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Biology · 2024 · 5 marks
CBSE 2024 · Region 3 · Set 1 · Q33
(a) (i) Describe the life cycle of Plasmodium from the time it enters the human body till a female Anopheles mosquito bites an infected person. (ii)…
(a)(i)
Describe the life cycle of Plasmodium from the time it enters the human body till a female Anopheles mosquito bites an infected person.
(ii)
Mention the two events of Plasmodium life cycle that occur within the female Anopheles body.
OR
(b)(i)
Write two differences between malignant tumor and benign tumor.
(ii)
Explain any three diagnostic techniques for the detection of cancer.
Marking-scheme solution
(i)
Life cycle of the Plasmodium from the period it enters the human body till a female
Anopheles mosquito bites an infected person.
-Plasmodium enters the human body as sporozoites (through the bite of infected Anopheles
mosquito)
-The plasmodium reproduces asexually in the liver cells initially;
-And then on releasing it in blood to attack the Red Blood cells (RBCs)
-Parasite (plasmodium) reproduces asexually in Red Blood cells (RBCs)
-Resulting in rupture/ bursting of the RBCs
-Several sexual stages (gametocytes) develop in RBCs
-Female Anopheles mosquito takes up gametocytes with blood meal.
(ii)
Fertilization of male and female gametocytes,
-production of sporozoites,
-migration of sporozoites into salivary glands of mosquito
Malignant Cancer
Benign Cancer
1) Mass proliferating cells called
neoplastic or tumor cells grows rapidly.
2) It spreads to other [parts of the body or
causes metastasis.
3) Invading and damaging the normal
tissues
1) Tumor cells grows rapidly.
2) It is confined to their original location,
or causes no metastasis.
3) Causes little damage in the tissues.
(ii)
Biopsy and/histopathological studies , a piece of suspected tissue or blood or bone marrow cut into thin section is stained and examined by pathologist.
Radiography , use of X-rays
-CT /Computed tomography , to generate $\displaystyle 3$-dimensional image of the internal organs by
using X-rays.
-MRI , uses strong magnetic field and non ionising radiations to accurately detect
pathological and physiological changes in the living tissue.
-Antibodies against specific antigens , are used for detection of certain cancer.
Technique of Molecular Biology , applied to detect genes in an individual with inherited susceptibility to certain cancer.
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CBSE Class 12 Biology past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.