*Question*
Answer the following question given this paragraph: 18.2 Formation of New Species Speciation occurs along two main pathways: geographic separation (allopatric speciation) and through mechanisms that occur within a shared habitat (sympatric speciation). Both pathways isolate a population reproductively in some form. Mechanisms of reproductive isolation act as barriers between closely related species, enabling them to diverge and exist as genetically independent species. Prezygotic barriers block reproduction prior to formation of a zygote, whereas postzygotic barriers block reproduction after fertilization occurs. For a new species to develop, something must cause a breach in the reproductive barriers. Sympatric speciation can occur through errors in meiosis that form gametes with extra chromosomes (polyploidy). Autopolyploidy occurs within a single species, whereas allopolyploidy occurs between closely related species. Q: Both pathways that isolate a population reproductively in some form, allopatric and sympatric describe what, which means the creation of new species? Choices: - accumulation - extinction - bacterial - speciation A:
**Answer**
speciation

*Question*
Answer the following question given this paragraph: Types of organisms that make glucose by photosynthesis are pictured in Figure below . They include plants, plant-like protists such as algae, and some kinds of bacteria. Living things that make glucose are called autotrophs ("self feeders"). All other living things obtain glucose by eating autotrophs (or organisms that eat autotrophs). These living things are called heterotrophs ("other feeders"). Q: What are living things that obtain glucose by eating self feeders called? Choices: - producers - chimeras - viruses - heterotrophs A:
**Answer**
heterotrophs

*Question*
Answer the following question given this paragraph: The hybridization model helps explain molecules with double or triple bonds. Consider the ethene molecule (C 2 H 4 ), which contains a double covalent bond between the two carbon atoms and single bonds between the carbon atoms and the hydrogen atoms. The entire molecule is planar. Q: Which model helps explain molecules with double or triple bonds? Choices: - salinity model - reactivity model - particle model - hybridization model A:
**Answer**
hybridization model

*Question*
Answer the following question given this paragraph: Indeed, scientists discovered something astonishing. Many times in Earth's history, the magnetic poles have switched positions. North becomes south and south becomes north! When the north and south poles are aligned as they are now, geologists say it is normal polarity. When they are in the opposite position, they say that it is reversed polarity. Q: What feature of the land do contour lines show? Choices: - trails - flat surfaces - bodies of water - three-dimensional shape A:
**Answer**
three-dimensional shape