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 of specimen D.
(ii) State one way by which each of specimens C, D and E is of economic importance.
(b)(i) Classify specimens C, D and E into their phyla and classes.
(ii) List three observable characteristic features of each of the classes to which specimens C, D and E belong.
(iii) In a tabular form, state two observable differences between C and D.
(C) List four observable features of specimen E that are sensory in nature.
Explanation
(a)(i) Mode of nutrition of Specimen D- Parasitic
(ii) One economic importance of each Specimen C, D and E.
Specimen C/Grain Weevil: They destroy grains/reduce their food quality.
Increase production cost for farmers.
Therefore lowers the farmers income.
Specimen D/Tick: They infest cattle/dogs/suck blood thereby making them anemic; and reduce meat quality.
They transmit diseases.
They decrease resistance to diseases in cattle/dog.
Specimen E/Rat: They destroy stored food items/contamination of food. They spread diseases.
(b)(i) Classification of
|
Specimen |
Phylum |
Class |
| C | Arthropoda |
Insecta |
| D | Arthropoda |
Arachnida |
| E | Chordata |
Mammalia |
(ii) Observable characteristics: Class insecta/ Specimen C: Three body divisions/head, thorax and abdomen. Presence of 6 jointed/'3 pairs of jointed walking legs; presence of compound eyes. Presence of segmented thorax/prothorax, mesothorax and metathorax.
Presence of wings. Presence of body divisions/Cephalothorax and abdomen.
Presence of simple eyes/ocelli
Presence of two appendages for feeding/pedipalps and chelicera.
Class mammalian/specimen E :
Presence of hair/fur on body. Presence of external ears/pinnae. Presence of mammary glands. The presence of four limbs for locomotion.
Heterodont dentition.
(III) Observable differences between C& D:
| C/Grain Weevil | D/Tick |
| Three body division/head, thorax and abdomen |
Two body divisions/cephalothorax and abdomen |
| 3 pairs of legs/6 legs |
4 pairs of legs/8 legs |
|
Compound eyes |
Simple eye present |
|
Presence of wings |
Absence of wings |
|
Distinct tnorax / thorax present |
Thorax fused with head/cephalothorax |
|
Presence of antennae |
Absence of antennae |
(c) Observable features of Specimen E/Mammalia that are sensory in nature.
(i) external ears/pinnae (ii) Skin/fur (iii) Whiskers (iv) Eyes (v) Nostrils (vi) Tail