Cell Biology and Structure

Differentiation is the developmental process by which cells undergo structural changes to acquire specialized functions. Growth, cell division, and cell elongation are related processes but do not specifically define the acquisition of specialized form and function.

A carbon-to-nitrogen ratio is a ratio of carbon to the nitrogen in a plant. In general, a high C/N ratio produces a high acid content and low methane production. In plants young tissues have less C/N ratio. Plants with high C/N ratio have more mechanical tissues and larger root system.

Differentiation is the process by which cells move from a less specialized (such as stem cells) form to a more specialized form having a specific function. Dedifferentiation is the process whereby completely differentiated cells regress to a simpler state (such as stem cells) and gain the capacity to divide again. The process by which a group of once specialized cells (de-differentiated) return to their original specialized state is known as redifferentiation. Regeneration is the process of renewal or restoration of growth to recreate damaged tissues, limbs etc. So, the correct answer is 'dedifferentiation'.

The living differentiated cells, that have lost the capacity to divide can regain the power of division under certain conditions, this phenomenon is termed as de-differentiation. E.g.,formation of meristerns-interfascicular cambium (Formed from medullary rays) and cork cambium (formed from outer layer of cortex) from fully differentiated parenchyma cells. While doing so, such meristems/tissues are able to divide and produce cells that once again lose the capacity to deride but mature to perform specific functions, i.e., get redifferentiated. E.g., cells of secondary xylem, secondary phloem, periderm. Thus rediffrentiation can be defined as maturation or differentiation of dedifferentiated tissues. So, the correct answer is 'Redifferentiation'.

In callus culture, cell division in explant (differentiated mass of mature cells) forms and callus. Callus is an irregular unorganized and undifferentiated mass of actively dividing cells. The process is called dedifferentiation.

The phonomenon of generation of whole plant by single cell is totipotency.It is the characteristic of plants mostly. When a plant of defferentiated tissue is cultured in a nutrient medium. Cells that are not dividing or are at resting stage undergo some changes and attain dividibility and become meristematic again. The process of reversion or regaining of meristematic activity to form callus is known as dedifferentiation while redefferentiation is the process in which the cell gains its specialization again.

Ground tissue includes all tissues except epidermis and vascular bundles. The ground tissue comprises the bulk of the primary plant body. Parenchyma, collenchyma and sclerenchyma cells are common in the ground tissue.

The tissues present in a plant which are dermal nor vascular are called ground tissues.

• The ground tissues consist of the following:-

Cortex is the ground tissue present between epidermis and endodermis. It is mostly composed of parenchymatous cells. Parenchymatous cells are thin walled polyhedral, isodiametric living cells with sufficient cytoplasm, one or more nuclei and nucleolus. They serve to store food. Chlorophyll is present in chlorenchyma which are specialized to perform photosynthesis and are present in leaves. Thus, the correct answer is option A.

Ground tissue of plants consists of all tissues except epidermis and vascular tissues. It is divided into three types based on the nature of the cell walls. These are parenchyma, collenchyma and sclerenchyma. 

The tissues that are involved in the secretion of gums, resins, volatile oils, nectar and latex are known as secretory tissues. These are further differentiated into glandular and laticiferous. Glandular tissue consists of special structures or glands made up of isolated cells or small group cells with granular cytoplasm filling it and with a large nucleus. Thus, the correct answer is option C.

Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme. It gets activated on the addition of an organic or inorganic cofactor. It exists as hydrophilic colloid in the cytoplasm which makes it inert and prevents its dissociation. The hydrophilic part of the colloid is present on the surface which interacts with the water. 

Enzymes are inducible in nature because as the substrate molecules attaches to the active site of the enzyme, it induces a conformational change on the active site to fit in properly.