Question

Petiole of Australian Acacia helps in?
(a) Respiration
(b) Photosynthesis
(c) Transpiration
(d) Secretion

Answer 1

Hint: A leaf is a photosynthetic organ of a plant. It is basically of 3 parts- leaf base, petiole, and lamina. The leaf base is the part that is attached to the stem. The petiole is the part that connects the lamina to the stem. And lamina is the broad, flattened part of the leaf. There are several modifications of leaf i.e., modified structures of leaves that are produced to reduce water loss, trap insects, provide support, etc.

Complete answer:
 Petiole of Australian Acacia helps in photosynthesis. Petiole connects lamina to the stem and contains vascular tissues like xylem and phloem that allow the sap to flow through them. Thus, they provide a passage to plant sap, food, and nutrients to the leaf. Photosynthesis takes place in leaves so petiole is a part of the leaf photosynthesis and produces the products of photosynthesis.

Additional Information: - Petiole of Australian Acacia gets modified and becomes flat leaf-like and is called phyllode. The leaf itself gets reduced or vanishes and phyllode (petiole) takes over the photosynthetic function of the leaf.
- The vertical orientation of phyllodes protects them from the high intensity of sunlight and thus leaves are modified to protect themselves from sunlight.
- Plants are modified according to the conditions that they have to thrive in. Because they cannot move from one place to another to escape from danger so they have structural modifications.
So, the correct answer is `photosynthesis`.

Note: Leaf tendrils are modifications of leaf in which the whole leaf is modified into a thin wire-like structure for example in peas. Leaf spines are modified leaves to protect the plant from grazing animals as in Opuntia dilleni. Leaf pitcher is a modification wherein leaves are modified into pitcher shaped structures to trap insects to increase intake of phosphorus and nitrogen as in Nepenthes.