Zadanie 8, Paper 2, maj 2024, TZ2, Biologia IB HL
Wzorowane na: Biology HL Paper 2, May 2024, TZ2, pytanie 8. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
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Zadanie
Polecenie
(a) Draw and fully label a bacterial cell.
(b) Describe barriers that prevent pathogenic bacteria entering the body.
(c) Explain how immunity to pathogenic bacteria develops.
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Odpowiedź z klucza
(a)
A capsule is correctly drawn and labelled. ✔
A cell wall is correctly drawn and labelled, thicker than the plasma membrane. ✔
A plasma membrane is correctly positioned and labelled. ✔
Cytoplasm is shown and labelled. ✔
70S ribosomes are represented and labelled. ✔
A nucleoid or naked DNA is represented and labelled. ✔
Plasmids are represented and labelled. ✔
Pili OR a flagellum are represented and labelled; pili, if shown, should be shorter than the flagellum. ✔
(b)
Skin forms a physical barrier OR its low pH inhibits bacterial growth. ✔
Mucus traps bacteria. ✔
Stomach acid kills susceptible bacteria. ✔
Lysozyme in tears or saliva can damage bacteria. ✔
Clots seal breaks in the skin. ✔
Platelets release clotting factors. ✔
Prothrombin is converted into thrombin OR thrombin is activated OR thrombin converts fibrinogen into fibrin OR a fibrin mesh traps cells to form a clot. ✔
(c)
Bacteria carry antigens on their surfaces. ✔
Phagocytes engulf bacteria and display antigens. ✔
Antigen-specific helper T cells become activated. ✔
Activated helper T cells activate B cells. ✔
Clonal selection occurs OR B cells divide by mitosis. ✔
Plasma cells are formed. ✔
Memory cells are formed. ✔
Plasma cells secrete antibodies. ✔
The antibodies bind specifically to the antigen. ✔
Antibodies help eliminate the pathogen. ✔
Persistent memory cells allow a faster future response OR long-term immunity. ✔
On re-exposure, memory cells give rise to rapid production of the same specific antibodies. ✔
Vaccines supply pathogen antigens, for example in weakened or inactivated material. ✔
Vaccination can trigger immune memory without causing the corresponding disease. ✔
Quality of communication: clear on first reading, concise and without unnecessary repetition or irrelevant material. ✔
Schemat punktowania
Part (a): any 4 points, maximum 4. Part (b): any 3 points, maximum 3. Part (c): any 8 points, maximum 8. Award 1 independent communication mark. Maximum 16. Accept scientifically equivalent wording and relevant diagrams. Part (a) must be a labelled drawing. If it instead shows a eukaryotic cell or is not clearly bacterial, award at most 2 points for correctly represented distinctive prokaryotic features.