Leaving certificate biology
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Unit 1Ecology theory5 Topics|1 Quiz
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Nutrient recycling4 Topics|1 Quiz
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Ecological relationships and population dynamics2 Topics
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Human impact on the ecosystem2 Topics
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Study of a grassland ecosystem3 Topics
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Responses in the Flowering Plant4 Topics|1 Quiz
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Unit 3Sexual reproduction in the flowering plant1 Topic
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The human reproductive system3 Topics
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The menstrual cycle2 Topics
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Pregnancy2 Topics
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The circulatory system4 Topics
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Blood5 Topics
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The heart5 Topics
Ecological relationships and population dynamics
Populations
- A population comprises all the members of a species in an area
Biotic factors that control population size
1. Competition:
- Competition is the struggle between two or more organisms for a resource that is in short supply
Animals compete for:
- Food
- Water
- Shelter
- Territory
- Mates
Plants compete for:
- Space
- Light
- Water
- Minerals
Types of competition
- Contest competition:
Contest competition occurs when there is an active, physical struggle between different organisms
Example: male deer compete with each other for females
- Scramble competition:
Scrample competition means that all the competing organisms get some of the resources
Example: Seedlings growing in overcrowded conditions compete for resources but none get enough
2. Predation:
Predation occurs when an animal (predator) kills and eats another animal (prey) for food.
Adaptations of predators:
- The colour of a fox’s coat helps to camouflage
- Hawks excellent eyesight helps them tom see their prey
Adaptations of prey:
- Rabbits have large hind legs so they can run very fast
- Mice are very flexible, which allows them to hide in very small spaces
3. Symbiosis:
Symbiosis is a close relationship between different species that involves benefit to at least one of them
Types of symbiosis:
- Mutualism is where two different species live together and both benefit
Example: bacteria in the large intestine of humans that produce vitamin K
- Parasitism is where two different species live together and one (the parasite) benefits and causes the other (the host) harm
Example: Fleas on a dog
- Commensalism is where two different species live together and one benefits and the other neither benefits or is not harmed
Example: Birds nesting in a tree