Page 196 - Biology_F5

Comparative studies of natural groups of organisms

Activity 3.14: Dissection of a cockroach prevents water loss and makes them
to display the reproductive system resistant to desiccation, predators,
invasion by parasites, as well as
Materials physical and mechanical injury.
A fresh male or female cockroach, (b) They have modified and specialised
dissection kit, chloroform, dissecting mouthparts according to their feeding
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tray or board with wax intact, source of habits. Their mouthparts have
heat, and water mandibles for cutting and chewing,

piercing, and sucking as in mosquitoes.
Procedure
(a) Collect a fresh male or female (c) They have a well developed and
cockroach. With reasons, identify efficient respiratory system extending
the sex of your specimen. towards the individual cells in which

(b) Prepare a dissecting tray or dish gas exchange takes place.
and chloroform for anaesthetising (d) They possess flexible jointed
the specimen. appendages, which facilitate rapid

(c) Dissect the cockroach in a usual movement with minimum utilisation
way and deflect the gut to the left of muscles.
hand side of the animal, to fully (e) They possess sensory organs, such as
display the reproductive system. antennae, compound eyes, and cerci,
which are capable of detecting slight
Questions movements, sounds, or chemicals.
1. Describe the reproductive system
of the dissected specimen. (f) They undergo moulting (ecdysis)
process during development by
2. Compare the displayed reproductive removing their hard covers, and
system of the dissected specimen become soft to facilitate growth.
with those depicted in Figure 3.55
or 3.56. (g) Their small and flattened body shapes
3. Classify the organism to the class enable them to hide into small cracks
and crevices, where they live.
level.
(h) They possess coloured cuticle, which
provides camouflage against predators.
Adaptations of Arthropods to their
environment (i) Wings help them in dispersal and
colonisation of new habitats.
Arthropods are the most abundant and
diverse group of animals on the earth. They Economic importance of Arthropods

possess the following adaptive features, Arthropods play an important role in the
which enabled them to be successful and world. However, not all arthropods are
diverse: useful; some are harmful to other living
(a) They possess an exoskeleton, which organisms.

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