The Paris Climate Conference, also known as COP21, was held in 2015 in Paris, France. Countries from around the world adopted the Paris Agreement to limit global warming and reduce greenhouse gas emissions through international cooperation.

The ureter is the muscular tube that carries urine from each kidney to the urinary bladder. Humans have two ureters, and they transport urine through rhythmic muscular contractions known as peristalsis.

A camera lens forms a real, inverted, and usually diminished image on the film or image sensor. The lens focuses incoming light rays onto a surface, allowing the captured image to be recorded accurately for photography or digital imaging.

Producers such as green plants absorb usable nitrogen compounds from the soil, including ammonia (NH₃) and nitrates. Nitrogen is essential for making proteins, chlorophyll, and nucleic acids necessary for plant growth and ecosystem balance.

Thomas Harriot was an English astronomer who made some of the earliest recorded telescopic observations of sunspots in 1610. His work predates many later astronomers and helped establish systematic solar observation in astronomy.