Question

population size
for questions 1 - 3, complete each statement by writing in the correct word.

1. when a population size ____________ or remains steady, this is often a sign of a healthy population.
2. if a population size begins to ____________ rapidly, this can be a signal that extinction is coming.
3. instead of counting each organism individually, ecologists use ____________ methods to estimate population sizes.
4. explain why the passenger pigeon, which was once the most abundant bird in north america, disappeared completely.
5. describe how you could determine the population size of a specific type of plant in a large forest without counting all of the plants.

population density
for questions 6 and 7, circle the letter of the correct answer.

1. a populations density describes how

a. old the population is.
b. crowded the population is.
c. big the population is.
d. fast the population is declining.

1. which piece of information is used along with population size to calculate population density?

a. area
b. weight
c. age
d. location

1. how can high population density be helpful to a population?
2. how can high population density be harmful to a population?

Explanation:

1. A stable or growing population often indicates health as resources are sufficient to support it.
2. A rapid decline in population size can be a precursor to extinction due to factors like habitat loss or over - hunting.
3. Ecologists use sampling methods (e.g., quadrat sampling for plants) to estimate population sizes as counting every organism is often impractical.
4. The passenger pigeon disappeared mainly due to over - hunting for food and sport, and habitat destruction.
5. One could use quadrat sampling. Place randomly - located quadrats in the forest, count the plants of the specific type in each quadrat, calculate the average number per quadrat, and then estimate the total population based on the total forest area and quadrat area.
6. Population density measures how crowded a population is, defined as the number of individuals per unit area.
7. Population density is calculated as population size divided by area, so area is used along with population size.
8. High population density can be helpful as it can increase mating opportunities, enhance social cooperation for resource acquisition and defense, and facilitate the spread of beneficial behaviors or genes.
9. High population density can be harmful as it can lead to increased competition for limited resources (food, water, space), higher stress levels, and a greater risk of disease transmission.

Answer:

1. grows
2. decline
3. sampling
4. Over - hunting and habitat destruction led to its extinction.
5. Use quadrat sampling: place quadrats randomly, count plants in each, find average per quadrat, and estimate total population based on forest and quadrat areas.
6. B. crowded the population is.
7. A. area
8. It can increase mating opportunities, enhance social cooperation, and spread beneficial traits.
9. It can cause increased resource competition, higher stress, and more disease transmission.