Problem 1 - Campbell Biology

Question

Which of these is not part of insect immunity? (A) enzyme activation of pathogen-killing chemicals (B) activation of natural killer cells (C) phagocytosis by hemocytes (D) production of antimicrobial peptides

Step-by-Step Solution

Answer

The correct answer is (B) activation of natural killer cells.

Step 1: Understand Insect Immunity Mechanisms

Insect immunity primarily involves innate immune responses. Key mechanisms include enzyme activation of pathogen-killing chemicals, phagocytosis by hemocytes, and production of antimicrobial peptides.

Step 2: Identify Natural Killer Cells

Natural killer cells are part of the vertebrate immune system, not the insect immune system. This means they are not involved in the insect immune response.

Step 3: Compare with Given Options

Compare each option with known insect immunity mechanisms. Options (A), (C), and (D) are components of insect immunity. Option (B), natural killer cells, is not.

Step 4: Conclusion

The correct answer is the option describing a mechanism that is not part of insect immunity.

Key Concepts

innate immune responses

Insects rely on innate immune responses to protect themselves from pathogens. Unlike vertebrates, they do not have an adaptive immune system. This means they cannot 'remember' pathogens for future responses.
Innate immune responses are immediate and nonspecific. They attack any invader without distinction. Key components include enzyme activation, cellular defense mechanisms, and production of antimicrobial substances.
When a pathogen enters an insect's body, innate immune responses are activated promptly. The speed of this response is vital for survival, as insects often have short life spans and cannot afford prolonged infections.

phagocytosis by hemocytes

Phagocytosis by hemocytes is a critical part of an insect's immune system.
Hemocytes are blood cells in insects, much like white blood cells in humans.
These cells engulf and digest pathogens and debris through a process called phagocytosis. Phagocytosis involves hemocytes recognizing and binding to the pathogen. Once bound, the pathogen is engulfed into a compartment called a phagosome.
The phagosome fuses with lysosomes, which contain digestive enzymes, leading to the destruction of the pathogen.

antimicrobial peptides

Antimicrobial peptides (AMPs) are an essential defense mechanism in insects. These are small proteins that can kill bacteria, fungi, and viruses. When a pathogen is detected, insects produce AMPs rapidly to combat the infection.
AMPs work by disrupting the membranes of pathogens, leading to their death. They are effective against a broad range of microorganisms and act swiftly.
Some well-known insect AMPs include defensins, cecropins, and attacins. Each AMP has specific targets and methods of action, providing a versatile defense strategy.