Bihar STET Paper 1 cheat sheet

Environmental Studies

• Food chain: producer to primary consumer to secondary consumer to decomposer; energy transfer follows the 10 percent rule, so food chains rarely exceed four or five trophic levels.

• Photosynthesis: chlorophyll traps sunlight; carbon dioxide and water convert to glucose and oxygen; oxygen is released as a by-product.

• Human digestive order: mouth (salivary amylase) to oesophagus to stomach (HCl, pepsin) to small intestine (bile, pancreatic juice, villi absorption) to large intestine.

• Blood: red blood cells carry oxygen via haemoglobin, white blood cells fight infection, platelets help clotting; the heart has four chambers and double circulation.

• Water cycle stages: evaporation, transpiration, condensation, precipitation, collection; groundwater recharge depends on infiltration and percolation.

• Air composition: about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, 0.04 percent carbon dioxide; carbon dioxide and water vapour are greenhouse gases.

• States of matter: solids have fixed shape and volume, liquids fixed volume only, gases neither; change of state involves latent heat without temperature change during melting or boiling.

• Community helpers and services: municipal bodies handle water supply, sanitation and solid waste; primary health centres and anganwadis provide local health and nutrition services.

• Pollution controls: reduce, reuse, recycle; biodegradable waste decomposes, non-biodegradable waste such as plastic persists; noise is measured in decibels.