Fill in the gaps:
Question: Fill in the gaps: (a) Ascending limb of Henles loop is ____________to water whereas the descending limb is___________to it. (b) Reabsorption of water from distal parts of the tubules is facilitated by hormone____________. (c)Dialysis fluid contains all the constituents as in plasma except ________. (d) A healthy adult human excretes (on an average) _______ gm of urea/day. Solution: (a)Ascending limb of Henles loop isto water, whereas the descending limb isto it. (b)Reabsorption of wate...
Read More →What is meant by the term bond order? Calculate the bond order of
Question: What is meant by the term bond order? Calculate the bond order of: $\mathrm{N}_{2}, \mathrm{O}_{2}, \mathrm{O}_{2}^{+}$and $\mathrm{O}_{2}^{-}$. Solution: Bond order is defined as one half of the difference between the number of electrons present in the bonding and anti-bonding orbitals of a molecule. IfNais equal to the number of electrons in an anti-bonding orbital, thenNbis equal to the number of electrons in a bonding orbital. Bond order $=\frac{1}{2}\left(N_{\mathrm{b}}-N_{\mathrm...
Read More →Name the following:
Question: Name the following: (a)A chordate animal having flame cells as excretory structures (b) Cortical portions projecting between the medullary pyramids in the human kidney (c) A loop of capillary running parallel to the Henles loop. Solution: (a)Amphioxus is an example of a chordate that has flame cells as excretory structures. Flame cell is a type of excretory and osmoregulatory system. (b)The cortical portions projecting between the medullary pyramids in the human kidney are the columns ...
Read More →What is the significance of juxtaglomerular apparatus (JGA) in kidney function?
Question: What is the significance of juxtaglomerular apparatus (JGA) in kidney function? Solution: Juxtaglomerular apparatus (JGA) is a complex structure made up of a few cells of glomerulus, distal tubule, and afferent and efferent arterioles. It is located in a specialised region of a nephron, wherein the afferent arteriole and the distal convoluted tubule (DLT) come in direct contact with each other. The juxtaglomerular apparatus contains specialised cells of the afferent arteriole known as ...
Read More →What is the significance of juxtaglomerular apparatus (JGA) in kidney function?
Question: What is the significance of juxtaglomerular apparatus (JGA) in kidney function? Solution: Juxtaglomerular apparatus (JGA) is a complex structure made up of a few cells of glomerulus, distal tubule, and afferent and efferent arterioles. It is located in a specialised region of a nephron, wherein the afferent arteriole and the distal convoluted tubule (DLT) come in direct contact with each other. The juxtaglomerular apparatus contains specialised cells of the afferent arteriole known as ...
Read More →Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why?
Question: Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why? Solution: Terrestrial animals are either ureotelic or uricotelic, and not ammonotelic. This is because of the following two main reasons: (a) Ammonia is highly toxic in nature. Therefore, it needs to be converted into a less toxic form such as urea or uric acid. (b) Terrestrial animals need to conserve water. Since ammonia is soluble in water, it cannot be eliminated continuously. Hence, it is conve...
Read More →What is meant by the term osmoregulation?
Question: What is meant by the term osmoregulation? Solution: Osmoregulation is a homeostatic mechanism that regulates the optimum temperature of water and salts in the tissues and body fluids. It maintains the internal environment of the body by water and ionic concentration....
Read More →Match the items of column I with those of column II:
Question: Match the items of columnIwith those of columnII: Solution:...
Read More →Explain micturition.
Question: Explain micturition. Solution: Micturition is the process by which the urine from the urinary bladder is excreted. As the urine accumulates, the muscular walls of the bladder expand. The walls stimulate the sensory nerves in the bladder, setting up a reflex action. This reflex stimulates the urge to pass out urine. To discharge urine, the urethral sphincter relaxes and the smooth muscles of the bladder contract. This forces the urine out from the bladder. An adult human excretes about ...
Read More →Define hydrogen bond. Is it weaker or stronger than the van der Waals forces?
Question: Define hydrogen bond. Is it weaker or stronger than the van der Waals forces? Solution: A hydrogen bond is defined as an attractive force acting between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule (may be of the same kind). Due to a difference between electronegativities, the bond pair between hydrogen and the electronegative atom gets drifted far away from the hydrogen atom. As a result, a hydrogen atom becomes e...
Read More →Describe the role of liver, lungs and skin in excretion.
Question: Describe the role of liver, lungs and skin in excretion. Solution: Liver, lungs, and skin also play an important role in the process of excretion. Role of the liver: Liver is the largest gland in vertebrates. It helps in the excretion of cholesterol, steroid hormones, vitamins, drugs, and other waste materials through bile. Urea is formed in the liver by the ornithine cycle. Ammonia a toxic substance is quickly changed into urea in the liver and thence eliminated from the body. Liver a...
Read More →Give a brief account of the counter current mechanism.
Question: Give a brief account of the counter current mechanism. Solution: The counter current mechanism operating inside the kidney is the main adaptation for the conservation of water. There are two counter current mechanisms inside the kidneys. They are Henles loop and vasa rectae. Henles loop is a U-shaped part of the nephron. Blood flows in the two limbs of the tube in opposite directions and this gives rise to counter currents. The Vasa recta is an efferent arteriole, which forms a capilla...
Read More →Describe the hybridisation in case of PCl5
Question: Describe the hybridisation in case of PCl5. Why are the axial bonds longer as compared to equatorial bonds? Solution: The ground state and excited state outer electronic configurations of phosphorus (Z = 15) are: Phosphorus atom issp3dhybridized in the excited state. These orbitals are filled by the electron pairs donated by five Cl atoms as: PCl5 The fivesp3dhybrid orbitals are directed towards the five corners of the trigonal bipyramidals. Hence, the geometry of PCl5can be represente...
