Botany and Plant Science

This is the correct option. The cell walls of sclerenchyma are greatly thickened with lignin. Lignin is a complex polymer which acts as a cement and hardens the cell walls.

 Synergid cells are two specialized cells that lie adjacent to the egg cell in the female gametophyte of angiosperms and play an essential role in pollen tube guidance and function.

 In adventitious embryony (sporophytic apomixis), an embryo is formed directly (not from a gametophyte) from nucellus or integument tissue.Adventive embryony is important in several species of Citrus, in Garcinia, Euphorbia dulcis, Mangifera indica etc.

 In a woody dicotyledonous tree,primary growth is tissue is present in Flowers, fruits and leaves because these are the active sites of growth.

 Top-shaped multiciliate male gametes, and the mature seed which bears only one embryo with two cotyledons, are characteristic features of Cycads.In Cycas pollination is anemophilous (by wind). The 3-celled microspores liberate from mega-sporangia are blown away by wind. Finally microspores reach on ovules and get enlarged in the pollination drop (ooze) of micropyle. As the ooze dries up, the microspores are drawn into the pollen chamber.

 Genes for cytoplasmic male sterility in plants are generally located in Mitochondrial genome. Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the cell nucleus and, in plants, in the chloroplast.

Bryophyllum reproduces vegetatively through adventitious buds that develop along the leaf margins (notches). These buds can grow into new complete plants when they fall on suitable soil or are planted. This is a classic example of vegetative propagation through leaves.

Spores are reproductive cells produced in fungi, algae, and some plants. They are produced inside specialized structures called sporangia (singular: sporangium). The capsule is part of the sporangium structure in some organisms, but spores form within the sporangium itself.

In Bryophyllum vegetative propagation, adventitious buds develop from the notches (indentations) along the leaf margins. These buds can grow into complete plantlets. The shoot tip and internodes are not involved in this specific type of leaf-based propagation.

In fungi like Rhizopus, the sporangium (spore case) develops on specialized, thread-like structures called hyphae. These hyphae are erect and support the sporangium above the substrate. Spores are the reproductive cells (not the structures), constrictions are unrelated, and buds are a different reproductive mode.

Direct lateral conjugation is seen in S. jogensis.

Pectin forms the outer cell wall of Spirogyra.

Spirogyra is unbranched, i.e. it is a linear filament with no branching.

Scalariform conjugation leads to formation of a single Spirogyra strand.

Cotyledons develop from embryos.