Deck 40: Annelids, Molluscs, Nematodes and Arthropods

Question 1

Metameric segmentation

A) is similar to the repetition of tapeworm proglottids.
B) is only found in successful and diverse groups.
C) involves repetition of key functional structures.
D) is similar to strobilisation in tapeworms.
E) adds new segments at the anterior end of the animal.

Answer 1

involves repetition of key functional structures.

Question 2

Metameric segmentation

A) permits specialisation of some segments.
B) is easiest to see in arthropods.
C) produces adults with a variable number of segments.
D) occurred earliest in the platyhelminths.
E) forces animals to remain small.

Answer 2

permits specialisation of some segments.

Question 3

Both annelids and arthropods share the features

A) metameric segmentation, protostome development and a schizocoelic coelom.
B) protostome development, a chitinous exoskeleton and a schizocoelic coelom.
C) tagmatisation, metameric segmentation and a schizocoelic coelom.
D) metameric segmentation, protostome development, a chitinous exoskeleton.
E) protostome development, a closed vascular system and a chitinous exoskeleton.

Answer 3

metameric segmentation, protostome development and a schizocoelic coelom.

Question 4

The coelom probably evolved in the first annelids

A) as an out-pocketing of the embryonic gut.
B) as an adaptation for burrowing.
C) as part of the vascular system to enable transportation of food materials.
D) much later than metameric segmentation.
E) after the evolution of the vascular system.

Question 5

Metanephridia, which are open tubes with funnels,

A) occur in all polychaete worms.
B) are part of the vascular system of annelids.
C) are only repeated in very few segments in oligochaete worms.
D) occur in all oligochaetes and leeches.
E) occur in earthworms and contains the respiratory pigment.

Question 6

It would be correct to describe annelids as

A) segmented.
B) pseudocoelomate.
C) having an open vascular system.
D) having a soft exoskeleton.
E) having a dorsal nerve cord.

Question 7

Annelids in class Clitellata are characterised by

A) body segmentation.
B) have a trochophore larva.
C) a clitellum.
D) chitinous bristles on parapodia.
E) copulation by hypodermic impregnation.

Question 8

The function of the clitellum in clitellate worms is to

A) filter food from the surrounding water current.
B) protect the trochophore larva.
C) secrete a cocoon for the eggs.
D) function in respiration and locomotion.
E) hold the animal secure in its burrow.

Question 9

Leeches

A) lack a clitellum.
B) feed only on blood.
C) have a trochophore larva.
D) have internal fertilisation.
E) have chitinous bristles, the chaetae.

Question 10

Which of the following classes of annelids have parapodia?

A) Oligochaeta
B) Polychaeta
C) Hirudinea
D) Clitellata
E) All of the answers are correct

Question 11

Most bivalves

A) use cilia on their gills to filter feed.
B) are sessile or slow-moving.
C) have no distinct head.
D) have two shell plates which enclose the body.
E) All of the answers are correct.

Question 12

All modern molluscs have retained the radula, EXCEPT

A) chitons.
B) gastropods.
C) bivalves.
D) seaphopodia.
E) cephalopods.

Question 13

The modern molluscan class in which the visceral mass has undergone torsion contains

A) chitons.
B) gastropods.
C) bivalves.
D) seaphopodia.
E) cephalopods.

Question 14

In pulmonate snails, gas exchange occurs

A) through a single gill on the left side of the mantle cavity.
B) in a lung cavity with a single restricted opening.
C) at the tips of the finest branches of tracheoles.
D) through the mouth as the gills have been lost.
E) through a pair of sheet-like gills on either side of the foot.

Question 15

In cephalopods, chromatophores

A) allow them to see in colour.
B) allow them to change the colour patterns on their skin.
C) are branching cells that are indirectly under hormonal control.
D) allow them to see in colour and are branching cells that are indirectly under hormonal control.
E) allow them to change the colour patterns on their skin and are branching cells that are indirectly under hormonal control.

Question 16

Compared to other molluscan groups, cephalopods have a particularly well developed

A) gas exchange and circulatory system.
B) behaviour.
C) locomotion.
D) brain and sight.
E) All of the answers are correct.

Question 17

Nematodes are classified separately from the coelomate groups because

A) they lack a body cavity.
B) the body cavity forms within the mesoderm.
C) the body cavity forms between the endoderm and the mesoderm.
D) they have a collagenous cuticle.
E) of their extensive adoption of a parasitic habit.

Question 18

Which feature is NOT found in nematodes?

