TEST OF PRACTICAL KNOWLEDGE QUESTION Study carefully specimens C, D and E and use them to answer questions 2(a) to 2(c). (a) (i) State the mode of nutrition...

Answer Details

(a)(i) Mode of nutrition of specimen D (tick): parasitic (it sucks blood from its host).

(a)(ii) One way each is of economic importance

• C (grain weevil): it destroys stored grains and lowers their quality, reducing the farmer's income.
• D (tick): it infests cattle and dogs, sucking blood and making them anaemic, and it transmits diseases.
• E (rat): it destroys and contaminates stored food and spreads diseases.

(b)(i) Classification into phyla and classes

(b)(ii) Three observable characteristic features of each class

• Insecta (C): body in three divisions (head, thorax, abdomen); three pairs of jointed walking legs; a pair of antennae; compound eyes (and usually wings).
• Arachnida (D): body in two divisions (cephalothorax and abdomen); four pairs of legs; no antennae; simple eyes; feeding appendages (pedipalps and chelicerae).
• Mammalia (E): body covered with hair/fur; external ears (pinnae); mammary glands; four limbs; heterodont dentition.

(b)(iii) Two observable differences between C and D

(c) Four observable sensory features of specimen E (rat): the eyes (sight), the external ears/pinnae (hearing), the nostrils (smell) and the whiskers (touch).