GED Science Test #9 2 — Questions and Answers
Question 1: The immune system's B cells produce _______ to fight infections.
- Antibodies (Correct answer)
- Antigens
- Enzymes
- Hormones
Correct answer: Antibodies
B cells (B lymphocytes) produce antibodies — proteins that recognize and bind to specific antigens on pathogens, marking them for destruction. This is part of the adaptive immune response.
Question 2: Which gas makes up the largest percentage of Earth's atmosphere?
- Nitrogen (Nâ‚‚) (Correct answer)
- Oxygen (Oâ‚‚)
- Carbon dioxide (COâ‚‚)
- Argon (Ar)
Correct answer: Nitrogen (Nâ‚‚)
Nitrogen makes up approximately 78% of Earth's atmosphere, followed by oxygen (21%), argon (0.9%), and carbon dioxide (0.04%). Despite being essential for life, most organisms cannot use atmospheric nitrogen directly.
Question 3: In which phase of mitosis do chromosomes line up along the center of the cell?
- Metaphase (Correct answer)
- Prophase
- Anaphase
- Telophase
Correct answer: Metaphase
During metaphase, chromosomes align along the metaphase plate (cell equator). This alignment ensures that when the chromosomes are pulled apart in anaphase, each daughter cell receives the correct set of chromosomes.
Question 4: A table shows that as temperature increases from 20°C to 60°C, enzyme activity first increases then sharply decreases at 50°C. What is the best explanation for this?
- High temperatures denature the enzyme, changing its shape (Correct answer)
- The substrate runs out at high temperatures
- Enzymes require cold temperatures to function
- Temperature has no effect on enzyme activity
Correct answer: High temperatures denature the enzyme, changing its shape
Enzymes have an optimal temperature. Above this, high heat causes denaturation — the enzyme's protein structure unfolds, destroying its active site and stopping catalytic activity.
Question 5: Newton's Third Law states that for every action:
- There is an equal and opposite reaction (Correct answer)
- There is an equal reaction in the same direction
- The force depends on the mass of the object
- The acceleration is proportional to the net force
Correct answer: There is an equal and opposite reaction
Newton's Third Law: for every action force, there is an equal and opposite reaction force. For example, when you push on a wall, the wall pushes back on you with equal force.
Question 6: Which of the following is a renewable energy source?
- Solar energy (Correct answer)
- Coal
- Natural gas
- Nuclear energy
Correct answer: Solar energy
Solar energy is renewable because it comes from the sun, which provides an essentially unlimited supply. Coal and natural gas are fossil fuels that take millions of years to form and are non-renewable. Nuclear energy uses uranium, which is finite.
GED Science Test #9 2
The immune system's B cells produce _______ to fight infections.