Daily NEET MCQ- April 20, 2022 - NEET MCQ

Conductors have low resistivities in the range of 10-8 Ωm to 10-6 Ωm. Metals are good conductors. Conductors are objects or types of material that allows the flow of charge in one or more directions, and a result, the resistance offered against the flow of charge will be less.

A wire bound resistor is an electrical passive component that limits current. Wire-bound resistors are made by winding the wires of an alloy like manganin on an insulating base. They are relatively insensitive to temperature.

Trichloromethane is slowly oxidized in air in the presence of light to form an extremely poisonous gas, carbonyl chloride, also called as phosgene.

Carbon tetrachloride is used as a cleaning fluid, degreasing agent, spot remover and a fire extinguisher.

The antiseptic properties of iodoform are due to the liberation of free iodine and not due the properties and characteristics of iodoform itself.

The dragonflies are very useful to get rid of mosquitoes. The very familiar beetle with red and black markings-the Ladybird is useful to get rid of aphids.

Biocontrol agents are the organisms which are the natural enemies of insect pests or the disease-causing microbes which can be used for our own benefit. For example, bacteria Bacillus thuringiensis which can be introduced to control butterfly caterpillars.

Bacillus thuringiensis is often available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees, where they are eaten by the insect larvae.

Due to the development of various methods of genetic engineering, in the last decade or so, scientists have introduced Bacillus thuringiensis toxin genes into the plants. Bt-cotton is one such example, which is being cultivated in some states of our country.

Trichoderma species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens.