Cell Biology and Structure

• Glycocalyx or pericellular matrix is a carbohydrate-enriched coating of glycoprotein and a glycolipid that covers the cell membranes of few bacteria, epithelial cells and other cells. 
  
• It is mainly used in the recognition of the cell (distinguish between healthy and diseased cells) and also regulates the endothelial vascular tissues.
  
• So, the correct answer is 'Plasmalemma'.

Gram staining differentiates bacteria by the chemical and physical properties of their cell walls by detecting peptidoglycan, which is present in a thick layer in gram-positive bacteria. In a gram stain test, gram-positive bacteria retain the crystal violet dye, while a counterstain (safranin or fuchsine) added after the crystal violet gives all gram-negative bacteria a red or pink colouring.

The large, bubble-shaped epidermal cells that occur on the upper surface of the leaves of monocots are called as bulliform cells. They are also called as motor cells. They help in the unfolding of developing leaves. It involves in the rolling and unrolling of mature leaves in response to alternating wet and dry periods.

• Guard cells are specialized epidermal cells present on the surface of leaves and stems of plants that control the gaseous exchange in plants.
• The guard cells form stomatal pores through which gaseous exchange and transpiration take place.
• In monocots, the guard cells are dumbbell shape.
• In dicots, they are kidney or bean shaped.
• So, the correct answer is 'Beans'.

Palisade tissues are present just beneath the epidermis and are composed of elongated cells arranged parallel to each other in one to three layers. These cells are marked by the presence of abundant chloroplast and thus provide the site for photosynthesis. Loosely arranged irregular cells with large intercellular spaces make the spongy parenchyma, which is present just beneath the palisade tissue. They contain less chloroplast as compared to that of palisade tissue. Thus, the correct answer is option A.

The cortex is the outermost layer of the stem or root of a plant, bounded on the outside by the epidermis and on the inside by the endodermis. In plants, it is composed mostly of differentiated cells, usually large thin-walled parenchyma cells of the ground tissue system. The outer cortical cells often acquire irregularly thickened cell walls, and are called as collenchyma cells. Some of the outer cortical cells may contain chloroplasts but usually these cells lacks chloroplast. It is responsible for the transportation of materials into the central cylinder of the root through diffusion and may also be used for food storage in the form of starch. cortex, in plants, tissue of unspecialized cells lying between the epidermis and the vascular or conducting, tissues of stems and roots.
Cortical cells may contain stored carbohydrates or other substances such as resins, latex, essential oils, and tannins. Cells of cortex are living and contains nucleus and nucleolus.
Thus, the correct answer is option A.

• Minerals crystals are found in plant cell walls in the form of calcium oxalate, carbonate or silica.
  
• Cystoliths refers to the deposition of calcium carbonate in the epidermal cells of leaves of the plants belonging to the genus Acanthaceae and Urticaceae (stinging nettles).
• So, the correct answer is 'Cystoliths'.

In the eukaryotic cell, the nucleus is separated from the cytoplasm by a double lipid bilayer membrane known as a nuclear membrane. It encloses the genetic material of a cell. It is also known as karyotheca.

A eukaryotic cell has a nucleus bounded by a double wall membrane structure known as a nuclear membrane. The nuclear membrane has nuclear pore that regulates the exchange of materials between cytoplasm and nucleoplasm. The nucleus contains the chromatin threads and the nucleolus. The gel-like texture of the nucleoplasm embedded with chromatin threads gives it a dense appearance.

The DNA is the genetic material of the organism which is present in the nucleus. The DNA is bound to the histone proteins and packaged in the nucleus. The DNA contains the segments of genes which encode for the proteins. This genetic information is present in the nucleus of the living cells. 

DNA is stored in the nucleus, while proteins are assembled from free amino acids in the cytoplasm in structures called ribosomes.

Nucleus and mitochondria are double membrane-bound organelles while ribosome is not membrane bound. Prokaryotes are the organisms that lack any membrane-bound organelles which means that out of given options, only ribosomes are present in them. 

The nucleus is the largest and most significant living organelle of the cell. All the cellular activities of the cell are regulated by the nucleus. Hence it is called brain or control centre of the cell. The nucleus is surrounded by a double unit membrane from all sites. The chromosomes and genes which have genetical characters and transmit from one generation to another are found in the nucleus. Thus option D is the correct answer.