Biology
Investigating the effects of different factors on diffusion, osmosis and membrane permeability involves an understanding of the properties of phospholipids and proteins covered in the section on Biological molecules.
Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and unfamiliar contexts.
Learning Outcomes
- Membrane Systems
Endoplasmic reticulum (ER) consists of a series of membranes creating channels within the cytoplasm, which are continuous with the nuclear membrane. They also form sheets that enclose cellular spaces called cisternae. ER provides a large surface area...
- #27 Summary Of Cell Membrane
1 The basic structure of a membrane is a 7 nm thick phospholipid bilayer with protein molecules spanning the bilayer or within one or other layer. Phospholipids and some proteins move within the layers. Hence the structure is described as a fluid mosaic...
- # 26 Surface Area To Volume Ratios, Investigating Diffusion
As the radius of a cell ? from 1x to 3x (left), the surface area ? from 1x to 9x, and the volume ? from 1x to 27x. Source: Nature Education As a cell increases in size, there is less surface area in proportion to its volume. Relatively there...
- # 25 Passive And Active Transport Across Cell Membranes
Substances can enter or leave a cell in 2 ways: 1) Passive a) Simple Diffusion b) Facilitated Diffusion c) Osmosis (water only) 2) Active a) Molecules b) Particles I. Passive transport across cell membranes 1. Diffusion Molecules and ions move...
- #24 Cell Membranes - Fluid Mosaic Model Of The Plasma Menbrane
The fluid-mosaic model describes the plasma membrane that surrounds animal cell. The membrane has 2 layers of phospholipids (fats with phosphorous attached), which at body temperature are like vegetable oil (fluid). 1. Fluid Mosaic Model Because...
Biology
#23.2 Cell membranes and transport - Syllabus 2016
4.1 Fluid mosaic membranes
4.2 Movement of substances into and out of cells
4.2 Movement of substances into and out of cells
The fluid mosaic model introduced in 1972 describes the way in which biological molecules are arranged to form cell membranes. The model has stood the test of time as a way to visualise membrane structure and continues to be modified as understanding improves of the ways in which substances cross membranes, how cells interact and how cells respond to signals. The model also provides the basis for our understanding of passive and active movement between cells and their surroundings, cell to cell interactions and long distance cell signalling.
Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and unfamiliar contexts.
Learning Outcomes
Candidates should be able to:
4.1 Fluid mosaic membranes
The structure of cell surface membranes allows movement of substances between cells and their surroundings and allows cells to communicate with each other by cell signalling.
4.1 Fluid mosaic membranes
The structure of cell surface membranes allows movement of substances between cells and their surroundings and allows cells to communicate with each other by cell signalling.
a) describe and explain the fluid mosaic model of membrane structure, including an outline of the roles of phospholipids, cholesterol, glycolipids, proteins and glycoproteins
b) outline the roles of cell surface membranes including references to carrier proteins, channel proteins, cell surface receptors and cell surface antigens
c) outline the process of cell signalling involving the release of chemicals that combine with cell surface receptors on target cells, leading to specific responses
4.2 Movement of substances into and out of cells
The fluid mosaic model allows an understanding of how substances enter and exit cells by a variety of different mechanisms.
Investigating the effect of increasing the size of model cells allows an understanding of the constraints of obtaining resources across the cell surface and moving substances out of cells.
a) describe and explain the processes of diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis (no calculations involving water potential will be set)
b) investigate simple diffusion using plant tissue and non-living materials, such as glucose solutions, Visking tubing and agar
c) calculate surface areas and volumes of simple shapes (e.g. cubes) to illustrate the principle that surface area to volume ratios decrease with increasing size
d) investigate the effect of changing surface area to volume ratio on diffusion using agar blocks of different sizes
e) investigate the effects of immersing plant tissues in solutions of different water potential, using the results to estimate the water potential of the tissues
f) explain the movement of water between cells and solutions with different water potentials and explain the different effects on plant and animal cells
b) outline the roles of cell surface membranes including references to carrier proteins, channel proteins, cell surface receptors and cell surface antigens
c) outline the process of cell signalling involving the release of chemicals that combine with cell surface receptors on target cells, leading to specific responses
4.2 Movement of substances into and out of cells
The fluid mosaic model allows an understanding of how substances enter and exit cells by a variety of different mechanisms.
Investigating the effect of increasing the size of model cells allows an understanding of the constraints of obtaining resources across the cell surface and moving substances out of cells.
a) describe and explain the processes of diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis (no calculations involving water potential will be set)
b) investigate simple diffusion using plant tissue and non-living materials, such as glucose solutions, Visking tubing and agar
c) calculate surface areas and volumes of simple shapes (e.g. cubes) to illustrate the principle that surface area to volume ratios decrease with increasing size
d) investigate the effect of changing surface area to volume ratio on diffusion using agar blocks of different sizes
e) investigate the effects of immersing plant tissues in solutions of different water potential, using the results to estimate the water potential of the tissues
f) explain the movement of water between cells and solutions with different water potentials and explain the different effects on plant and animal cells
- Membrane Systems
Endoplasmic reticulum (ER) consists of a series of membranes creating channels within the cytoplasm, which are continuous with the nuclear membrane. They also form sheets that enclose cellular spaces called cisternae. ER provides a large surface area...
- #27 Summary Of Cell Membrane
1 The basic structure of a membrane is a 7 nm thick phospholipid bilayer with protein molecules spanning the bilayer or within one or other layer. Phospholipids and some proteins move within the layers. Hence the structure is described as a fluid mosaic...
- # 26 Surface Area To Volume Ratios, Investigating Diffusion
As the radius of a cell ? from 1x to 3x (left), the surface area ? from 1x to 9x, and the volume ? from 1x to 27x. Source: Nature Education As a cell increases in size, there is less surface area in proportion to its volume. Relatively there...
- # 25 Passive And Active Transport Across Cell Membranes
Substances can enter or leave a cell in 2 ways: 1) Passive a) Simple Diffusion b) Facilitated Diffusion c) Osmosis (water only) 2) Active a) Molecules b) Particles I. Passive transport across cell membranes 1. Diffusion Molecules and ions move...
- #24 Cell Membranes - Fluid Mosaic Model Of The Plasma Menbrane
The fluid-mosaic model describes the plasma membrane that surrounds animal cell. The membrane has 2 layers of phospholipids (fats with phosphorous attached), which at body temperature are like vegetable oil (fluid). 1. Fluid Mosaic Model Because...