Biology and chemistry foundations in scientific passages
Use basic cell, inheritance, ecological and matter concepts while letting each passage supply the experiment-specific information.
What you will tackle
- Interpret cells, photosynthesis/respiration, inheritance and ecological context
- Distinguish atoms, elements, compounds and mixtures
- Use conservation of atoms/mass and interpret concentration or pH trends
- Apply familiar background without replacing passage evidence
Biological terms organise a mechanism
Cells are basic living units. Photosynthesis uses light energy to build organic molecules from carbon dioxide and water; respiration releases usable energy from chemical stores. Genes are DNA-based units of inheritance; an allele is a variant. In an ecosystem, changing one population may affect feeding relationships, but a specific causal result still requires evidence.
Chemical changes rearrange matter
An element contains one type of atom, a compound has chemically combined elements, and a mixture contains substances together without requiring a fixed chemical formula. A balanced equation conserves atoms. In a closed system this supports conservation of total mass. Concentration measures amount per volume; lower pH indicates greater acidity on the usual aqueous scale. Read any unfamiliar reaction or measurement definition from the passage.
Build your notes, then practise
Work on paper before opening an explanation. Guided tasks provide a starting point; independent tasks remove the scaffolding; application tasks ask you to justify a method or interpretation in context.
Guided practice
Guided 1
Classify oxygen gas O₂, water H₂O and salt dissolved in water. For 2H₂ + O₂ → 2H₂O, count atoms on both sides. Distinguish photosynthesis from respiration in terms of energy.
Show a starting hint
A molecule can contain atoms of one element or more than one element.
Compare with the explained answer
- O₂ is an element, H₂O a compound and salt solution a mixture.
- Both sides contain 4 hydrogen and 2 oxygen atoms.
- Photosynthesis captures light energy into organic stores; respiration releases usable energy from stores.
Answer / response criteria: Element; compound; mixture; atoms conserved; energy roles differ as stated.
Independent practice
Independent 1
A solution changes from pH 6 to pH 4. Which is more acidic? If 10 g of solute is distributed through 500 mL, find g/L. Explain whether an offspring's allele must be a newly created gene.
Compare with the explained answer
- The pH 4 solution is more acidic on the usual scale.
- 500 mL = 0.5 L, so concentration is 10/0.5 = 20 g/L.
- An allele is a gene variant and can be inherited; it need not be newly created in that offspring.
Answer / response criteria: pH 4; 20 g/L; an inherited allele need not be a newly created gene.
Application practice
Application 1
An enclosed plant system is illuminated and later kept dark. The passage supplies gas measurements. Explain why a prediction about net gas change must consider both photosynthesis and respiration, and why observed mass loss would require checking whether the system was truly closed.
Compare with the explained answer
- In light, both photosynthesis and respiration can occur; net change combines their effects.
- In darkness, photosynthesis lacks its light input while respiration can continue.
- Apparent mass loss can reflect matter leaving, measurement limitations or an incorrectly assumed system boundary.
Answer / response criteria: Use net process rates and the stated system boundary; do not treat illumination as proof that respiration stops.
What can you explain now?
An enclosed plant system is illuminated and later kept dark. The passage supplies gas measurements. Explain why a prediction about net gas change must consider both photosynthesis and respiration, and why observed mass loss would require checking whether the system was truly closed.
Compare with the explanation
Use net process rates and the stated system boundary; do not treat illumination as proof that respiration stops.
Explain the reasoning before comparing. This review records your self-assessment rather than an official score or mastery decision.
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Source and review status
Coverage follows the named requirements and examples in the 2026–2027 ACT test guide and subject descriptions. That guide explicitly does not list every possible topic. The broader coded College and Career Readiness Standards are also mapped to conceptual teaching and practice; this does not calibrate a learner to a score band. The separate scientific-background context list and reading-complexity rubric have their own stated limits.
Original teaching and explained self-check practice are available. Specialist review and difficulty calibration remain pending. Essays require self-check or teacher review and are not automatically marked or awarded official scores.
Official source specification / guide