NEET Practice Questions (MCQs) with Answers & Solutions

Bacterial blight of chick pea (Cicer arietinum) is caused by bacterium Xanthomonas campestris. The ejected tissues collapse and are digested by bacteria. Rapid spread of bacterial infection occurs through vascular strand. The stems and leaves of infected plant give blighted or burnt up appearance. Control measures include rogueing; 3-year crop rotation, disease free seeds, spray of copper fungicides and antibiotics besides showing disease resistant varieties.

Bordeaux mixture is most common fungicide. It was first discovered by Millardet in 1882 at university of BOrdeaux France to control downy mildew of grapes. It is prepared by mixing copper sulphate, lime and water in the ration of 4 : 4 : 50

Disease                       Causing organism

Leaf blight of rice             –Xanthomonas oryzae

Red strip of sugarcane      – Pseudomonas rubrilineans

Fire blight of apple           – Erwinia amylovora

Early blight of potato       – Alternaria solani.

True or rigid cell wall is absent in mycoplasma, but their cytoplasm is surrounded by a tri-laminar (triple layered), highly elastic cell membrane of about 10 nm in thickness.

Morels and truffles are edible fungi that are highly prized for their flavor and aroma. They are not poisonous mushrooms. Penicillium is a multicellular fungus that produces antibiotics, Neurospora is used in biochemical genetics studies, and yeast is a unicellular fungus used in fermentation.

Chrysophytes are placed under the kingdom-Protista. This group includes diatoms and golden algae (desmids). Most of them are photosynthetic. In diatoms, the cell walls form two thin overlapping shells, which fit together as in a soap box.

Nuclear membrane is absent in Monera (bacteria). Monera belongs to the prokaryotic kingdom, which lacks a true nucleus bound by a nuclear membrane. The genetic material in bacteria is present as a single circular DNA molecule in the cytoplasm.

Archaebacteria are likely to be present in deep sea water due to their ability to thrive in extreme environments. They are a group of prokaryotic organisms distinct from bacteria, found in diverse habitats like hot springs, salt marshes, and deep ocean floors.

The enzyme lysozyme is used to convert the rod-shaped cells of Bacillus megatarium to spherical protoplasts by breaking down the peptidoglycan layer of the bacterial cell wall, resulting in the loss of the characteristic rod shape.

Ribosome are the particle of ribonucleoprotein, which is the site of translation of mRNA into protein during protein synthesis. Both prokaryotes and eukaryotes have ribosomes but prokaryotic ribosomes are smaller than the eukaryotic ribosomes and are assembled from different RNA and protein molecules. Prokaryotes have only one type of RNA i.e., 70s type while the eukaryotic ribosomes are of two types i.e., 70s type and 80s. Centrosome, peroxisomes and glyoxisomes are the cell organelles present in eukaryotic cells.