🟦 Population Changes
A population has more births than deaths. What happens to its size?
It increases.
What do organisms get from food that helps them survive and reproduce?
Energy storage molecules (ESMs).
What is a consumer?
An organism that eats another organism.
What does a food web show?
Feeding relationships among organisms in an ecosystem.
What is competition?
When two populations use the same resource.
A population has the same number of births and deaths. What happens?
It stays stable.
What usually happens to births when a population has more resources available?
Births can increase.
If the number of consumers increases, what could happen to the deaths in the population they eat?
Deaths could increase.
What is a direct effect?
An effect between populations that have a direct feeding relationship.
Two populations eat the same resource. What are these populations doing?
Competing.
A population has 45 births and 70 deaths. What happens to the population?
It decreases.
More zooplankton become available for moon jellies. What could happen to moon jelly births?
Births could increase.
If the number of consumers decreases, what could happen to the population they eat?
It could increase because fewer organisms are eaten.
What is an indirect effect?
When one population affects another through one or more other populations.
If one competitor decreases, what could happen to the amount of food available to the other competitor?
More food could become available.
A population has deaths occurring but is still increasing. How is this possible?
The number of births is greater than the number of deaths.
Complete the chain:
More resources → more ESMs → more reproduction → ________.
More births.
Sea turtles eat moon jellies. What could happen to moon jelly deaths if the sea turtle population decreases?
Moon jelly deaths could decrease.
A population increases, causing its food population to decrease. Another population also eats that food. How could the second consumer be affected?
It could decrease because less food is available.
Sardines and moon jellies both depend on zooplankton. If sardines decrease, what could happen to the amount of zooplankton available to moon jellies?
More zooplankton could become available.
The moon jelly population in Glacier Sea increased. What must have been true about births and deaths?
Births were greater than deaths.
Explain how a decrease in a population's food resource could cause its population to decrease.
Less food means fewer ESMs are available, which can lead to less reproduction and fewer births.
Complete the chain:
Fewer consumers → ________ → fewer deaths → prey population increases.
Fewer organisms are eaten.
Why should scientists examine the entire food web when explaining a population change?
A change in one population can indirectly affect several other populations.
Complete the chain:
Fewer sardines → more zooplankton available → ________ → more moon jelly births → moon jelly population increases.
More ESMs available to moon jellies.