NCEA Level 2 Biology cheat sheet

Internal standards are assessed by teacher-observed practical work or a written report; evidence must be your own and collected under supervised conditions, so keep raw data sheets, logbooks and dated drafts.

AS91153 (Practical investigation, 4 credits) requires a purpose, a testable hypothesis, a controlled variable plan, replicated measurements, processing of data (mean, range, graph), a biological conclusion and discussion of validity.

AS91154 (Biological validity of information, 4 credits) requires you to judge the credibility of a source by author expertise, publication process, date, citations, and whether claims are supported by evidence rather than anecdote.

AS91155 (Adaptation of plants or animals, 3 credits) requires linking a named structural, behavioural or physiological adaptation to the habitat and explaining the selection pressure that favours it.

AS91158 (Pattern in an ecosystem, 3 credits) requires a described pattern (e.g. zonation, succession, species richness gradient) plus an explanation using abiotic factors, competition or predation, and biological interaction evidence.

AS91160 (Microorganisms and the environment, 3 credits) requires describing a procedure for culturing or controlling microbes, aseptic technique, and explaining the effect of an environmental factor on microbial growth.

In ecology fieldwork, sampling methods must match the organism: quadrats (with random placement) for sessile organisms, transects for gradients, pitfall traps for ground invertebrates, and mark-recapture for mobile animals.

Reliability is increased by replication and repeat sampling; validity depends on whether the method actually measures the variable claimed, so identify confounding variables explicitly.

Merit and Excellence require explaining (not describing) and then evaluating - comparing alternatives, discussing limitations, and justifying the conclusion with specific evidence from your own data.

AS91156 (Life processes at the cellular level, 4 credits) covers photosynthesis and respiration: photosynthesis as light energy converted to chemical energy in glucose, respiration as glucose breakdown releasing ATP.

Photosynthesis equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2, occurring in chloroplasts; light reactions on thylakoid membranes, Calvin cycle in the stroma.

Aerobic respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP, beginning with glycolysis in the cytoplasm and continuing in mitochondria; anaerobic respiration in animals yields lactate, in yeast yields ethanol and CO2.

AS91157 (Genetic variation, 4 credits) requires explaining meiosis, crossing over and independent assortment, mutation, and fertilisation as sources of variation, and predicting ratios using monohybrid and dihybrid crosses.

Monohybrid cross of heterozygotes gives 3:1 phenotype and 1:2:1 genotype; a dihybrid cross of two heterozygotes gives 9:3:3:1 if genes are unlinked; test crosses identify unknown genotypes.

AS91159 (Gene expression, 4 credits) covers DNA structure, the role of DNA in protein synthesis via transcription (in the nucleus) and translation (at ribosomes), and how the environment can affect phenotype.

Mutation in a gene alters the mRNA codon sequence and therefore the amino acid sequence and protein shape, which can change the phenotype; a base substitution may be silent, missense or nonsense.

AS91169 (Biological issues, 4 credits) requires explaining the biological concepts behind an issue, the perspectives of different groups, and evaluating a proposed personal or societal response.

In externals, command words matter: describe = state features; explain = give reasons using biological ideas; discuss/evaluate = weigh evidence and reach a justified judgement.