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Excretory Products & Their Elimination: MCQs

Test your understanding of excretory products, human excretory system, and kidney function with these multiple-choice questions.

Test Your Knowledge

Showing questions 21 - 40 of 169

21. The animals which do not actively control the osmotic condition of their body fluids are

Osmoconformers
Osmoregulator
Hyperosmotic
Hypertonic

Osmoconformers are organisms that allow their internal body fluid osmolarity to fluctuate and match that of their external environment, without expending significant energy to regulate it. In contrast, osmoregulators actively maintain a relatively constant internal osmotic condition.

22. Which of the following can be termed as osmoconformers?

All marine invertebrates
Hagfish
All fresh water invertebrates
Both (1) & (2)

Animals that do not actively control the osmotic condition of their body fluids are called osmoconformers. The sources indicate that Myxine (Hagfish) is an example of an animal that does not maintain a constant internal osmolarity different from the surrounding medium. Additionally, all marine invertebrates are generally known to be osmoconformers, allowing their body fluids to be isotonic with seawater.

23. A fresh water fish maintains osmoregulation by

Continuously taking in water and eliminating excess of salts
Eliminating excess of water and taking up salts from the environment
Taking both water and salt from the environment
Eliminating both salt and water into the environment

Freshwater fish live in a hypotonic environment, meaning water constantly tends to enter their bodies by osmosis, and salts tend to diffuse out. To counteract this, they maintain osmoregulation by eliminating excess water (producing large volumes of dilute urine) and actively taking up salts from their environment (e.g., through specialized cells in their gills). *This explanation draws on general biological knowledge as this specific mechanism for freshwater fish is not detailed in the provided sources.*

24. Which of the following mean is used by fresh water organisms to prevent net gain of water or net loss of body salts?

Contractile vacuole
Large volume of dilute urine
Ionocytes
All of these

Freshwater organisms employ various strategies to manage water balance in their hypotonic environments. These include: * Contractile vacuoles: Specialized organelles in many freshwater protozoans (like Amoeba) that actively expel excess water. * Large volume of dilute urine: Kidneys of freshwater fish and amphibians produce copious amounts of very dilute urine to excrete excess water without losing too many vital salts. * Ionocytes: Specialized cells (e.g., in fish gills) that actively absorb ions from the surrounding water to compensate for salt loss. Therefore, all of these mechanisms contribute to osmoregulation in freshwater organisms. *This explanation draws on general biological knowledge as these specific mechanisms are not detailed in the provided sources for freshwater organisms.*

25. Marine bony fish have body fluids hypotonic to sea water and tend to lose water from the body throug': a. Gill membrane b. Oral membrane c. Anal membrane

a only
a, b & c
a & c only
b & c only

Marine bony fish live in a hypertonic environment, meaning water tends to leave their bodies by osmosis, and salts tend to enter. To counteract water loss, they drink seawater and actively excrete excess salts. Water loss occurs across all permeable body surfaces in contact with the water, including the gill membrane, oral membrane, and anal membrane. Therefore, water loss occurs through all three mentioned membranes. *This explanation draws on general biological knowledge as these specific membranes for water loss are not detailed in the provided sources for marine bony fish.*

26. Divalent cations are generally eliminated in marine fishes through

Gill membrane
Anal membrane
Faecal matter
Oral membrane

Marine fish ingest seawater, which contains high concentrations of various ions, including divalent cations like magnesium (Mg²⁺) and sulfate (SO₄²⁻). While gills are primarily involved in monovalent ion (Na⁺, Cl⁻) excretion, divalent cations are generally eliminated through the faecal matter as they are poorly absorbed in the intestine. *This explanation draws on general biological knowledge as the specific elimination route for divalent cations in marine fish is not detailed in the provided sources.*

27. Body fluids of shark and coeloacanths can be termed as

Hyperosmotic and hypoionic to sea water
Hypo-osmotic and hypoionic to sea water
Hyperosmotic and hyperionic to sea water
Hypo-osmotic and hyperionic to sea water

