In this Grade 7 Life Science lesson from Chapter 2, students learn how materials move into and out of cells through the cell membrane using processes such as diffusion, osmosis, passive transport, and active transport. The lesson explains how concentration gradients drive diffusion and explores the role of energy in active versus passive transport. Students also examine how a cell's surface area affects the efficiency of material transport.
Section 1
Molecules Spread Through Diffusion
Molecules move from areas of higher concentration to lower concentration without using energy. This passive transport process helps cells maintain necessary conditions by moving oxygen in and carbon dioxide out.
Section 2
Water Crosses Cell Membranes Through Osmosis
Osmosis occurs when water molecules diffuse through cell membranes from areas of higher water concentration to lower concentration, causing cells to shrink or expand depending on surrounding conditions.
Section 3
Cells Use Energy to Transport Materials Actively
Unlike passive transport, active transport requires energy to move substances against concentration gradients. This process helps cells remove waste, maintain salt balance, and acquire necessary resources.
Section 4
Cell Size Limits Material Transport
As cells grow, their volume increases faster than surface area, limiting material exchange with the environment. This surface area-to-volume ratio explains why most cells remain microscopic.
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Section 1
Molecules Spread Through Diffusion
Molecules move from areas of higher concentration to lower concentration without using energy. This passive transport process helps cells maintain necessary conditions by moving oxygen in and carbon dioxide out.
Section 2
Water Crosses Cell Membranes Through Osmosis
Osmosis occurs when water molecules diffuse through cell membranes from areas of higher water concentration to lower concentration, causing cells to shrink or expand depending on surrounding conditions.
Section 3
Cells Use Energy to Transport Materials Actively
Unlike passive transport, active transport requires energy to move substances against concentration gradients. This process helps cells remove waste, maintain salt balance, and acquire necessary resources.
Section 4
Cell Size Limits Material Transport
As cells grow, their volume increases faster than surface area, limiting material exchange with the environment. This surface area-to-volume ratio explains why most cells remain microscopic.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter