Biological Science Last Minute Revision
Quick-fire revision of key terms, processes, and facts for AP SSC Class 10 Biological Science (General Science Paper II). Read through this the night before and morning of your BSE AP exam.
Life Processes — Quick Recall
- →Photosynthesis: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂; in chloroplasts; stomata open in light
- →Aerobic respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP; in mitochondria
- →Anaerobic (yeast): glucose → ethanol + CO₂; (muscle): glucose → lactic acid
- →Heart: 4 chambers; right side = deoxygenated blood; left side = oxygenated blood; 2 circuits (pulmonary + systemic)
Excretion and Transport
- →Nephron: Bowman's capsule (filtration) → PCT (reabsorption) → Loop of Henle → DCT → collecting duct → urine
- →Dialysis: artificial kidney; used when kidneys fail
- →Blood = plasma + RBC + WBC + platelets; RBC has haemoglobin; WBC fights infection
- →Arteries = away from heart (thick wall, high pressure); Veins = towards heart (valves to prevent backflow)
Control and Coordination
- →Neuron: dendrite → cell body → axon → synapse (chemical transmission between neurons)
- →Reflex arc: receptor → sensory neuron → spinal cord → motor neuron → effector (no brain involved)
- →Brain: cerebrum (thinking) · cerebellum (balance) · medulla (involuntary: breathing, heartbeat)
- →Hormones (slow, long-lasting): insulin (glucose), thyroxine (metabolism), adrenaline (stress), growth hormone
Plant Hormones — Key Facts
- →Auxin: made at tip; causes bending towards light by elongating cells on shaded side
- →Gibberellin: stem elongation, seed germination; used to increase fruit size in agriculture
- →Abscisic acid (ABA): inhibitor; closes stomata during drought; causes leaf fall
- →Ethylene: gaseous hormone; ripens fruits; causes senescence (ageing of leaves and flowers)
Reproduction — Quick Recall
- →Asexual: fission, budding, fragmentation, regeneration, spore formation, vegetative propagation — no gametes
- →Pollination: transfer of pollen from anther to stigma; fertilisation: pollen tube → ovule → zygote
- →Menstrual cycle: ~28 days; ovulation day 14; if no fertilisation → menstruation (shedding of endometrium)
- →Human reproduction: testes (sperm) + ovary (egg) → zygote → embryo → foetus → birth (~9 months)
Heredity — Key Concepts
- →Mendel: TT × tt → all Tt (F₁ all tall); F₁ × F₁ → 3 tall : 1 dwarf (F₂); T = dominant, t = recessive
- →Monohybrid cross F₂ ratio: 3:1 (phenotype), 1:2:1 (genotype) · Dihybrid F₂ ratio: 9:3:3:1
- →Sex determination: XX = female, XY = male; father gives X or Y → determines sex of child
- →Acquired traits (not inherited) vs inherited traits (passed via germ cells to offspring)
Environment — Must Know
- →10% energy rule: only 10% of energy at one trophic level passes to the next (rest lost as heat)
- →Biomagnification: non-biodegradable chemicals (DDT, mercury) accumulate more at higher trophic levels
- →Ozone layer: absorbs UV; depleted by CFCs (chlorofluorocarbons) from refrigerators and ACs
- →Waste management: reduce, reuse, recycle; biodegradable vs non-biodegradable waste
Exam Day Strategy
- →Diagrams: draw large, neat, labelled; use pencil for diagrams, pen for labels and description
- →Definition questions: always include the 'what', 'where', and 'result' in one sentence
- →8-mark essay (Section IV): write in sub-sections (definition/types/diagram/examples) with a neat labelled diagram
- →Attempt all questions — partial answers get partial marks; never leave a question blank