ASVAB General Science Practice Test 58747

Questions 5
Topics Acidity, Crust, Health Benefits of Vitamins & Minerals, Scavengers

Study Guide


An acid is a substance that gives up positively charged hydrogen ions (H+) when dissolved in water. A base (alkaline) gives up negatively charged hydroxide ions (OH-) when dissolved in water. pH is a scale that measures of how basic or acidic a solution is. Numbered from 0 to 14, solutions with a pH of 7 are neutral, less than 7 are acidic, more than 7 are alkaline.


The crust is the Earth's outermost layer and is divided into oceanic and continental types. Oceanic crust is 3 miles (5 km) to 6 miles (10 km) thick and is composed primarily of denser rock. Continental crust is 20 to 30 miles (30 to 50 km) thick and composed primarily of less dense rock. The crust makes up approximately one percent of the Earth's total volume.

Health Benefits of Vitamins & Minerals
Vitamin / Mineral Sources Health Benefits
Calcium Dairy products (milk, yogurt, cheese), spinach. Aids bone growth and repair, muscle function.
Iron Red meat, beans, whole grains. Allows red blood cells to transfer oxygen to body tissues.
Magnesium Nuts, whole grains, green leafy vegetables. Muscle, nerve, and enzyme function.
Potassium Bananas, nuts, seeds. Helps balance fluid levels in the body.
Vitamin A Liver, milk, eggs, carrots. Vision, immune system, cell growth.
Vitamin C Green and red peppers, citrus fruits, broccoli. Collagen formation, immune system function, antioxidant (helps protect cells from damage).
Vitamin D Exposure to sunlight. Helps calcium strengthen bones, muscle, nerve, and immune system function.

Like decomposers, scavengers also break down the dead bodies of plants and animals into simple nutrients. The difference is that scavengers operate on much larger refuse and dead animals (carrion). Decomposers then consume the much smaller particles left over by the scavengers.