How do glasshouses increase yield?
Reveal answer
Warmth + extra CO₂ + light + no pests → more photosynthesis.
Key words: CO₂
6(a) FOOD PRODUCTION · RECALL
6.1 Glasshouses and polythene tunnels
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Why burn paraffin in a glasshouse?
Reveal answer
Adds heat and CO₂.
Key words: heat
Cheaper alternative to a glasshouse?
Reveal answer
Polythene tunnel.
Key words: polythene
Why do glasshouses warm up?
Reveal answer
Light enters → infrared trapped.
Key words: infrared
What is meant by the term yield?
Reveal answer
The amount of useful crop produced per area.
Key words: yield
What is meant by the term polythene tunnel?
Reveal answer
A tunnel-shaped plastic structure that encloses crops.
Key words: polythene tunnel
What is meant by the term hydroponics?
Reveal answer
Growing plants in mineral nutrient solutions without soil.
Key words: hydroponics
Controlled conditions in protected cropping, Temperature. How it is controlled? Effect on yield?
Reveal answer
How it is controlled: Trapped heat; heaters. Effect on yield: Faster enzyme-controlled reactions and growth; longer season.
Key words: Temperature
Controlled conditions in protected cropping, Light. How it is controlled? Effect on yield?
Reveal answer
How it is controlled: Transparent cover; artificial lighting. Effect on yield: Photosynthesis continues for longer each day.
Key words: Light
Controlled conditions in protected cropping, Carbon dioxide. How it is controlled? Effect on yield?
Reveal answer
How it is controlled: Paraffin heaters or CO₂ supply. Effect on yield: Removes CO₂ as a limiting factor.
Key words: Carbon dioxide
Controlled conditions in protected cropping, Water and minerals. How it is controlled? Effect on yield?
Reveal answer
How it is controlled: Irrigation or hydroponics. Effect on yield: Prevents wilting and mineral deficiency.
Key words: Water and minerals
Controlled conditions in protected cropping, Pests and weather. How it is controlled? Effect on yield?
Reveal answer
How it is controlled: Physical barrier. Effect on yield: Less crop damage and loss.
Key words: Pests and weather
True or false, and why? “Glasshouses make plants grow by giving them more oxygen.”
Reveal answer
False. They mainly control temperature, light and carbon dioxide for photosynthesis.
True or false, and why? “Enclosed crops cannot get pests.”
Reveal answer
False. Pests can enter and may spread quickly in warm, humid conditions.
True or false, and why? “Increasing one factor always increases yield.”
Reveal answer
False. Only increasing the limiting factor increases the rate.