Q: What are the two best known baryons? Read this paragraph and choose the correct option from the provided answers: Particles that are composed of three quarks are called baryons . The two best known baryons are protons and neutrons. A proton is composed of two up quarks and one down quark (uud). The charge on the proton is the result of adding the charges on these quarks . Neutrons are composed of one up quark and two down quarks (udd). The charge on the neutron is the result of adding the charges on these quarks . Choices: - flux and neurons - electrons and neutrons - shafts and neutrons - protons and neutrons A:
protons and neutrons

Q: What do scientists believe are the oldest eukaryotes? Read this paragraph and choose the correct option from the provided answers: Scientists think that protists are the oldest eukaryotes. They most likely evolved from prokaryotic cells, as explained by the endosymbiotic theory. This theory is well-supported by evidence. Choices: - prokaryotes - worms - arthropods - protists A:
protists

Q: The first few species to colonize a disturbed area are called what? Read this paragraph and choose the correct option from the provided answers: The first few species to colonize a disturbed area are called pioneer species. In primary succession, pioneer species must be organisms that can live on bare rock. They usually include bacteria and lichens (see Figure below ). Along with wind and water, the pioneer species help weather the rock and form soil. Once soil begins to form, plants can move in. The first plants are usually grasses and other small plants that can grow in thin, poor soil. As more plants grow and die, organic matter is added to the soil. This improves the soil and helps it hold water. The improved soil allows shrubs and trees to move into the area. Choices: - producer species - original species - colonization species - pioneer species A:
pioneer species