1. Excretion is the process in which all metabolic wastes are passed out of the body. Excretion in humans occurs in several processes through various organs and internal organs of the body.

2. Diffusion is the most common process of excretion in lower organisms. The human body is an extraordinary machine, where various life-processes (respiration, circulation, digestion, etc.) occur simultaneously. As a result, many of the waste products produced in our bodies are in various forms including carbon dioxide, water, and nitrogenous products such as urea, ammonia, and uric acid.

1. Ornithology is a branch of zoology that studies birds. It studies different species of birds, their size, shape, colour, behaviour, habitat, reproduction and other aspects.

2. Ornithologists use a variety of methods to collect information about birds, such as field surveys, bird watching, studying bird behavior, and studying fossils.

The tibia and fibula are the two bones found in the human leg. The tibia, also known as the shinbone, is the larger and stronger of the two bones and is located on the inner side of the leg. The fibula is the smaller bone and runs parallel to the tibia on the outer side of the leg.