1. What is a species?
a. A species is a group of organisms that interbreed to
produce fertile offspring.
2. What is a population?
a. A population consists of all individuals of the same
species living in the same habitat at the same time.
3. What is a habitat?
a. A habitat is the place where an organism lives.
4. What is a community?
a. A community includes all organisms of all trophic levels
living in the same area at the same time.
5. What is an ecosystem?
a. An ecosystem is a self-contained community, including
all the living organisms, the physical features that
influence them, and their interactions.
6. What is an ecological niche?
a. An ecological niche is the role or function of an
organism in an ecosystem, including its habitat, feeding
behavior, interactions with other species, and
contribution to energy flow and nutrient cycles.
7. What is the difference between a food chain and a
food web?
a. A food chain is a linear sequence of energy transfer
through feeding relationships, while a food web is a
complex network of interconnected food chains,
representing the realistic feeding relationships in an
ecosystem.
8. Why are food webs advantageous over food chains?
a. Food webs provide greater stability to ecosystems by
allowing species to adapt when a food source is scarce.
They also represent the complexity of ecosystems more
realistically, showing that organisms can play multiple
roles.
Energy Flow and Productivity
9. What is the main source of energy for most
ecosystems?
a. The sun is the main source of energy for most
ecosystems.
10. Describe the process of energy flow through the
trophic levels.
Energy flows from producers (plants) to primary consumers
(herbivores), secondary consumers (carnivores), and tertiary
consumers (top predators).
11. What is Gross Primary Productivity (GPP)?
GPP is the total amount of energy absorbed by plants from
sunlight during photosynthesis.
12. What is Net Primary Productivity (NPP)?
NPP is the energy left for growth and transfer to other
organisms after plants use energy for respiration.
13. What percentage of energy is transferred to:
a) Plants from sunlight?
About 1% of sunlight energy is captured by plants.
b) Each trophic level in a food chain?
Only 10% of energy is transferred to the next trophic level.
14. List three reasons why energy is lost at each
trophic level.
Energy is lost because:
a) Some energy is used for respiration.
b) Energy is lost as heat.
c) Not all parts of the plant or prey are consumed or fully
digested.
15. What is chemosynthesis, and why is it important?
Chemosynthesis is a process where certain bacteria use
energy from chemical bonds (e.g., H₂S) to produce glucose.
It is important in ecosystems where sunlight is unavailable,
such as deep-sea hydrothermal vents.
Pyramids of Biomass and Numbers
16. What does a pyramid of biomass represent, and
why is dry mass used?
A pyramid of biomass shows the size of organisms in an
ecosystem by measuring their dry mass, which is preferred
because water content in organisms varies.
17. Why is determining the dry mass of animals
easier than plants?
Water content in animal tissues is relatively consistent
(about 70%), while it varies significantly in plants.
18. List two limitations of pyramids of numbers.
Limitations include:
a) Organisms of different sizes are treated equally.
b) They do not account for decomposers or parasites.
19. Why does the number of individuals decrease
with each trophic level in a pyramid of numbers?
Fewer individuals can be supported at higher trophic levels
because of energy loss at each level.
20. What are the key differences between pyramids
of numbers and pyramids of biomass?
Pyramids of numbers show the count of organisms at each
trophic level, while pyramids of biomass show their dry
mass.
Additional Questions
21. Why might juvenile organisms feed at different
trophic levels compared to adults?
Juveniles often have different feeding behaviors or diets,
allowing them to avoid competition with adults.
22. How is energy lost during photosynthesis?
Energy is lost because:
a) Some sunlight misses the plant entirely.
b) Some sunlight is reflected by leaves.
c) Only certain wavelengths of light are absorbed by
chlorophyll.
23. Why are there usually fewer tertiary consumers
in an ecosystem compared to producers?
Energy loss at each trophic level limits the energy available
to support large populations of tertiary consumers.
