Life Science
Life Science on the Grade 5 OST focuses on interactions in ecosystems and on how organisms get traits. You will interpret food webs, explain energy flow, and separate inherited traits from learned behaviors.
Core rules and concepts
- Producers make their own food by photosynthesis, using sunlight, water, and carbon dioxide; they store energy in food.
- Consumers get energy by eating other organisms. Decomposers break down dead matter and wastes, returning nutrients to the soil.
- A food chain traces one path of energy; a food web shows overlapping paths. Arrows point from the organism being eaten to the eater, showing the direction energy flows.
- Energy decreases at each level: most is used for life processes or released as heat, so top predators are fewer.
- An organism's traits can be inherited from parents or learned from experience. Adaptations are inherited features that help survival in a habitat.
- A change to one population can affect others. If a predator declines, prey may increase; if prey declines, predators may decline.
Worked example
In a pond, algae are eaten by water fleas, which are eaten by small fish, which are eaten by herons. A disease kills many small fish. Reasoning: herons have less food, so their population may drop. Water fleas face fewer predators, so they may increase and eat more algae, reducing algae. The web has multiple links, so effects can spread beyond one pair.
Traps that cost marks
- Drawing arrows backward; arrows show energy flow to the eater.
- Saying plants eat soil; soil supplies water and minerals, while food is made in leaves.
- Calling a learned behavior inherited.
- Assuming removing one organism affects only its direct predator.