EducatorSharmin

Average Speed The distance travelled in unit time by an object is called its speed. Average speed is defined as distance travelled per unit time.  For example, if you cycle 2.4 km in 10 minutes, then your average speed would be                        2400 m/ 10 x 60 s                           =  24/6 m/s                          = 4 m/s 1. The distance between Mumbai and Pune is 180 km. A bus takes about 4 hours to cover the distance. What is the average speed of the bus? Solution: Average speed  = Distance / time                           = 180/4 km/h                           = 45 km/h The most commonly used units for speed are km/h and m/s. Speed...

Adaptations of Rice for Wet Environments:   Although rice can grow in dry conditions, it is often grown in 'paddies'- fields where the ground is intentionally flooded. Rice can tolerate growing in water, whereas most of the weeds that might compete with it are not able to do so.   Most plants cannot grow in deep water because their roots do not get enough oxygen. Oxygen is required for aerobic respiration, which provides ATP as an energy source for active transport and other energy-consuming processes such as cell division. Nor, if the leaves are submerged, can photosynthesis take place, because there is not enough CO2 available. This happens because gases diffuse much more slowly in water than they do in the air. Moreover, the concentration of dissolved O2 and dissolved CO2 in water are much less than they are in the air.  Some varieties of rice respond to flooding by growing taller. this allows O2 and CO2 t obe exchanges through the stomata on the leaves. Ethanol is tox...

Cystic Fibrosis: Cystic fibrosis is a genetic disorder in which abnormally thick mucus is produced in the lungs and other parts of the body. A person with cystic fibrosis is very prone to bacterial infections in the lungs because it is difficult for the mucus to be removed, allowing bacteria to bread in it. People with cystic fibrosis need daily therapy to help them to cough up this mucus. The thick mucus adversely affects many other parts of the body. The pancreatic duct may become blocked, and people with cystic fibrosis often take pancreatic enzymes by mouth to help with digestion. Around 90% of men with cystic fibrosis are sterile because thick secretions block ducts in the reproductive system. Cystic fibrosis is caused by a recessive allele of the gene that codes for a transporter protein called CFTR. This protein sits in the cell surface membranes of cells in the alveoli and allows chloride ions to pass out of the cells. The recessive allele codes for a faulty version of this pro...