A) A mouth and an anus
B) Segmentation
C) Parasitism
D) Small, tapering, cylindrical bodies
E) Anterior sense organs

Question 19

Locomotion in nematodes is achieved by

A) antagonistic longitudinal muscles that work against each other producing a sideways undulation.
B) longitudinal muscles that increase the hydrostatic pressure in the pseudocoelom causing it to undulate.
C) a series of hairs that project backwards and engage the substrate allowing the animal to move forward only.
D) successive waves of body contraction that move along the length of the animal.
E) rapid expulsion of water through a muscular tube.

Question 20

The following is a description of an animal parasite. The parasite is an endoparasite, found in human lymph tissue, which can cause extensive swelling of limbs and genital organs. The animal described is most likely to be

A) Wucheria bancrofti.
B) Echinococcus granulosus.
C) Schistosoma japonicum.
D) Fasciola hepatica.
E) Taenia sp.

Question 21

Studies using DNA sequences suggest that the three arthropod subphyla Chelicerata, Crustacea and Uniramia

A) had three different evolutionary origins.
B) have probably evolved from a common ancestor.
C) evolved jointed appendages and exoskeletons independently.
D) have polyphyletic origin as chelicerates have spiral cleavage.
E) should actually be in different phyla.

Question 22

Tagmata are

A) parts of an exoskeleton.
B) appendages around the mouth.
C) branched in crustaceans and primitive chelicerates.
D) groups of segments with special functions.
E) appendages attached to the cephalothorax of an insect.

Question 23

The coelom in arthropods

A) is important in locomotion.
B) is a pseudocoel.
C) is greatly reduced.
D) is important for locomotion.
E) does not develop until after metamorphosis.

Question 24

In arthropods, the haemocoel

A) consists of space in the body filled with a circulating fluid.
B) consists of a heart and the blood.
C) is reduced and virtually absent in adults.
D) an elongate dorsal vessel which pumps blood through the body.
E) All of the answers are correct.

Question 25

The arthropod blood vascular system is termed an open system because

A) blood is not always enclosed in vessels.
B) there is no heart to pump the blood.
C) it does not have a haemocoel.
D) it originated from the coelom which is open.
E) All of the answers are correct.

Question 26

The class Arachnida includes spiders, scorpions, tick and mites, and their relatives. To what subphylum do arachnids belong?

A) Chelicerata
B) Crustacea
C) Trilobita
D) Hexapoda
E) Uniramia

Question 27

The group of arthropods that includes the insects is called the Uniramia because

A) they only have one pair of antennae.
B) their appendages are unbranched.
C) they only have one pair of legs per segment.
D) their body parts have fused into a single segment.
E) they only have one pair of legs per tagma.

Question 28

A feature that distinguishes insects from crustaceans can be most easily seen in

A) the circulatory system.
B) the number of antennae.
C) their respiratory system.
D) the occurrence of mandibles.
E) their mode of reproduction.

Question 29

Insects are important to human activity because they are often

A) carriers of human diseases.
B) consumers of crops or carriers of disease of domestic animals.
C) pollinators of crops.
D) provide food.
E) All of the answers are correct.

Question 30

Which of the following animals are segmented?

A) Nematodes.
B) Molluscs.
C) Annelids.
D) Annelids and nematodes.
E) Annelids and molluscs.

Question 31

Which of the following statements are CORRECT?

A) Annelids, arthropods and molluscs have an internal body cavity, the coelom which develops between the inner and outer layers of the mesoderm.
B) Nematodes have a body cavity that develops from the blastocoel and so is not a true coelom.
C) DNA evidence of phylogeny indicates that molluscs and annelids are related on one evolutionary branch, the Lophotrochozoa.
D) Molluscs and nematodes are non-segmented animals.
E) All of these statements are correct.

Question 32

The radula is

A) the toothed tongue of cephalopods and molluscs.
B) the proteinaceous cuticle of nematodes.
C) the beak-like mouthparts of arthropods.
D) the gas-filled chambers used for buoyancy in bivalves.
E) the greatly developed head of gastropods.

Question 33

In contrast to most polychaetea, oligochaetes

A) undergo asexual reproduction, common in aquatic organisms.
B) have gonads in only a few body segments.
C) are hermaphroditic, but cross-fertilise by storing sperm in sacs called spermathecae
D) have only 4 pairs of simple bristles per segment.
E) All of the answers are correct.

Question 34

Hirudin is

A) single-celled photoreceptors, a 'little eye' of leeches.
B) the sac used to store sperm in earthworms.
C) the free-living larvae of polychaetes.
D) an anticoagulant protein secreted by many leeches.
E) the proteinaceous cuticle of nematodes.

