Ecological Communities and Keystone Species

What are keystone species?

• Species that are not influential in ecological communities

• Species whose influences on ecological communities are less than expected based on their abundance

• Species whose influences on ecological communities are greater than would be expected on the basis of their abundance

• Species that have no role in ecosystem functions

Why are elephants considered keystone species?

• Because they are the largest land animals

• Because they have no impact on the structure of vegetation

• Because they can alter the entire structure of the vegetation in areas into which they migrate

• Because they only consume small plants

What is one of the effects of elephants' grazing pattern on the ecosystem?

• It promotes a predominance of taller plant species with large leaves

• It has no significant effect on plant species

• It promotes a predominance of lower growing grasses with small leaves

• It leads to an increase in the abundance of shrubs

What enables termites to break down plant cellulose?

• Their strong jaws

• Symbiotic microorganisms in their gut

• The soil they live in

• Their ability to shift large quantities of soil

What is the effect of termites on nutrient processing in tropical environments?

• They decrease the rates of nutrient processing

• They have no effect on nutrient processing

• They increase the rates of nutrient processing

• They shift the nutrients to other environments

Which species is known as the ochre star?

• Pisaster ochraceous

• Termite

• Mussel

• Algal species

What happens to the mussel population if the ochre star is removed from its environment?

• It decreases and algal species dominate

• It remains the same, with no effect on other species

• It increases, leading to a decrease in the number of herbivore species

• It increases, leading to an increase in the number of herbivore species

What is the focus of ecology as a scientific study?

• The chemical reactions within organisms

• The energy transfer between organisms and their environments

• The geological formations of the earth

• The historical development of species

How is ecology best described?

• A branch of mathematics

• A type of philosophy

• A science of relationships

• A form of art

Which of the following is an example of a biotic factor?

• Water

• Soil

• Fungi

• Temperature