Plant Transport and Physiology

In the case of potato, it requires more photoperiod to induce flowering. Whereas for the formation of tuber, it requires very less photoperiod. Thus, it is told that potato is LDP for inducing flowering; but SDP for tuber formation. The flower-inducing florigen and tuber-inducing tuberigen signals are functionally exchangeable. Flowering and tuberization are distinct reproduction strategies, both of which involve the sensing of the photoperiod and generation of a signal in the leaves (process called as induction), the subsequent transport of the signal (known as florigen or tuberigen), and the response in a distant organ, the vegetative meristem, or stolon tips (also called evocation).

Fluoride toxicity in plants typically manifests as necrosis (tissue death) and chlorosis (yellowing) starting at the leaf margins and tips, where fluoride accumulates due to transpiration.

Water is essential in the following ways:-

Phytochrome is responsible for absorption of red and far red light it is involved in red-far red light interconversion. Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far red region of the visible spectrum.

Phytochrome is blue colored pigment present in the plants. It is a photoreceptor chromoprotein. It is mainly found in flowering plants. These are responsible for flowering. It mainly absorbs red and far-red radiation in plants and induces flowering process.

Phytochromes are photoreceptor found in plants that detects light. The different phytochromes are involved in different biological responses to red light. P$ _r$ is inactive form whereas P$ _{fr}$ is active form of phytochrome. When exposed to red light,  P$ _r$ is converted to P$ _{fr}$. This active form then initiate many biological processes in plants.

Plants require four factors for its growth like:-

The endodermis is the central, innermost layer of cortex in some land plants. It is made of compact living cells surrounded by an outer ring of endodermal cells that are impregnated with hydrophobic substances (Casparian Strip) to restrict apoplastic flow of water to the inside. The endodermis is the boundary between the cortex and the stele. In many seedless vascular plants, the endodermis is a distinctly visible layer of cells immediately outside the vascular cylinder (stele) in roots and shoots. In most seed plants, especially woody types, an endodermis is absent from the stems but is present in roots. 

Stoma (plural stomata) is a pore, found in the epidermis of leaves, stems and other organs that is used to control gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening. Stomata is absent in cork or phellem. A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases. Cork contains lenticels. Thus, option A is correct. Passage cells are endodermal cells of older roots which have retained thin walls and Casparian strips rather than becoming suberized and waterproof like the other cells around them, to continue to allow some symplastic flow to the inside. Experimental evidence suggests that passage cells function to allow transfer of solutes such as calcium and magnesium into the stele, in order to eventually reach the transpiration system. Sieve tube elements lacks nuclei. Quiescent zone is present in root apex. 

Urtica is a well-known example of a plant that exhibits anomalous secondary growth, specifically the presence of phloem or parenchyma islands within the wood.

Cellulosic materials are comprised of lignin, hemicellulose as well as cellulose. So, these are called as lignocellulosic materials. One main function of lignin is to provide structural support for the plant. Cellulose molecules are consisting of long chains of glucose molecules. This is for that the starch molecules to have a different structural configuration. So, the preparation of pure cellulose by removing lignin is an important step in the manufacture of pulp. It is for the paper industry from the woody tissues of plants to make a better quality paper.

Removal of water from the wood by prolonged heating at approximately $50^{0} C$. The other options are not relevant.

Thus, the correct answer is option D.

The epidermis is a single layer of cells found on outer layers in different parts of the plant. It forms a barrier between the underlying tissues in a plant with the surrounding environment. Therefore, it is protected from adverse environmental conditions.

The presence of stomata and guard cells in the epidermal tissue will help in the exchange of $O _{2}$ and $CO _{2}$.

Conduction of water and minerals in plants takes place in conducting vessels. It is located in the core, known as xylem. Thus conduction of water is not the function of the epidermis but, it is of xylem.

The correct option is C.

Bulliform cells are the special cells known for its peculiar bubble like shape. It is found in the higher plants. The turgor pressure created due to the water present in the cells is lost during stress like transpiration or infection which allows the leaf to roll up. Once adequate water is available, these cells enlarge and the leaves open again. So, bulliform cells are found in the leaf of wheat (grasses) and not in seeds of sunflower, a pod of pea and tuber of potato. Thus, option B is correct.