Biology Paper 2 - Jogger notes

Description

These contain everything for paper 2, but some paper 2 can be found in biology IGCSE flashcards, so use both before exam
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Resource summary

Question Answer
Mutations Occur when the chromosome does not copy itself properly. They are spontaneous
Mutation A rare, random change in the organism's DNA that can be inherited
Carcinogen Chemicals that can increase chances of mutations, which can cause cancer, by making the cells divide uncontrollably
Precipitation When water falls from clouds, this can be in form of rain, sleet or snow
Decomposers They break down the proteins in animal waste, animals, and plants, into ammonia, which is a nitrogen compound
Difference between nitrifying bacteria, and nitrogen fixing bacteria Nitrifying bacteria converts ammonia in decaying matter into nitrates Nitrogen fixing bacteria converts nitrogen in air into nitrates that plants can use
Fermenters Used for industrial scale production of microbial products
Fermenter decription Large containers
Conditions of fermenters Designed to increase product yield as much as possible
Use of superheated steam To kill any microorganisms-vessels are sterilised between uses with this
Why do microorganisms decrease product yield? Because they contaminate the product, and they compete with the lactobacillus bacteria for nutrients for growth
Why must pH be monitored? To keep optimum pH for maximum yield and fast rate of reaction
Aceptic and abiotic Sterile, and non living- ecosystems consist of the organisms and the abiotic conditions in an area, like light, temp, pH of soil
Why is it important that air cannot get into fermenters used in production of beer? So that the yeast ferment the sugar ANaerobically, to produce ethanol
Why do you pasteurise milk and beer? To kill off the microoganisms, and to kill off any yeast so that fermentation completely stops. Beer tastes better when unpasteurised and aged in right conditions, but big breweries pasteurise beer as there is a risk unpasteurised beer will spoil
Transgenic organisms These organisms contain a gene from a different species in their DNA-like transgenic bacteria such as bacteria with the gene for human insulin
Gene Code for a particular protein A gene is a section of a molecule of DNA
How can gm be used in medicine? You can genetically modify the DNA of cows and goats by inserting the human genes for making useful proteins in them, so that they produce medicine in their milk . For example, human antibodies can be used in therapy to treat some cancers, and multiple sclerosis, and arthritis.
Iris reflex In bright light, circular muscles contract, so radial relax, and pupils constrict
Accomodation How the eye focuses light by changing the shape of the lens To look at distant objects, cilary muscles relax, suspensory ligaments pull tight, and lens becomes thin
Why do old people need reading glasses? Because, as you get older, your lens loses flexibility so it cannot easily spring back into a round shape to focus on near objects, so reading glasses are necessary to focus the light
Short sighted people Problem: either the eyeball is too long, or the cornea or lens bends light to much Result: image is brought into focus in front of the retina.
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