Parent plan · Week 7 · Cells, Membranes & Exchange — connect, practice and revise — Life Science: Biology

Parent teaching plan · 36 weeks

Units to teach or revisit

Chapter 2 · Cells, Membranes & Exchange

Assigned readings

Follow the chapter question: How do cell boundaries and internal structures support life?

This week’s goals

Read A boundary that exchanges, signals and remains organized at this chapter’s launch, then use its linked unit explanations and source records in the assigned sessions.

Five flexible sessions, normally about 50–60 minutes. Unit study uses three sessions. The sample keeps a complete 90-minute extended sitting paired with about 30 minutes of correction; extend teaching when needed.

Session 1 · Cellular Transport — connect and apply

Facilitated diffusion uses a channel or carrier for down-gradient transport. Active transport couples energy transfer to movement against the relevant driving gradient, directly through ATP or indirectly through another gradient. Primary active transport uses a direct energy source; secondary transport can use a gradient maintained by other processes. A pump and a passive carrier can both become saturated as capacity is limited. Therefore, protein involvement or a plateau alone does not establish whether the step is active; use direction, gradients, coupling and controlled energy perturbations.

Your task

Study Parts 3–4 and any named source records. Attempt the whole-unit application with labeled mechanisms, correct quantities and a limitation.

  1. Prepare the assigned reading and identify the question.
  2. Trace the figures and retain a labeled first model or prior attempt.
  3. Complete the stated task before opening guidance.
  4. Compare reasoning with criteria, explain a correction and retain the revised evidence.
Hint and response guidance

Name the structures, quantities, system boundary and assumptions before selecting a mechanism.

No. Both can have limited protein capacity; gradient direction and energy coupling provide additional tests. Not without the stated controls; adhered solution, solute transfer or damage may contribute. The simple model assumes those alternatives are limited.

  • Use the stated evidence and correct units.
  • Explain a biological mechanism or relationship.
  • Show intermediate reasoning with a labeled figure or calculation.
  • State a limitation and a useful revision/test.

Session 2 · Cellular Transport — explain and transfer

Use the worked case and a changed condition to test independent understanding.

Your task

Study the illustrated worked case, attempt varied practice and the changed independent case, then revise the opening model and complete the exit check.

  1. Prepare the assigned reading and identify the question.
  2. Trace the figures and retain a labeled first model or prior attempt.
  3. Complete the stated task before opening guidance.
  4. Compare reasoning with criteria, explain a correction and retain the revised evidence.
Hint and response guidance

Name the structures, quantities, system boundary and assumptions before selecting a mechanism.

The change is −3/12×100 = −25%. Net water loss is consistent with a hypertonic external solution under the model. Comparable blotting, membrane integrity and limits on solute loss are needed before assigning all mass change to water.

  • Use the stated evidence and correct units.
  • Explain a biological mechanism or relationship.
  • Show intermediate reasoning with a labeled figure or calculation.
  • State a limitation and a useful revision/test.

Session 3 · Cell Size & Exchange — observe and build

Illustrative evidence case. Similar-shaped cube models grow in area and volume at different powers, and internal diffusion distance also increases.

Your task

Read the chapter background and unit language. Make a first model, study the core explanation and Parts 1–2, then attempt their visual questions and checks.

  1. Prepare the assigned reading and identify the question.
  2. Trace the figures and retain a labeled first model or prior attempt.
  3. Complete the stated task before opening guidance.
  4. Compare reasoning with criteria, explain a correction and retain the revised evidence.
Hint and response guidance

Name the structures, quantities, system boundary and assumptions before selecting a mechanism.

The ratios are 2 mm⁻¹ and 1 mm⁻¹; doubling length halves area per volume. About four, because the characteristic time scales with the square of distance.

  • Use the stated evidence and correct units.
  • Explain a biological mechanism or relationship.
  • Show intermediate reasoning with a labeled figure or calculation.
  • State a limitation and a useful revision/test.

Session 4 · Cell Size & Exchange — connect and apply

A fold can increase exchange area within a compact region. A thin barrier reduces the distance across which a substance must move. Circulation maintains delivery and removal by bulk transport, affecting gradients at exchange surfaces. These mechanisms should not be collapsed into one vague explanation that every surface is “large.” Intestinal villi, respiratory surfaces and internal membranes use different combinations under their conditions. A structural observation supports a plausible function, but actual rates also need permeability, driving conditions and activity measurements.

Your task

Study Parts 3–4 and any named source records. Attempt the whole-unit application with labeled mechanisms, correct quantities and a limitation.

  1. Prepare the assigned reading and identify the question.
  2. Trace the figures and retain a labeled first model or prior attempt.
  3. Complete the stated task before opening guidance.
  4. Compare reasoning with criteria, explain a correction and retain the revised evidence.
Hint and response guidance

Name the structures, quantities, system boundary and assumptions before selecting a mechanism.

No. Area supports capacity, but driving conditions, permeability and supply/removal also determine rate. Yes. Its area is 162 versus 6 mm², but its ratio is 2 versus 6 mm⁻¹; volume grows faster.

  • Use the stated evidence and correct units.
  • Explain a biological mechanism or relationship.
  • Show intermediate reasoning with a labeled figure or calculation.
  • State a limitation and a useful revision/test.

Session 5 · Cell Size & Exchange — explain and transfer

Use the worked case and a changed condition to test independent understanding.

Your task

Study the illustrated worked case, attempt varied practice and the changed independent case, then revise the opening model and complete the exit check.

  1. Prepare the assigned reading and identify the question.
  2. Trace the figures and retain a labeled first model or prior attempt.
  3. Complete the stated task before opening guidance.
  4. Compare reasoning with criteria, explain a correction and retain the revised evidence.
Hint and response guidance

Name the structures, quantities, system boundary and assumptions before selecting a mechanism.

At 2 mm: area 24 mm², volume 8 mm³, ratio 3 mm⁻¹. At 4 mm: area 96 mm², volume 64 mm³, ratio 1.5 mm⁻¹. Total surface increases while area per volume falls; actual exchange also depends on pathways and demand.

  • Use the stated evidence and correct units.
  • Explain a biological mechanism or relationship.
  • Show intermediate reasoning with a labeled figure or calculation.
  • State a limitation and a useful revision/test.

Submit this week

Parent / teacher weekly conference

Discuss an actual attempt before opening guidance. Use written-response criteria and notebook evidence to choose support. These home-study sessions do not certify mandated investigations or school laboratory eligibility.

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