Biology Quiz 2

The age of a tree can be determined by counting the rings from the pith of the trunk to the bark. Tree rings are the most accurate indicator of a tree's age. Finding the age of a tree by counting annual growth rings is called dendrochronology.

Smallpox has been eradicated from the world. It was a serious infectious disease caused by the variola virus. World Health Organization (WHO) declared smallpox eradicated in 1980.

Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen (anaerobically), primarily consisting of methane and carbon dioxide. Biogas can be produced from raw materials such as agricultural waste, municipal waste, plant material, sewage, green waste or food waste. Although, cattle dung has been recognised as the chief raw material for biogas plants.

Besides carbohydrates, a major source of energy in our food is constituted by Fats. Fat has more than twice as many calories per gram as carbohydrates and proteins. A gram of fat has about 9 calories, while a gram of carbohydrate or protein has about 4 calories.

Charles Darwin (1809-1882) and Alfred Russel Wallace (1823-1913) were contemporary naturalists who proposed a similar theory of organic evolution. Wallace greatly admired On the Origin of Species. In turn, Darwin regarded Wallace as the one man who truly understood the idea of evolution by natural selection.

The kidney is the organ that excretes water, fat and various catabolic wastes. The kidneys remove waste products called urea from the blood through tiny filtering units called nephrons. There are about one million nephrons in each kidney.

The human skeleton of an adult consists of around 206 bones. There are typically around 270 bones in human infants, which fuse to become 206 to 213 bones in the human adult.

The medical term used for sleeplessness is Insomnia. It is a common sleep disorder that can make it hard to fall asleep, hard to stay asleep or cause to wake up too early and not be able to get back to sleep.

BCG (Bacille Calmette-Guerin) is a vaccine for tuberculosis (also known as TB) disease. TB is a serious infection that affects the lungs and sometimes other parts of the body, such as the brain (meningitis), bones, joints and kidneys.

Acetabularia is the biggest single-celled organism. It is genus of single-celled green algae (family Polyphysaceae) found in subtropical seas. The algae are among the largest single-celled organisms and also feature an unusually large nucleus.