Grade achieved: 9. I have put an immense amount of hard work into making this set of notes and it was well worth it as it enabled me to achieve the highest grade possible. My notes are based on class notes, online resources and the CGP textbook attached. Please don't hesitate to contact me for more...
Edexcel GCSE Biology Topic 1 - Key Concepts in Biology
Edexcel GCSE Biology Topic 2 - Cells and Control
Edexcel GCSE Biology Topic 3 - Genetics
All for this textbook (10)
Written for
GCSE
GCSE
Science
200
All documents for this subject (2033)
1
review
By: farhhan2211 • 1 year ago
Excellent clear notes - thank you
Seller
Follow
nasr786
Reviews received
Content preview
Ecosystems and Material Cycles CGP Topic 9
An ecosystem is a biological community of interacting organisms and their physical environment
Interdependence in Organisms
Habitat The place where an organism lives, e.g. a field.
Population All the organisms of one species living in a habitat.
Community All the organisms of different species living in a habitat.
Abiotic factors Non-living factors of the environment, e.g. temperature.
Biotic factors Living factors of the environment, e.g. food.
Ecosystem A community of organisms along with all the non-living (abiotic) parts of their
environment.
1. A fox is an individual organism.
2. It may belong to a population of foxes living in a woodland habitat.
3. The foxes are part of the community of other animals, birds, plants, trees and insects living in the
same habitat.
4. This community, along with abiotic factors such as the soil type, rainfall and light intensity in the
woodland make up the ecosystem.
Organisms depend on each other for things like food and
shelter in order to survive and reproduce. This is known as
interdependence. It means that a change in the population of
one species can have huge knock on effects for other species
in the same community.
e.g. If one organism is removed, others will be affected too.
Mutualism is an example of interdependence in ecosystems. It is a relationship between two organisms
where both organisms benefit.
E.g. Bees visit flowers to get nectar/pollen. And as they move from plant to plant they pollinate the
flowers. Bees get food and flowers get to have sex and produce varied offspring.
Parasitism is another example of interdependence. Parasites live very closely with a host species (e.g. in
or on them). The parasite takes what it needs to survive, but the host doesn't benefit and is often
harmed.
e.g. Fleas are parasites of mammals such as dogs. Fleas feed on their host's blood, but don't offer
anything in return. They can cause serious disease in cats and dogs too.
, Changes to the Ecosystem
Changes to the biotic (living) and abiotic (non-living) factors in an environment will affect everything living
there. For every change there will be winners and losers:
- Some populations will increase, whereas other populations will decrease
- And the distribution of populations may change too while some populations might not change
much at all
Light
Temperature Plants need light for photosynthesis – they
Organisms survive best at certain temperatures. If the are the producers in most ecosystems
temperature changes, some organisms might die but some
might move in from elsewhere. As trees grow and provide more shade,
grasses may be replaced by fungi (or mosses,
As temperatures rise, Britain might become more hospitable to etc.) which are better able to cope with the
species that couldn't survive here before. Certain birds or fish. lower light intensity. Pollution might reduce
While in Australia rising sea temperature might kill corals of the amount of light reaching a habitat.
the great barrier reef.
Pollutants
Pollution refers to the presence of harmful substances in the environment – substances which may have
harmful or poisonous affects
E.g. The number of fish in polluted rivers may decrease.
Lichens can’t survive if the concentration of sulphur dioxide (an air pollutant) is too high. An increase in SO2 from
cars is bad for lichen numbers. But some hardy species might thrive in conditions other organisms can’t tolerate
Predators Water
All organisms have their place in the food chain/food webs. In a All organisms need water to live so a
community containing prey and predators (as most of them do), change in the availability of water usually
the population of any species is usually limited by the amount of has a big effect on communities.
food available.
E.g. daisies grow best in soils that are
E.g. if the number of lions (predators) decreases then the number slightly damp. If the soil becomes
of gazelles (their prey) might increase because fewer of them will waterlogged or too dry, the population of
be eaten by the lions. daisies in that area will decrease.
Competition
There is only a finite amount of each resource (e.g. land, food, mates etc.). And organisms must compete with
each other for access to these resources. Organisms with characteristics enabling them to compete better are
more likely to survive and reproduce – driving evolution
E.g. Red and grey squirrels live in the same habitat and eat the same food. Competition with the grey squirrels for
these resources in some areas means there's not enough food for the reds - the population of red squirrels is
decreasing, partly as a result of this.
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 nasr786. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.22. You're not tied to anything after your purchase.