Cartilaginous fish, such as sharks, are unique in their osmoregulation. They retain a large amount of urea in their blood and tissue fluids as a major osmolyte. This high concentration of urea, along with trimethylamine oxide (TMAO), makes their body fluids have an overall solute concentration (osmolarity) higher than that of seawater, thus making them hyperosmotic. However, despite their high overall osmolarity, their concentration of specific inorganic ions (like Na+ and Cl-) is still lower than that of seawater, making them hypoionic in terms of salts. This adaptation helps them avoid net water loss to the marine environment.

28. Consider the following water conservation mechanisms A. Nasal countercurrent mechanism B. Dependence on metabolic water C. Highly hypertonic urine D. Living more on protein rich diet The kangaroo rat living in desert can survive without drinking water because of

A, B & C
A, B & D
B, C & D
A, C & D

Kangaroo rats are desert-adapted mammals known for their remarkable water conservation abilities, allowing them to survive without drinking free water. Their key mechanisms include: * Nasal countercurrent mechanism (A): Efficiently reclaims water vapor from exhaled air. * Dependence on metabolic water (B): Generates a significant portion of their water needs from the metabolic oxidation of food (e.g., fats). * Highly hypertonic urine (C): Their kidneys, particularly their very long Loops of Henle, produce extremely concentrated urine, minimizing water loss. * Living on a protein-rich diet (D) would actually increase water requirements for the excretion of urea (a nitrogenous waste product of protein metabolism), making it counterproductive for water conservation. Therefore, the correct combination of mechanisms is A, B, and C. *This explanation draws on general biological knowledge as these specific mechanisms for kangaroo rats are not detailed in the provided sources.*

29. Select the true statement

In fishes kidney playa major role in ammonia excretion
Ammonia is 100,000 times less toxic than urea
Sharks retain a large amount of urea in the blood as a major osmolyte to balance the osmolarity of the body fluids
Most terrestrial reptile excrete ammonia

Let's analyze each statement based on the provided sources: * Sharks retain a large amount of urea in the blood as a major osmolyte to balance the osmolarity of the body fluids: This statement is explicitly supported by the source, which mentions that cartilaginous fish (e.g., sharks) retain part of the urea produced in the kidney for osmoregulation. * Ammonia is 100,000 times less toxic than urea: This is incorrect. The source states that ammonia is very toxic, and urea is comparatively less toxic, specifically 100,000 times less toxic than ammonia. * Most terrestrial reptile excrete ammonia: This is incorrect. Terrestrial reptiles are primarily uricotelic, meaning they excrete uric acid, which helps in significant water conservation. Ammonia requires large amounts of water for excretion. * In fishes kidney playa major role in ammonia excretion: This is incorrect. In fishes, ammonia (NH₄⁺) primarily diffuses out across gill epithelium, rather than being solely excreted by the kidneys.

30. One of the following can retain a large amount of urea in the blood and tissue fluid

Mammals including man
Toad, Frog, Prawn
Sharks, Electric ray, Sting ray
Alligators, Terrapins, Turtles

Animals are classified based on their main excretory product. Ureotelic animals (excreting mainly urea) include cartilaginous fish, amphibians, and mammals. Specifically, the source states that in ureotelic animals, 'entire amount of urea produced is not excreted out but a part is retained in kidney and is involved in osmoregulation'. Examples of cartilaginous fish that retain urea for osmoregulation include sharks, and this would extend to other cartilaginous fish like electric rays and sting rays.

31. Deamination is the first step in urea formation. It means the

Reduction of ammonia
Oxidation of ammonia
Addition of amino group to a non-amino organic molecule
Removal of amino group from an amino acid

The source states that ammonia, the first metabolic waste product of protein metabolism, is produced in the liver by the process of deamination. Deamination is the biochemical process that involves the removal of an amino group (-NH₂) from an amino acid, converting it into ammonia and a keto acid.