Read More →Indicate whether the following statements are true or false:
Question: Indicate whether the following statements are true or false: (a)Micturition is carried out by a reflex. (b) ADH helps in water elimination, making the urine hypotonic. (c) Protein-free fluid is filtered from blood plasma into the Bowmans capsule. (d) Henles loop plays an important role in concentrating the urine. (e) Glucose is actively reabsorbed in the proximal convoluted tubule. Solution: (a)True (b)False (c)True (d)True (e)True...
Read More →Explain the autoregulatory mechanism of GFR.
Question: Explain the autoregulatory mechanism of GFR. Solution: The mechanism by which the kidney regulates the glomerular filtration rate is autoregulative. It is carried out by the juxtaglomerular apparatus. Juxtaglomerular apparatus is a microscopic structure located between the vascular pole of the renal corpuscle and the returning distal convoluted tubule of the same nephron. It plays a role in regulating the renal blood flow and glomerular filtration rate. When there is a fall in the glom...
Read More →Define Glomerular Filtration Rate (GFR)
Question: Define Glomerular Filtration Rate (GFR) Solution: Glomerular filtration rate is the amount of glomerular filtrate formed in all the nephrons of both the kidneys per minute. In a healthy individual, it is about 125 mL/minute. Glomerular filtrate contains glucose, amino acids, sodium, potassium, urea, uric acid, ketone bodies, and large amounts of water....
Read More →Write the significance of a plus and a minus sign shown in representing the orbitals.
Question: Write the significance of a plus and a minus sign shown in representing the orbitals. Solution: Molecular orbitals are represented by wave functions. A plus sign in an orbital indicates a positive wave function while a minus sign in an orbital represents a negative wave function....
Read More →Compare the relative stability of the following species and indicate their magnetic properties;
Question: Compare the relative stability of the following species and indicate theirmagnetic properties; $\mathrm{O}_{2}, \mathrm{O}_{2}^{+}, \mathrm{O}_{2}^{-}$(superoxide), $\mathrm{O}_{2}^{2-}$ (peroxide) Solution: There are 16 electrons in a molecule of dioxygen, 8 from each oxygen atom. The electronic configuration of oxygen molecule can be written as: Since the 1sorbital of each oxygen atom is not involved in boding, the number of bonding electrons = 8 =Nband the number of anti-bonding orb...
Read More →Define Glomerular Filtration Rate (GFR)
Question: Define Glomerular Filtration Rate (GFR) Solution: Glomerular filtration rate is the amount of glomerular filtrate formed in all the nephrons of both the kidneys per minute. In a healthy individual, it is about 125 mL/minute. Glomerular filtrate contains glucose, amino acids, sodium, potassium, urea, uric acid, ketone bodies, and large amounts of water....
Read More →Draw a standard ECG and explain the different segments in it.
Question: Draw a standard ECG and explain the different segments in it. Solution: Electrocardiogram isa graphical representation of the cardiac cycle produced by an electrograph. The diagrammatic representation of a standard ECG is shown below. A typical human electrocardiogram has five waves P, Q, R, S, and T. The P, R, and T-waves are above the base line and are known as positive waves. The Q and S-waves are below the base line and are known as negative waves. The P-wave is of atrial origin, w...
Read More →Explain heart sounds.
Question: Explain heart sounds. Solution: Heart sounds are noisesgenerated by the closing and opening of the heart valves. In a healthy individual, there are two normal heart sounds calledlubanddub.Lubis the first heart sound. It is associated with the closure of the tricuspid and bicuspid valves at the beginning of systole. The second heart sounddubis associated with the closure of the semilunar valves at the beginning of diastole. These sounds provide important information about the condition ...
Read More →Define a cardiac cycle and the cardiac output.
Question: Define a cardiac cycle and the cardiac output. Solution: Cardiac cycle is defined as the complete cycle of events in the heart from the beginning of oneheart beat to the beginning of the next. It comprises three stages atrial systole, ventricular systole, and complete cardiac diastole. Cardiac output is defined as the amount of blood pumped out bythe ventricles in a minute....
Read More →What is the significance of atrio-ventricular node and atrio-ventricular bundle in the functioning of heart?
Question: What is the significance of atrio-ventricular node and atrio-ventricular bundle in the functioning of heart? Solution: The atrioventricular (AV) node is present in the right atrium, near the base of the inter-auricular septum that separates the right auricle from the ventricle. It gives rise to the bundle of His that conducts the cardiac impulses from the auricles to the ventricles. As the bundle of His passes the ventricle along the inter-ventricular septum, it divides into two branch...
Read More →Sino-atrial node is called the pacemaker of our heart. Why?
Question: Sino-atrial node is called the pacemaker of our heart. Why? Solution: The sino-atrial (SA) node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. The cardiac impulse originating from the SA node triggers a sequence of electrical events in the heart, thereby controlling the sequence of muscle contraction that pumps blood out of the heart. Since the SA node initiates and maintains the rhythmicity of the heart, it is known as the natural pacema...
Read More →Use molecular orbital theory to explain why the Be2 molecule does not exist.
Question: Use molecular orbital theory to explain why the Be2molecule does not exist. Solution: The electronic configuration of Beryllium is $1 s^{2} 2 s^{2}$. The molecular orbital electronic configuration for Be2molecule can be written as: Hence, the bond order for $\mathrm{Be}_{2}$ is $\frac{1}{2}\left(N_{b}-N_{a}\right)$. Where, Nb= Number of electrons in bonding orbitals Na= Number of electrons in anti-bonding orbitals $\therefore$ Bond order of $\mathrm{Be}_{2}=\frac{1}{2}(4-4)=0$ A negati...
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