Biology (Combined Science) · GCSE · OCR · OCR GCSE Combined Science A (Gateway Science) — Biology — Higher (J250) · Specification point · B2.1 · Scaling up
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B2.1 Supplying the cell
Summary Cells transport many substances across their membranes by diffusion, osmosis and active transport. Stem cells are found in both plants and animals. These stem cells can divide, differentiate and become specialised to form tissues, organs and organ systems. Underlying knowledge and understanding Learners should be familiar with the role of diffusion in the movement of materials in and between cells.
Common misconceptions Learners commonly show some confusion regarding surface area to volume ratio, particularly how larger animals have a smaller surface area to volume ratio. They also show some confusion as to stem cells: where they are found and their roles. Care should be taken to give clear definitions when covering this content.
| Reference | Mathematical learning outcomes | Maths skills |
|---|---|---|
BM2.1i | use percentiles and calculate percentage gain and loss of mass | M1c |
| Learning outcomes | To include | Maths |
|---|
| Working scientifically |
|---|
| Practical suggestions |
|---|
B2.1a explain how substances are transported into and out of cells through diffusion, osmosis and active transport | examples of substances moved, direction of movement, concentration gradients and use of the term water potential (no mathematical use of water potential required) | M1c, M1d | WS2a, WS2b, WS2c, WS2d | Observation of osmosis in plant cells using a light microscope. Demonstration of ‘creaming yeast’ to show osmosis. (PAG B1, PAG B5) Investigation of changes in mass of vegetable chips when placed in sucrose/salt solutions of varying concentrations. (PAG B4) |
B2.1b describe the process of mitosis in growth, including the cell cycle | the stages of the cell cycle as cell growth, DNA replication, more cell growth, movement of chromosomes | WS2a, WS2b, WS2c, WS2d | Modelling of mitosis using everyday objects e.g. shoes, socks etc. Observation of mitosis in stained root tip cells. (PAG B1, PAG B4) | |
B2.1c explain the importance of cell differentiation | the production of specialised cells allowing organisms to become more efficient and examples of specialised cells | WS2a, WS2b, WS2c, WS2d | Examination of a range of specialised cells using a light microscope. (PAG B1, PAG B4, PAG B5) | |
B2.1d recall that stem cells are present in embryonic and adult animals, and meristems in plants | Demonstration of cloning using cauliflower. (PAG B4) | |||
B2.1e describe the functions of stem cells in embryonic and adult animals, and meristems in plants | division to produce a range of different cell types for development, growth and repair | WS1.1e, WS1.1f, WS1.1h | ||
B2.1f describe the difference between embryonic and adult stem cells in animals | Research into the different types of stem cells. |