Perpetual Help System Essay

1. What do you think is the function of the nictating membrane, and why ? The nictitating membrane is a protective, semi-transparent third eyelid. It allows vision while giving the eye extra protection. In the case of frogs, the protection is needed when the frog is out of the water. The clear nictitating membrane allows the frog to keep looking for prey – and looking out for herons and other hunters! – while its eyes are protected from dust and from the drying effects of the air. 2. A frog does not chew its food, what do the positions of its teeth suggest about how the frog uses them ? That they are intended for gripping, not for chewing. The 4 teeth a frog has, are positioned with 2 on the sides and 2 in the center, and are angled toward the throat. This helps keep the food going in the direction of the digestive tract†¦but unable to back out of the mouth. 3. Trace the path of food through the digestive tract. In the frog’s mouth there is a front hinged tongue. This flips food into the gullet, which is the entrance to the esophagus. The food is moved down into the stomach by muscle contraction. The stomach breaks food down mechanically using its multiple muscle layers. It also secretes enzymes to convert complex nutrients into simpler ones. The enzymatic breakdown continues in the small intestine where the simpler nutrients are also then absorbed. The left over material is passed on to the large intestine where water may be absorbed from the mixture. 4. Trace the path of blood through the circulatory system. The Deoxygenated blood flows from the body into the right atrium. Oxygenated blood from the lungs flows into the left atrium. Since frogs have only one ventricle, the oxygenated and deoxygenated blood mixes in the ventricle. From there, blood flows into the truncus arteriosus that contains a spiral valve to separate and lead the blood out into the body. 5. Trace the path of air through the respiratory system. Nostrils -> Nasal Cavity -> Pharynx -> Larynx -> Trachea -> Bronchi -> Bronchioles -> Lungs -> Alveoli 6. Trace the path of sperm in a male and eggs in a female. Male: Testes produce sperm, move through sperm ducts into the cloaca. Female: Ovaries produce eggs, move through oviducts into uteri, then through the coaca. 7. Trace the path of urine in both sexes. Urine is formed in the distal tubules of the nephron in the kidneys. It accumulates in the renal pelvis, then travels down the ureters to the bladder. Then it goes through the urethra to the outside. 8. Which part of the frog’s nervous system can be its abdominal cavity and hid legs? The Spincal cord and the muscualr system which mainly takes place in the thigh 9. Suppose in a living frog the spinal nerve extending to the leg muscle were cut. What ability would the frog lose? Why? In any vertebrates, all coordinated response movements and actions would be disabled from the point the nerve was injured and down. Severed spinal damage will kill the animal. 10. The abdominal cavity of a frog at the end of hibernation season would contain very fat bodies or move at all. What is the function of the fat bodies? To pertain its energy lose, from being lack to food. 11. Structures of an animal’s body that fit it for its environment are adaptions. How do frog’s powerful legs help it to fit into a life both in water and land? On land, the frog’s hind legs are what enables the frog to leap, and in the water, it uses its hind legs for swimming. Being able to leap quickly on land, and to swim just a quickly is one of the frog’s best defenses in avoiding predators. 12. During 1 mating of frogs, female lays some 2000 to 3000 eggs in water as the male sheds millions of sperm over them. How do these large numbers relate to the frog’s fitness for life in water? Frogs are very fit for life in water reproductively, because the large numbers of eggs and offspring will help to ensure some individuals survive to reproductive adulthood.