9i8 



TEST QUESTIONS FOR STUDENTS 



35. Explain how meiotic or reducing division differs from ordinary 

 mitotic or equation division. 



36. How does a starfish climb up a rock ? [{a) Making tube-feet 

 tense with water from water-vascular system, pressing them against 

 the rock, fixing them by a back-flow forming a partial vacuum at the 

 tip, drawing the body up by contracting the muscles of the tube-feet, 

 fixing another set of tube-feet and freeing the first set by the injection 

 of water forcibly from the muscular ampullae.] 



37. How does the " test " of a sea-urchin differ fundamentally from 

 the shell or skeleton of a cup-coral ? 



38. Compare the external features of a starfish and a sea-urchin, 

 indicating the parts that correspond. [The dorsal surface of the starfish 

 = the apical disc of the sea-urchin ; the ventral surface of the starfish 

 with the ambulacra! groove and tube-feet = the ambulacral areas of the 

 sea-urchin ; the sides of the arms of the starfish = the inter-ambulacral 

 areas of the sea-urchin : the madreporic plates correspond ; the mouth 

 and the anus occupy corresponding positions in the two types ; and 

 so on.] 



39. Give an illustrated account of the typical process of cell-division. 

 What is the advantage of so complicated a process ? 



40. What is meant by a " synthetic type " ? Illustrate with 

 reference to Peripatus. [A type which shows characteristic features of 

 two very different classes or groups. It m.ay be regarded as a con- 

 necting-link or as a collateral relative of a connecting-link between the 

 two classes or groups. Thus Peripatus is like Annelids in its muscu- 

 lature, simple limbs, nephridia, etc., and like Tracheates in having 

 limbs in the service of the mouth, antennae, tracheae, etc.] 



41. State briefly what takes place inside the pupa-case of an insect. 

 [A continuation of processes of disintegration or histolysis of larval 

 organs, and of processes of reconstruction or histogenesis on a new 

 architectural plan — that of the adult or imago. In the reconstruction 

 an important part is played by clusters of formative cells which grow 

 inwards from the body-wall and serve as foci of new development. 

 They are called imaginal folds or discs.] 



42. Why has a drone-bee no sting ? 



43. Why do not aquatic insects drown ? 



44. Why is a tapeworm not digested in the intestine of its host ? 



45. Give a working definition of instinctive behaviour. [A routine 

 chain of effective actions, performed more or less independently of 

 learning, in virtue of an inborn prearrangement of nerve-cells and 

 muscle-cells (forming reflex arcs), but suffused with awareness, and 

 backed by endeavour, e.g. a young bee visiting a flower ; a young 

 spider spinning its web.] 



46. What is the morphological nature of (a) a bee's sting, [b) a 

 spider's spinnerets, (c) a locust's ovipositor, {d) a scorpion's " pectines." 

 [Transformed abdominal appendages.] 



47. Explain carefully how you would distinguish between a spider 

 and an insect, even if the insect were wingless. 



48. Give an illustrated account of the life-history of the common 

 house-fly, Musca domestica, and indicate briefly how its habits render 

 dangerous to man. 



