Biology (Part-2) (CDS-Solved Paper)

Cobalt is associated with the molecular structure of vitamin-B12. That is why it is also known as cyanocobalamin. Growth hormones do not contain cobalt, but they are peptide in nature. Haemoglobin contains iron as a haeme pigment. Intestinal enzymes are proteins in nature.

The absorption of water takes place only in the large intestine of alimentary canal and renal tubule of kidney. Hepatic cells of liver are phagocytic in nature and pancreatic duct carries pancreatic juice.

The evolution of human genus took place during the Pleistocene, the time period that spanned from 1.8 to 11700 million years ago. Mammals had first appeared in the late Triassic 240 million years ago at about the same time as dinosaurs.

During the period of Paleocene, lasted from about 66-56 million years ago, mammals occupied a larger part of the vacant ecological niches. Permian is a geological period extends from 299 to 241 million years ago, in which frogs appeared first time.

Cambrian period is the first geological time period of the Paleozoic era, lasted from 541 to 485.4 million years ago during which period invertebrate evolved and developed.

Measles is caused by the virus (paramyxovirus), which is highly contagious. It is spread through dropped transmission from the nose, throat and mouth of someone, who is infected with the virus.

Bacteria cause many diseases as typhoid, cholera, tuberculosis by many species. Protozoans cause, sleeping-sickness, kala-azar, amoebiasis and diarrhea. Worm leads to ascariasis, elephantiasis, guinea worm diseases.

All white blood cells including lymphocytes and neutrophils are originate from bone marrow. Lymph nodes are sites where WBCs remain accumulated and they fight with bacteria, virus and other foreign agents. In the spleen RBCs are destroyed and in kidney tubule selective reabsorption occurs, finally urine is formed.

The DOTS strategy ensures that infectious TB patients are diagnosed and treated effectively till cure, by ensuring availability of the full course of drugs and a system for monitoring patient compliance to the treatment. Other three options are not correct in relation to DOTS.

In human digestive system, the process of digestion starts in mouth or buccal cavity where salivary amylase (enzyme present in saliva) breakdown starch into dextrin and maltose. In oesophagus no digestion of food occurs.

In stomach gastric juice is secreted releasing propepsinogen and prorennin converting into pepsin and rennin which digest protein, in the presence of hydrochloric acid.

In the duodenum bile, pancreatic juice and intestinal juice is secreted, which release different enzymes for digestion of incompletely digested protein, carbohydrate and fat.

Manganese is one of the micronutrients that is derived from soil and is needed in small amounts. It functions with enzyme systems involved in breakdown of carbohydrates and nitrogen metabolism.

Calcium (Ca) element is an important component of middle lamella in cell wall. It is also required for cell division, cell enlargement and translocation of carbohydrate.

Magnesium (Mg) is a component of chlorophyll. It is important in synthesis of fat and respiration. It binds two subunits of ribosomes. Potassium (K) is important for K⁺ / Na⁺ pump essential for maintaining normal gradient during active transport.

It also plays important role in opening and closing of stomata. It is helpful in maintaining turgidity of cell.

Tuberculosis is the disease caused by bacterium Mycobacterium tuberculosis. It spreads through the air through coughing, sneezing by infected person, etc.
Dengue spread by female Aedes aegypti mosquito transmitting arbovirus. HIV spread through injection, blood transfusion and sexual contacts.

The water cycle or hydrological cycle is a continuous cycle where water evaporates, travels into the air and becomes part of a cloud, falls down to the earth as precipitation and then evaporates again.

This repeats again and again in a never-ending cycle. Water keeps moving and changing from a solid to a liquid to a gas, over and over again. Precipitation creates runoff that travels over the ground surface and helps to fill lakes and rivers.

It also percolates or moves downward through openings in the soil to replenish aquifers under the ground.