Answer the following question given this paragraph: The earliest placental mammals may have evolved about 110 million years ago. The ancestor of placental mammals may be the extinct genus Eomaia . Fossils of Eomaia have been found in what is now China. It was only about 10 centimeters (4 inches) long. It was a tree climber and probably ate insects and worms. Eomaia had several traits of placental mammals. Figure below shows how Eomaia may have looked. Q: What may be the ancestor of placental mammals? A:

OPTIONS:
- fungi
- spirogyra
- amphibians
- eomaia

Answer: eomaia

Answer the following question given this paragraph: Lakes, ponds, streams, springs, and wetlands are fresh water bodies. The organisms that live in them are part of freshwater ecosystems. These ecosystems vary by temperature, pressure (in lakes), and the amount of light that penetrates. The type of plants that grow in these ecosystems varies. Q: Lakes, ponds, streams, springs, and wetlands are? A:

OPTIONS:
- salt water bodies
- man-made structures
- land formations
- fresh water bodies

Answer: fresh water bodies

Answer the following question given this paragraph: Nuclear changes occur with a simultaneous release of energy. Where does this energy come from? If we could precisely measure the masses of the reactants and the products of a nuclear reaction, we would notice that the amount of mass drops slightly in the conversion from reactants to products. Consider the following nuclear reaction, in which the molar mass of each species is indicated to four decimal places:. Q: Nuclear changes occur with a simultaneous release of what, and a slight drop in mass? A:

OPTIONS:
- oil
- mineral
- hydrogen
- energy

Answer: energy

Answer the following question given this paragraph: Mutagenesis may occur spontaneously or be induced. A spontaneous mutation can just happen. These mutations are not caused by an environmental factor, but occur during normal cellular processes. A spontaneous mutation may be due to a mistake during DNA replication or transcription. Mutations may also occur during mitosis and meiosis. A mutation caused by an environmental factor, or mutagen , is known as an induced mutation . Typical mutagens include chemicals, like those inhaled while smoking, and radiation, such as X-rays, ultraviolet light, and nuclear radiation. Table below lists some spontaneous mutations that are common. Q: Induced mutations are caused by environmental factors. what term is used to describe a mutation that has no environmental cause? A:

OPTIONS:
- cancerous mutation
- evident mutation
- numerous mutation
- spontaneous mutation

Answer:
spontaneous mutation