7th grade · Science · Unit 10 of 16
Ecosystems
Living and non-living parts
What your child practices
Biotic and abiotic parts of an ecosystem, how they interact, and the limiting factors and carrying capacity that decide how many organisms an ecosystem can support.
Alabama Course of Study content standard: 7.6; 7.7; 7.8 · how resources and limiting factors affect populations, and how organisms interact
How we explain it
Children can open this short lesson before they practice.
- An ecosystem is living things (biotic) and their non-living surroundings (abiotic) interacting.
- Abiotic parts include water, light, soil and temperature.
- A limiting factor, such as food or space, caps how many organisms an area can support: its carrying capacity.
Example: Is sunlight a biotic or an abiotic part of a pond ecosystem? Biotic means living or once living. Sunlight is not alive. Answer: abiotic
Ecosystems in Alabama
In the Alabama Course of Study, this is unit 10 of 16 in 7th grade Science, after Cycles & Succession and before Biodiversity.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Why can a small pond support fewer fish than a large lake?
- Pond fish are always larger
- Ponds have no producers
- Fish need less food in ponds
- It has less space, food and dissolved oxygen
It has less space, food and dissolved oxygen
Hint: A bigger ecosystem has more of the resources that limit a population.
Question 2
Biotic or abiotic? Sort each part of an ecosystem.
Sort into: 🌱 biotic (living) · 🪨 abiotic (non-living)
- 🌬️wind
- 🌡️the temperature
- 🌳a maple tree
- 🦠bacteria in the soil
- ☀️sunlight
- 🍄a mushroom
- 💧water in a stream
- 🐸a frog
🌱 biotic (living): a maple tree, bacteria in the soil, a mushroom, a frog · 🪨 abiotic (non-living): wind, the temperature, sunlight, water in a stream
Hint: Biotic parts are living things (plants, animals, fungi, bacteria). Abiotic parts are the non-living things, such as sunlight, water, air, rock and temperature.
Question 3
What is a limiting factor?
- The biggest animal in an ecosystem
- Something that restricts how many organisms an ecosystem can support
- A rule that limits hunting
- A food that all organisms eat
Something that restricts how many organisms an ecosystem can support
Hint: Food, water, space, shelter, disease and predators can all limit a population.
Question 4
A beaver builds a dam and floods a meadow. What does this show?
- A living thing can change the non-living parts of its ecosystem
- Energy is created by animals
- Producers have eaten the consumers
- Only abiotic factors can change an ecosystem
A living thing can change the non-living parts of its ecosystem
Hint: The beaver (biotic) changed the water level and land (abiotic).
Question 5
Lake water warms during a heat wave and holds less dissolved oxygen. How might this affect fish?
- Fish breathe more easily
- All fish grow faster
- Fish that need a lot of oxygen may struggle to survive
- Fish are not affected at all
Fish that need a lot of oxygen may struggle to survive
Hint: Warm water holds less dissolved oxygen, an abiotic factor that fish need.
Question 6
A disease kills many trees in a forest. What is a likely effect?
- Only abiotic factors are affected
- More sunlight stops reaching the forest floor
- Animals that depend on those trees lose food or shelter
- Nothing else in the ecosystem changes
Animals that depend on those trees lose food or shelter
Hint: Trees are producers and also give shelter. Losing them affects the animals that use them.