Study guide: Cells and Organism Organization
Explain cell structures and levels of biological organization.
Ideas to explain in your own words
- The cell models here include a membrane and genetic information. Eukaryotic cell models have a membrane-bound nucleus; prokaryotic cells lack one. A plant is not the only kind of eukaryote.
- Organelles have functions and interact. The membrane regulates exchange; the nucleus contains much genetic information in eukaryotes. Mitochondria help transfer chemical energy into usable forms; they do not create energy.
- In multicellular organisms, cells can form tissues, organs and interacting organ systems. An organ often includes several tissue types. A cell is not a tiny complete organ system.
- Microscope images and drawings use magnification. A larger drawing need not mean a larger actual cell. Compare scale bars before comparing image sizes; the supplied cases are schematic.
Useful vocabulary
- prokaryotic
- cell lacks a membrane-bound nucleus
- membrane
- regulates exchange across cell boundary
- cell
- smallest living structural unit here
- actual size
- physical size of the specimen
Watch your reasoning
- Confusing prokaryotic with eukaryotic although their functions or changes differ.
- Confusing membrane with nucleus although their functions or changes differ.
- Confusing cell with tissue although their functions or changes differ.
A worked review example
Worked supplied problem: Model A has membrane and DNA but no nucleus. Model B has a nucleus but no chloroplast. Compare justified identities. Solution: A fits a prokaryotic model. B fits a eukaryotic model; lacking a chloroplast does not make B prokaryotic or prove it is an animal, because many eukaryotes lack chloroplasts. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place. Worked supplied problem: A leaf-cell model loses chloroplast function but keeps mitochondria. Predict what pathway is directly affected. Solution: Light-driven photosynthesis is directly affected. Mitochondria do not replace chloroplast light capture. Cellular respiration can still occur if suitable materials and functioning processes remain available. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place. Worked supplied problem: A heart drawing includes muscle, connective and nerve tissues. Explain why calling the whole heart one tissue is inaccurate. Solution: An organ contains multiple tissues cooperating in a function. Heart muscle is one tissue component; the whole heart is an organ participating in a circulatory system. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place. Worked supplied problem: Drawing A is 20 mm long at 100× magnification; drawing B is 30 mm at 300×. Compare actual represented lengths. Solution: A represents 20/100=0.2 mm; B represents 30/300=0.1 mm. Although B’s drawing is larger, A’s represented cell is twice as long. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place.
Make a practice plan
- Explain the mechanism in Compare cell types using a labeled case.
- Complete Explain cell structures and correct the specific misconception in its feedback.
- Resolve a changed case from Order organization levels, then combine the four ideas in the transfer task.