Tag: botany

Gram - negative bacteria display the following characteristics: outer membrane containing lipopolysaccharide (which consists of lipid A, core polysaccharide, and O antigen) in its outer leaflet and phospholipids in the inner leaflet; porins exist in the outer membrane, which act like pores for particular molecules; lipoproteins are attached to the polysaccharide membrane.

Gram positive cells are characterized by presence of single thick layer of cell wall which is made up of peptidogycan, teichoic acid and lipoteichoic acid. Teichoic acid is acidic polymer of ribitol phosphate /glycerol phosphate and is covalently linked to peptidoglycan layer. Acetic acid is organic compound and is the main component of vinegar. Glutamic acid is one of the 20 standard amino acids and also serves as neurotransmitter. Malic acid is organic compound and serves as important intermediate in number of biochemical pathways; Kreb cycle and Glyoxalate cycle, etc. Thus, the correct answer is option B.

Eosin is an acidic dye with negatively charged chromophore and stains positively charged molecules such as certain WBCs; presence of acidic substances in large quantity with negatively charged surfaces on bacterial cells inhibit their staining with eosin. Option A is incorrect. Haematoxylin is positive/basic dye which stains acidic substances carrying negative charge and is used with eosin in histology; option C is incorrect. Carmine is a natural dye produced by insect Dactylopius coccus and is used food and cosmetics; option D is incorrect. Gram staining includes staining of both Gram positive and Gram negative bacterial cell purple with crystal violet followed by stabilization of dye in peptidoglyacan layer with mordant—Gram’s iodine and application of alcohol to dissolve outer membrane and dye from peptidoglycan layer. Presence of thick peptidogycan layer in Gram positive cells make them retain the dye after alcohol treatment while Gram negative bacteria become colourless. Thus, option B is the correct answer. 

Bentham and Hooker's system of classification is the natural system of clarification. It is based on AP de Candolle's system. AP de Candolle gave a new system of classification of plants based on characteristics of vascular tissues much before Bentham and Hooker's system. 

Tautonym is the taxonomic designation used for certain animals assigned with same generic name and specific name. E.g. Rattus rattus (rat), Catla catla (catla), etc. Family Leguminosae is divided into three sub-families, i.e., Papilionacea ($=$Fabaceae), Mimosaceae and Caesalpiniaceae.

The leaves of the plant possess the mesophyll tissue which contains the cellular organelle chloroplast. This organelle contains the chlorophyll pigments which are responsible for the absorption of light and conversion of this energy to synthesize food by the process of photosynthesis. 

In spinach, leaves have modified functions. They are modified to store food and water. They store their food in leaves. So, leaves of spinach are a rich source of nutrition and are frequently consumed. 

Amphistomatic: A leaf is said to be called as amphistomatic when the stomata are present on both the side of the leaf.

A simple leaf has a single leaf blade or lamina inserted into the petiole. It may have incisions but these incisions do not divide the blade into leaflets. It shows the presence of an axillary bud at its axil. For example mango. 

When white light is incident on an object , it absorbs some constituent colours of white light and some are reflected back , the combination of reflected colours decides the colour of an object that we see.