Life Science
The Life Science domain of the Grade 5 MCAS STE test asks you to explain how plants grow, how matter and energy move through ecosystems, how structures help organisms survive, how organisms change over their life cycles, and how traits and fossils give evidence about living things. Questions often use food webs, diagrams, or short investigations.
Plants and food
- Plants make their own food through photosynthesis. They use energy from sunlight, carbon dioxide from the air, and water from the soil to make sugar and release oxygen.
- Most of a plant's mass comes from carbon dioxide and water, not from soil. Soil supplies water and minerals that roots absorb.
- Roots anchor and absorb; stems support and transport; leaves capture sunlight.
Ecosystems
- A food chain starts with a producer. Arrows point from the organism being eaten to the eater, showing the direction matter and energy travel.
- Energy flows one way from the Sun and is eventually released as heat. Matter cycles.
- Decomposers break down dead organisms and wastes, returning nutrients to the soil.
Life cycles, traits, and evidence
- Complete metamorphosis: egg, larva, pupa, adult (butterfly). Incomplete: egg, nymph, adult (grasshopper).
- Offspring inherit traits from parents, but the environment can affect how traits appear.
- Fossils, usually found in sedimentary rock, show that organisms and environments were different in the past.
Worked example
A sealed terrarium with soil, plants, and snails is weighed, left in light for a month, and weighed again. Its mass is unchanged. Explain. Plants take in carbon dioxide and water and make sugar; snails eat plants; decomposers recycle wastes. Because the terrarium is sealed, no matter escapes or enters, so total mass is conserved. Energy still enters as light and leaves as heat.
Traps that cost marks
- Saying plants get their food from soil.
- Drawing food-chain arrows backward.
- Saying energy cycles instead of flowing one way.
- Assuming every trait is inherited with no environmental effect.