3.2.4 Cell recognition and the immune system 2

What is the primary role of surface molecules on cells?

• To provide energy to the cell

• To identify the cell to the immune system

• To transport nutrients into the cell

• To store genetic information

Answer explanation

Surface molecules on cells primarily function to identify the cell to the immune system, allowing the body to distinguish between self and non-self cells, which is crucial for immune response.

Which of the following is NOT identified by the immune system using surface molecules?

• Pathogens

• Cells from other organisms of the same species

• Normal body cells

• Toxins

Answer explanation

The immune system distinguishes between pathogens, foreign cells, and toxins using surface molecules. Normal body cells are recognized as self and are not targeted, making them the correct answer as they are NOT identified by the immune system.

What is an antigen?

• A type of white blood cell

• A molecule that triggers an immune response

• A protein that transports oxygen

• A type of enzyme

Answer explanation

An antigen is a molecule that triggers an immune response, prompting the body to recognize and fight off pathogens. The other options do not accurately describe what an antigen is.

How does antigen variability affect disease prevention?

• It makes it easier to develop vaccines

• It can lead to the failure of vaccines

• It has no effect on disease prevention

• It reduces the need for vaccines

Answer explanation

Antigen variability can lead to the failure of vaccines because pathogens may change their surface proteins, making previously effective vaccines less effective or ineffective against new strains.

What is the process called where pathogens are engulfed and destroyed by immune cells?

• Photosynthesis

• Phagocytosis

• Mitosis

• Osmosis

Answer explanation

The process where immune cells engulf and destroy pathogens is called phagocytosis. This is a crucial mechanism of the immune response, unlike photosynthesis, mitosis, or osmosis, which serve different biological functions.

Which enzyme is responsible for the destruction of ingested pathogens?

• Amylase

• Lysozyme

• Lipase

• Protease

Answer explanation

Lysozyme is an enzyme that breaks down the cell walls of bacteria, effectively destroying ingested pathogens. It is found in various body fluids, including saliva and tears, making it crucial for immune defense.

What is the role of T lymphocytes in the immune response?

• To produce antibodies

• To respond to foreign antigens

• To transport oxygen

• To digest food particles

Answer explanation

T lymphocytes, or T cells, play a crucial role in the immune response by recognizing and responding to foreign antigens, which are substances that trigger an immune reaction. This makes 'To respond to foreign antigens' the correct choice.

What is the function of antigen-presenting cells in the cellular response?

• To produce antibodies

• To present antigens to T cells

• To destroy pathogens directly

• To transport nutrients

Answer explanation

Antigen-presenting cells (APCs) play a crucial role in the immune response by presenting antigens to T cells. This interaction is essential for T cell activation and the subsequent cellular response against pathogens.

How do helper T cells (TH cells) assist in the immune response?

• By producing antibodies

• By stimulating cytotoxic T cells, B cells, and phagocytes

• By engulfing pathogens

• By transporting oxygen

Answer explanation

Helper T cells (TH cells) assist the immune response by stimulating cytotoxic T cells, B cells, and phagocytes, enhancing their ability to fight infections. They do not produce antibodies or engulf pathogens.

What is the primary role of B lymphocytes in the immune response?

• To produce antibodies

• To destroy pathogens directly

• To transport oxygen

• To digest food particles

Answer explanation

The primary role of B lymphocytes in the immune response is to produce antibodies. These antibodies bind to specific antigens on pathogens, marking them for destruction and helping to neutralize infections.