GED Science Test #9 2

Question 1

The immune system's B cells produce _______ to fight infections.

Accepted Answer

Antibodies

Answer

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?

Accepted Answer

Nitrogen (N₂)

Answer

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?

Accepted Answer

Metaphase

Answer

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?

Accepted Answer

High temperatures denature the enzyme, changing its shape

Answer

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:

Accepted Answer

There is an equal and opposite reaction

Answer

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.

GED Practice Test

GED Practice Test

GED Science Test #9 2