{"count":14,"total":74,"data":[{"id":"q2","topicId":"photosynthesis","command":"Explain","type":"explain","marks":4,"prompt":"Explain how light intensity acts as a limiting factor for photosynthesis.","markScheme":["Define limiting factor as the factor in shortest supply controlling the rate (1)","Rate increases as light intensity rises (1)","Plateau reached when another factor (CO₂, temperature) becomes limiting (1)","Reference to commercial use, e.g. supplementary lighting in glasshouses (1)"],"modelAnswer":"A limiting factor is the environmental factor in shortest supply that controls the rate of photosynthesis. As light intensity increases, the rate of photosynthesis increases proportionally because more light energy is available to drive the light-dependent reactions. The rate then plateaus once another factor, typically carbon dioxide concentration or temperature, becomes limiting. Growers exploit this in protected cultivation by providing supplementary lighting to maintain higher rates during winter months."},{"id":"q-resp2","topicId":"respiration","command":"Explain","type":"explain","marks":4,"prompt":"Explain why waterlogged soil is harmful to plant roots.","markScheme":["Waterlogging displaces air from soil pores (1)","Roots are deprived of oxygen so aerobic respiration cannot occur (1)","Roots switch to anaerobic respiration producing ethanol, which is toxic (1)","Root death follows, leading to wilting and entry points for pathogens (e.g. Phytophthora) (1)"],"modelAnswer":"Waterlogging fills the soil pore spaces with water, displacing air. Roots then lack oxygen and cannot carry out aerobic respiration, so they switch to anaerobic respiration which produces ethanol — a toxin that damages root tissue. The dying roots are unable to absorb water, causing the plant to wilt, and the damaged tissue allows entry of pathogens such as Phytophthora."},{"id":"q-cls1","topicId":"plant-classification","command":"Explain","type":"explain","marks":4,"prompt":"Explain why botanical names are preferred to common names in horticulture.","markScheme":["Common names vary by region and language (1)","Botanical names are unique and internationally recognised (1)","Allow precise communication, e.g. between nurseries and gardeners (1)","Genus + species (binomial) identifies one plant unambiguously (1)"],"modelAnswer":"Common names vary between regions and languages, so the same plant can have several names or different plants can share a name. Botanical names use the Latin binomial — genus followed by species — which is unique and internationally recognised. This allows nurseries, garden designers and growers to communicate precisely about exactly the same plant, which is essential when ordering, prescribing chemical treatments or specifying for landscape contracts."},{"id":"q-ph","topicId":"soil-improvement","command":"Explain","type":"explain","marks":4,"prompt":"Explain why and how lime is applied to an acidic vegetable plot.","markScheme":["Why: raise pH so nutrients (P, K, Ca, Mg) become more available (1)","Why: reduces clubroot risk in brassicas (1)","How: apply ground limestone in autumn/winter at recommended rate (1)","How: incorporate into top 10–15 cm; do not apply with manure (1)"],"modelAnswer":"Lime is applied to acidic soil to raise the pH towards 6.5–7.0, the range in which most vegetable nutrients (especially phosphorus, calcium and magnesium) are most available. A pH near 7 also discourages clubroot in brassicas. Ground limestone (calcium carbonate) is applied in autumn or winter at a rate determined by a pH test (typically 250–500 g/m²), spread evenly and lightly incorporated into the top 10–15 cm of soil. Lime is not applied at the same time as manure or nitrogenous fertiliser, as ammonia would be lost."},{"id":"q-water","topicId":"water-management","command":"Explain","type":"explain","marks":4,"prompt":"Explain the benefits of mulching the surface of an ornamental border.","markScheme":["Conserves soil moisture by reducing evaporation (1)","Suppresses annual weeds by excluding light (1)","Moderates soil temperature, insulating roots (1)","Organic mulches add OM, improving structure and fertility (1)"],"modelAnswer":"A surface mulch conserves soil moisture by reducing direct evaporation, allowing less frequent watering. It suppresses annual weeds by excluding light from weed seeds, and moderates soil temperature — keeping roots cooler in summer and warmer in winter. Organic mulches such as bark or composted green waste also break down to add organic matter, improving soil structure and fertility over time."},{"id":"q-fruit","topicId":"top-fruit","command":"Explain","type":"explain","marks":4,"prompt":"Explain why rootstocks are used for apple production.","markScheme":["Control tree size for a given site (1)","Bring trees into cropping earlier (precocity) (1)","Provide disease/pest tolerance (e.g. crown rot) (1)","Allow consistent propagation of named cultivars (which do not come true from seed) (1)"],"modelAnswer":"Rootstocks control the eventual size of the tree — for example M27 produces a dwarf tree suitable for cordons, while MM106 makes a semi-vigorous bush. They also bring trees into cropping earlier (precocity) and can confer tolerance to soil-borne pests and diseases such as crown rot. Crucially, named apple cultivars do not come true from seed, so grafting onto a rootstock is the only way to propagate them reliably and consistently."},{"id":"q7","topicId":"pruning","command":"Explain","type":"mock","marks":6,"prompt":"Explain how and why a mature apple tree on MM106 rootstock would be pruned in winter.","markScheme":["Timing: dormant season, Nov–Feb when sap is down (1)","Remove dead, diseased and damaged wood first (1)","Remove crossing/rubbing branches to open centre (1)","Shorten leaders by one third to outward-facing bud (1)","Spur prune laterals to 3–5 buds to encourage fruiting (1)","Reason: improve light/air, balance growth vs fruiting, manage size (1)"],"modelAnswer":"Winter pruning is carried out in the dormant season, typically November to February, when the tree is not in active growth and disease pressure is low. Begin by removing the three Ds — dead, diseased and damaged wood — then take out crossing or rubbing branches to create an open, goblet-shaped framework that admits light and air. Shorten the leaders by approximately one third, cutting to an outward-facing bud to encourage an open habit. Lateral shoots are spur pruned back to three to five buds to promote the formation of fruiting spurs. The purpose is to balance vegetative growth with fruit production, improve fruit quality through better light penetration, and maintain a manageable tree size on the semi-vigorous MM106 rootstock."