Answer the following question given this paragraph: A: During a chemical reaction, chemical changes take place. Some chemical bonds break and new chemical bonds form. Q: During a what type of reaction do chemical changes take place? Choices: - toxic - biological - nuclear - chemical A:
chemical
Answer the following question given this paragraph: Like other catalysts, enzymes are not reactants in the reactions they control. They help the reactants interact but are not used up in the reactions. Instead, they may be used over and over again. Unlike other catalysts, enzymes are usually highly specific for particular chemical reactions. They generally catalyze only one or a few types of reactions. Q: Enzymes are a type of what, and as such, they are not reactants in the reactions they control? Choices: - hormone - metabolite - neurotransmitter - catalyst A:
catalyst
Q: Answer the following question given this paragraph: Q: What does rearrangements of chromosomes contribute to the emergence of? Choices: - clones - extinction - fewer species - new species A:
A: new species
Question: Answer the following question given this paragraph: The energy of electromagnetic waves depends on their frequency. Low-frequency waves have little energy and are normally harmless. High-frequency waves have a lot of energy and are potentially very harmful. Q: Which form of electromagnetic waves have more energy: low frequency wave or high frequency waves? Choices: - neither - low frequency waves - the same - high frequency waves A:
Answer: high frequency waves
*Question*
Answer the following question given this paragraph: On the ventral side of the embryonic disc, opposite the amnion, cells in the lower layer of the embryonic disk (the hypoblast) extend into the blastocyst cavity and form a yolk sac. The yolk sac supplies some nutrients absorbed from the trophoblast and also provides primitive blood circulation to the developing embryo for the second and third week of development. When the placenta takes over nourishing the embryo at approximately week 4, the yolk sac has been greatly reduced in size and its main function is to serve as the source of blood cells and germ cells (cells that will give rise to gametes). During week 3, a finger-like outpocketing of the yolk sac develops into the allantois, a primitive excretory duct of the embryo that will become part of the urinary bladder. Together, the stalks of the yolk sac and allantois establish the outer structure of the umbilical cord. The last of the extra-embryonic membranes is the chorion, which is the one membrane that surrounds all others. The development of the chorion will be discussed in more detail shortly, as it relates to the growth and development of the placenta. Q: On the ventral side of the embryonic disc, opposite the amnion, cells in the lower layer of the embryonic disk (the hypoblast) extend into the blastocyst cavity and form this? Choices: - embryo sac - neural sac - algae sac - yolk sac A:
**Answer**
yolk sac
Q: Answer the following question given this paragraph: Some birds have lost the ability to fly during the course of their evolution. Several flightless birds are shown in Figure below . They include the ostrich, kiwi, rhea, cassowary, and moa. All of these birds have long legs and are adapted for running. The penguins shown in the figure are also flightless birds, but they have a very different body shape. That's because they are adapted for swimming rather than running. Q: The ostrich, kiwi, rhea, cassowary, and moa are examples of what kind of birds? Choices: - predators - raptors - prehistoric - flightless A:
A: flightless