Class 11 Biology — Chapter 7: STRUCTURAL ORGANISATION IN ANIMALS

Understand the hierarchy of biological organization in multicellular animals, starting from cells, which group to form tissues, then organs, and finally organ systems. This organization allows for an efficient division of labour within the organism.

Recognize the frog as a poikilothermic (cold-blooded) amphibian that exhibits adaptations like camouflage for protection, and undergoes aestivation (summer sleep) and hibernation (winter sleep) to survive extreme temperatures.

Identify the external features of a frog, including its smooth, moist skin, head and trunk, nictitating membrane over the eyes, and tympanum. Differentiate between male and female frogs based on sexual dimorphism features like vocal sacs and copulatory pads in males.

Trace the path of food through the frog's short alimentary canal (buccal cavity, oesophagus, stomach, intestine, rectum, cloaca) and understand the roles of the liver and pancreas in producing bile and digestive enzymes for chemical digestion.

Explain the three modes of respiration in a frog, which are essential for its amphibious life: cutaneous respiration through the skin (in water and on land), buccal respiration, and pulmonary respiration using lungs (on land).

Describe the closed-type blood vascular system, focusing on the three-chambered heart (two atria, one ventricle), the role of the sinus venosus and conus arteriosus, and the presence of special hepatic and renal portal systems. Understand the basic components of blood and lymph.

Identify the organs of the excretory system, including the pair of kidneys, ureters, cloaca, and urinary bladder. Understand that the frog is a ureotelic animal, meaning it excretes urea as its primary nitrogenous waste.

Gain a basic understanding of the frog's highly evolved neural and endocrine systems for control and coordination. Differentiate between male and female systems, noting that male ureters act as a urinogenital duct while female ureters and oviducts open separately into the cloaca.