Biology
What NSEJS biology tests
Cell structure, plant physiology, human physiology, genetics, diversity and ecology, with items that reward mechanism over labels - why the nephron reabsorbs, why the Calvin cycle cannot run in the dark.
- Cells: prokaryotes lack membrane-bound organelles; mitochondria and chloroplasts are double-membraned; ribosomes occur in both cell types. Plant cells add a wall, a large vacuole and plastids.
- Photosynthesis: the light reaction on thylakoids yields ATP, NADPH and O₂ from water; the Calvin cycle in the stroma fixes CO₂.
- Circulation: cardiac output = stroke volume × heart rate; arteries carry blood away from the heart, not necessarily oxygenated blood.
- Excretion: filtration at the glomerulus, then selective reabsorption along the tubule.
- Genetics: Mendel's law of segregation; genotype and phenotype are distinct; each gamete carries one allele per gene.
Worked example. Two heterozygous tall pea plants (Tt × Tt) are crossed. Each parent forms T and t gametes in equal numbers, so the 2 × 2 Punnett square gives TT : Tt : tt = 1 : 2 : 1, and phenotypes in the ratio 3 tall : 1 dwarf. Therefore P(dwarf) = 1/4 and P(pure-breeding tall) = 1/4, but among the tall offspring the chance of being heterozygous is 2/3 - the classic misread.
Traps. Quoting 1 : 2 : 1 as the phenotype ratio; assuming the dominant allele is the common one; claiming all arteries carry oxygenated blood (the pulmonary artery does not); believing plants respire only at night; treating a human gamete as diploid.