Question

11. Protonephridia, metanephridia, and the kidneys of vertebrates A. each rely on cilia or flagella to move fluid into the excretory ducts B. have specific secretory mechanisms which allow only wastes to reach the excretory ducts C. remove wastes but do not control salts D. begin excretion by discarding food, water, salts and waste

12. Animals with protonephridia, metanephridia, or kidneys need them because A. these animals are sessile B. they have mesoderm C. these animals have no other mechanisms for removing wastes D. only these animals produce ammonia

13. Nitrogenous wastes have increasing toxicity in the following order A. [lowest] uric acid, ammonia, urea [highest] B. [lowest] urea, uric acid, ammonia [highest] C. [lowest] uric acid, urea, ammonia [highest] D. [lowest] ammonia, urea, uric acid [highest]

14. Nitrogenous wastes have increasing solubility in the following order A. [lowest] ammonia, uric acid, urea [highest] B. [lowest] urea, uric acid, ammonia [highest] C. [lowest] uric acid, urea, ammonia [highest] D. [lowest] ammonia, urea, uric acid [highest]

15. Lymphatic fluid
A. is an ultrafiltrate of the blood
B. bathes tissues of vertebrates
C. is similar to the fluid in Bowman's capsule
D. all of the above

Answer 1

11 . ANSWER - OPTION B

EXPLANATION –

· Proto nephridia - type of excretory system found in flat worms .They are network of bind ended tubes opening only to the exterior.These tubes branch through out the body and ends in structures called flame bulbs( a tuft of cilia that beats forcing fluids to come through the tubes).The urine is released or emptied via nephridiophore.

· Meta nephridia – Mostly seen in annelids and they are highly segmented.Each segment contains a pair of metanephridia.Tubules are bathed in coelomic fluid and surrounded by capillaries.The nephrostome collects fluid from coelom (ultrafiltration) and transport to epithelia in lumen of tubules .Their reabsorption occurs and molecules are secreted.Urine exits via nephridiophore.

· Kidneys main purpose is to separate urea,mineral salts ,toxins ,waste products.They maintains the osmotic balance in vertebrates by conserving water,salts and electrolytes.they are bean shaped reddish brown organs.The fundamental units of kidneys are called Nephrons – physiological unit used for filtration of blood ,secretion and reabsorption of materials.

12. ANSWER – C

  EXPLANATION ;

                        Most animals requires a excretory system for eliminating toxic wastes and for maintaining the osmoregulation as well.As organisms evolved from simple organisms to complex organisms the organs and organs system also developed.So unlike small and simple organisms larger ones need much more regulated and complex excretory system owing to their larger size and biochemical complexity.As organisms evolved organogenesis leading to specialized organ systems and organs developed,.Even though the functions of each organ system are inter –related and balanced ,each organ system is entitled with a specific function.So complex organisms like vertebrates,annelids etc need a specific excretory system for excretory function.They are evolved with a specific excretory system,no other systems or mechanisms performs the excretory function rather than the assigned specific organs /organ systems.

13. ANSWER – OPTION C

EXPLANATION –

· In animals nitrogenous wastes are produced from excess amino acids through the process called deamination.

· Ammonia is the direct product of deamination.Ammonia is highly toxic and highly soluble in water.In liver ammonia is converted into urea ,a less toxic compound.

                      2NH3 + CO2  → CO(NH2)2 + H2O

· Uric acid is formed directly from amino acids via a series of reactions that produces its complex ring structure.

14. ANSWER – OPTION C

EXPLANATION –

· Nitrogenous waste - produced in the body needs to be excreted from the body as they are toxic to an organism,hence either converted into less toxic form and released / released as such.

· This nitrogenous wastes are excreted in 3 forms - ammonia, uric acid & urea,depending on the complexity of the organism and the environment they are habituated.

· Ammonia is more water-soluble & most toxic. It requires less energy for excretion. Animals excreting nitrogenous waste in the form of ammonia are called as ammonotelic. Egs - Aquatic animals like protozoans, crustaceans, poriferans, fishes (Availability of water is not a limiting factor).

· Urea requires comparatively more energy & less toxic in nature. Animals excreting nitrogenous waste in the form of urea are called as ureotelic. Egs - mammals including humans.

· Uric acid is least soluble in water & least toxic. However, it requires a large amount of energy. Egs - reptiles, birds.

15. ANSWER – OPTION D

EXPLANATION –

· The word lymph literally means – clear fluid, the word "lymph" has derived from the Latin word lympha, which means "connected to water".

· They are derived from tissue fluid.

· Lymph contains white blood cells and aids in immunity and concentration of WBC’s is higher than in plasma.

· Lymph flows only in one direction unlike blood.

· When the interstitial fluid begins to accumulate,they are collected& removed by tiny lymphatic vessels & returned to the blood. As soon as the interstitial fluid enters the lymph capillaries, it is called lymph.