Question

A. Origin of Life- Scientists Hypotheses Disproving Spontaneous Generation (Word Bank: air, sealed, open, bacteria, gauze, spontaneously) Through the early 1800s, people believed organisms could ________________ develop, an idea known as spontaneous generation. In 1668, many believed maggots were spontaneous generated from rotting meat. Francis Redi’s experiment disproved this by experimenting with meat in open_jars, tightly snealed_jars and jars covered with cloth netting. It was also believed that bacteria spontaneously generated in broth. Lazzaro Spallanzani removed the _________ from a flask, __________ the broth and sealed the flask. No bacteria generated without exposure to the air. Some people still supported spontaneous generation but thought that air was a ________ force, necessary for it to occur. In 1859, Louis Pasteur completely disproved spontaneous generation by using a special flask that allow ______________ in but captured bacteria before it could get to the broth. No _________________ grew in the flask after boiling = no spontaneous generation. 2. First Life (Word Bank: eukaryotes, prokaryotic, variety, self-replicating, organic, photosynthesis, oxygen) Earth’s atmosphere had to be very hot and with little oxygen for the first ________________ molecules to first form. Organic molecules clumped together for form ______________________ structures that later evolved into cells. __________________________ cells were the first to evolve. When cells gained the ability to do ___________________________, they used up carbon dioxide and put more __________________ into the atmosphere.

Answer 1

Spontaneous generation, the idea that life could arise from non-life, was refuted by experiments from Francesco Redi, Lazzaro Spallanzani, and conclusively by Louis Pasteur, leading to the scientific consensus that life can only come from existing life. The first life on Earth likely formed from organic molecules in a hot, low-oxygen environment, eventually evolving into the first prokaryotic cells capable of photosynthesis.

Step-by-step explanation:

Through the early 1800s, people believed organisms could spontaneously develop, an idea known as spontaneous generation. In 1668, Francesco Redi's experiment using meat in open jars, tightly sealed jars, and jars covered with gauze demonstrated that maggots did not spontaneously generate, but rather were the offspring of flies.

Lazzaro Spallanzani further refuted spontaneous generation by boiling broth, removing the air from a flask, and then sealing it, indicating no bacteria grew without exposure to the air. Later, Louis Pasteur's famous swan-neck flask experiment provided conclusive evidence, showing that when air was allowed in but microbes were trapped by the neck's design, no bacteria grew after boiling, thereby disproving spontaneous generation.

Regarding the first life, Earth's atmosphere was likely very hot and with little oxygen for the first organic molecules to form. These molecules assembled into self-replicating structures that evolved into cells, with prokaryotic cells being the earliest. With the development of photosynthesis, cells consumed carbon dioxide and released oxygen into the atmosphere.