Answer the following question given this paragraph: Friction is a force that opposes motion. Any two objects in contact have what is called a mutual coefficient of friction. To find the force of friction between them, we multiply the normal force by this coefficient. Like the forces above, it arises due to electromagnetic interactions of atoms in two objects. There are actually two coefficients of friction: static and kinetic. Static friction will oppose initial motion of two objects relative to each other. Once the objects are moving, however, kinetic friction will oppose their continuing motion. Kinetic friction is lower than static friction, so it is easier to keep an object in motion than to set it in motion. There are some things about friction that are not very intuitive:. Q: What is a force that opposes motion? Choices: - tension - momentum - thrust - friction A:
friction
------
Answer the following question given this paragraph: Vacuoles are membrane-bound organelles that can have secretory, excretory, and storage functions. Vacuoles are usually much larger than vesicles. Many organisms will use vacuoles as storage areas and some plant cells have very large vacuoles. The large central vacuole of the plant cell is used for osmotic control (storage of water) and nutrient storage. Contractile vacuoles are found in certain protists. These vacuoles take water from the cytoplasm and excrete it from the cell to avoid bursting due to osmotic pressure. Q: These vacuoles take water from the cytoplasm and excrete it from the cell to avoid bursting due to what? Choices: - apoptotic pressure - static pressure - impervious pressure - osmotic pressure A:
osmotic pressure
------
Answer the following question given this paragraph: 30.3 Roots Roots help to anchor a plant, absorb water and minerals, and serve as storage sites for food. Taproots and fibrous roots are the two main types of root systems. In a taproot system, a main root grows vertically downward with a few lateral roots. Fibrous root systems arise at the base of the stem, where a cluster of roots forms a dense network that is shallower than a taproot. The growing root tip is protected by a root cap. The root tip has three main zones: a zone of cell division (cells are actively dividing), a zone of elongation (cells increase in length), and a zone of maturation (cells differentiate to form different kinds of cells). Root vascular tissue conducts water, minerals, and sugars. In some habitats, the roots of certain plants may be modified to form aerial roots or epiphytic roots. Q: What is the growing root tip protected by? Choices: - root flap - tip cap - root hinge - root cap A:
root cap
------
Answer the following question given this paragraph: The freezing point of a substance is the temperature at which it freezes. The freezing point of pure water is 0C. Q: What is the temperature at which a substance freezes known as? Choices: - absolute zero - zero point - drop point - freezing point A:
freezing point
------