},{"id":"q-est","topicId":"establishment","command":"Explain","type":"explain","marks":5,"prompt":"Explain the aftercare needed for a newly planted tree in its first two years.","markScheme":["Water deeply during dry periods — focus on first growing season (1)","Maintain a weed-free area 1 m around base (1)","Mulch annually to retain moisture and add OM (1)","Check, adjust and remove stake/tie after 2 years (1)","Formative prune to develop balanced framework (1)"],"modelAnswer":"During the first growing season water the tree deeply once a week in dry weather, soaking the rootball area, and continue in dry spells through year two. Keep a one-metre weed-free circle around the base to remove competition for water and nutrients, and renew an organic mulch annually, leaving a gap around the stem. Inspect the stake and tie every few months, loosening as the trunk thickens, and remove after about two years once the tree is anchored. Carry out light formative pruning in the dormant season to remove damaged, crossing or competing leaders and to build a balanced framework."},{"id":"q-graft","topicId":"grafting","command":"Explain","type":"explain","marks":4,"prompt":"Explain why whip-and-tongue grafting is used to propagate apple cultivars.","markScheme":["Apples do not come true from seed (1)","Whip-and-tongue gives large cambial contact and a strong mechanical join (1)","Allows pairing of named scion with a chosen rootstock for size control (1)","Carried out late winter when both partners are dormant but sap rising (1)"],"modelAnswer":"Named apple cultivars do not come true from seed, so they must be propagated vegetatively. The whip-and-tongue graft creates matching sloping cuts with an interlocking tongue, giving a large area of cambial contact and a strong mechanical join that resists slipping. It allows the chosen scion cultivar to be paired with a selected rootstock to control eventual tree size and vigour. It is carried out in late winter, when both partners are still dormant but the sap is starting to rise, ensuring rapid callusing and successful union."},{"id":"qx-trans2","topicId":"transpiration","command":"Explain","type":"explain","marks":4,"prompt":"Explain how stomata regulate water loss from a leaf.","markScheme":["Stomata are pores flanked by guard cells (1)","Guard cells become turgid in light, opening pore (1)","Loss of turgor at night/drought closes pore (1)","Open stomata allow CO₂ in but also water vapour out (1)"],"modelAnswer":"Stomata are pores in the leaf epidermis, each flanked by a pair of guard cells. In light, guard cells take up potassium ions and water, become turgid and bow apart, opening the pore. In darkness or drought stress they lose turgor and close, reducing water loss. The plant balances CO₂ uptake for photosynthesis with water loss by transpiration."},{"id":"qx-soil2","topicId":"soils","command":"Explain","type":"explain","marks":4,"prompt":"Explain the importance of good soil structure for plant growth.","markScheme":["Aggregated peds with pore spaces (1)","Macropores hold air for root respiration (1)","Micropores retain water (1)","Allows root penetration and drainage (1)"],"modelAnswer":"Soil structure refers to how particles bind into aggregates. A good crumb structure provides macropores that hold air for root respiration and micropores that retain water. It allows roots to penetrate easily and excess water to drain, while resisting capping and erosion."},{"id":"qx-rot2","topicId":"crop-rotation","command":"Explain","type":"explain","marks":4,"prompt":"Explain why potatoes and tomatoes should not follow each other in rotation.","markScheme":["Both Solanaceae (same family) (1)","Share blight (Phytophthora infestans) (1)","Soil pests (eelworm) build up (1)","Similar nutrient demand depletes soil (1)"],"modelAnswer":"Potatoes and tomatoes are both Solanaceae and share major pests and diseases — most notably potato blight (Phytophthora infestans) and potato cyst nematode. Following one with the other lets pathogens build up. They also draw on a similar nutrient profile. Separate them by at least three years in rotation."},{"id":"qx-site2","topicId":"site-assessment","command":"Explain","type":"explain","marks":4,"prompt":"Explain why aspect is critical when planning a planting scheme.","markScheme":["Determines hours of direct sun (1)","South-facing = sun-lovers, drought tolerant (1)","North-facing = shade-tolerant, often damper (1)","Frost pockets in lower / northerly positions (1)"],"modelAnswer":"Aspect determines the hours of direct sunlight and therefore which plants will thrive. South-facing borders suit sun-lovers and drought-tolerant Mediterranean species (lavender, cistus). North-facing borders need shade-tolerant plants (Sarcococca, Helleborus) and may stay damper. East-facing sites can suffer from early morning sun on frosted buds (damaging Camellia), and lower positions can be frost pockets."},{"id":"qx-prune4","topicId":"pruning","command":"Explain","type":"explain","marks":4,"prompt":"Explain when and how to prune a Forsythia.","markScheme":["Immediately after flowering (Apr/May) (1)","Cut flowered stems back to strong new shoots (1)","Remove one in three oldest stems to base (1)","Flowers on previous year's wood (1)"],"modelAnswer":"Forsythia flowers on the previous year's wood, so prune immediately after flowering in April or early May. Cut flowered stems back to strong new shoots lower down, and remove around one in three of the oldest stems to the base to encourage vigorous replacement growth that will ripen and flower next spring."}]}