Question

part 3: density - dependent & density - independent factors
limiting factors can be density - dependent or density - independent.
density - dependent factors influence a population based on its size. the larger and
denser the population, the stronger the effect. competition for resources and the
spread of disease are examples of density - dependent factors. as the population
becomes more crowded, individuals must compete more for food, water, and space,
and diseases can spread more quickly.
density - independent factors affect a population regardless of its size or density. natural
disasters like forest fires, floods, or hurricanes are examples. if a forest fire breaks out, it
doesnt matter whether there are 10 or 1,000 organisms in the area - the fire will cause
damage based on its severity, not the population size.
in the table below, read each situation. decide if the limiting factor is density - independent or density
dependent.
disease spreads faster in a packed
chicken farm than in a small flock.
a forest fire burns down trees and kills
animals in its path.
there isnt enough food , so animals
must compete to survive.
a hurricane destroys a population s
habitat near the coast.
more predators start hunting deer
because the deer population is large.
in a crowded pond, fish compete for
oxygen and food.
a flood washes away nests and shelters
for many animals.
a volcano erupts, covering the land with
ash and killing plants and animals.
a sudden cold snap freezes crops and
affects animals that rely on them for
food.
too many plants grow in one area,
causing competition for sunlight.
parasites spread more easily in a large,
dense population of birds.
a chemical spill poisons a river, killing
fish regardless of how many live there.

Explanation:

• Disease spreads faster in a packed chicken farm than in a small flock:
• The limiting factor is disease.
• Since the spread is affected by population density (packed vs. small flock), it is density - dependent.
• A forest fire burns down trees and kills animals in its path:
• The limiting factor is forest fire.
• Forest fire is a natural disaster that affects the population regardless of its size, so it is density - independent.
• There isn't enough food, so animals must compete to survive:
• The limiting factor is food.
• Competition for food is more intense when the population is larger (denser), so it is density - dependent.
• A hurricane destroys a population's habitat near the coast:
• The limiting factor is hurricane.
• A hurricane is a natural disaster that affects the population regardless of its size, so it is density - independent.
• More predators start hunting deer because the deer population is large:
• The limiting factor is predation.
• The increase in predation is due to the large deer population (density), so it is density - dependent.
• In a crowded pond, fish compete for oxygen and food:
• The limiting factors are oxygen and food.
• Competition is more significant in a crowded (dense) population, so it is density - dependent.
• A flood washes away nests and shelters for many animals:
• The limiting factor is flood.
• A flood is a natural disaster that affects the population regardless of its size, so it is density - independent.
• A volcano erupts, covering the land with ash and killing plants and animals:
• The limiting factor is volcano eruption.
• A volcano eruption is a natural disaster that affects the population regardless of its size, so it is density - independent.
• A sudden cold snap freezes crops and affects animals that rely on them for food:
• The limiting factor is cold snap.
• A cold snap is a natural event that affects the population regardless of its size, so it is density - independent.
• Too many plants grow in one area, causing competition for sunlight:
• The limiting factor is sunlight.
• Competition for sunlight is more intense when there are too many plants (dense population), so it is density - dependent.
• Parasites spread more easily in a large, dense population of birds:
• The limiting factor is parasites.
• The spread is affected by population density (large, dense population), so it is density - dependent.
• A chemical spill poisons a river, killing fish regardless of how many live there:
• The limiting factor is chemical spill.
• The chemical spill kills fish regardless of population size, so it is density - independent.

Answer:

1. Disease; Density - dependent
2. Forest fire; Density - independent
3. Food; Density - dependent
4. Hurricane; Density - independent
5. Predation; Density - dependent
6. Oxygen and food; Density - dependent
7. Flood; Density - independent
8. Volcano eruption; Density - independent
9. Cold snap; Density - independent
10. Sunlight; Density - dependent
11. Parasites; Density - dependent
12. Chemical spill; Density - independent