How are populations affected by conditions in an ecosystem? B3.4 Flashcards
(13 cards)
What are abiotic factors, and how do they affect communities?
Abiotic factors are non-living parts of an ecosystem, like temperature, water, sunlight, and soil quality. These factors affect the survival and growth of organisms, influencing the distribution of species in a community.
What are biotic factors, and how do they affect communities?
Biotic factors are living components, such as predators, prey, plants, and competition. They affect community structure, population size, and interactions between organisms (e.g., predator-prey relationships or food availability).
How do you carry out a field investigation to study organism distribution and abundance?
Use quadrats to sample random areas and count organisms within each quadrat. For larger areas, use transects to measure how distribution changes across a distance, recording organisms at set intervals.
How do you calculate the arithmetic mean in population studies?
Add up all values in the dataset and divide by the total number of values. This gives the average value, useful for comparing population sizes or abundance across samples.
How are fractions and percentages used in population data?
Fractions and percentages help represent parts of a whole population, like the percentage of a particular species in a sample or the fraction of quadrats where an organism is found.
How do you choose appropriate scales for plotting data on a graph?
Select scales that fit the range of data points without leaving too much empty space. Ensure increments are evenly spaced and labels are clear for accurate data interpretation.
How do you interpret information from charts, graphs, and tables in population studies?
Look for patterns or trends, such as increases or decreases in population size, and compare data points. Summarize findings in relation to abiotic or biotic factors affecting the population.
What is a transect?
A transect is a line across a habitat or ecosystem along which samples are taken at regular intervals. It’s often used to study how the distribution of organisms changes across a gradient, such as from a sunny to a shaded area. A tape measure or string is laid out, and data is collected along the line, typically at set points.
What is a quadrat?
A quadrat is a square frame (usually made of metal or wood) placed on the ground to define a specific area for sampling. Within the quadrat, researchers count or estimate the abundance of organisms. Quadrats are often used to measure the population size or density of plants or slow-moving animals in a certain area.
What are biotic factors and how do they affect population size?
Biotic factors are living components of an ecosystem that influence population size.
Examples include:
* Food availability
* Predation
* Competition
* Disease and parasites
* Human activity
What are abiotic factors and how do they influence populations?
**Abiotic factors **are non living environmental factors affecting populations.
Examples include:
* Temperature- affects enzyme activity and metabolism, influencing survival and reproduction
* Light intensity- affects photosynthesis, impacting food chains
* Water availability- essential for life; droughts cause population declines
* Soil pH and mineral content- determines plant growth, impacting herbivore populations
* Oxygen and CO2 levels- affects respiration rates in plants and animals
Explain the predator- prey cycle and how it affects population sizes
- Prey population increases -> more food for predators -> predator population increases
- More predators -> more prey killed -> prey population decreases
- Less prey -> less food for predators -> predator population decreases
- Fewer predators -> prey population starts to recover, restarting the cycle.
This cycle is an example of negative feedback which maintains ecosystem stability.
What is the difference between immigration and emigration?
Immigration- organisms leaving a population- which increases population size
Emigration- organisms leaving a population- decreases population size
These movements can be influenced by environmental conditions, competition and human activity.
