Invertebrate Zoology

Coxal glands are the excretory organs in spiders.

In echinoderms, specialised amoebocytes found in the coelomic fluid perform excretion.

This option is correct.

Correct answer. Hearts in earthworm are found in 7^th, 9^th, 12^th, 13^th segments.

The dorsal vessel is involved in forward movement of blood in an earthworm.

Oxygen is distributed in the body of cockroaches through network of tubes called trachea.

Butterflies and moths: Siphoning type of mouth parts.

The parotids are located behind the ears of toads.

Silkworm grows in size and when the caterpillar is ready to enter the next stage of its life cycle called ‘pupa’, it swings its head from side to side in the form of figure of 8.

Amoeba is a unicellular organism with no specialized tissues or organs. It relies on diffusion within its cytoplasm to transport nutrients and does not require a circulatory or blood system. Digested food spreads directly through the cell.

Protozoans are primarily classified based on their locomotory organelles - flagella, cilia, or pseudopodia. Size, shape, and reproduction methods vary within groups but locomotory structures are the fundamental basis of classification.

Protozoa are single-celled eukaryotic organisms that move using specialized structures. Different groups of protozoa use different locomotory organs: some use whip-like flagella for propulsion, others use hair-like cilia that beat in coordinated waves, and amoeboid protozoa extend cytoplasmic projections called pseudopodia to crawl. Since various protozoa use each of these structures depending on their classification, all options are correct.

Euglena is a single-celled organism belonging to the phylum Euglenozoa within the group of protists. Like other protozoans and many microorganisms, it exists as an individual cell that performs all life functions within one cellular unit. Multicellular organisms consist of many specialized cells working together, acellular refers to entities without cells (like viruses), and syncytial describes multinucleate cytoplasm without cell boundaries - none of which describe Euglena.

Euglena exhibits a unique combination of plant-like and animal-like characteristics, earning it the description of a 'connecting link' between the two kingdoms. Like plants, Euglena contains chloroplasts and can perform photosynthesis when sunlight is available. Like animals, when deprived of light, it can ingest food and move using flagella. This dual-mode nutrition and locomotion bridge the traditional plant-animal dichotomy, making it the best answer among options.