Question 35

Gastropods show major evolutionary changes relative to molluscs in that

A) they have greater development of the head.
B) the visceral mass has twisted through 180 $\degree$ .
C) the body has undergone torsion.
D) the shell has become spiral.
E) All of the answers are correct.

Question 36

Nematodes

A) are small non-segmented round worms most closely related on the phylogenetic tree to earthworms (oligochaetes).
B) are covered with a thick chitinous cuticle secreted by the epidermal cells.
C) have a fixed number of cells in the organism and mitotic division does not occur after hatching.
D) have circular muscles around a tubular body that are usually tapered at the ends.
E) contain a coelom, similar to other members of their phylogenetic group, the protostomes.

Question 37

The Cuticulata, which includes diverse organisms such as arthropods and nematodes, is so called because

A) all organisms in this group have a body covering that consists of a single-layered cuticle.
B) all organisms in this group have a body covering that consists of a two-layered cuticle.
C) all organisms in this group have a body covering that consists of a triple-layered cuticle.
D) all organisms in this group have a body covering that consists of a unique cuticle composed of cartilaginous tissue.
E) unlike most other protostomes, this group is so called because it entirely lacks a cuticle.

Question 38

A scientist is experimenting on a species of male crab by altering its usual levels of ecdysteroid hormones. What would be an obvious morphological response from this treatment?

A) The crab will prematurely begin its mating cycle.
B) The crab's circadian rhythms will not follow the normal day/night cycle, resulting in the crab being active at night and sheltering in the day.
C) The crab's moulting process will be abnormal.
D) The crab's testes will shrink markedly.
E) The crab's compound eyes will reduce, and start to mimic small antennae-like appendages.

Question 39

An entomologist is asked to examine an unknown organism from the Cuticulata that has a head plus four additional segments, 8 legs and is only around 1mm in length. However, it is late on a Friday afternoon and the scientist really wants to go to the pub, so he decides to leave the examination until the following week. He cleans up his bench and accidentally puts the unknown organism in a freezer over the weekend. Realising his mistake on the Monday, he removes the organism from the freezer and leaves it on his bench to defrost before deciding what to do. Distracted, he forgets about the organism again and in his absence a colleague sets up an experiment on his bench using a hot flame, which heats the organism to more than 80 $\degree$ C and desiccates it almost completely. Upon returning to his bench, the scientist is convinced that the organism must surely be dead, but to his surprise he discovers that once some moisture is added and it returns to ambient temperature, the organism shows signs of life. Ironically, this litany of errors has made the scientist's job much easier as to survive such conditions this organism must be a(n)

A) Tardigrade.
B) Onychophoran.
C) Pycnogonid.
D) Merostome.
E) Myriapod.

Question 40

Peristaltic locomotion is dependant on

A) segments controlled by individual muscles and nerves.
B) segments filled with coelom.
C) segments under hydro-static pressure.
D) all the options listed here are correct.
E) successive waves of segment contraction.

Question 41

Molluscs that exhibit torsion have the unusual situation of dealing with their anus discharging directly over their head and mouth. Which of the following arguments can explain this phenomenon?

A) It is a larval adaptation, allowing protective withdrawal of the head into the mantle cavity.
B) It increases the ventilatory current over the gills during forward locomotion.
C) It allows the anterior and posterior openings of the digestive tract to be adjacent and the body protected within the shell.
D) It allows the ability to completely close the shell entrance and seal it with an operculum.
E) All of the arguments could be equally valid.

Question 42

The arthropod exoskeleton has many advantages. Which of the following is NOT one of them?

A) Minimising water loss
B) Physical protection from predation
C) Flexibility for movement
D) Internal sites for muscle attachment
E) Improved electrochemical gradient maintenance

Question 43

What is the main disadvantage of the arthropod exoskeleton?

A) It has to be moulted periodically
B) Difficulties with temperature regulation
C) Reduced motility and manoeuvrability
D) Gas exchange inhibition
E) Chitin leakage of ions and subsequent disruption of internal electrochemical gradients

Question 44

Which of the following characteristics is true of a pseudocoelom?

A) It is a fluid-filled space between two mesoderm layers.
B) It allowed the evolution of advanced internal organ systems.
C) It is a residual of the blastocoel.
D) It develops by splitting of the mesoderm.
E) It is important in the mechanics of locomotion.

Question 45

The nematode nervous system consists of a ganglionated ring surrounding the

A) foregut.
B) thorax.
C) body segments.
D) proteinaceous cuticle.
E) ventral, dorsal and lateral epidermis.