Animal Diversity Questions and Answers

Answer: A

Amoeba's mode of nutrition is holozoic.

Holozoic nutrition involves taking in solid food and digesting it inside the body. Amoeba engulfs food particles such as bacteria and smaller protists with pseudopodia (phagocytosis), digests them in a food vacuole, absorbs the products and expels the undigested remains.

Saprophytes absorb dissolved food from dead matter, symbiotic nutrition depends on a partner organism, and autotrophs make their own food by photosynthesis, none of which describes Amoeba.

Answer: A

Names from subgenera upwards are uninomial.

Under the International Code of Zoological Nomenclature, every name of a taxon above the species group (subgenus, genus, family, order, class and so on) is a single word: Felis, Felidae, Carnivora, Mammalia. A subgeneric name is also one word, written in brackets between the genus and the species name.

Binomial names (genus plus specific epithet) are used only for species, and trinomials (adding a subspecific name, as in Panthera tigris tigris) only for subspecies. Polynomials, descriptive Latin phrases, were the pre-Linnaean practice that binomial nomenclature replaced.

Answer: B

The female genital pore of Pheretima posthuma is in segment 14.

The Indian earthworm has a single female genital pore on the mid-ventral side of the 14th segment, which lies within the clitellum (segments 14 to 16). The ova leave through it into the cocoon secreted by the clitellum.

The other numbers belong to other openings or none. The paired male genital pores are on segment 18, and the four pairs of spermathecal pores lie between segments 5 and 9. Segments 11 and 21 carry no genital pores, so neither can be the answer.

Answer: B

The feature adult urochordates keep is the siphon.

The tunicate larva is a free-swimming tadpole with a notochord in its tail and a dorsal hollow nerve cord, the chordate features that place the group in the phylum. At metamorphosis the larva attaches by its front end and becomes a sac-like filter feeder. The tail with its notochord is absorbed, and the nerve cord is reduced to a single ganglion. The adult draws water in through an incurrent (oral) siphon and passes it out through an excurrent (atrial) siphon.

So the notochord and the nerve cord (spelt chord in the paper) are lost, and urochordates have no true coelom; its place is taken by the atrial cavity. The siphons are the one listed feature present in the adult.

Answer: B

The operculum is absent in the hammer-head.

The hammerhead is a shark, a cartilaginous fish (Chondrichthyes). Sharks have five to seven separate gill slits on each side, each opening directly to the outside with no bony cover. A bony operculum covering the gills is a feature of the bony fishes (Osteichthyes).

Latimeria, the coelacanth, is a lobe-finned bony fish and has an operculum. Labeo (rohu and its relatives) and the salmon are ray-finned bony fishes, which also have a gill cover that pumps water over the gills.

Answer: C

Tetrapods originated from the Sarcopterygians.

Sarcopterygians are the lobe-finned fishes. Their fleshy fins contain a bony skeleton with a single proximal bone, the forerunner of the tetrapod humerus or femur, and transitional fossils such as Eusthenopteron and Tiktaalik link them to early limbed vertebrates.

Actinopterygians are the ray-finned fishes, the line leading to most modern fish. Chondropterygians are cartilaginous fishes such as sharks and rays, and Holocephalians (chimaeras) are a group within them. None of these gave rise to tetrapods.

Answer: A

Pseudo-metameric segmentation is a feature of Cestoda.

The body of a tapeworm is a chain (strobila) of proglottids budded off from the neck. They look like segments, and each contains a complete set of reproductive organs, but they are not true metameres: they are formed by budding from the front, not as repeated units with a segmented coelom, muscles and nerves, so the condition is called pseudometamerism.

Nematodes and trematodes are unsegmented, and Ectoprocta (bryozoans) are colonial animals whose individuals are not segmented.

Answer: B

Arenicola and Amphitrite are Sedantary tube-dwelling polychaetes.

Arenicola, the lugworm, lives in a U-shaped burrow in sand, and Amphitrite lives in a mucus-lined tube in mud, collecting food with long tentacles. Both are sedentary polychaete annelids, unlike errant forms such as Nereis.

The 'missing link' between annelids and arthropods is Peripatus (Onychophora), and trilobites are extinct marine arthropods, so the other options do not fit two living worms.

Answer: C

The keyed answer is Heloderma, the only venomous lizard among the options.

Heloderma contains the Gila monster and the beaded lizards, which deliver venom from glands in the lower jaw through grooved teeth. These lizards live in the south-western United States, Mexico and Central America, so the stem's 'South America' is loose; the point of the question is that this is the venomous genus.

The other three are harmless: Calotes is the garden lizard (agamid), Hemidactylus the house gecko, and Mabuya a skink. None produces venom.

Answer: D

Taxonomic hierarchy is the stepwise arrangement of all categories for classification of animals and plants (printed 'Stepswise').

Linnaeus introduced a ranked system in which categories are arranged in descending order: kingdom, phylum or division, class, order, family, genus and species. Each rank includes one or more ranks below it.

Classification based on the fossil record is phylogenetic study, not the hierarchy itself. A list of taxonomists or a committee that decides names describes people, not the ordering of categories; nomenclature is governed by codes such as ICZN and ICN.