Pesticides and Pest Control

Heavy metal is not associated with biological magnification. Biological magnification is the increasing concentration of a chemical like toxic substance, in organism’s tissue at successively higher level in the food chain.

This is the correct option. Convolvulus is not a bio-pesticide. It is a twining plant with trumpet-shaped flowers, of which some kinds are invasive weeds and others are cultivated for their bright flowers.

Chara is a green alga, it looks like land plants due to the stem-like and  root-like morphology. They are common in fresh water and used to kill mosquito larvae.

DDT is an organochloride insecticide.

Azadirachtin:  Natural insect repellent obtained from Azadirachta indica (Neem), Rotenone: A powerful insecticide obtained from roots of Derris elliptica and Lonchocarpus spp., Pyrethrum: A contact insecticide obtained from the plant Chrasanthemum  cinerariaefolium.

Use of pesticides and  biocides can be controlled by using better technology that does not pollute the soil. Use of genetically modified crops can reduce the use of fertilisers and pesticides, but it has serious impact on food chain and food web.

This is the correct option. Insecticide is any pesticide used to kill, deter or control insects. Weedicide is a chemical agent that destroys unwanted plants, but not wanted ones. Fungicide is a biocidal chemical compound or biological organism used to kill or inhibit fungi or fungal spores.

This option is correct because Agrobacterium radiobacter is an effective, commercially applied, biological control agent for the prevention of crown gall disease.

This is the correct option. Malathion is not a weedicide. It is a type of contact insecticide that is used on stem and leaf cutting and boring type of insects.

Insecto is a diatomaceous earth product isolated from diatoms and is used to control the insects, which have their soft body parts exposed but covered by a waxy film to prevent dehydration. When they came in contact with diatoms in Insecto, the silica frustule break the waxy film on the insects causing them to dehydrate and die.

Pesticides are chemicals, get sprayed in fields to kill natural enemies like insects.  It is harmful to the natural enemies but not to crops and humans. Its over use may destroy the crop and can also be harmful to humans too.  So this is the correct answer.

Blue vitriol, DDT, BHC and potassium nitrate, none of these are common used pesticides. Pesticides are substances or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Pesticides are a special kind of products for crop protection. Some common pesticides are glyphosates, atrazine, metolachlor, etc.

DDT is an organochlorine. Organic compounds that have been chlorinated, have very low biodegradation, get accumulated in environment and cause many problems. DDT comes under these. Hence, it is correct.

Excessive use of pesticides pollutes the lithosphere. Lithosphere is the solid crust from the center of the earth to the outer surface. It gets polluted due to dumping of pesticides and herbicides.