Which are the special proteins in muscles that contract and relax to cause movement?

 

Urea is produced in the liver and is a metabolite (breakdown product) of amino acids. Ammonium ions are formed in the breakdown of amino acids. Some are used in the biosynthesis of nitrogen compounds. Excess ammonium ions are converted to urea.

During respiration, about 97% of oxygen is transported by Red Blood Cells in blood and the remaining 3% gets dissolved in the plasma.Around 20-25% of carbon dioxide is carried by haemoglobin as carbamino-haemoglobin.

Oxygen enters the blood from the lungs and carbon dioxide is expelled out of the blood into the lungs. The blood serves to transport both gases. Oxygen is carried to the cells. Carbon dioxide is carried away from the cells.

Asterias has bilateral symmetry only at larval stagebut fivefold symmetry (pentamerism, a special type of radial symmetry) as adults.

Nereis do not possess any symmetry elements in their body organisation.

Saprophytic fungi feed on dead plant and animal remains. Many are extremely beneficial, breaking down this organic material into humus, minerals and nutrients that can be utilised by plants. Agaricus is one among them.

In vascular plants, the lateral meristem is one of two meristems in which growth occurs in order to increase stem girth. A meristem is the region of plant tissue found on the tips of roots and shoots. It is where cell division occurs to produce new growth.

Smooth Endoplasmic Reticulumdoes not contain ribosomes on its surface for which it is regarded as smooth. So, proteins cannotbe synthesised by SER provided protein synthesis is the primary task of ribosomes.