The structural proteins collagen and elastin are present in white collagen fibres and yellow elastic fibres respectively, which are connective tissue fibres. Neuroglial cells are specialised cells found in the brain and spinal cord supporting the neurons and their firbres. The muscles of biceps are voluntary and striated.

Carbon dioxide is transported in the blood from the tissue to the lungs in three ways: (i) dissolved in solution; (ii) buffered with bicarbonate and (iii) bound to proteins, particularly haemoglobin. Majority of the carbon dioxide in the blood is carried by means of a bicarbonate buffer system. So, the correct option is 'hydrogen carbonate'.

Blood performs many important functions within the body. These functions include the supply of oxygen to tissues (bound to hemoglobin, which is carried in red cells), the supply of nutrients such as glucose, amino acids, and fatty acids (dissolved in the blood or bound to plasma proteins e.g., blood lipids), transport of gases etc.

Blood maintains water balance in the body by bringing constant exchange of water between circulating blood and tissue fluid. Regulating pH and transportation of excretory material are other functions performed by blood.

About 2/3 of the average human body is water, mostly within the cells. The amount of water in the human body ranges from 50-75%. The average adult human body is 50-65% water, averaging around 57-60%. The percentage of water in infants is much higher, typically around 75-78% water, dropping to 65% by one year of age. Thus, option B is correct.

Blood Is an important fluid connective tissue which circulates throughout the body. It performs some very important functions like transport of oxygen from lungs to the cells, transport of food material, Transport of excretory material, Transport of other substances and Transport of cell wreckage. etc. 

Blood allows heat transfer of heat from deeper tissues to the surface of the body where it can be lost. Hormones are carried by blood from endocrine glands to place of use, Also glucose and other nutrients are transported from alimentary canal through blood to different cells in the body.

The main function of the cardiovascular system is, therefore, to maintain blood flow to all parts of the body, to allow it to survive. Veins deliver used blood from the body back to the heart. In the lungs, the blood picks up oxygen that we breathe in and gets rid of carbon dioxide, which we breathe out.

Blood transports the digested food from the alimentary canal to the tissue. Blood also distribute hormones secreted by the endocrine glands. The blood helps in keeping the temperature of the body uniform by distributing heat. Thus option C is the correct answer. 

Blood performs the important task of protecting the body from the infections and disease-causing bacteria. The white blood cells found in blood are responsible for safeguarding the different organs of the body by producing antibodies and proteins which are capable of fighting off and killing the germs and viruses that cause serious damage to the body cells. The platelets present in blood handle the task of limiting blood loss in the wake of an injury by helping the blood to clot quickly. 

Lymph has no RBCs but about 99% are lymphocytes usually of the small type, the remaining 1% is made up of leucocytes.

(b) Blood is colourless in insects. insects have tracheal respiration. It is carried on by an extensive system of inter-communicating tubes called trachea.

Urea is synthesized in the liver from ammonia and carbon dioxide. The urea synthesis is a five-step cyclic process, with five distinctive enzymes. This urea is released into the bloodstream from the liver cells. Through blood, urea is transported to kidneys where the blood is filtered and urea is passed out of the body in the urine. Hence the waste matters (urea) are transported by the blood.

Blood clotting factors are needed for blood to clot (coagulation). Prothrombin is one of the clotting factors made by the liver. During normal blood coagulation, a coagulation cascade activates prothrombin by converting it into the serine protease thrombin. Thrombin then converts the soluble fibrinogen into insoluble fibrin strands. These strands are then cross-linked by factor XIII to form a blood clot. As soon as blood from a wound is exposed to the air, the platelets disintegrate and react with fibrinogen to create fibrin: a mass of tiny threads. This triggers a whole series of reactions that rely on adequate levels of calcium and vitamin K to work. Calcium is also an important part of the blood clotting process. Elastin is a highly elastic protein in connective tissue and allows many tissues in the body to resume their shape after stretching or contracting. It is not present in the blood.

A person cannot expel all the air from the lungs even after forceful expiration. The volume of air which remains in the lungs after the most forceful expiration is called residual volume, it is about 1100 mL to 1200 mL A rise in $PCO _{2}$ decreases the $O _{2}$ affinity of haemoglobin.

The ability of the body to regulate its internal physiological processes in order to maintain the equilibrium is called the dynamic equilibrium. It is performed to keep the physiological responses from fluctuating with the external conditions of the environment. Different organ system work under the regulation of hypothalamus and medulla maintain the dynamic homeostasis. 

The amount of oxygen in the blood is 20.8ml or 20.8 volume. Oxygen is carried in the blood in two forms: dissolved and bound to hemoglobin.