B3.4 Humans and their environment Flashcards
What may waste pollute?
WATER- with sewage, fertiliser, toxic chemicals
AIR–with smoke, gases such as sulfur dioxide which contributes to acid rain
LAND- with toxic chemicals such as pesticides and herbicides, which may be washed off the land into water ways
What 4 ways do humans reduce the amount of land available for other animals and plants?
by building
quarrying
farming
dumping waste
Why is deforestation happening?
to provide timber
to provide land for agriculture- Crops can be grow from which biofuels, based on ethanol can be produced. There is an increase in cattle and in rice fields to provide more food.
What has deforestation caused?
An increase in the release of carbon dioxide into the atmosphere (because of burning and the activities of microorganisms)
A reduction in the rate at which carbon dioxide is removed from the atmosphere and ‘locked up’ for many years as wood
A reduction in biodiversity
What has led to an increase in methane in the atmosphere?
The increase in the numbers of cattle and rice fields.
These organisms produce methane
What 2 organisms produce a lot of methane?
cattle, rice fields
What is an impact of the destruction of peat bogs?
Increase in carbon dioxide in the atmosphere
This is because peat bogs store carbon dioxide. When the peat is drained it starts to decompose as CO2 is released
What are peat bogs?
Areas of land that are acidic and waterlogged.
Plants that live in peat bogs do not fully decay when they die because there is not enough oxygen for microorganisms.
The partly-rotted plants gradually build up to form peat
why are ‘peat free’ composts increasing in importance?
As using peat releases carbon dioxide into the atmosphere
Using peat free composts (bark chippings, manure, ect) reduces the demand for peat
so less carbon dioxide is being added to the atmosphere
What is global warming?
an increase in the Earth’s temperature of only a few degrees Celsius
What are some predicted impacts of global warming?
- May cause big changes in the Earth’s climate
- May cause a rise in sea level
- May reduce biodiversity
- May cause changes in migration patterns, eg in birds
- May result in changes in the distribution of species
What does ‘sequestered’ mean?
locked up
What is an important factor in removing carbon dioxide from the atmosphere?
CO2 can be sequestered (locked up) in oceans, lakes and ponds
How are biofuels made?
from natural products by fermentation
Biogas, mainly methane, can be produced by anaerobic fermentation of a wide range of plant products or waste material containing carbohydrates
How can the efficiency of food production be improved?
- By reducing the number of stages in food chains
(As at each stage in the food chain, less material and less energy are contained in the biomass of organisms)
- By restricting energy loss from food animals by limiting their movement and controlling the temperature of their surrounding
- By developing new food sources like mycoprotein
Why is more waste being produced?
due to rapid growth in the human population and an increase in the standard of living
What is an example of sustainable food production?
Fish stocks in the oceans are declining
It is important to maintain fish stocks at a level where breeding continues or certain species may disappear altogether in some areas
Net size and fishing quotas play an important role in the conservation of fish stocks
What are fishing quotas and how do they play an important role in the conservation of fish stocks?
they are limits on the number and size of fish that can be caught in certain areas
This prevents certain species from being overfished
How does the limit of net size play an important role in conservation of fish stocks?
There are different limits of the mesh size of the fish net depending on what’s being fished
This is to reduce the number of ‘unwanted’ fish- ones ones that are accidentally caught. The bigger mesh size will let the ‘unwanted’ fish escape
Also means that younger fish will slip through the net, allowing them to reach breeding age
What fungus is used to produce mycoprotein?
Fusarium
How is Fusarium used to produced mycoprotein?
The fungus is grown on glucose syrup, in aerobic conditions, and the biomass is harvested and purified
What is mycoprotein?
a protein rich food, suitable for vegetarians
grown using the fungus Fusarium
What are the 2 main factors in the conservation of fish stocks?
Net size
Fishing quotas
What are the 2 main types of biogas generators?
Batch generators- make biogas in small batches. They’re manually loaded up with waste, which is left to digest, and the by products are cleared away at the end of each session- eg used in third world countries, supplying a single family
Continuous generators- make biogas all the time. Waste in continually fed in, and biogas is produced at a steady rate- eg used in large scale biogas projects- commercial generators