The medical condition where the lens of the eye becomes opaque is: MCQ with Answer and Explanation

Explanation:
The lymphatic system drains excess tissue fluid (lymph) back to the venous blood. Blood circulation is the cardiovascular system; lymph nodes filter lymph; thymus is a primary lymphoid organ.

Explanation:
Ex-situ (off-site) conservation involves protecting endangered species outside their natural habitats. Zoological parks, botanical gardens, seed banks, and cryopreservation facilities are examples of ex-situ conservation. This method allows for controlled breeding, research, and education, and can be a last resort for species whose natural habitats are severely degraded or destroyed.

Explanation:
Molecular oxygen (O₂) accepts electrons at the end of the electron transport chain, combining with protons to form water (metabolic water). Without oxygen, the chain backs up, stopping ATP production. This is why oxygen is vital for aerobic respiration. NAD⁺ and FAD are electron carriers, cytochrome c a component.