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B1 ILTS – 09

Human Health and Disease

Zoology · Class 12 Chapter 8 · error and blank review

Test date 06-09-2026Marks obtained 526NEET 2027 · Gr 12 Live Full Course
2questions in this chapter
1answered wrong
1left blank

Weak areas from this paper

Confusing the mechanism with the outcomerecurring

Q170

Reverse transcription is the famous, examinable, distinctive step of HIV biology — and that is exactly why it was chosen. But the question asked when symptoms appear, and reverse transcription happens silently, possibly years earlier.

The underlying gap is a small one: the difference between being infected and being ill. The molecular pathway seems well known; what was missed is where along that pathway the clinical picture starts.

Fix to drill. For any disease question, keep two timelines side by side: what the pathogen is doing, and what the patient is experiencing. AIDS, hepatitis and typhoid are all asked this way — the answer is usually on the patient timeline, not the pathogen one.

Negatively worded stemsattempt rate

Q158

Q158 asks which option is not a treatment. It was left blank, so there is no evidence of a misread here — but questions of this shape reward a fixed habit, because three of the four options are true statements and the instinct is to look for a true one.

The content itself is straightforward: NCERT gives the diagnosis list and the treatment list in adjacent paragraphs.

Fix to drill. Circle the word not, except or incorrect as soon as you see it, then mark each option true or false in the margin and pick the odd one. Two extra seconds, and the reversal stops costing marks.

Small sample from this chapterwatch

Q158, Q170

Only two questions from Human Health and Disease appeared on this paper, and one of those was blank. That is too little to read a pattern from.

What can be said: the HIV pathway is largely known, and the diagnosis-versus-treatment lists were not tested at all because the question was skipped. Both are high-frequency NEET topics that deserve a full revision pass before the next test rather than a targeted fix.

Fix to drill. Revise the chapter's four list-based topics as flashcards: cancer diagnosis versus treatment, the HIV sequence, the immunity types, and the drug categories. Lists are where this chapter is examined.
Question by question
Q158Left blankDiagnosis versus treatment of cancer

Which of the following is not a method of cancer treatment?

  • Immunotherapy
  • Biopsy
  • Surgery
  • Radiotherapy
Given
Four procedures associated with cancer: immunotherapy, biopsy, surgery, radiotherapy.
Asked
Which one is not a treatment.
Concepts

NCERT separates cancer management into two lists, and the question is testing whether you keep them apart.

Detection and diagnosis: biopsy and histopathological studies, blood and bone marrow tests, CT, MRI, and antibodies against cancer-specific antigens.

Treatment: surgery, radiotherapy, chemotherapy, and immunotherapy (including α-interferon, which activates the immune system).

A biopsy removes a small piece of tissue so it can be examined under a microscope. It answers “is this cancer, and what kind?” It removes no meaningful amount of tumour and cures nothing.

Watch the word not in the stem — three options are correct statements and the odd one out is the answer.

Formula
diagnosis: biopsy, histopathology, CT, MRI,
          antibodies to cancer-specific antigens

treatment: surgery, radiotherapy, chemotherapy,
          immunotherapy (α-interferon)
Baby steps
  1. Note the not — you are looking for the one that does not belong.
  2. Surgery removes the tumour: treatment. Radiotherapy kills tumour cells: treatment. Immunotherapy activates the patient's immune system: treatment.
  3. Biopsy takes a tissue sample for examination. It identifies the disease; it does not act against it.
  4. Answer: biopsy.
Answer — biopsy — it is a diagnostic method, not a treatment
diagnosis finds the cancer; therapy removes or kills itdiagnosisbiopsy and histopathologyCT scanMRIantibodies againstcancer-specific antigenstreatmentsurgeryradiotherapychemotherapyimmunotherapy(α-interferon)biopsy is the odd one out — it is how cancer is found, never how it is cured

Two NCERT lists; biopsy sits firmly in the left-hand one.

Shortcut
Sort by what the procedure does to the tumour. Does it remove, kill or attack it? Treatment. Does it only look at it or sample it? Diagnosis. That test handles this whole family of questions.
Q170Marked wrongWhen AIDS symptoms appear

At which stage of HIV infection does one usually show symptoms of AIDS?

  • Within 15 days of sexual contact with an infected person
  • When the infecting retrovirus enters host cells
  • When viral DNA is produced by reverse transcriptase
  • When HIV replicates rapidly in helper T-lymphocytes and damages large number of T-lymphocytes
Given
The sequence of events in HIV infection.
Asked
At which stage AIDS symptoms usually appear.
Concepts

Infection and disease are not the same event, and the gap between them can be years. Follow the sequence:

1. HIV enters the body and infects macrophages. 2. Reverse transcriptase makes viral DNA from the viral RNA. 3. That DNA integrates into the host genome and directs production of new virus particles. 4. The virus enters helper T-lymphocytes (TH), replicates, and progressively destroys them.

Steps 1 to 3 are silent. The person is infected and infectious, but well. NCERT gives this asymptomatic period as anywhere from a few months to many years.

Symptoms appear only at step 4, once the helper T-cell count has fallen far enough that immunity fails. What follows — recurrent fever, weight loss, diarrhoea, and the opportunistic infections such as Mycobacterium, Toxoplasma and fungi — are consequences of the missing T cells, not of the virus directly.

Formula
HIV → macrophage
  → reverse transcriptase makes viral DNA
  → integrates into host genome
  → infects helper T cells (TH)
  → TH count falls → AIDS symptoms

asymptomatic period: months to years
Baby steps
  1. Separate the two questions the options are confusing: when does infection happen, and when does disease appear?
  2. Options B and C both describe early molecular events. They mark infection, and the patient has no symptoms at that point.
  3. Option A puts symptoms at 15 days, which contradicts the long asymptomatic period NCERT describes.
  4. Symptoms require immune failure, and immune failure requires the helper T-cell population to be destroyed. That is option D.
Answer — when HIV replicates rapidly in helper T-lymphocytes and destroys large numbers of them
You marked: “when viral DNA is produced by reverse transcriptase” — that is a real and important step, but it happens early and silently, often years before any symptom. The chosen option describes infection; the question asks about disease.
entryvirus enters amacrophagereversetranscriptionRNA → viral DNAintegrationviral DNA joinshost genomereplication inhelper T cellsT-cell countcollapsesno symptoms · can last months to yearsAIDS symptoms appearinfection is not disease — symptoms wait for the helper T cells to fallreverse transcription and integration happen early and silently

The molecular steps run early and silently; symptoms wait for the T-cell collapse.

Shortcut
For any “when do symptoms appear” question, ask what the symptoms are caused by. AIDS symptoms are caused by the absence of helper T cells, so they cannot appear until those cells are gone. Working backwards from the cause of the symptom picks the option every time.