Food Webs & Food Chains
What do arrows in a food web represent?
The flow of energy.
What do organisms compete for in an ecosystem?
Resources such as food, water, and shelter.
What is a predator?
An animal that hunts and eats other animals.
What are the three symbiotic relationships?
Mutualism, Commensalism, & Parasitism
What does biotic mean?
Living or once-living components of an ecosystem.
In a food chain, which type of organism is always at the base?
Producers
Give an example of two animals that might compete in the same habitat.
Lions and hyenas competing for prey.
Give an example of a predator-prey relationship.
Lion (predator) and zebra (prey).
A bird eats ticks off a zebra's back. The bird gets a meal, and the zebra gets rid of pests. What type of symbiotic relationship is this, and explain?
Mutualism, because both species benefit— the bird gets food, and the zebra is helped by having ticks removed.
What does abiotic mean?
Non-living components of an ecosystem.
True or False: A food chain shows multiple feeding relationships among organisms.
False, that's a food web.
How does competition affect population size in an ecosystem?
It can limit population growth as organisms vie for limited resources.
What happens to the prey population when the predator population increases?
The prey population decreases.
A remora fish attaches itself to a shark. The remora gets a free ride and eats leftover scraps of the shark’s meals. The shark is not affected. What type of symbiotic relationship is this, and why?
Commensalism, because the remora benefits from getting food and transportation, while the shark is neither helped nor harmed.
Is sunlight biotic or abiotic?
Abiotic
Name one reason why food webs are more accurate than food chains in describing ecosystems.
They show all the complex feeding relationships between organisms.
In a dense forest, two species of birds are observed feeding on the same type of insect found in the trees. As summer progresses, one bird species becomes more abundant while the other is seen less frequently. What are the two bird species competing for in this scenario?
They are competing for food resources (the insects) in the forest.
How do predator-prey relationships help maintain balance in an ecosystem?
They control population sizes and keep species in check.
A roundworm infects the intestines of a human. As the roundworm feeds on the nutrients the person consumes, the individual experiences symptoms like fatigue and abdominal pain. What type of symbiotic relationship is this, and how does it affect each organism?
Parasitism, because the roundworm benefits by obtaining nutrients from the human, while the human is harmed by experiencing negative health effects.
Give two examples of abiotic factors
Water, temperature, sunlight, soil.
What is the role of decomposers in a food web?
They break down dead organisms and recycle nutrients into the ecosystem.
In a grassy savanna, two different species of herbivores, one that grazes close to the ground and another that eats taller grass, live in the same area. After a dry spell, the taller grass becomes scarce. What are these herbivores competing for, and what might happen to the species that cannot adapt?
They are competing for food resources (the grass). The species that cannot adapt may decline in population or even face extinction if it cannot find alternative food sources.
A pack of wolves hunts a herd of deer. If the wolf population decreases due to disease, what is likely to happen to the deer population, and why?
The deer population will likely increase because there will be fewer predators hunting them.
A farmer plants crops in a field and notices that some fungi grow around the plant roots, helping the plants absorb more nutrients. In return, the fungi receive sugars produced by the plants. What type of symbiotic relationship is this, and why?
Mutualism, because the plants get help absorbing nutrients, and the fungi get sugars for energy.
In a desert, cacti have thick, waxy skins to store water, and animals such as lizards can tolerate high temperatures. Which type of factors—biotic or abiotic—are causing these adaptations, and what are some examples?
Abiotic factors, like high temperatures and limited water, are causing these adaptations. The desert's harsh environment is forcing plants and animals to adapt in order to survive.