Lines of Defence

Which lines of defence involve non-specific responses?

• First and second lines of defence

• Third line of defence

• Only the first line of defence

• Only the second line of defence

Answer explanation

The first and second lines of defence involve non-specific responses to pathogens. The first line includes physical and chemical barriers, while the second line involves innate immune responses, both acting broadly against invaders.

What process do phagocytes use to engulf and destroy pathogens?

• Phagocytosis

• Photosynthesis

• Mitosis

• Osmosis

Answer explanation

Phagocytes use phagocytosis to engulf and destroy pathogens. This process involves the cell membrane wrapping around the pathogen, forming a vesicle that is then fused with lysosomes to digest the invader.

What does the lymphatic system contain?

• Lymph

• Red blood cells

• Platelets

• Neurons

Answer explanation

The lymphatic system contains lymph, a fluid that helps transport immune cells and remove waste. Red blood cells, platelets, and neurons are not components of the lymphatic system.

What role do T lymphocytes play in the third line of defence?

• They directly attack infected cells.

• They produce antibodies.

• They act as a barrier to pathogens.

• They engulf and digest pathogens.

Answer explanation

T lymphocytes, or T cells, are crucial in the third line of defense as they directly attack infected cells, helping to eliminate pathogens. This distinguishes them from other immune responses like antibody production.

What is the primary function of the lymphatic system?

• Transport oxygen

• Regulate body temperature

• Remove waste products

• Maintain fluid balance

Answer explanation

The primary function of the lymphatic system is to maintain fluid balance by collecting excess fluid from tissues and returning it to the bloodstream, preventing edema and ensuring proper circulation.

Which cells are responsible for producing antibodies?

• B lymphocytes

• T lymphocytes

• Macrophages

• Neutrophils

Answer explanation

B lymphocytes are the cells responsible for producing antibodies, which are crucial for the immune response. T lymphocytes help in cell-mediated immunity, while macrophages and neutrophils are involved in phagocytosis.

What is the role of the second line of defence in the immune system?

• To produce antibodies

• To create a physical barrier

• To initiate an inflammatory response

• To directly attack pathogens

Answer explanation

The second line of defence in the immune system primarily initiates an inflammatory response, which helps to contain and eliminate pathogens, unlike the first line that creates barriers or the third line that produces antibodies.

What is the main component of lymph?

• Red blood cells

• White blood cells

• Plasma

• Platelets

Answer explanation

The main component of lymph is plasma, which is a clear fluid that carries nutrients, waste products, and immune cells. Unlike blood, lymph does not contain red blood cells or platelets, making plasma the correct choice.

Which type of immunity is provided by vaccines?

• Innate immunity

• Passive immunity

• Active immunity

• Natural immunity

Answer explanation

Vaccines provide active immunity by stimulating the immune system to produce antibodies against specific pathogens, leading to long-term protection.

What is the primary function of macrophages in the immune system?

• To produce antibodies

• To engulf and digest pathogens

• To transport oxygen

• To regulate body temperature

Answer explanation

The primary function of macrophages in the immune system is to engulf and digest pathogens. They play a crucial role in identifying and eliminating harmful microorganisms, making them essential for immune defense.