7th grade · Science · Unit 2 of 10
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.
Alaska content standards learning standard: MS-LS2-1; MS-LS2-2 · how resources limit populations and how organisms interact in ecosystems
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 Alaska
In the Alaska content standards, this is unit 2 of 10 in 7th grade Science, after Atoms & Elements and before Food Chains & Energy.
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.
Source: Alaska Department of Education and Early Development
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
A disease kills many trees in a forest. What is a likely effect?
- More sunlight stops reaching the forest floor
- Animals that depend on those trees lose food or shelter
- Nothing else in the ecosystem changes
- Only abiotic factors are affected
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.
Question 2
A group of wolves of the same species living in a park is a…
- community
- decomposer
- habitat
- population
population
Hint: A population is all the members of one species in an area.
Question 3
Biotic or abiotic? Sort each part of an ecosystem.
Sort into: 🌱 biotic (living) · 🪨 abiotic (non-living)
- 🌬️wind
- 🪨a boulder
- 🌡️the temperature
- 💧water in a stream
- 🦠bacteria in the soil
- 🦫a beaver
- 🍄a mushroom
- 🌳a maple tree
🌱 biotic (living): bacteria in the soil, a beaver, a mushroom, a maple tree · 🪨 abiotic (non-living): wind, a boulder, the temperature, 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 4
Which is the best example of a limiting factor that is not about food?
- more insects hatching in spring
- an increase in plant growth
- a long, warm summer with plenty of rain
- a shortage of nesting sites for cavity-nesting birds
a shortage of nesting sites for cavity-nesting birds
Hint: Space and shelter limit populations as well as food.
Question 5
What is a habitat?
- A group of the same species
- The food an organism eats
- The place where an organism lives and finds what it needs
- The energy from the Sun
The place where an organism lives and finds what it needs
Hint: A habitat provides food, water, shelter and space.
Question 6
Lake water warms during a heat wave and holds less dissolved oxygen. How might this affect fish?
- Fish that need a lot of oxygen may struggle to survive
- Fish breathe more easily
- All fish grow faster
- 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.