Question

ecology
what is ecology?
what are the levels of organization from smallest to largest?
what things cause a population to increase in size? what causes the population to decrease?
food pyramid
what is a trophic level?
what percent of stored energy in an organism is passed to the next trophic level?
what are the three ecological pyramids and what information do they give?
what is the difference between a food chain and food web?
symbiosis
what is symbiosis?

Explanation:

Ecology is a branch of biology. It studies the relationships between organisms and their environment. The levels of ecological organization from smallest to largest are organism, population, community, ecosystem, and biosphere. Factors increasing population size include birth and immigration; factors decreasing it are death and emigration. A trophic level is the position an organism occupies in a food chain. About 10% of stored energy in an organism is passed to the next trophic level. The three ecological pyramids are the pyramid of numbers, biomass, and energy, which show the number of organisms, total mass of organisms, and energy flow respectively. A food - chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another, while a food - web is a complex network of multiple interconnected food - chains. Symbiosis is a close and long - term biological interaction between two different biological organisms.

Answer:

What is ecology: The study of relationships between organisms and their environment.
What are the levels of organization from smallest to largest: Organism, population, community, ecosystem, biosphere.
What things cause a population to increase in size: Birth, immigration. What causes the population to decrease: Death, emigration.
What is a trophic level: The position an organism occupies in a food chain.
What percent of stored energy in an organism is passed to the next trophic level: 10%.
What are the three ecological pyramids and what information do they give: Pyramid of numbers (number of organisms), biomass (total mass of organisms), energy (energy flow).
What is the difference between a food - chain and food - web: A food - chain is linear, a food - web is a complex network of interconnected food - chains.
What is symbiosis: A close and long - term biological interaction between two different biological organisms.