biology mcqs
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 141 - 160 of 169
141. Which is mismatched–
Let's examine each pair: * Bowman's capsule - Glomerular filtration: Correct. Bowman's capsule is the site where glomerular filtration (ultrafiltration) occurs. * PCT - Absorption of Na+ and K+: Correct. The Proximal Convoluted Tubule (PCT) is a major site for the active reabsorption of essential substances, including Na+ and K+. * DCT - Absorption of glucose: This is mismatched. Glucose is almost entirely reabsorbed in the Proximal Convoluted Tubule (PCT), not the Distal Convoluted Tubule (DCT).
142. Loop of Henle is associated with :
The Loop of Henle is an integral part of the nephron (also called uriniferous tubule), which is the structural and functional unit of the kidney. The kidney, in turn, is the central organ of the excretory system responsible for urine formation and waste elimination.
143. The complete reabsorption of glucose takes place in -
The Proximal Convoluted Tubule (PCT) is highly specialized for reabsorption and is the major site where essential substances are recovered from the glomerular filtrate. The source states that the whole of glucose is reabsorbed in the PCT, meaning under normal physiological conditions, no glucose should be found in the urine.
144. Which of the following is metabolic waste of protein metabolism : -
Protein metabolism involves the breakdown of amino acids. This process initially produces ammonia (NH₃) through deamination. Ammonia is then converted to urea in the liver for safer transport and excretion. Creatinine is another nitrogenous waste product derived from the metabolism of creatine phosphate in muscles, which is also linked to protein metabolism. Therefore, urea, ammonia, and creatinine are all significant metabolic wastes of protein metabolism.
145. Glomerular filtrate contains : -
Glomerular filtration is a nonselective process that allows small molecules to pass through the filtration barrier but retains large ones. The resulting glomerular filtrate is chemically similar to blood plasma but specifically excludes large-sized components such as blood cells (platelets, leucocytes, erythrocytes) and proteins. Therefore, it can be accurately described as blood without blood cells and proteins.
146. Glomerular hydrostatic pressure is present in-
The glomerular hydrostatic pressure (GHP) refers to the blood pressure within the capillaries of the glomerulus. This pressure is the main driving force that pushes fluid and small solutes out of the blood and into Bowman's capsule during glomerular filtration. The glomerulus is an integral part of the uriniferous tubule system (nephron).
147. Diuresis is condition, which is characterized by
Diuresis is a physiological state or condition where there is an increase in the volume of urine excreted. This can be caused by substances (diuretics) that inhibit water reabsorption in the kidneys, leading to higher urine output.
148. Liquid which collects in the cavity of Bowmans’ Capsule is :-
The liquid that collects in the lumen or capsular space of Bowman's capsule is the glomerular filtrate. This filtrate is formed through ultrafiltration of blood and is chemically similar to blood plasma, but it specifically lacks large molecules like blood proteins and blood cells, as these components are retained in the bloodstream. So, it is essentially blood plasma minus blood proteins.
149. Mammalain kidney resemble contractile vacuole of Amoeba in excretion of :
Both the mammalian kidney and the contractile vacuole of Amoeba serve a crucial function in osmoregulation, which is the maintenance of water balance. In freshwater Amoeba, the contractile vacuole actively pumps out excess water that enters the cell by osmosis from the hypotonic environment, preventing lysis. Similarly, mammalian kidneys play a vital role in regulating body fluid volume by excreting excess water (or conserving it as needed), thereby maintaining internal osmotic balance. *This explanation draws on general biological knowledge regarding osmoregulation in different organisms as the specific comparison is not detailed in the provided sources.*
150. ADH acts on the : -
ADH (Antidiuretic Hormone), also known as Vasopressin, is a key hormone in the regulation of water balance. It primarily acts on the walls of the collecting tubules and collecting ducts in the kidney. In the presence of ADH, these segments become permeable to water, facilitating its reabsorption from the filtrate and leading to the formation of more concentrated urine.
151. Enzyme ‘Renin’ is secreted by :
The enzyme renin is a crucial component of the Renin-Angiotensin-Aldosterone System (RAAS), which regulates blood pressure and volume. Renin is specifically released by the cells of the Juxtaglomerular Apparatus (JGA), which are specialized cells located in the kidney, in response to a decrease in blood pressure or volume in the afferent arteriole.
152. Absorption Na+ and K+ ions does not occur in : -
Let's review where reabsorption of Na+ and K+ occurs: * Proximal Convoluted Tubule (PCT): Active reabsorption of Na+ and K+ is significant. * Loop of Henle: The thick ascending segment actively transports NaCl (and K+) out. * Distal Convoluted Tubule (DCT): Na+ is actively reabsorbed under the influence of aldosterone. * Bowman's capsule: This structure is primarily involved in glomerular filtration, where blood plasma is filtered into the capsular space. It is not a site for the reabsorption (absorption) of ions. Therefore, absorption of Na+ and K+ ions does not occur in Bowman’s capsule.
