10. (a) (i) Draw a pyramid of numbers to represent the information in the food chain below - Leaving Cert Biology - Question 10 - 2018

The organisms at the top of food chains are referred to as top consumers or tertiary consumers. They are also known as predators because they prey on other organisms in the food chain.

Pyramids of numbers are typically restricted to three or four levels due to:

• Energy Transfer Efficiency: At each level, energy transfer is inefficient, often leading to a significant loss of energy. This loss limits the number of levels that can be supported.
• Population Size: As you move up the pyramid, the number of organisms decreases as less energy is available to support them, resulting in fewer levels beyond three or four.

Several factors influence the size of the human population, including:

• War: High death rate or decrease in population.
• Famine: High death rate or decrease in population.
• Disease: High death rate or decrease in population.
• Contraception: Low birth rate or decrease in population.

Organisms exhibit various adaptations to survive in their environment:

• Structural Adaptations: These are physical features of an organism that aid in survival. For example, the thick fur of polar bears provides insulation against cold temperatures.
• Behavioral Adaptations: These are actions or behaviors that organisms exhibit for survival. For example, birds migrating to warmer climates during winter to find food.

Conservation involves the management of natural resources to prevent extinction and maintain biodiversity. It ensures:

• Management of the environment: Practices that support biodiversity and sustainable use of resources.
• Prevention of extinction: Efforts to protect endangered species through legislation and protected areas.

To estimate the size of an animal population, the following steps can be utilized:

1. Capture Method: Use methods such as trapping or netting to capture individuals.

2. Marking: Mark the captured animals in a way that does not harm them (e.g., with paint or tags).

3. Release: Release the marked population back into their habitat.

4. Recapture: After some time, capture a sample of the population again.

5. Calculate Population Size: Use the mark-recapture formula:

   $ext{Population Size} = \frac{(Number \, Marked) \, (Total \, Caught) }{(Number \, Recaptured)}$

One plant from the ecosystem could be the Cattail (Typha), which thrives under specific abiotic conditions:

1. Water Availability: Cattails require wet soil or shallow water for growth.
2. Sunlight: They prefer areas with full sunlight for optimal photosynthesis.

To measure the abiotic condition of water availability, a soil moisture meter can be used:

• Insert the sensor of the moisture meter into the soil near the root zone of the cattail.
• Record the moisture level indicated on the meter to determine the water content of the soil.