Question

What is the arrangement of flowers in Sunflower (Helianthus annuus)?
A) Acropetal
B) Basipetal
C) Centripetal
D) Centrifugal

Answer 1

Hint: The arrangement of flowers on the floral axis of a plant is termed an inflorescence. It can be of two types: Racemose/Indefinite type and the second one is Cymose/Definite type.
Complete answer:
A) Acropetal - in this type of inflorescence the main axis continues to grow and does not terminate in a flower and flowers are born laterally in an acropetal order or acropetal succession. Where old flowers are arranged on the lower side and young flowers are arranged on the upper side of the plant.
B) Basipetal - In this type of inflorescence, the main axis or peduncle terminates in a flower. The older flowers are arranged on the upper side and younger flowers are arranged towards the base of the plant. This type of arrangement is called the basipetal succession of basipetal order.
C) Centripetal - The opening of a flower in the racemose inflorescence is in a centripetal manner. This means the centripetal manner of flower opening is the opening of the flower from the center to the outside of the inflorescence. For example Sunflower.
D) Centrifugal- The opening of a flower in the cymose inflorescence is in a Centrifugal manner. This means the centrifugal manner of flower opening is the opening of the flower from the outside to the center of the inflorescence.
Thus, C is the correct option.

Note: A flower is a modified shoot wherein shoots apical meristem changes to floral meristem. Internodes to not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. Depending on whether the apex gets converted into a flower or continues to grow, two major types of the inflorescence are defined- racemose and cymose.