Ecosystems — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A close, long-term relationship between two different species is called symbiosis.
Symbiosis means two different species living in a close, ongoing relationship, which can be beneficial, neutral, or harmful depending on the type.
2. In mutualism, both species benefit from the relationship.
Mutualism is a win-win relationship where both species gain something, like bees getting nectar while pollinating flowers for the plant.
3. In commensalism, one species benefits while the other is neither helped nor harmed.
In commensalism, one organism gains an advantage while the other is completely unaffected, like barnacles riding on a whale without hurting it.
4. A parasite lives on or inside another organism and takes nutrients at the host's expense.
A parasite survives by feeding off a host organism, stealing nutrients and often making the host weaker or sick in the process.
5. Bees pollinating flowers while collecting nectar is an example of mutualism.
Bees and flowers both benefit: the bee gets sweet nectar for food, and the flower gets its pollen spread to other plants for reproduction.
6. When two species compete for the same food or space, the interaction is called competition.
Competition happens when two or more species need the same limited resource, like two bird species fighting over the same nesting spots in a tree.
7. A tick feeding on a deer's blood is an example of parasitism.
A tick benefits by drinking the deer's blood for nutrition, while the deer is harmed and may get diseases, making this a clear case of parasitism.
8. Small birds that ride on a rhinoceros to eat insects are an example of mutualism.
Both species benefit: the birds get an easy meal of insects and ticks, while the rhinoceros gets cleaned of pests that could cause infection.
9. A remora fish attaching to a shark for free transportation without affecting the shark is commensalism.
The remora benefits by hitching a ride and eating the shark's leftover scraps, while the shark is neither helped nor harmed by the remora's presence.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Clownfish living safely among sea anemone tentacles
→ Mutualism — clownfish gets protection and anemone gets food scraps
Commensalism — barnacles get a surface to live on; whale is unaffected
Tapeworm living inside a dog's intestines
→ Parasitism — tapeworm absorbs nutrients and the dog loses nourishment
Mutualism — clownfish gets protection and anemone gets food scraps
Barnacles growing on a whale's skin
→ Commensalism — barnacles get a surface to live on; whale is unaffected
Mutualism — fungus gets food from algae and algae gets moisture from fungus
Fungi and algae forming lichen on a rock
→ Mutualism — fungus gets food from algae and algae gets moisture from fungus
Parasitism — tapeworm absorbs nutrients and the dog loses nourishment
Correct matches: Clownfish living safely among sea anemone tentacles → Mutualism — clownfish gets protection and anemone gets food scraps; Tapeworm living inside a dog's intestines → Parasitism — tapeworm absorbs nutrients and the dog loses nourishment; Barnacles growing on a whale's skin → Commensalism — barnacles get a surface to live on; whale is unaffected; Fungi and algae forming lichen on a rock → Mutualism — fungus gets food from algae and algae gets moisture from fungus.