Biology · Animal Kingdom · NEET
Book lungs are ONLY for breathing (respiration). They are stacked, thin plates that look like the pages of a book, and air passes over them so oxygen can enter the blood. They have nothing to do with waste. Scorpions and spiders use book lungs. This is a very common NEET trap, so remember: book lungs = respiration, never excretion.
Malpighian tubules do excretion in arthropods. They are thin thread-like tubes that pick up nitrogen waste (like uric acid) from the blood and pass it into the gut to be thrown out. NCERT says clearly: 'Excretion takes place through Malpighian tubules.' So Malpighian tubules = excretion, not breathing.
They do opposite jobs. Book lungs = respiration (bring in oxygen, remove carbon dioxide). Malpighian tubules = excretion (remove nitrogen waste from blood). Book lungs deal with GAS. Malpighian tubules deal with WASTE. NEET often puts both in one match-the-column question to see if you can keep them separate.
No. NCERT says arthropod respiratory organs are 'gills, book lungs or tracheal system.' So it depends on the animal. Scorpions and spiders (arachnids) use book lungs. Insects like cockroach and mosquito use a tracheal system (air tubes). Aquatic arthropods like prawns use gills. But almost all arthropods use Malpighian tubules for excretion.
Because it is easy to swap them in your memory. Both sound like special organ names, both belong to arthropods, and students often write 'book lungs excrete' by mistake. NEET uses this in match-the-column and 'which organ does what' questions. If you lock in respiration vs excretion, you will get these marks every time.
The scorpion. In NEET 2020 the answer paired 'book lungs' with Scorpion. Scorpions are arachnids, and arachnids breathe using book lungs. So if you see 'book lungs' in a question, think scorpion or spider.
Match the following columns and select the correct option. Column-I (a) Gregarious, polyphagous pest (b) Adult with radial symmetry and larva with bilateral symmetry (c) Book lungs (d) Bioluminescence Column-II (i) Asterias (ii) Scorpion (iii) Ctenoplana (iv) Locusta
Match the following organisms with their respective characteristics: Column I A. Pila B. Bombyx C. Pleurobrachia D. Taenia Column II i. Flame cells ii. Comb plates iii. Radula iv. Malpighian tubules
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes, book lungs are a special arthropod feature, seen mainly in arachnids like scorpions and spiders. They are not found in other phyla.
No. Insects such as the cockroach breathe through a tracheal system (a network of air tubes), not book lungs. But the cockroach still uses Malpighian tubules for excretion.
They mainly remove nitrogen waste. In insects like the cockroach this is uric acid, which is why they are called uricotelic. The waste goes into the gut and out with the faeces.
No. Kidneys are found in vertebrates. Malpighian tubules do a similar job (excretion) but are the excretory organs of arthropods, especially insects.
They are covered in the Animal Kingdom chapter under Phylum Arthropoda in NCERT Class 11 Biology.
