Why this is wrongGlycosides act as chemical defense substances against microbes, not as the recognition component behind structural immunity.
BDetoxification enzymes.
Why this is wrongDetoxification enzymes neutralize pathogen toxins; they are a chemical countermeasure, not the recognition trigger.
CReceptors. Correct answer
DCanavanine
Why this is wrongCanavanine is a toxic non-protein amino acid used against microbes, not the recognition receptor that induces the structural response.
Why this is correctReceptors are structural components that enable recognition and immune response, unlike soluble biochemical toxins or enzymes.
The concept is plant biochemical defenses and which one underlies recognition-based (structural) immunity. Receptors are the components that detect the pathogen and switch on the plant's immune mechanisms, so they underlie the structural response, unlike glycosides, detoxifying enzymes, or canavanine, which act as chemical weapons against the microbe. Method: separate the recognition and trigger substance (receptors) from the chemical toxins and enzymes, and pick the one that starts the response.
2.Which of the following bones produces immune cells?
1 mark
APhalanges.
Why this is wrongThe phalanges are small bones with minimal red-marrow activity and are not a significant site of immune-cell production.
BWrist.
Why this is wrongThe wrist is a joint region made of several small carpal bones rather than a single marrow-rich bone that produces immune cells.
CCarpal.
Why this is wrongCarpal bones are small bones of the wrist with little red marrow and do not serve as a main site of immune-cell production.
DSternum. Correct answer
Why this is correctRed bone marrow in flat bones such as the sternum produces immune cells.
Immune cells (lymphocytes and other white blood cells) are produced by the red bone marrow. Red bone marrow is most active in flat bones and the ends of long bones, and the sternum is a classic flat bone rich in red marrow, which is why the sternum is used clinically for marrow sampling. The phalanges, wrist, and carpal bones contain little active red marrow.
3.A child suffers from a disease called "Cystic Fibrosis "which leads to production of very thick mucus. Which of the following natural lines of defense will directly affected?
1 mark
ASecond line: inflammatory response
Why this is wrongThe inflammatory response is a second-line internal defense; thickened mucus affects a surface barrier, not inflammation.
BFirst line: all natural barriers
Why this is wrongOnly the mucus barrier is impaired, so it is not accurate to say all natural barriers of the first line are affected.
CFirst line : some natural barriers Correct answer
DSecond line: Natural killer cells
Why this is wrongNatural killer cells belong to the second line of defense; thickened mucus affects an external barrier, not these internal cells.
Why this is correctMucus is one of the first-line natural barriers, so only some first-line barriers are directly affected.
The first line of natural defense is made of physical and chemical barriers such as skin, mucus, tears, and gastric acid. Mucus is one specific first-line barrier, so when cystic fibrosis thickens the mucus, only that particular barrier is directly impaired. The problem is therefore localized to some first-line barriers, not the whole first line and not the second-line internal defenses.