Biological World

 

 

 

  Common flora used traditionally in agriculture ecosystem One of most common and important plant used in agricultural operations is Neem (Azadirachta indica). The properties of Neem as insecticide, antifeedant, hormonal, antifungal, antiviral and nematicide properties are well known. These activities are brought out with neem use in the form of leaves, leaf extracts, seeds, cakes, oil and fruit extracts (Lokanadhanet al., 2012). This plant control about 200 species of insects i.e. Aphids, leaf miners, looper, thrips, mealy bugs etc. It kills all chewing and sucking insects, also disrupts their life cycle and sexual behavior (Kaur and Ohri, 2018). Azadirachtin, salannin, and other limonoids present in neem oil inhibit ecdysone 20-monooxygenase, the enzyme responsible for catalyzing the final step in conversion of ecdysone to the active hormone, 20-hydroxyecdysone, which controls the insect metamorphosis process (Campos et al., 2016). In addition to that the neem seed cake also cont...

  1. The stain used to visualise motochondria is (a) Fast green            (b) Safranin          (c) Aceto carmine         (d)  Janus green   2.    A common characteristic feature of plant sieve tube cells and most of mammalian erythrocytes is (a) Complete  Absence of mitochondria          (b) Presence of cell wall (c) Presence of haemoglobin                           (d) Complete Absence of nucleus   3.    Regarding the mineral nutrition of plants, which one of the following statements is correct? (a) The availability of iron to plants decrease with the increase of acidity of the soil (b)  The presence of CO2 dissolved in the soil water reduces the sol...