This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Urine Formation – 1”.
1. Which of the following is not a process of urine formation?
a) Glomerular filtration
Explanation: Urine formation involves three main processes namely, glomerular filtration, reabsorption, and secretion, that take place in different parts of the nephron.
2. Which of the following is the first step towards urine formation?
a) Glomerular filtration
Explanation: The first step in the urine formation is the filtration of blood, which is carried out by the glomerulus and is therefore known as glomerular filtration.
3. On average, how much volume of blood is filtered by the kidneys per minute?
a) 100-150 ml
b) 500 ml
c) 1100-1200 ml
d) 5000 ml
Explanation: On average, our kidneys filter 1100-1200 ml of blood every minute. This blood that is filtered per minute constitutes for about 1/5th of the total blood pumped out by each ventricle of the heart in a minute. Therefore, we can say that the whole blood of our body gets filtered in approximately 5 minutes.
4. How many layers of glomerular epithelium are involved in the filtration of blood?
Explanation: Three layers of the glomerular epithelium of the Malpighian corpuscle are involved in the filtration of the blood. These layers include the endothelium of glomerular blood vessels, the epithelium of Bowman’s capsule and a basement membrane between these two layers.
5. Podocytes are present in the epithelial lining of PCT.
Explanation: No, the podocytes are not present in the epithelial lining of PCT. Instead, the epithelial cells of the Bowman’s capsule are called podocytes. These cells are arranged very closed to each other but some minute spaces are left between these cells for the filtration to take place.
6. Which of the following are not passed on to the lumen of Bowman’s capsule during glomerular filtration?
a) Fat molecules
Explanation: Proteins are not passed on to the lumen of Bowman’s capsule during glomerular filtration because the blood is filtered so finely through the podocytes of the Bowman’s capsule that almost all the constituents of the plasma except the proteins pass onto the lumen of Bowman’s capsule. This process of filtration of blood is known as ultra-filtration.
7. What is the percentage of cortical nephrons concerning the total nephrons present in the kidneys?
Explanation: Cortical nephrons constitute for about 75-80% of the total nephrons present in the kidneys. These nephrons have reduced Henle’s loop and vasa recta. Sometimes both of them may be absent.
8. Which of the following type of nephrons are prominently present in the desert mammals?
a) Cortical nephrons
b) No nephrons are present
c) Medullary nephrons
d) Juxta-medullary nephrons
Explanation: In desert mammals, juxtamedullary nephrons are present because they have a very long loop of Henle which helps in the reabsorption of water as more as possible.
9. What is the full form of GFR?
a) Glomerulus filtering unit
b) Glomerular filtration rate
c) Globulin fast rate
d) Globulin filtering rate
Explanation: GFR stands for the Glomerular filtration rate. It is the amount of the filtrate formed by the kidneys per minute. It plays an important role in determining the health status of the kidneys.
10. In approximately how many minutes, the whole blood of the body is filtered through the kidneys?
a) 10 minutes
b) 7 minutes
c) 4-5 minutes
d) 2 minutes
Explanation: As we know that our kidney filters approximately 1100-1200 ml of the blood per minute and our cardiac output is 5 times this volume, therefore our kidneys take approximately 4-5 minutes to filter the whole blood of the body.
11. Which of the following pair of amino acids are removed by the ornithine cycle?
a) CO2 and H2O
b) H2O and O2
c) CO2 and urea
d) Ammonia and CO2
Explanation: CO2 and ammonia are a pair of waste substances removed from the blood during the ornithine cycle. The most abundant, harmful, and universal waste product of metabolism is CO2.
12. Urea formation takes place in the adipocytes.
Explanation: Urea formation takes place in the hepatocytes of the liver. The cycle of the formation of urea is called an ornithine cycle of the urea cycle or the Krebs-Henseleit cycle.
13. What is the starting point of the ornithine cycle?
a) Ornithine amino acid
b) Citrulline amino acid
d) Fumeric acid
Explanation: Ornithine amino acid is the starting point of the urea formation in the Krebs-Hanseleit cycle or the urea cycle. Ornithine and citrulline are the main amino acids of the urea formation.
14. How many moles of ATP are required in the formation of urea?
Explanation: Three moles of ATP are required in the formation of urea by the ornithine cycle. 1 ATP is utilized in the cytoplasm while 2 moles of ATP are required in the mitochondria.
15. Which of the following is the main enzyme in the ornithine cycle?
b) Carbamyl phosphatase
Explanation: Arginase is the main enzyme involved in the ornithine cycle which converts arginine into ornithine amino acid. The argininosuccinate enzyme is required to convert argininosuccinic acid to arginine.
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