*Question*
Q: Deep ocean currents are caused by differences in what property at the top and bottom?   Read this paragraph and choose the correct option from the provided answers:  Currents also flow deep below the surface of the ocean. Deep currents are caused by differences in density at the top and bottom. Density is defined as the amount of mass per unit of volume. More dense water takes up less space than less dense water. It has the same mass but less volume. Water that is more dense sinks. Less dense water rises. What can make water more dense?.   Choices:  - diameter  - mass  - velocity  - density   A:
**Answer**
density

*Question*
Q: What are the two types of endoplasmic reticulum?   Read this paragraph and choose the correct option from the provided answers:  There are two types of endoplasmic reticulum. They are called rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). Both types are shown in Figure below .   Choices:  - thick & smooth  - rough & thin  - rough & thick  - rough & smooth   A:
**Answer**
rough & smooth

*Question*
Q: What are the two most abundant elements in the universe?   Read this paragraph and choose the correct option from the provided answers:  Hydrogen and helium are the most abundant elements in the universe.   Choices:  - hydrogen and oxygen  - nitrogen and carbon  - oxygen and carbon  - hydrogen and helium   A:
**Answer**
hydrogen and helium

*Question*
Q: Which system carries out long-distance transport of materials between the root and shoot systems?   Read this paragraph and choose the correct option from the provided answers:     Choices:  - circulatory tissue system  - reproductive tissue system  - perceptual tissue system  - vascular tissue system   A:
**Answer**

vascular tissue system