HSC Exam Practice

Sample response. Artificial insemination is the deliberate introduction of semen, collected from a selected male, into the female reproductive tract without natural mating, so that fertilisation occurs using sperm from the chosen male.

Marking notes. 1 mark — identifies it as the introduction of semen from a selected male into the female reproductive tract. 1 mark — explicitly states "without natural mating" or "to control which sperm fertilises the egg".

Sample response. Step 1 — Semen is collected from a selected high-merit Holstein bull (e.g. ranked on Australian Breeding Values). Step 2 — The semen is tested, diluted and/or frozen for storage and transport. Step 3 — At the correct time in the cow's reproductive cycle (typically detected by oestrous behaviour), the semen is introduced into her reproductive tract using a catheter, allowing fertilisation by sperm from the chosen bull.

Marking notes. 1 mark per step in correct order; the timing of insertion in the female's cycle must be referenced for the third mark.

Sample response. Artificial insemination — the breeder moves sperm (in semen); fertilisation occurs internally in the female reproductive tract. Artificial pollination — the breeder moves pollen (carrying male gametes); fertilisation occurs inside the ovule of the recipient flower after pollen lands on the stigma.

Marking notes. 1 mark — correct gamete + site for AI. 1 mark — correct gamete + site for AP.

Sample response. Both technologies control the reproductive event — which sperm enters the female tract (AI) or which pollen reaches the stigma (AP). They do not alter the DNA sequence of any gamete; the alleles carried by the sperm or pollen were already produced by ordinary meiosis in the selected parent. Fertilisation, gamete fusion and the development of offspring proceed by normal biological mechanisms. The technologies therefore change which alleles combine, not the base sequence inside any gene.

Marking notes. 1 mark — identifies that AI/AP control the reproductive event (which gametes combine). 1 mark — states that DNA sequence is not edited; alleles arise from normal meiosis in the parent. 1 mark — explicitly distinguishes "changing which alleles combine" from "changing DNA sequence" (the syllabus contrast with direct genetic technologies).

Sample response (a). Both herds start at almost the same yield (≈6 200 L/cow/year). Across Years 1–5, Herd X (natural service) rises only slightly (6 200 → ≈6 350 L, ≈2% increase), while Herd Y (AI) rises substantially and continuously (6 250 → ≈7 510 L, ≈20% increase). The gap between the herds widens every year.

Sample response (b). AI lets Herd Y inseminate its cows with semen from a small number of selected, top-ranked Holstein bulls rather than the stud's average on-farm bulls. This is controlled breeding: the breeder chooses which sperm fertilises each ovum. Because the chosen bulls carry alleles associated with high milk yield, the probability that their daughters inherit yield-related allele combinations is greater than for daughters of average bulls — this is trait control, expressed across the whole herd. Herd X, breeding from its own less selectively chosen bulls, gains far less in each generation, so its average yield rises only slightly.

Marking notes. Part (a) — 1 mark for identifying both starting yields as similar and Herd Y rising faster; 1 mark for quoting at least one supporting figure (e.g. 7 510 vs 6 350 L). Part (b) — 1 mark for explicitly invoking selected males (high-merit bulls / ABV); 1 mark for using controlled breeding correctly (breeder chooses which sperm fertilises each egg); 1 mark for linking allele inheritance to herd-wide yield trend (trait control + productivity).

Sample response. Percentage increase = (32 − 18) ÷ 18 × 100 ≈ 78%. Kiwifruit are dioecious — male and female flowers are on separate vines — and the flowers are not particularly attractive to bees, so open pollination often fails to deliver enough pollen to female-flower stigmas, capping fruit set and yield. Artificial pollination, by definition the deliberate transfer of chosen pollen to a stigma, directly bypasses that bottleneck: the grower places ample selected pollen on every female stigma, lifting fertilisation rates and therefore tonnes-per-hectare yield.

Marking notes. 1 mark — correct percentage calculation (≈78%, accept 77–78%). 1 mark — identifies that kiwifruit's dioecious / poor-bee-attractant biology limits open pollination. 1 mark — explicitly connects the lesson's definition of artificial pollination (deliberate transfer of chosen pollen to the stigma) to overcoming that limit and lifting yield.

Sample response. Artificial insemination (AI) and artificial pollination (AP) are reproductive technologies that increase human control over fertilisation. AI operates in animal reproduction — semen is collected from a selected male (e.g. a Holstein–Friesian dairy bull rated highly on the Australian Breeding Values index, or a Merino ram rated on MERINOSELECT for clean fleece weight), prepared or frozen, and introduced into the female reproductive tract at the correct point in her cycle. AP operates in flowering-plant reproduction — pollen is collected from a chosen donor and transferred onto the stigma of a selected recipient flower while unwanted pollen is excluded; in commercial Australian use, kiwifruit growers in the NSW Riverina routinely hand-pollinate because the flowers are dioecious and poorly visited by bees, and Tasmanian apple breeders make controlled crosses to combine yield with disease resistance. The two technologies are similar in purpose — both control which parental gametes combine, both are forms of controlled breeding, and both aim to make selected inherited trait combinations more likely in offspring — but differ in process: AI moves sperm and fertilisation occurs internally; AP moves pollen and fertilisation occurs inside the ovule after pollen lands on the stigma. The outcome of each is also bounded: neither edits any DNA sequence — they only change which alleles combine, while meiosis and fertilisation in the parents are unchanged — and neither guarantees an individual offspring's phenotype because traits such as milk yield, fleece weight and fruit yield are polygenic and influenced by environment. Overall, AI and AP are highly useful in Australian agriculture because they raise the probability of desirable inherited trait combinations and let elite parents contribute to large numbers of offspring, but their power is best described as probabilistic trait control, not deterministic genetic engineering.

Marking notes. 1 mark — defines AI and AP and assigns them to animal / flowering-plant systems. 1 mark — names a valid Australian agricultural example for AI (e.g. Holstein dairy, Merino sheep, beef cattle). 1 mark — names a valid Australian agricultural example for AP (e.g. Riverina kiwifruit, Tasmanian apple, Goulburn Valley pear). 1 mark — describes the AI process step-by-step (collect, prepare/store, introduce). 1 mark — describes the AP process step-by-step (collect from donor, transfer to recipient stigma, exclude unwanted pollen). 1 mark — explicitly contrasts the two on at least one further criterion (gamete moved, site of fertilisation, intended outcome or agricultural context). 1 mark — reaches an explicit evaluative judgement that invokes the outcome limit (no DNA editing; no guaranteed phenotype; probability not certainty) and links AI/AP to controlled breeding and productivity.