Question

Spines present on the areoles of Opuntia represent
a) Stem
b) Leaves
c) Buds
d) Phyllodes

Answer 1

Hint: Opuntia, also known as prickly pear, is a flowering cactus genus in the Cactaceae family. Opuntia can be found from the Peace River in western Canada almost all the way to the southernmost point of South America.

Complete answer:
Opuntia species are erect or spreading cacti that range in size from small low-growing shrubs to treelike specimens reaching heights of up to 5 metres (16 feet). They're made up of flat joints with paddlelike cladodes (photosynthetic stem segments) sprouting from the ends.
They reproduce easily asexually, and the paddles are easy to root for cultivation. The cladodes have glochidia—small bristles with backward-facing barbs in the areoles—in addition to longer spines.
The showy flowers are usually yellow, pink, or orange in colour, and many have touch-sensitive stamens, which are thought to increase pollen load for insect pollinators. The fruit is typically a reddish berry with spines on it.
In Opuntia, the spines represent the reduced leaves. To protect the plants from grazing animals and excessive transpiration, the leaf sections are modified into spines.
Because of transpiration, in which sun rays extract water from the leaves, Opuntia leaves spines have tiny thorns instead of leaves.
Since cactus grow in deserts and lose water if leaves are present, the spines in Opuntia aid in preventing transpiration.

The correct answer is option (B) Leaves.

Note:
In arid and dryland areas, cactus is used as a fodder crop for livestock. The thick skin of the nopal cactus can be harvested to replace leather in an environmentally friendly way. Bioplastic can be made from nopal juice.