During which one of the following stages of Arabidopsis embryogenesis, cell elongation throughout the embryonic axis and further development of the cotyledons occur?
Globular stage
Torpedo stage
Heart stage
Mature stage
During the torpedo stage of Arabidopsis embryogenesis, cell elongation throughout the embryonic axis and further development of the cotyledons occur. In this stage, the embryo undergoes significant growth and morphological changes. The cotyledons, which are embryonic leaves, begin to expand and differentiate. The torpedo stage is characterized by the elongation of the embryo along its longitudinal axis, giving it a torpedo-like shape. This stage follows the heart stage and precedes the walking-stick stage in Arabidopsis embryogenesis. Hence, the correct answer is option 2.