use of biological resources biology p2 Flashcards
what is the yield?
how much of something is produced
- can be increased by growing crops in glasshouses of polythene tunnels
- these allow farmers to control:CO2 levels and temperature
- keeping them enclosed keeps them free of pests and diseases
- use artificial light
- trap the sun’s heat and keep plants warm
- increase CO2 by using a paraffin heater- CO2 is a by-product
what happens when you increase CO2 levels?
-increased yield and increased rate of photosynthesis
what happens when you increase temperature?
increased yield and increased rate of reaction
why are fertilisers used?
- add nutrients to the soil(nitrogen, potassium and phosphates) to make proteins
- can be chemical or organic
- increase crop yield
what are pesticides?
- chemicals that are used to kill pests
- herbicides (kill plants)
- insecticides (kill insects)
why is biological control good and bad?
they are long lasting and can be less harmful to wildlife but introducing new wildlife can be a problem
why are pesticides bad?
poisonous to humans so be careful how much to put on food
they can harm other wildlife
what is biological control?
an alternative to pesticides. It means using other organisms to reduce the numbers of pests, by either encouraging wild organisms or adding new ones
what’s an example of biological control?
where: Australia
pest: cane beetles
problem: eating sugarcane crops
solutions: introduce cane toads to eat the beetles
issues: toads become pests because they poison the native species that eat them
what are the advantages/disadvantages of pesticides ?
adv: chemicals kill most things, fast acting, many specialised types
disadv: kill things you don’t want them to kill, can get into soil and waterways, expensive
what are the advantages/disadvantages of biological control?
adv: cheap, no chemicals used
disadv: introduced species can take over and become pests, slower process, less reliable
define biotechnology
the use of living organisms to make useful chemicals and products or to perform an industrial task
how is yeast used to brew beer?
1) need to get the sugar out of the grain
- beer is made from grain (barley)
- the grains are allowed to germinate for a few days were starch is broken down into sugar by enzymes- grains are then dried in a kiln= malting
- the malted grain is then mashed up and water added to make a sugary solution with lots of bits in it- then sieved
- hops are added to give bitter flavour
2) yeast is added to mixture then its incubated. the yeast ferments the sugar into alcohol. the fermenting vessels are designed to stop unwanted microorganisms and air getting in
- the rising conc of alcohol in the mixture due to anaerobic respiration starts to kill the yeast. as the yeast dies, fermentation slows down
- different species of yeast can tolerate different levels of alcohol.
- some species can be used to produce strong beer with a high concentration of alcohol
3) the beer is drawn off through a tap. sometimes chemicals called CLARIFYING AGENTS are used to remove particles and make it clearer
4) the beer is then pasteurised- heated to kill any yeast left in the beer and stop fermentation
when does beer taste better?
if it’s unpasteurised and aged in the right conditions but big breweries pasteurise it as there’s a risk that unpasteurised beer will spoil if not left in the right conditions after its sold
why might some organisms be selectively bred?
1- maximum yield of meat, grain, milk
2- good health and disease resistance
3- temperament, speed, fertility, good mothering skills
4- plants have attractive flowers, nice smell
stages of selective breeding?
1) from existing stock, select the ones with the best characteristics
2) breed them with each other
3) select the best of the offspring and breed them together
4) continue this process over several generations, and the desirable trait gets stronger and stronger- better yields
what can selective breeding be useful for?3 things
1- increase the productivity of cows-selectively bred to produce offspring with e.g. high meat yield
2- increase the number of offspring in sheep- females who produce large numbers of offspring bred with rams whose mothers had large no. offspring
3- increase crop yield- get 2 desirable characteristics
tall wheat plants have good grain yield but easily damaged by wind and rain
dwarf wheat plants can resist wind and rain but have a lower grain yield
-both are cross-bred so new variety with the best characteristics- dwarf wheat plants which could resist bad weather and had a high grain yield
what do fish farms do?
rear fish in a controlled way that’s designed to produce as many fish as possible
how are salmon fished in cages?
1) kept in cages in the sea to stop them using as much energy swimming about
2) the cage protects them from interspecific predation
3) the’re fed a diet of food pellets that’s carefully controlled to maximise the amount of energy they get. The better the quality of food, the quicker and bigger the fish will grow= good source of protein
4) young fish are reared in special tanks so as many survive as poss
5) younger fish kept separate from bigger fish, and to provide regular food-make sure the big fish don’t eat the little ones. this is intraspecific predation
however:
6) fish kept in cages are more prone to disease and parasites. One pest is sea lice, which can be treated with pesticides to kill them. To avoid pollution from chemical pesticides, biological pest control can be used instead: small fish called a wrasse eats the lice off the backs of the salmon
7) the fish can be selectively bred to produce less aggressive, faster-growing fish
how else are fish farmed?
in tanks or ponds where conditions can be controlled
- water is monitored to check the temp, pH and O2 levels
- control food supplied and give exactly the right sort
- the water can be removed and filtered to get rid of waste food and fish poo. this keeps the water clean for the fish and avoids pollution wherever the water ends up
