Condensed notes on the topics in the Biology GCSE (AQA spec but also relevant to many other courses) that I found the hardest to remember and understand. Topics include:
- Human Influences on the Environment (including effects of farming and pollution)
- Gas Exchange and Transport in Plants
Ec...
Biology
Human Influences on the Environment
Eutrophication
• Fertilisers or sewage are leached into water
• Nitrate levels rise
• Causes algae to grow – algal bloom
• Light is blocked so plants can’t photosynthesize
• Plants die and are decayed by bacteria
• Water becomes anoxic – more respiration from bacteria
• Aerobic fish die
Pesticides
Chemical Pesticides – chemical poisons that kill pests (e.g. DDT)
• Easy to use
• Fast effect
• Cheap
• Reduces biodiversity
• Pesticide resistance
• Bioaccumulation
Biological control – using a predator to control pest numbers (e.g. cane toad)
• Single use
• Specific to pest
• No bioaccumulation or toxins
• Difficult to contain and control
• Doesn’t completely eliminate pest
• Imbalance to food chain and ecosystem
Acid Rain
Sulfuric Acid – sulphur dioxide released from fossil fuels, dissolves in rain
Nitric Acid – nitrogen oxides released in car fumes, dissolve in rain
Effects:
• Damages leaves and roots- can’t photosynthesize or get minerals
• Acidic lakes – fish die/don’t hatch, amphibians’ skin is damaged
• Ions dissolve more, so are leached away with rain, reducing soil fertility
, Carbon Monoxide
Made during incomplete combustion of fossil fuels and plastics
Bonds strongly to haemoglobin in blood, reducing its ability to carry oxygen
Global Warming
Greenhouse Gases:
• Carbon dioxide – from fossil fuels
• Methane – from agriculture, e.g. cows, rice
• CFCs – from aerosols and refrigerators
Greenhouse gases – short-wave radiation from sun is absorbed and reflected by
greenhouse gases as long-wave radiation – stuck in atmosphere
Effects:
• Rising sea levels
• Changes in ocean currents
• Changes in rainfall patterns
• Changes in migration patterns
• New crop pests
• Species extinction
Deforestation
Causes:
• Agriculture
• Population increase – housing
• Wood used for timber
Effects:
• Erosion of soil
• Ions leached
• Imbalance of water cycle
• Carbon dioxide levels rise
• Oxygen levels decrease
• Loss of habitats
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller minniefn. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.98. You're not tied to anything after your purchase.