153. Urea synthesis takes place in :-
The synthesis of urea from ammonia (NH₃) and carbon dioxide (CO₂) occurs through the urea cycle (ornithine cycle). This metabolic pathway is primarily localized to the liver. Once synthesized, urea is then transported via the bloodstream to the kidneys for filtration and excretion.
154. Glycosuria is the condition, where a man :
Glycosuria is explicitly defined as the presence of glucose in urine. It typically occurs when blood glucose levels are elevated, exceeding the renal tubules' capacity to reabsorb all the filtered glucose.
155. Find the incorrect statement regarding mechanism of urine formation in man :
Let's evaluate each statement regarding urine formation: * Tubular secretion takes place in the PCT (and DCT). (Correct) * Aldosterone induces greater reabsorption of sodium in the DCT. (Correct) * The counter-current mechanism is crucial for concentrating the urine, not diluting it. It achieves this by establishing and maintaining a high osmotic gradient in the renal medulla, which facilitates water reabsorption from the collecting ducts. Therefore, this statement is incorrect. * The glomerular filtration rate (GFR) is indeed about 125 mL per minute. (Correct).
156. If one litre of water is introduced in human blood, then :
Introducing one liter of pure water into human blood would significantly dilute the plasma, making it hypotonic (lower solute concentration). This hypotonicity would cause red blood cells (RBCs) to swell as water moves into them by osmosis. Severe swelling can lead to RBC lysis (bursting), not collapsing (which is typically shriveling in hypertonic solutions). The decrease in blood osmolarity would inhibit ADH release, leading to reduced water reabsorption in the kidneys and consequently a significant increase in urine production. *Note: The option states 'RBC collapses', which is biologically inaccurate for a hypotonic solution; however, 'Urine production increases' is correct, and I must adhere to the provided answer key.*
157. In which of the following organisms its excretory organs are correctly stated?
Let's evaluate each option based on the sources: * Human: Kidneys, sebaceous glands, and lungs are excretory organs. Tear glands are not listed. (Incorrect) * Earthworm: As an annelid, the main excretory structures are nephridia. Earthworms possess different types of nephridia (pharyngeal, integumentary, and septal), which collectively handle excretion. This statement is correct. * Cockroach: As an insect, its main excretory organs are Malpighian tubules. Enteric caeca are parts of the digestive system, not primary excretory organs. (Incorrect) * Frog: Adult frogs use kidneys for excretion. While skin (for gas exchange and some waste) and buccal epithelium (for gas exchange) contribute to overall body functions, the primary specialized excretory organs are the kidneys. (Less precisely correct compared to Earthworm). Therefore, the Earthworm option is the most accurately stated.
158. Urea synthesis takes place primarily in liver because :
Urea is produced from ammonia and carbon dioxide in the liver. This process, the urea cycle, requires a specific set of enzymes. The primary reason urea synthesis takes place predominantly in the liver is that the entire enzymatic machinery for the urea cycle, including key enzymes like arginase, is exclusively or primarily present in liver cells. This allows for efficient detoxification of ammonia into urea before it is transported to the kidneys for excretion. *This explanation draws on general biochemical knowledge as the specific enzymes of the urea cycle are not detailed in the provided sources, though the source does state urea is produced in the liver.*
159. Which one of the following correctly explains the function of a specific part of a human nephron?
Let's evaluate each option: * Podocytes: These specialized cells in Bowman's capsule have pedicels that form slit pores or filtration slits, through which filterable components of blood pass into the capsule during ultrafiltration. This statement is correct. * Henle's loop: The Loop of Henle's primary role is to establish a concentration gradient in the medulla and concentrate the filtrate, not to perform most reabsorption. The Proximal Convoluted Tubule (PCT) is the major site of reabsorption. (Incorrect) * Distal convoluted tubule: While the DCT is involved in ion transport and fine-tuning, its primary role concerning K+ is often secretion to eliminate excess K+ from the body, rather than extensive reabsorption into capillaries. (Ambiguous/Potentially incorrect depending on context of K+ balance) * Afferent arteriole: This vessel carries blood to the glomerulus, not away from it towards the renal vein. The efferent arteriole carries blood away from the glomerulus. (Incorrect)
160. Uricotelic mode of passing out nitrogenous wastes is found in :
Uricotelism is a mode of excretion where the main nitrogenous waste product is uric acid. This adaptation is particularly important for water conservation, especially for terrestrial animals. The sources explicitly list reptiles and birds as examples of uricotelic animals, along with insects like cockroaches.