Invertebrate Zoology

Yes, this is the single characteristic of those listed that determines that the cockroach is an insect.

Flame cells are specialized excretory cells found in flatworms (platyhelminthes) that remove waste materials from the body. They function by filtering waste through cilia that flicker like a flame, creating current to draw fluid through. Nephridia are found in annelids, malpighian tubules in insects, and kidneys in vertebrates.

This is the correct option. Platyhelminthes have protonephridia as the excretory structures. Annelids have tubular excretory structures called nephridia. Crustaceans have antennal glands to perform the excretory functions.

Glomerulus is a tuft of capillaries formed by the afferent arteriole.

Cockroaches, spiders, and house flies are all arthropods characterized by jointed appendages, segmented bodies, and exoskeleton. Snail is a mollusc with a soft body and shell (or no shell in slugs). Molluscs are a completely different phylum from arthropods.

Earthworms are called 'friends of farmers' because they burrow through the soil, creating channels that allow air and water to reach plant roots. Their digestive process breaks down organic matter, converting it into nutrient-rich castings (vermicast) that enhance soil fertility and structure. Leeches are parasitic, Sycon is a marine sponge, and Ascaris is an intestinal parasitic roundworm - none provide agricultural benefits.

Centipedes are venomous arthropods that can inflict painful bites on humans. Their modified front legs (forcipules) inject venom that can cause localized pain, swelling, and in some cases, systemic reactions. While millipedes are generally harmless (some produce irritating fluids), prawns are food sources, and cockroaches are disease vectors but not directly harmful through venom, centipedes pose the most direct physical threat through their venomous bite.

A caterpillar spins a cocoon made of either silk or some other similar fibrous material that is then spun around the the insect during their pupal stage. Pupal stage is the life stage of a silk worm insect. 

Cockroaches and earthworms are free living organisms, i.e. they do not live in or on the body of any other living organisms.

Metameres are the outer segments of the cuticle.

Funaria is a genus of nematode. Hence, this answer is correct.

Complete metamorphosis (holometabolous) has four stages: egg, larva, pupa, and adult. Butterflies undergo complete metamorphosis (caterpillar → chrysalis → butterfly). Bed bugs, grasshoppers, and silverfish undergo incomplete metamorphosis (hemimetabolous) where juveniles resemble small adults without a pupal stage.

Insects breathe through a branched network of tubes called tracheae that open out onto the chest and abdomen. Oxygen is pulled into the body through openings in their abdomens called spiracles. Once the oxygen has been pulled in, the outermost vents close and the air is forced into increasingly smaller pipes known as tubules, until it reaches the required cells. Lungs are a pair of large organs in our chest and are a part of our respiratory system. All vertebrate animals, which live on land, have lungs.

Vermiculture means worm growing or worm farming. When earthworms are used primarily for the production of compost, the practice is referred to as vermicomposting.

Keeping in sight the form of mouth parts found in the order diptera, the fly-caterpillar association is build through 'endoparasitism', where a parasite lives within its host’s body.