Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsShort Answer Type

81.

Name two internal characteristic features of class-Mammalia


The internal characteristic features of Class- Mammalia are:

(i) Body cavity is divided by a muscular diaphragm between thorax and abdomen.

(ii) Body is maintained at a hugh and constant temperature by means of internal regulation.


82.

What is enterohepatic circulation of bile salt? Mention its significance.


Circulation of substances such as bile salts, which are absorbed from the intestine and carried to the liver, where they are secreted into the bile and again enter the intestine, is known as enterohepatic circulation of bile salt.

It is important because 95% of the salt gets recycled and each of the bile salt molecule gets reused about 20 times.


83.

What is pro-enzyme?


A proenzyme (or zymogen) is an inactive enzyme precursor. It requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site) for it to become  an active enzyme. It is secreted by pancreas.


84.

Mention the location and function of juxtaglomerular apparatus.


The juxtaglomerular apparatus is a microscopic structure in the kidney, which regulates the function of each nephron. It is named for its proximity to the glomerulus, it is found between the vascular pole of the renal corpuscle and the returning distal convoluted tubule of the same nephron. 

It is important in regulating blood pressure, body fluid and electrolytes.


85.

What is telomere? State its function.


Telomere is the end of chromosome, which consists of tandemly repeated short sequences of DNA. Each time a cell divides some sequences of the telomere are lost, eventually (after 60-100 divisions in an average cell) the cell dies. Replication of telomeres is directed by telomerase, an enzyme consisting of RNA and protein that is inactive in normal cells of higher organisms.


86.

What is axon reflex?


Axon reflex is a neuron reflex in which an afferent impulse travels along a nerve fibre away from the cell body until it reaches a branching, where it is diverted to an end organ without entering the cell body. It does not involve a complete reflex arc and therefore it is not a true reflex.


87.

Name two sulphur containing and two basic amino acids.


There are two amino acids which contain a sulphur atom: cysteine and methionine. 

 


88.

State the advantages of composite fish culture.


In this system, both local and imported fish, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them by having different types of food habitats.

Advantages:

  1. Increases the yield of fish.
  2. Helps in maximum fish production.
  3. Availability for consumption.
  4. Can help farmers increase their financial position.
  5. Also creates employment for skilled and unskilled youths.


89.

What is riophorins?


Ribophorins are ribosome receptor proteins that aids in the binding of ribosomes to the rough endoplasmic reticulum. It is an integral protein within the rough endoplasmic reticular membrane. As it is directly related with protein translation, ribophorins are not found in smooth endoplasmic reticulum.


90.

What is cochlear microphonics?


Cochlear microphonic is the electrical potential generated in the hair cells of the organ of Corti in response to acoustic stimulation.