32. Removal of metabolic waste in the form of urea is called

Ammoniotelism
Ureotelism
Uricotelism
Aminotelism

Animals are classified based on their main excretory product. The mode of excretion where the excretory product is mainly urea is called ureotelism. In contrast, ammonotelism refers to ammonia excretion, and uricotelism refers to uric acid excretion.

33. Uric acid is produced by the breakdown of

Proteins
Amino acids
Nucleic acids
Starch

The source mentions that uric acid is a component of urine and is derived from nucleic acid metabolism (purine). Purines are nitrogenous bases found in DNA and RNA, and their breakdown leads to uric acid.

34. Guano, the faecal matter of birds contains

Insoluble crystals of uric acid
Insoluble crystals of urates
Both (1) & (2)
Urea

Bird droppings, known as guano, consist of uric acid and phosphate-rich faeces. Birds are uricotelic, meaning they excrete uric acid. Uric acid is almost insoluble in water and can be passed out as a precipitate or in crystalline form. Urates are salts of uric acid, also found in crystalline form. Therefore, guano contains both insoluble crystals of uric acid and urates.

35. Flame cells (solenocytes) are excretory structures of

Annelida
Arthropoda
Flat worms
Crustaceans (Prawn)

The source lists Protonephridia or flame cells as the main excretory structure for Platyhelminthes (Flatworms), which include organisms like Planaria, Liver fluke, and Tapeworm. Solenocytes are mentioned as excretory structures for Cephalochordates, which are a type of protonephridia.

36. Antennary or green glands which are excretory and osmoregulatory organs of crustacean consist of

End sac
Renal sac
Antenna
Lateral and transverse ducts

Antennary or green glands are the main excretory structures in Crustaceans (e.g., Prawn). While the specific internal components like 'End sac' are not detailed in the provided source, the green gland typically consists of an end sac, labyrinth, and a bladder that opens to the outside. The end sac is the initial filtration site. *This specific structural detail draws on general biological knowledge as it is not explicitly defined in the provided sources.*

37. The kidneys not only remove the waste products from the blood but also playa very important role in maintaining

Equilibrium of the body
Temperature of the body
Constant composition of the blood irrespective of the nature of the food or fluid intake
Blood pressure constant

Beyond waste elimination, the kidneys are crucial for osmoregulation, which involves maintaining the fluid and electrolyte balance in the body. This includes regulating blood volume, blood pressure, and plasma osmolarity. By adjusting reabsorption and secretion, kidneys ensure the constant composition of the blood and interstitial fluid, regardless of dietary intake, which is essential for homeostasis.

38. The outer cortex of the kidney in a T.S. appears granular or dotted because of

Granular cytoplasm
The presence of loops of Henle
The presence of collecting ducts
Much convoluted uriniferous tubules and Malpighian corpuscles in this region

The renal cortex is the outer functional layer of the kidney, described as dark in color and granular in nature. This granular appearance is due to the presence of numerous Malpighian corpuscles (which consist of the glomerulus and Bowman's capsule) and the highly twisted and coiled segments of the uriniferous tubules, specifically the Proximal Convoluted Tubules (PCT) and Distal Convoluted Tubules (DCT), which are predominantly located in the cortex.

39. The concavity on the medial side of kidney is known as

Renal pelvis
Hilum
Calyces
Pyramid

Towards the center of the inner concave surface of the kidney is a notch called the hilum. This hilum serves as the entry and exit point for the ureter, blood vessels (renal artery and vein), and nerves. Inner to the hilum is a broad funnel-shaped space called the renal pelvis.

40. Podocytes are associated with

PCT part of nephron
Glomerulus
Bowman's capsule
Loop of Henle

Podocytes are specialized cells found in the inner visceral layer of Bowman's capsule. These cells have numerous interdigitated evaginations called pedicels or feet, which rest over the basement membrane and enclose slit pores or filtration slits. These slits are crucial for the filtration of blood components into Bowman's capsule during urine formation.

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