Crops Flashcards
What is a crop?
a plant grown for food
what is a yield?
how much can be harvested for food from a plant.
why do crops grown in greenhouses grow faster than crops in fields?
they are exposed to conditions which means that they can grow earlier in the year and grow in places they wouldn’t norma.y grow
what are the conditions provided for crops in greenhouses?
- Temperature
- Light
- Carbon Dioxide
- Water
why do crops grown in glasshouses produce higher yields?
They are warmer as the glass traps thereat energy.
What do higher temperatures in greenhouses/glasshouses cause?
Increase. the rate of photosynthesis by increasing enzyme activity.
how is CO2 concentration increased in glasshouses?
by using paraffin heaters
why is a high CO2 concentration beneficial?
More CO2 = more photosynthesis which means more glucose which results in more starch, more glucose and higher yields.
what are polytunnels?
These structures made from polythene warm up the soil and protect the crops from frosts, therefore planners can be grown earlier in the year.
what are fertilisers?
chemicals that are used by farmers to increase the yield of crops.
what do fertilisers contain?
nitrogen - growth of leaves and stems
phosphorus - healthy roots
potassium - healthy leaves and stems
magnesium - make chlorophyll
what are pests?
living organisms that decrease the yield of crops
what do insects do to crops?
eat the crops or spread disease
what do weeds do to crops?
compete with the crops for light, nutrients and water in the soil.
what do fungi do to crops?
moulds that grow on pollen causing disease
what are pesticides?
chemicals that kill pests
what is the pesticide that kills insects called?
insecticide
what is the pesticide that kills fungi called?
fungicide
what is the pesticide that kills weeds called?
herbicide
what are the problems with pesticides?
they can kill all organisms, not just pests.
they can contaminate food chains.
they can contaminate food products with chemicals that can be harmful to humans.
name a fish that is commonly eaten and where it is farmed
salmon, Scotland.
why are the fish kept in cages in the sea?
to stop them using too much energy
why is there a net over the top of the fish cage?
to stop predators like birds being able to get to the fish
what is the fish’s diet like in fish farming?
They are fed on a carefully controlled diet of pellets to maximise the amount of energy they get. The better the quality of food is the quicker and bigger the fish will grow.
name a pest that can affect the fish in fish farming
sea lice
name a method of biological pest control that is used in fish farming
wrasse - eat the sea lice
what is biological pest control?
Uses natural predators, parasites of pathogens to control pests
advantages of biological pest control
- only targets pest species
- reduces use of pesticides
name some advantages of fish farming
- selective breeding is used to improve quality of the fish
- kept in large tanks where water quality is carefully managed
Disadvantages of fish farming
- fish are at greater risk of infection
- wild fish have to be killed to make food for farmed fish
what is interspecific competition?
competition for food between members of different species
what is intraspecific competition?
competition for food between members of the same species
how is yeast beneficial in breadmaking?
When yeast respires it releases carbon dioxide which makes the bread rise
how is yeast beneficial in producing alcohol?
It respires anaerobically to make ethanol
what is the bacteria that is added to milk to make yoghurt?
lactobacillus bulgaricus
how does lactobacillus bulgaricus turn milk into yoghurt?
It respires anaerobically
lactose —–> lactic acid.
The lactic acid lowers the pH which dentures the proteins in the milk. The protein becomes unsoluble which thickens the milk.
what are industrial fermenters used for?
to grow microorganisms on a large scale.
what are the conditions required to grow microorganisms in an industrial fermenter?
- aseptic precations
- nutrients
- optimum pH and temp
- agitation (stirring)
