AFCT General Science Concepts 2 — Questions and Answers
Question 1: What is the primary function of white blood cells in the human body?
- Transport oxygen
- Fight infections (Correct answer)
- Clot blood
- Produce hormones
Correct answer: Fight infections
White blood cells (leukocytes) are the body's primary defense against infections and foreign invaders.
White blood cells, or leukocytes, are key components of the immune system. They identify and destroy pathogens such as bacteria, viruses, and parasites. Different types serve different roles: neutrophils attack bacteria, lymphocytes produce antibodies, and macrophages engulf debris and microorganisms.
Question 2: What is the chemical formula for table salt?
- NaOH
- NaCl (Correct answer)
- KCl
- CaCO3
Correct answer: NaCl
Table salt is sodium chloride, with the chemical formula NaCl.
Table salt is sodium chloride (NaCl), an ionic compound formed by the transfer of an electron from sodium (Na) to chlorine (Cl). This creates Na+ and Cl- ions held together by electrostatic attraction in a crystal lattice structure. NaCl is essential for human health and is the most commonly used salt in food preparation.
Question 3: Which planet in our solar system has the most moons?
- Jupiter
- Saturn (Correct answer)
- Uranus
- Neptune
Correct answer: Saturn
Saturn has the most confirmed moons of any planet in our solar system, surpassing Jupiter in recent discoveries.
As of recent astronomical surveys, Saturn holds the record for the most known moons in our solar system, with over 140 confirmed natural satellites. Jupiter is a close second with over 90 known moons. Both gas giants have numerous small irregular moons that continue to be discovered.
Question 4: What type of energy transformation occurs when a battery powers a flashlight?
- Kinetic to potential
- Chemical to electrical to light (Correct answer)
- Nuclear to thermal
- Mechanical to electrical
Correct answer: Chemical to electrical to light
A battery converts stored chemical energy into electrical energy, which then powers the bulb to produce light energy.
In a battery-powered flashlight, three energy transformations occur in sequence. First, chemical energy stored in the battery is converted to electrical energy through electrochemical reactions. This electrical energy flows to the bulb, where it is converted to light energy (and some heat). This demonstrates the law of conservation of energy.
Question 5: What is the function of the ozone layer in Earth's atmosphere?
- Produces oxygen for breathing
- Blocks harmful ultraviolet radiation (Correct answer)
- Regulates global temperatures
- Creates weather patterns
Correct answer: Blocks harmful ultraviolet radiation
The ozone layer in the stratosphere absorbs and blocks most of the sun's harmful ultraviolet (UV) radiation from reaching Earth's surface.
The ozone layer is a region of the stratosphere, approximately 15-35 km above Earth's surface, with high concentrations of ozone (O3). It absorbs approximately 97-99% of the sun's medium-frequency ultraviolet light (UV-B), which can cause skin cancer, cataracts, and damage to marine ecosystems.
Question 6: Which of the following is an example of a chemical change?
- Ice melting into water
- Cutting paper with scissors
- Iron rusting (Correct answer)
- Dissolving sugar in water
Correct answer: Iron rusting
Rusting (oxidation of iron) is a chemical change because it produces a new substance with different properties from the original iron.
Iron rusting is a chemical change because iron reacts with oxygen and water to form iron oxide (Fe2O3), a completely different substance. Chemical changes involve breaking and forming chemical bonds. Melting ice, cutting paper, and dissolving sugar are physical changes since no new substances are formed and they can be reversed.
AFCT General Science Concepts 2
What is the primary function of white blood cells in the human body?