P2 Radiation and life Revision by J Bach St. Mary’s school

Gamma* x-rays* UV* visible IR micro radio Increasing wavelength Increasing frequency/penetrating power/ likelihood of ionisation (see*)/ cell damage Electromagnetic spectrum γ

Using models Ray Wave Photon

Ionising Radiation Radiation where the photons have enough energy to knock electrons off the atom changing it into a positively charged ion. atom (no charge) This will now react with other atoms e.g. DNA damage Ion (positively charged) Lost electron

Safety with radiation UV –Sun-creams of varying spf –Clothing –“Slip, slap, slop” Micro –Metal screens Gamma/ x-rays –Lead screens Two approaches to safety… Precautionary Principle… removing a group from a potential risk just in case! ALARA principle [as low as reasonably achievable] accepting risk but taking measures to minimise it!

Factors affecting the damaging effects of radiation Energy of photon [packet of radiated energy] Intensity [number of photons arriving per second] Duration of exposure Medium through which the radiation travels (some absorb more than others) Distance from source

Where does the radiation go to? reflected Absorbed so surroundings warm up Transmitted From source Molecules vibrate detected

The Greenhouse Effect 1)Heat and light energy reach us from the sun… but most of the UV radiation is absorbed by ozone 2) …a lot of this heat is reflected off the Earth’s surface… 3) …some of the heat escapes back into space… 4) …while some of it is reflected back to the Earth – this is called The Greenhouse Effect (involves the gases CO 2, CH 4 and H 2 O) Temperatures are stable if the energy leaving the atmosphere equals that gained! Less leaving than entering means global warming

Increasing the Greenhouse Effect 1._________ of fossil fuels (releasing CO 2 ) 2.__________ (removing trees that remove CO 2 ) 3.Increased micro organism activity (from rotting ______) 4.Cattle and rice fields (they both produce _______) These changes will cause GLOBAL WARMING RISING SEA LEVELS/FLOODING due to ice caps melting and __________ of water CLIMATE CHANGE with severe weather for some countries LOSS OF HABITATS and so extinction of many species Words – methane, combustion, deforestation, waste, expansion

Global Warming Is it worrying that… 1)The 10 warmest years of the last century have all occurred within the last 15 years 2)Sea levels have risen by between 12 and 24cm in the last 100 years… By looking at trends we can predict future temperatures and rainfall using computer modelling. The models are only as good as the data input into them and many contradict each other. However most agree on the increasing average global temperatures... ?