TEST OF PRACTICAL KNOWLEDGE QUESTION Study carefully specimens J, K and L and use them to answer questions 4(a) to 4(d). (a)(i) State the class of each of s...

Answer Details

(a)(i) Class of each specimen

• Specimen J (tilapia): Class Osteichthyes (bony fishes).
• Specimen K (toad): Class Amphibia.
• Specimen L (lizard): Class Reptilia.

(a)(ii) Three reasons for placing each specimen in its class

Specimen J (Osteichthyes):

• The body is covered with thin, overlapping bony scales.
• It possesses paired fins (pectoral and pelvic fins).
• A lateral line runs along each side of the body.
• The gills are covered by a bony operculum (gill cover).

Specimen K (Amphibia):

• The skin is moist and warty (glandular), without scales.
• The hind limbs bear webbed digits.
• It has large, bulging eyes.
• A visible ear drum (tympanum) lies behind each eye.

Specimen L (Reptilia):

• The skin is dry and covered with horny scales.
• It has two pairs of limbs bearing clawed digits.
• The teeth are all alike (homodont dentition).
• It possesses a well-developed, retractable tongue.

(b) Two structural adaptations for escaping predators

Specimen K (toad):

• Poison (parotoid) glands in the skin secrete an irritant substance that repels predators.
• Long, muscular hind limbs enable it to leap swiftly away from danger, while counter-shading of the dorsal and ventral surfaces camouflages it.

Specimen L (lizard):

• The tail is detachable (autotomy); it can be shed to distract a predator while the lizard escapes.
• The skin colouration blends with the surroundings (camouflage), concealing it from predators.

(c) Drawing, 8 - 10 cm long, of the lateral view of specimen J (tilapia)

The lateral (side) view of the tilapia is shown below, drawn 8 - 10 cm long with the parts clearly labelled.

(d)(i) Two similarities between specimens J and L

• Both possess eyes and a pair of nostrils on the head.
• Both have a body covered with scales and bear a tail.

(d)(ii) Two observable differences between J and L