Using Quadrats -PRACTICAL Flashcards
Ecology (14 cards)
What is a habitat?
The place where an organism lives, e.g., a playing field
A habitat provides the necessary conditions for an organism to survive.
What does the distribution of an organism refer to?
Where an organism is found, e.g., in a port of the playing field
Distribution can vary based on environmental factors.
How can environmental factors affect the distribution of an organism?
An organism might be more common in one area than another due to differences in environmental factors
For example, daisies are more common in open areas than under trees due to light availability.
What are two methods to study the distribution of an organism?
- Measure how common an organism is in two sample areas
- Study how the distribution changes across an area
These methods provide quantitative data about the distribution.
What is a quadrat?
A square frame enclosing a known area, e.g., 1 m²
Quadrats are used to sample populations of organisms in an area.
What is the first step in using quadrats to study organism distribution?
Place a 1 m² quadrat on the ground at a random point within the first sample area
Randomization helps avoid bias in sampling.
What should you do after placing a quadrat on the ground?
Count all the organisms within the quadrat
This counting should be repeated in multiple quadrats to gather data.
How do you calculate the mean number of organisms per quadrat?
Total number of organisms / Number of quadrats
This gives an average count for the sampled area.
If Anna counted the number of daisies in 7 quadrats and recorded the counts: 18, 20, 22, 23, 23, 23, 25, what is the mean number of daisies per quadrat?
22 daisies per quadrat
The mean is calculated as 154 total daisies divided by 7 quadrats.
What is the next step after calculating the mean number of organisms per quadrat in the first sample area?
Repeat steps 1 to 4 in the second sample area
This allows for comparison between different areas.
How can you estimate the population size of an organism in one area?
Multiply the mean number of organisms per m² by the total area (in m²)
This calculation gives an estimate of the total population in the habitat.
If the mean number of daisies per quadrat is 21 and the field has an area of 800 m², what is the estimated population of daisies?
16,800 daisies
Calculation: 800 m² x 21 daisies/m² = 16,800 daisies.
True or False: The mean number of organisms per m² is the same as the mean number of organisms per quadrat.
True
Both values represent average densities within the sampled area.
Fill in the blank: A quadrat is a square frame enclosing a known area, e.g., _______.
1 m²
Quadrats can vary in size but are often standardized for sampling.
