Organic compounds
11. American scientists Stanley Miller and Harold Urey used an apparatus similar to
the one in the diagram to simulate how life could have formed on Earth. The apparatus
contained hydrogen gas, water vapor, ammonia, and methane. These gases were subjected
to a spark, to simulate lightning. They found that organic molecules could form from the
inorganic gases. Their theory of how life began, however, did not hold up under further
testing. What crucial fact did they not have when they conducted their experiment?
A There was no lightning in Earth's early atmosphere.
B Ammonia and methane were not in the early atmosphere.
C The chemicals used in the experiment were contaminated,
D Organic molecules already existed before the atmosphere formed.
12

How many cells are our body made of ? ♡

For a to be healthy, it has to have lots of different kinds of plants and animals. all of the different types of plants and animals in an ecosystem. name four types of ecosystems from those listed in the video. b) c) d) most living things live here. all living things depend on how an ecosystem like a game of sticks? why should we build new buildings on existing land? name four extinct species from those listed in the video. b) c) d) the best way to wipe out a species is to the largest ecosystem in the world is this percent of the world is covered by water. how many of all species in the world live in the ocean? list five things you can do to increase biodiversity. b) c) d) e) how many species are we losing per hour?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.