From Molecules to Organisms: Structures and Processes
What you must know
This domain connects cell structure to body function. Understand that cells are the basic unit of life, that cell membranes control what enters and leaves, that mitochondria release energy from food, and that chloroplasts in plant cells capture light for photosynthesis. Plant cells also have cell walls and large central vacuoles.
Know photosynthesis (carbon dioxide + water + light → glucose + oxygen) and cellular respiration (glucose + oxygen → carbon dioxide + water + energy). These are complementary: plants make food and release oxygen; nearly all organisms, including plants, break down food to release usable energy. Recognize that body systems are organized from cells to tissues to organs to organ systems, and that systems interact - the circulatory, respiratory, and digestive systems cooperate to deliver oxygen and nutrients and remove wastes.
Understand that specialized cells and structures serve specific functions, and that organisms maintain stable internal conditions (homeostasis) through feedback such as sweating or shivering.
Traps to watch
- Plants do both photosynthesis and cellular respiration; they do not only photosynthesize.
- Respiration is not the same as breathing; breathing exchanges gases, respiration releases energy in cells.
- Mitochondria are in plant cells too, not only animal cells.
- Structure-function questions want a reason tied to the shape or feature.
Rule of thumb
Link every structure to a job: membrane = gatekeeper, mitochondria = power plant, chloroplast = solar panel. For system questions, follow the input to the output.
Worked example
A muscle cell needs energy to contract. Glucose and oxygen arrive via blood; mitochondria use them in cellular respiration to release energy, producing carbon dioxide that blood carries away.