Download BSc in Applied Biotechnology 1 BO0038

PROGRAM
BSc in Applied Biotechnology
SEMESTER
1
SUBJECT
BO0038 - BIOLOGY OF CHORDATES
BOOK ID
B0602
SESSION
Fall 2015
No
Q 1
Question/Answer key
Marks Total Marks
10
Describe the endoskeleton of frog
A 1
( Unit 5 ; Section 5.4 )
Describing the endoskeleton of frog
The endoskeleton of frog consists of:
A) skull
B) vertebral column,
C) pectoral and pelvic girdles and
D) Limb skeleton.
• Axial skeleton: The skull and vertebral column form the axial skeleton.
A) Skull:
The skull and vertebral column from the axial skeleton.
The skull of frog consists of:
A cranium with sensory capsules
Upper and lower jaws
A hyoid apparatus
The cranium or brain box is small and narrow, lying at the center of the skull
in between the cavities of the eyeballs, the orbits.
The cranium is composed of many bones such as occipitals, exoccipitals,
frontals, parietals, a parasphenoid and a spherethmoid.
The olfactory capsules one on each side, lie in front of the cranium.
The upper jaw forms the margin of the skull made of three bones namely
premaxilla, maxilla and quadratojugal.
The hyoid apparatus forms the supporting cartilage to the tongue.
B) Vertebral column
Vertebral column consists of 10 vertebrae.
The first, eighth, ninth and tenth vertebrae differ in their structure from the
other vertebrae.
The second to seventh vertebrae are typical vertebrae, as they have a similar
structure.
The typical vertebra consists of a solid mass called centrum which is concave
in front and convex behind. This type is called procoelous vertebra.
A ring like neural arch with a neural spine and a pair of transverse processes
are present.
• Appendicular skeleton: Pectoral and pelvic girdles, forelimb skeleton and hind
limb skeleton form the appendicular skeleton
C) Pectoral girdle
The pectoral girdle consists of two halves, united ventrally and separated
dorsally to form an arch.
Each half of pectoral girdle consists of the bones namely supra-scapula,
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scapula, clavicle, coracoid and precoracoid.
The pectoral girdle supports the forelimb skeleton.
Pelvic girdle
The pelvic girdle is attached to the vertebral column. It is ‘V’ shaped formed of
two halves.
Each half of pectoral girdle consists of three bones namely ilium, ischium and
pubis.
The pelvic girdle supports the hind limb skeleton. Ribs are absent in Frog.
D) Limb skeleton: Fore limb and hind limb form limb skeleton.
Forelimb skeleton:
The upper arm of forelimb is supported by the humerus bone.
Its proximal region fits into the glenoid cavity to form the shoulder joint.
The fore arm is supported by the radio-ulna which is formed by the union of
radius and ulna.
The upper arm articulates with the fore arm at the elbow joint.
The wrist consists of six carpals, arranged in two rows. The palm is supported
by five metacarpals.
There are four fingers supported by phalanges.
Hind limb skeleton
The thigh region consists of the femur.
The proximal end of this bone fits into the acetabulum.
The ankle is short, having four bones, arranged in two rows.
The proximal row has two long bones which are called astragalus and
calcaneum.
These bones provide surfaces for the attachment of the hind limb muscles
and thus are helpful in leaping movements. The distal row has two small bones
called the tarsals.
The foot is supported by five long bones, the metatarsals.
There are five toes, each toe supported by the phalanges.
In addition to the five toes, there is a supplemental toe in each foot. This toe
is known as the prehallux or calcar.
This species of frog is given the name Rana hexa dactyla due to the presence
of this sixth toe.
Q 2
10
Describe the respiratory system of pigeon.
A 2
( Unit 7 ; Section 7.3 )
Describing the respiratory system of pigeon
The respiratory tract of pigeon includes:
a) a pair of external nostrils,
b) a pair of internal nostrils which open into the buccal cavity,
c) the glottis lying at the base of the tongue, the larynx supported by the
cartilages,
d) The trachea, the syrinx, the paired bronchi and a pair of lungs with air sacs.
A) Syrinx:
The syrinx is the voice box or sound producing organ, characteristic of birds.
It lies at the region where the trachea divides into branches.
The syrinx has a special membrane called membrane semilunaris and its
vibration produces the sound, when the air passes through the membrane.
B) Lungs:
The lungs are compact, highly vascular, non-elastic, solid and spongy sacs.
The bronchus on each side is continued into a mesobronchus, secondary
bronchi and parabronchi which end in bronchioles or air capillaries.
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The latter are inter connected with each other and are richly supplied with
blood capillaries.
The gaseous exchange occurs in these capillaries.
C) Air sacs:
In pigeon, there are nine air sacs, attached to the lungs.
The air sacs are thin walled, elastic, non-vascular and transparent sacs.
Exchange of gases does not occur in the air sacs and they are only the
reservoirs of air.
The nine air sacs include a median interclavicular, a pair of cervical, a pair of
anterior thoracic, a pair of posterior thoracic and a pair of abdominal air sacs.
These air sacs serve three important functions.
They serve to have double oxygenation, a process in which oxygenation
occurs twice during inspiration.
The air sacs help in regulating the body temperature.
They also help for buoyancy, a weight reducing adaptation.
Respiration in pigeon involves inspiration and expiration.
In pigeon and other birds, expiration is an active process and inspiration is a
passive process.
In mammals and other vertebrates, it is a reverse process, where inspiration
is an active process and expiration is a passive process.
The intercostal muscles lying between the ribs, the abdominal muscles, the
ribs and the sternum play an important role in respiration.
Q 3
10
Describe the digestive system in Petromyzon.
A 3
( Unit 3 ; Section 3.4 )
Describing the digestive system of petromyzon
• In Petromyzon the mouth is present in the buccal funnel. Jaws are absent.
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• The buccal funnel or sucker is used for attachment to the body of a fish or
other host animals. The mouth leads into a buccal cavity. T
• The rasping tongue with horny teeth is protrusible and by its movement, can
open or close the mouth.
• The buccal cavity leads into two tubular structures, a dorsal oesophagus and a
ventral respiratory pharynx. This is the pharyngeal region which ends in a
respiratory tube. This tube contains seven internal gill slits on each side.
Presence of this respiratory tube is a special feature of Petromyzon.
• The narrow tubular oesophagus leads into a straight tube, the intestine. The
latter contains a spiral valve, having a role in digestion and absorption. The
intestine leads into rectum which opens outside by anus in the cloacal region.
• The digestive glands include a pair of salivary glands or buccal glands and a
large bilobed liver. These buccal glands secrete an anticoagulant substance.
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• A gall bladder and a bile duct are present in the larva but are absent in the
adult.
• Petromyzon is adapted for a parasitic mode of feeding.
• The buccal funnel serves for attachment to the host fish.
• The rasping tongue serves to remove small pieces of tissues of the host
animal.
• The anticoagulant secretion injected into the wound prevents clotting of blood.
Petromyzon sucks the blood and body fluids of the host animal.
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