside ovary. Reason: Placenta develops from ovary wall.

✅ C Answer: A

Question 24

Assertion: Pea shows marginal placentation.

Reason: Ovules are attached along the ventral suture.

✅ C Answer: A

Question 25

Assertion: Mustard shows parietal placentation.

Reason: Ovules are attached to the central axis.

✅ C Answer: C

Question 26

Assertion: Tomato shows axile placentation. Reason: Ovules are attached to a central column.

✅ C Answer: A

Question 27

Assertion: Free central placentation is seen in Dianthus.

Reason: Ovules are borne on a central axis without septa.

✅ C Answer: A

Question 28

Assertion: Sunflower shows basal placentation. Reason: Single ovule is attached at the base of ovary.

✅ C Answer: A

Question 29

Assertion: Bract is a modified leaf.

Reason: It subtends a flower or inflorescence.

✅ C Answer: A

Question 30

Assertion: Achlamydeous flowers lack sepals and petals.

Reason: They lack both calyx and corolla.

✅ C Answer: A