➤ In the leptotene stage of prophase I of meiosis, chromosomes begin to condense and become visible as long, thread-like structures.
★ It is the first sub-stage of prophase I, preceding zygotene where synapsis begins.

➤ Allen’s rule states that endothermic animals in cold climates have shorter ears and limbs to reduce surface area and heat loss.
★ This is a thermoregulatory adaptation seen in animals like arctic foxes and polar bears.

➤ Fucoxanthin is the primary xanthophyll pigment in brown algae and diatoms, giving them their brownish-green colour.
★ It plays a role in photosynthesis and is studied for its anti-obesity and antioxidant properties.

➤ Gonyaulax is a genus of dinoflagellates, many of which are bioluminescent and some species cause red tide.
★ Dinoflagellates are mostly marine plankton with two flagella and cellulose plates.

➤ Pteropus is a flying fox or fruit bat, which is a mammal and not a bird.
★ The other options (Psittacula, Neophron, and Struthio) are all bird species.

➤ Gorter and Grendel discovered that lipid monolayers from erythrocytes could be used to measure molecular surface area.
★ Their work led to the lipid bilayer model of cell membranes.

➤ Spirogyra exhibits isogamous reproduction, where both gametes are non-flagellated and look alike.
★ The fusion of isogamous gametes leads to the formation of zygotes.

➤ Guava exhibits opposite phyllotaxy, where two leaves arise from the same node but on opposite sides.
★ This arrangement is commonly found in many dicot plants.

➤ Allen’s rule explains that in cold regions, animals tend to have shorter limbs and appendages to conserve body heat.
★ This helps reduce heat dissipation in cold environments.

➤ Mosquito – Hexapoda
➤ Daphnia – Crustacea
➤ Julus – Myriapoda
➤ Limulus – Chelicerata
★ This classification is based on arthropod groups.