Exams › NEET › Biology › Excretory Products and their Elimination
64 questions with worked solutions.
Q1. Brush border is characteristic of
Answer: proximal convoluted tubule
The proximal convoluted tubule has a prominent brush border made of microvilli to maximize reabsorption of water, ions, glucose, and amino acids. The neck of the nephron and collecting tubule do not have this characteristic brush border.
Q2. Proximal and distal convoluted tubules are parts of
Answer: Nephron
The proximal and distal convoluted tubules are specific segments of the nephron, the kidney’s basic structural and functional unit. They are not parts of reproductive ducts or tubules.
Q3. Reabsorption of useful substances from glomerular filtrate occurs in
Answer: Proximal convoluted tubule
The proximal convoluted tubule is the main site where useful substances from the glomerular filtrate are reabsorbed back into the blood. It reabsorbs most glucose, amino acids, water, and salts, making it the key reabsorptive segment.
Q4. Excretion in Amoeba occurs through:
Answer: diffusion through body surface
Amoeba is unicellular, so it does not have specialized excretory organs. Its metabolic wastes, especially carbon dioxide and ammonia, diffuse out through the body surface (cell membrane).
Answer: excretory organs of insects
Malpighian tubules are the excretory structures in insects, where they help remove nitrogenous wastes and regulate water balance. They are not respiratory organs and are not found as the main excretory organs in annelids.
Answer: metanephros
Adult rabbits are mammals, and mammals retain the metanephros as their permanent kidney. Pronephros and mesonephros are embryonic/temporary stages, while opisthonephros is typical of many fishes and amphibians.
Q7. A person who is one along hunger strike and is surviving only on water, will have
Answer: less urea in his urine
During a hunger strike with only water intake, the body has little or no incoming protein, so amino acid deamination decreases and less urea is produced. Since urea is the main nitrogenous waste from protein metabolism, its urinary excretion falls.
Q8. Presence of RBC in urine is
Answer: Haematuria
RBCs in urine indicate blood is present in the urinary tract, which is called haematuria. Urethiasis refers to stones, proteinuria means protein in urine, and alkaptonuria is a metabolic disorder.
Answer: Salamander - Kidney - Urea
Salamanders are amphibians, and amphibians generally have kidneys as the main excretory organs. They are ureotelic, meaning urea is the chief nitrogenous waste product.
Q10. Uricotelic mode of passing out nitrogenous wastes is found in
Answer: Reptiles and Bird
Uricotelic animals excrete nitrogenous waste mainly as uric acid, which is nearly insoluble and conserves water. Reptiles and birds are classic uricotelic groups, so that option is correct.
Q11. Uric acid is the chief nitrogenous component of the excretory products of
Answer: cockroach
Cockroaches are insects and are uricotelic, meaning they mainly excrete nitrogenous waste as uric acid. This helps conserve water because uric acid is poorly soluble.
Answer: Aquatic Amphibia, Frog - Pigeon, Lizards, Cockroach
Aquatic amphibians and frogs are ammonotelic, so they release ammonia. Pigeon, lizards, and cockroach are uricotelic, while humans are ureotelic, matching the given categorization.
Q13. A terrestrial animal must be able to
Answer: conserve water
Animals living on land are exposed to drying conditions, so they must retain enough water to maintain normal body functions. Excreting large amounts of water would be harmful, while conserving water helps prevent dehydration.
Q14. Which one of the following is a matching pair?
Answer: Sweat-thermoregulation
Sweat is produced by sweat glands and its evaporation from the skin removes heat, helping regulate body temperature. The other options pair a secretion with a function it does not primarily perform.
Q15. Earthworms are
Answer: ammonotelic when plenty of water is available
Earthworms live in moist environments and can excrete nitrogen mainly as ammonia when water is plentiful. Ammonia is highly toxic but requires lots of water to remove safely, so it fits conditions with abundant water.
Answer: Birds, reptiles and insects
Uricotelic animals eliminate nitrogenous waste mainly as uric acid, which is less toxic and conserves water. Birds, reptiles, and insects are classic uricotelic groups because this strategy suits terrestrial life and, in birds/reptiles, development in shelled eggs.
Q17. In ureotelic animals, urea is formed by the
Answer: Ornithine cycle
In ureotelic animals, excess nitrogen is converted to urea through the urea cycle, also called the ornithine cycle. This pathway occurs mainly in the liver and helps safely eliminate toxic ammonia.
Q18. Uric acid is nitrogenous waste in
Answer: Birds and lizards
Uric acid is the main nitrogenous waste in uricotelic animals, which excrete it as a nearly insoluble paste to save water. Birds and reptiles such as lizards are classic uricotelic groups.
Q19. Nitrogenous waste products are eliminated mainly as
Answer: ammonia in tadpole and urea in adult frog
Tadpoles are aquatic and mainly excrete ammonia because it diffuses easily into water. Adult frogs are more terrestrial and mainly convert nitrogenous waste to urea, which is less toxic and conserves water better.
Q20. In Ornithine cycle, which one pair of the following wastes are removed from the blood?
Answer: CO2 and ammonia
The ornithine (urea) cycle detoxifies ammonia by converting it into urea in the liver. Carbon dioxide is also used in the cycle, and the pair associated with wastes removed from blood here is carbon dioxide and ammonia.