Q4. Which species of Plasmodium causes malignant malaria?
Plasmodium falciparum; it is the most serious form and can even be fatal (NCERT page 131).
Q5. Where in the mosquito are the sporozoites of Plasmodium stored?
In its salivary glands, from which they are injected when it bites (NCERT page 131).
Q6. Which part of the body do filarial worms usually inflame, and what is the disease called?
The lymphatic vessels of the lower limbs, over many years; the disease is elephantiasis or filariasis (NCERT page 133). Beyond the NCERT text: the infection is now called lymphatic filariasis, and only some infected people develop elephantiasis (Wikipedia, “Lymphatic filariasis”, facts in our words).
Q7. Why does ringworm often appear in the groin or between the toes?
Heat and moisture help the ringworm fungi grow, so they thrive in skin folds such as those (NCERT page 133).
Q8. Name a disease that vaccines have eradicated and two that they have largely controlled.
Smallpox has been eradicated; polio, diphtheria, pneumonia and tetanus (any two) have been controlled to a large extent (NCERT page 134). Beyond the NCERT text: the pneumonia vaccines can help prevent pneumococcal and flu pneumonia, not every kind (MedlinePlus, Pneumonia).