Glyoxysomes are specialized organelles found in certain plant cells, particularly in the endosperm of castor seeds. These organelles play a crucial role in the process of fatty acid metabolism, specifically in the conversion of stored lipids into carbohydrates.

Explanation:
Glyoxysomes are most commonly found in the endosperm of castor seeds. The endosperm is a tissue located within the seed that serves as a nutrient reserve for the developing embryo. In castor seeds, this endosperm is rich in lipids, which are stored in the form of triacylglycerols.

1. Role of glyoxysomes in fatty acid metabolism:
Glyoxysomes are involved in the process of fatty acid metabolism, specifically in the glyoxylate cycle. During germination of the castor seed, glyoxysomes break down the stored triacylglycerols into fatty acids. These fatty acids are then converted into carbohydrates through a series of enzymatic reactions involving the glyoxylate cycle. This conversion allows the developing embryo to utilize the stored lipids as an energy source for growth and development.

2. Function of glyoxysomes in other plant cells:
While glyoxysomes are primarily found in the endosperm of castor seeds, they can also be present in other plant cells, although to a lesser extent. For example, glyoxysomes have been observed in the cotyledons of certain seeds and in the peroxisomes of leaf cells. In these cells, glyoxysomes may have a similar role in fatty acid metabolism, contributing to the conversion of lipids into carbohydrates. However, it is important to note that glyoxysomes are not uniformly present in all plant cells or tissues.

3. Absence of glyoxysomes in other options:
a) Root hairs: Root hairs are specialized structures that increase the surface area of roots for absorption of water and nutrients. While peroxisomes are present in root hairs, glyoxysomes are not typically found in this cell type.
b) Endosperm of wheat: Unlike castor seeds, the endosperm of wheat does not contain significant amounts of lipids. Therefore, glyoxysomes are not expected to be present in the endosperm of wheat.
c) Palisade cells in leaf: Palisade cells are the main photosynthetic cells in leaves, involved in the process of photosynthesis. While they contain chloroplasts for photosynthesis, glyoxysomes are not typically found in these cells.

In conclusion, the correct answer is option 'D' - glyoxysomes are most likely to be found in the endosperm of castor seeds.