Tag: zoology

Questions Related to zoology

Which is true about the difference between cortical and juxtamedullary nephrons? 

zoology excretory system of human structure of nephron excretory system nephron

  1. Most nephrons are juxtamedullary.

  2. The efferent arteriole's of cortical nephrons give rise to most of the vasa recta.

  3. The aaferent arterioles of the juxtamedullary nephrons give rise to most of the vasa recta.

  4. Juxtamedullary nephrons generate a hyperosmotic medullary interstitium.

Show answer
Correct Option: D
Explanation:

Cortical nephrons either have short or absent loops of Henle. Only juxtamedullary nephrons have long loops of Henle, which plunge into the renal medulla and create a hypersomotic interstitium via counter current multiplication. 

So the correct option is D.

Of the total nephrons,the juxtamedullary nephrons constitute ........... %.

zoology excretory system of human structure of nephron excretory system nephron

  1. 15

  2. 45

  3. 65

  4. 85

Show answer
Correct Option: A
Explanation:

Nephron is the structural and functional unit of the kidney. Juxtamedullary nephrons are found only in birds and mammals. These are juxtamedullary on the basis of their Loop of Henle which is deep in the renal medulla and the renal corpuscle is in the medulla and only around 15-20% of the nephrons are juxtamedullary.

Malpighian tubules empty the excretory wastes  into the 

zoology excretory system of human structure of nephron excretory system nephron

  1. Ureter

  2. Gut

  3. Coelom

  4. Urinary bladder

Show answer
Correct Option: B
Explanation:

The excretory organs of insects are malpighian tubules. They collect water and uric acid from surrounding haemolymph (blood) and empty it into the gut.

Difference between glomerular filtrate and plasma is of

zoology excretory system of human structure of nephron excretory system nephron

  1. Proteins

  2. Potassium

  3. First is white whereas latter is yellow.

  4. First is yellow whereas latter is white.

Show answer
Correct Option: A
Explanation:

Blood plasma contains red and white blood cells, blood proteins, glucose, water, nitrogenous wastes, salt. Glomerular filtrate contains glucose, salt, water, nitrogenous wastes. Blood cells and plasma proteins are not filtered through the glomerular capillaries because they are relatively larger in size.

The renal threshold value of glucose is normally

zoology excretory system of human structure of nephron excretory system nephron

  1. 80 mg/100 ml

  2. 160-180 mg/100 ml

  3. 100-120 mg/100 ml

  4. 80-110 mg/100 ml

Show answer
Correct Option: B
Explanation:

The proximal tubule can only reabsorb a limited amount of glucose. When the blood glucose level exceeds about 160-180 mg/dl or 160-180 mg/100ml, the proximal tubule becomes overwhelmed and begins to excrete glucose in the urine. this point is called the renal threshold of glucose (RTG).
So, the correct answer is option B.

Function of glomerulus in mammalian kidney is

zoology excretory system of human structure of nephron excretory system nephron

  1. Reabsorption of salts

  2. Urine formation through blood filtration

  3. Urine collection

  4. All of the above

Show answer
Correct Option: B
Explanation:

A glomerulus is a network of capillaries responsible for the filtration of blood in the nephron the functional unit of the kidney. The glomerulus is surrounded by a single layer of epithelium called the Bowman's capsule constitute a renal corpuscle, the basic filtration unit of the kidney. 

So, the correct answer is option B.

The size of the filtration slits present in the glomerulus is

zoology excretory system of human structure of nephron excretory system nephron

  1. 10 cm.

  2. 15 nm.

  3. 25 nm.

  4. 10 nm.

Show answer
Correct Option: C
Explanation:

The filtration slits present in the endothelium of the glomerulus are of the size 25 nm that can allow the plasma and solutes to diffuse in but not the blood cells. So the filtrate in the Bowman's Capsule that has diffused in from the glomerulus is colourless due to an absence of RBCs.

Hence, the correct answer is '25 nm'.

The important muscle proteins that helps in the movement are 

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Actin and myosin

  2. Troponin

  3. Tropomyosin

  4. All of the above

Show answer
Correct Option: D
Explanation:
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). Contraction of a muscle fiber takes place by the sliding of the thin filaments over the thick filaments.
  • Myosin (thick) filament is also a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament. 
  • Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length. A complex protein troponin is distributed at regular intervals on the tropomyosin.
  • Hence, the important muscles proteins that help in the movement are actin and myosin, troponin and tropomyosin.
  • So, the correct answer is 'All of the above'.

In resting stage, binding sites for myosin on actin filaments are masked by

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Troponin

  2. Light meromyosin

  3. Heavy meromyosin

  4. Calcium ions

Show answer
Correct Option: A
Explanation:
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). Contraction of a muscle fiber takes place by the sliding of the thin filaments over the thick filaments.
  • Myosin (thick) filament is also a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament. 
  • Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length
  •  In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments.
  • So, the correct answer is 'Troponin'.

Thick filaments in muscles are polymerised proteins of

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Meromyosin

  2. Actin

  3. Troponin

  4. Tropomyosin

  5. Keratin

Show answer
Correct Option: A
Explanation:
  • Myofibrils are composed of two types of filaments i.e thin filament (actin) and thick filament (myosin).
  • Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively
  • Each myosin (thick) filament is a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament (Myosin).
  • Hence thick filaments in muscles are polymerized proteins of meromyosin.
  • So, the correct answer is 'Meromyosin'.