28.(A) (i) warm blooded (ii) forelimbs
(iii) skin gland (iv) tail
(v) beak (vi) crop
(vii) gizzard (viii) air sacs
(ix) four
(B) Amphibians are warm cold blooded animals. Their skull is
monocondylic dicondylic. The heart in amphibians is two
three chambered. Kidneys are metanephric mesonephric.
Their larval forms are ureotelic ammonotelic whereas
adults are ammonotelic ureotelic. Fertilisation is internal
external and twelve ten pairs of cranial nerves are present
in them.
- (a) 30. (c) 31. (d) 32. (b) 33. (a)
- (c) 35. (b) 36. (a) 37. (c) 38. (a)
- (a) A – Dorsal hollow nerve cord
B – Notochord
C – Pharyngeal gill slits
D – Post anal part (tail)
(b) Notochord (B) is a solid unjointed, stiff but flexible rod-
like structure situated on the dorsal side between the
dorsal hollow nerve cord and the alimentary canal.
(c) In Subphylum Cephalochordata, structure B
(notochord) is present throughout life and extends
from the anterior end to the posterior end of the body.
E.g. Branchiostoma.
(d) In Subphylum urochordata, structure B (notochord)
is present only in tail of the larva and disappears
in adults. Structure A (Nerve cord) is found in larva
but is replaced by dorsal ganglion in adult. E.g.
Herdmania.
- (a) A - Taenia B- Aurelia
C - Octopus D - Palamneus
(b) Organism A (Taenia) shows parasitic mode of nutrition.
Its body is divisible into scolex, neck and strobila.
Scolex contains cone like rostellum at its top. Rostellum
bears chitinous hooks in two circlets. On the middle
part of scolex, 4 cup shaped suckers are present. Hooks
and suckers are adhesive organs which help these
parasites to attach firmly to the body of host from
which they derive nutritiion. Hence, these structures
supplement their parasitic mode of nutrition.
(c) The epidermis of organism B consists of the following
cells. (i) Epitheliomuscular cells. They provide protection
and act as muscles. (ii) Cnidoblasts ( = stinging cells).
A cnidoblast (also called nematoblast) has nematocyst
(‘stinging organ’). The nematocyst consists of capsule,
shaft and thread tube. The nematocysts are used for
defence and offence. (iii) Interstitial cells. They are
reserve cells and are called totipotent cells which can
be converted into any type of cells, (iv) Nerve cells. They
form a primitive nervous system. (v) Sensory cells. They
are sensory in function.
(d) Organism C (Octopus) belongs to Phylum Mollusca. It
ejects inky fluid in water and forms a screen for defence
from its enemies.
(e) Body cavity is an extensive haemocoel filled with
blood and surrounding the heart, alimentary canal,
hepatopancreas, gonads, and other internal parts.
Coelom is reduced to vestiges associated with
reproductive system and certain glands. Musculature
includes one pair of muscles in cephalothorax and
eight pairs of dorso-ventral muscles in pre-adomen,
running from dorsal to ventral surface of body, on
either lateral side or body wall.