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Objective Questions of Zoology Class 11

Venous system 
  Sinus venosus is formed by the union of two precavals/anterior or superior venacavae and post
 caval/posterior or inferior venacava
  Pre caval is formed by:
i)External jugular vein that collects blood from the muscles of torgue and jaws
ii) Innominate vein that collects blood from orbit, brain and shoulder region.
iii) Subclavian vein which collects blood from the muscles of forelimbs and skin.
 Postcaval vein originates from the capillaries of kidneys and also collects blood from gonads and liver.
  Blood from the lungs is collected by pulmonary veins which open into left atrium as a common pulmonary vein
  Hepatic portal vein collects blood from alimentary canal, pancreas and releases into liver.
  Renal portal vein collects blood from lower parts of body and release them into kidneys.
  Blood of frog consists of plasma, eryth rocytes, leucocytes and thrombocytes.
  RBC are oval, nucleated & relatively larger in size
  Lymphatic system- consists of lymph capillaries, lymph vessels, lymphatic ducts, and hymph nodes.
  Lymph hearts are 2 pairs helping in pumping the lymph into veins.
  Integrating system-consists of nervous and endocrine systems.
 Nervous system includes central ner vous system (brain & spinal cord), peripheral nervous system (cranial nerves & spinal nerves) autonomous nervous system(sympathetic & para sympathetic)
  Brain- consists of forebrain (or prosencephalon), midbrain(or mesencep halon) and hind brain (or rhom bencephalon).
  Fore brain consists of a pair of olfactory lobes, a pair of cerebral hemispheres and diencephalon.
  Rhinocoels are ventricles of olfactory lobes.
 Para coels or lateral ventricles (1st  and 2nd) are enclosed by cerebral hemispheres.
  Cerebral hemispheres control voluntary actions
  Dience phalon is concerned with per ception of heat, cold, pain and integ rity of autonomous nervous system.
 Diocoel (3rd ventricle) is enclosed by diencephalon
 Mid brain consists of a pair of hollow optic lobes (corpora bigemina) enclosing optocoels.
 Optic lobes control vision.
  Hind brain consists of cerebellum (maintains equilibrium) and medulla oblongata (controls involun tary actions
  Fourth vertricle is enclosed by medulla
  Spinal cord is continuation of medulla.
  Spinal cord acts as middle man between brain and effectors.
 10 pairs of cranial nerves and 9 or 10 pairs of spinal nerves are present.

Sense organs: 
Eyes-Retina contains rods for dimlight vision and cones for color vision.
 Organs of hearing : Middle ear & internal ear are present
Columella auris, the middle earossicle, meets the cartilaginous stapedial plate which fuses with fenestra ovalis of anditory capsule.
Auditory capsule is formed by single prootic bone
 Internal ear/ membranous labyrinth consists of dorsal utriculus to which the 3 semicircular canals join and ventral sacculus.
Auditory capsule is filled by perilymph and internal ear is filled by endolymph in which calcium carbonate particles, otoliths, are present
 Internal ears are also called statoacoustic organs

Excretory system: 
 Frogs are ureotelic
 Mesonephric kidneys with ciliated nephrostomes on ventral surface are present in adults
 Tadpole larva of frog has pronephric kidneys
 Ureter/mesonephric duct/Wolffian duct arises from the outer margin of kidney and open into cloacal chamber.
 In males, as ureters carry both urine and sperms, they are called urinogenital ducts
 Urinary bladder opens separately into cloaca below the openings of ureters
 Frogs excrete hypotonic urine

Male reprodutive system 
  Testes are covered by mesorchium and attached to kidneys
  Vasa efferentia from each testis open into Bidder’s canal present in the kidney.
 Ureter acts vasdeferens
  Seminal vesicle is the swollen part of ureter just behind the kidney.
  Germinal epithelium is the lining of seminiferous tubules.
 Germinal epithelial cells undergo spermatogenesis

Female reproductive system
 Mesovarium is peritoneal covering by which ovaries are attached to kidneys.
 Eggs are mesolecithal and telotecithal
 Ova are released into body cavity
 Oviduct/Mullerian duct opens into the body cavity by ciliated oviducal funnel called ostium.
 Ovisacs are posterior dilated parts of the oviduct that open into cloacal chamber near the ureter.
 Copulation is called amplexus during which both male & female frogs release sperms and ova into the water
 Eggs released in large number called spawn and the spermatozoa released are called milt
Fertilisation external
 Development includes a gill breathing, herbivorous, ammonotelic tadpole larva which metamor- phoses into lung breathing, carnivorous, ureotelic adult frog.
 Class: Reptilia
 First group of true terrestrial tetrapods
 Labyrinthodont amphibians are the ancestors of reptiles
 Evolved during carboniferous period
 Mesozoic era is the age of reptiles
 Poikilothermic (ectothermic) amnio tes which lay cleidoic eggs on land.
 Study of reptiles is called herpetology.
 Body divided into head, neck, trunk and tail with rough, dry skin covered by epidermal scales, shields etc.
 Two pairs of pentadactyl limbs with clawed digits
 Teeth homodont, acrodont, polyphyodon odont. Thecodont in crocodiles and edentate in chelonians
 Skull monocondylic with temporal fossae
 Each half of lowerjaw is made of six bones.
 Vertebrae procoelous; sacral vertebrae two in number
 Sternum broad plate like; ‘T’ shaped interclavicle present between the two clavicles.
 Inter costal muscles are associated with ribs
 Vascular cloaca helps in respiration in turtles
 Heart with incompletely divided ventricle (incompletely 4-chambered) but crocodiles have 4- chambered heart
 Sinus venosus present but conus arteriosus absent
 Three aortic arches- two systemics and one pulmonary arise directly from ventricle.
 Renal portal system present; RBC nucleated
 Kidneys metanephric; uricotelic vertebrates (terrestrial adaptation)
12 pairs of cranial nerves (10 pairs in snakes)
 Jacobson’s organs, olfactory in function, are well developed in lizards & snakes
 Males with copulatory organ (absent in Sphenodon)
 Mesonephric duct/ Wolffian duct acts as vasdeferens
 Cloaca 3 chambered with anterior coprodaeum, middle urodaeum and posterior proctodaeum,
Fertilisation internal
Eggs cleidoic, megalecithal & telolecithal
* Cleavage meroblastic and discoidal
}}   Mostly oviparous; eggs develop on land as they are amniotes
}}  Crocodilians are the largest living reptiles.
}}   Extant reptiles are grouped under 4 orders

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