Q: What theory can explain virtually all the properties of metals? Read this paragraph and choose the correct option from the provided answers: Band theory can explain virtually all the properties of metals. Metals conduct electricity, for example, because only a very small amount of energy is required to excite an electron from a filled level to an empty one, where it is free to migrate rapidly throughout the crystal in response to an applied electric field. Similarly, metals have high heat capacities (as you no doubt remember from the last time a doctor or a nurse placed a stethoscope on your skin) because the electrons in the valence band can absorb thermal energy by being excited to the low-lying empty energy levels. Finally, metals are lustrous because light of various wavelengths can be absorbed, causing the valence electrons to be excited into any of the empty energy levels above the highest occupied level. When the electrons decay back to low-lying empty levels, they emit light of different wavelengths. Because electrons can be excited from many different filled levels in a metallic solid and can then decay back to any of many empty levels, light of varying wavelengths is absorbed and reemitted, which results in the characteristic shiny appearance that we associate with metals. Choices: - property law theory - formation theory - bonding theory - band theory A:
band theory

Q: What is the name of the organelle that helps make and transport proteins and lipids? Read this paragraph and choose the correct option from the provided answers: The endoplasmic reticulum (ER) is an organelle that helps make and transport proteins and lipids. It's made of folded membranes. Bits of membrane can pinch off to form tiny sacs called vesicles. The vesicles carry proteins or lipids away from the ER. Choices: - plasma membrane - nucleus - mitochondria - endoplasmic reticulum A:
endoplasmic reticulum

Q: Q: What is required to partially overcome the attractive forces between molecules in a solid to form a liquid? Read this paragraph and choose the correct option from the provided answers: Figure 14.7 (a) Energy is required to partially overcome the attractive forces between molecules in a solid to form a liquid. That same energy must be removed for freezing to take place. (b) Molecules are separated by large distances when going from liquid to vapor, requiring significant energy to overcome molecular attraction. The same energy must be removed for condensation to take place. There is no temperature change until a phase change is complete. Choices: - fuel - hydrogen - oxygen - energy A:
A: energy

Question: Q: Materials, such as iron, that exhibit strong magnetic effects are labeled what? Read this paragraph and choose the correct option from the provided answers: Magnetic poles always occur in pairs of north and southit is not possible to isolate north and south poles. All magnetism is created by electric current. Ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. The atoms in ferromagnetic materials act like small magnets (due to currents within the atoms) and can be aligned, usually in millimeter-sized regions called domains. Domains can grow and align on a larger scale, producing permanent magnets. Such a material is magnetized, or induced to be magnetic. Above a material's Curie temperature, thermal agitation destroys the alignment of atoms, and ferromagnetism disappears. Electromagnets employ electric currents to make magnetic fields, often aided by induced fields in ferromagnetic materials. Choices: - paramagnetic - superconducting - ultramagnetic - ferromagnetic A:
Answer: ferromagnetic

*Question*
Q: What are modified leaves that bear sporangia? Read this paragraph and choose the correct option from the provided answers: Choices: - spines - neutrophils - sporozoans - sporophylls A:
**Answer**
sporophylls

(Q).
Q: Which germ layers are essential for animal embryos to grow and develop into a body? Read this paragraph and choose the correct option from the provided answers: The three germ layers are the endoderm, the ectoderm, and the mesoderm. Cells in each germ layer differentiate into tissues and embryonic organs. The ectoderm gives rise to the nervous system and the epidermis, among other tissues. The mesoderm gives rise to the muscle cells and connective tissue in the body. The endoderm gives rise to the gut and many internal organs. Organogenesis Gastrulation leads to the formation of the three germ layers that give rise during further development to the different organs in the animal body. This process is called organogenesis. Organs develop from the germ layers through the process of differentiation. During differentiation, the embryonic stem cells express specific sets of genes that will determine their ultimate cell type. For example, some cells in the ectoderm will express the genes specific to skin cells. As a result, these cells will take on the shape and characteristics of epidermal cells. The process of differentiation is regulated by location-specific chemical signals from the cell's embryonic environment that sets in play a cascade of events that regulates gene expression. Choices: - histone and melatonin - keratinocytes , ectoderm , mesoderm - cytoplasm and chloroplasm - endoderm, ectoderm, mesoderm A:
(A).
endoderm, ectoderm, mesoderm