STRUCTURAL ORGANISATION IN ANIMALS

 

Reproductive system :

• Cockroaches are dioecious and sex organs are well developed.
• Male reproductive system consists of a pair of testes lying one on each in 4th and 6th segments.
• Vas deferens arises from each testis, opens into ejaculatory duct through seminal vesicle.
• Ejaculatory duct opens into the male gonopore situated ventral to anus.
• Accessory reproductive gland called mushroom gland present on 6th-7th segment.
• External genitalia represented by male gonopophysis or phallomere.
• Sperms are sorted in the seminal vesicles and are glued together in the form of bundles called spermatophores which are discharged during copulation.
• The female reproductive system consists of two large ovaries present in 2nd – 6th abdominal segments.
• Each ovary is formed a group of eight ovarian tubules or ovarioles, containing chain of developing ova.
• Oviduct of each ovary fused to form single median oviduct or vagina, which opens into genital chamber.
• A pair of spermatheca is present in the 6th segment which opens into genital chamber.
• Sperms are transferred through spermatophores.
• The fertilized eggs are encased in capsules called oothecae.
• Ootheca is dark reddish to blackish brown capsule about 3/8” long.
• On average, female produce 9-10 oothecae, each containing 14-16 eggs.
• Development is pourometabolous i.e development through nymphal stages.
• The nymph grows by molting about 13 times to reach the adult form.

FROG :

• Frog belongs to class Amphibia.
• Most common species in India is Rana tigrina.
• They are cold blooded animal; the body temperature varies according to environmental temperature.
• They have ability to change the body colour according to the environment.
• They undergo hibernation (summer sleep) and aestivation (winter sleep).

Morphology :

• The skin is smooth and moist, slippery due to mucus.
• Dorsal body is olive green with dark irregular spots.
• Ventral side of the body is uniformly pale yellow coloured.
• The frog never drinks water and absorb it through skin (hygroscopic).
• Body divisible into head and trunk. Neck is absent.
• On either side of the eyes a membranous tympanum (represents the external ear), to receive the sound waves.
• Forelimbs and hind limbs helps in swimming, leaping and burrowing.
• Fore limb have four digit and hind limb stronger and has five digits.
• Frog exhibit sexual dimorphism.
• Male frog distinguished from female frog:
  • Having sound producing vocal sac.
  • Copulatory pad or amplexury pad on the first digit of the fore limb.

Anatomy :

Digestive system :

• Digestive system consists of alimentary canal and digestive glands.
• Alimentary canal is short because frogs are carnivorous.
• Mouth opens into buccal cavity that leads into oesophagus through pharynx.
• Oesophagus is a short tube that opens into the stomach, which inturn continues as the intestine, rectum and finally opens outside by the cloaca.
• Liver secrete bile that stored in the gall bladder.
• Pancreas a digestive gland produces pancreatic juice containing digestive enzymes.
• Food is captured by bilobed tongue.
• Digestion of food takes place by the action of HCl and gastric juice secreted from the walls of the stomach.
• Partially digested food in the stomach is called chyme.
• Chyme passed from stomach to intestine, the duodenum.
• The duodenum receives the bile from gall bladder and pancreatic juice from pancreas through a common bile duct.
• Bile emulsifies fat and pancreatic juices digest carbohydrates and proteins.
• Final digestion takes place in intestine.
• Digested food is absorbed by intestinal villi and microvilli.
• The undigested food removed to outside through cloaca.

 

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
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