Biology

• Big molecules like starch and proteins cannot fit through the cell membrane
• Particles flow through the cell membrane from areas of higher concentration to areas of lower concentration
• The larger the surface area of the membrane, the faster the diffusion rate
• Osmosis is the passive movement of water particles from an area of higher water concentration to an area of lower water concentration
• Osmosis is a type of diffusion where water molecules pass through a partially permeable membrane
• Water molecules pass both ways through the membrane during osmosis
• Osmosis is the reason why it's bad to drink sea-water as it can cause cells to shrivel and die
• Active transport is the process of moving substances against a concentration gradient, from lower to higher concentration
• Root hair cells in plants have a large surface area for absorbing water and mineral ions from the soil
• Plants use active transport to absorb minerals from a dilute solution against a concentration gradient
• Active transport in humans is used to take up glucose from the gut and from kidney tubules
• Active transport requires energy from respiration to function
• Active transport is essential for the absorption of nutrients even when the concentration gradient is not favorable
• Active transport is used when there is a lower concentration of nutrients in the gut compared to the blood
• Active transport uses energy unlike diffusion
• Lab equipment used to transfer microorganisms to an agar jelly culture medium:
• Importance of sterilising Petri dishes and culture medium before use:
• Antiseptic most effective against bacteria in the investigation:
• Reason why a researcher should have used a control:
• Calculation of the area of inhibition zone for antibiotic X:
• Reason why no inhibition zone was formed around the disc soaked in antibiotic Z:
• Location where adult stem cells are found in the body:
• Number of cells a bacterial cell with a mean division time of 30 minutes will have produced in 3 hours:
• Two things that help maximise the rate of binary fission:
• What cell 'differentiation' means:
• Description of how a root hair cell is adapted for its function:
• Location of chromosomes in a cell:
• Type of cell that replicates by binary fission:
• Explanation of what is happening to the DNA during stage A of cell division:
• Suggestion of what happens at time B during cell division:
• Number of cells after the first cell division:
• How stem cells could be used to treat disorders:
• Explanation of why embryonic stem cells have the potential to treat more disorders than adult stem cells:
• Percentage of cells undergoing mitosis in a sample counted by a student:
• Way to tell if a cell is undergoing mitosis or not:
• Importance of stem cells in medicine and research:
• Process of differentiation in cells:
• Risks involved in using stem cells in medicine:
• Arguments for and against stem cell research:
• Embryonic stem cells are unwanted by-products of research that would be destroyed if not used for research