Assertion (A): Alstonia exhibits whorled phyllotaxy. Reason (R): In Alstonia, more than two leaves arise at a single node and form a whorl.
Whorled phyllotaxy is characterized by more than two leaves arising at a single node to form a whorl. Alstonia is the standard textbook example of this arrangement, so the Reason correctly explains the Assertion.
Question 272 of 300
📘 CLASS XI
Assertion (A): When a shoot tip transforms into a flower, the flower is always solitary. Reason (R): In cymose inflorescence, the apical meristem continues to grow indefinitely and bears flowers in an acropetal order.
When a shoot tip transforms into a flower, the apical growth ceases and the flower is solitary. The Reason is false because indefinite growth with acropetal succession occurs in racemose inflorescence, whereas cymose inflorescence has limited growth and basipetal succession.
Question 273 of 300
📘 CLASS XI
Assertion (A): In racemose inflorescence, the main axis continues to grow, and the flowers are borne in an acropetal succession. Reason (R): The apex of the floral axis in racemose inflorescence is not consumed in the formation of a flower.
In racemose inflorescence, the main axis remains meristematic and is not consumed in flower formation. As a result, it continues to grow, producing flowers laterally in acropetal succession. Therefore, the Reason correctly explains the Assertion.
Question 274 of 300
📘 CLASS XI
Assertion (A): In some flowers like lily, the calyx and corolla are not distinct and are termed perianth. Reason (R): Lily is a bisexual flower that contains both androecium and gynoecium.
In lily, the calyx and corolla are not differentiated and together form the perianth. Lily flowers are also bisexual, possessing both androecium and gynoecium. However, bisexuality does not explain the formation of a perianth.
Question 275 of 300
📘 CLASS XI
Assertion (A): Mustard, datura, and chilli are examples of actinomorphic flowers. Reason (R): Actinomorphic flowers can be divided into two equal radial halves in any radial plane passing through the centre.
Actinomorphic flowers possess radial symmetry and can be divided into two equal halves in any radial plane passing through the centre. Mustard, datura, and chilli exhibit this type of symmetry, so the Reason correctly explains the Assertion.
Question 276 of 300
📘 CLASS XI
Assertion (A): Pea, gulmohur, bean, and Cassia are described as zygomorphic flowers. Reason (R): Zygomorphic flowers can be divided into two similar halves only in one particular vertical plane.
Zygomorphic flowers possess bilateral symmetry and can be divided into two similar halves only in one particular vertical plane. Pea, gulmohur, bean, and Cassia are classic examples of zygomorphic flowers. Therefore, the Reason correctly explains the Assertion.
Question 277 of 300
📘 CLASS XI
Assertion (A): Canna is classified as an asymmetric flower. Reason (R): Canna can be divided into two similar halves by two vertical planes passing through the centre.
Canna is an asymmetric flower. Asymmetric flowers cannot be divided into two similar halves by any vertical plane passing through the centre. Hence, the Assertion is true but the Reason is false.
Question 278 of 300
📘 CLASS XI
Assertion (A): In plum, rose, and peach, the ovary is half inferior. Reason (R): In perigynous flowers, the gynoecium is situated in the centre, and other floral parts are located on the rim of the thalamus almost at the same level.
Plum, rose, and peach are examples of perigynous flowers. In these flowers, the gynoecium is central while the remaining floral parts arise from the rim of the thalamus at almost the same level, making the ovary half inferior. Hence, the Reason correctly explains the Assertion.
Question 279 of 300
📘 CLASS XI
Assertion (A): Guava and cucumber flowers possess an inferior ovary. Reason (R): In epigynous flowers, the margin of the thalamus grows upward, enclosing the ovary completely and fusing with it, while other floral parts arise above the ovary.
Guava and cucumber are epigynous flowers. In epigynous flowers, the thalamus encloses and fuses with the ovary, while the other floral parts arise above it, making the ovary inferior. Therefore, the Reason correctly explains the Assertion.
Question 280 of 300
📘 CLASS XI
Assertion (A): Mustard and brinjal possess superior ovaries, whereas ray florets of sunflower possess inferior ovaries. Reason (R): Mustard and brinjal have hypogynous flowers, while ray florets of sunflower have epigynous flowers.
Mustard and brinjal are hypogynous flowers with superior ovaries, whereas the ray florets of sunflower are epigynous with inferior ovaries. Thus, the floral position directly explains the ovary condition.
