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In relation to membranes in cells, explain what is meant by selective permeability - Leaving Cert Biology - Question c - 2010
Question c
In relation to membranes in cells, explain what is meant by selective permeability. Give two locations in a cell at which there is a selectively permeable membrane.... show full transcript
Worked Solution & Example Answer:In relation to membranes in cells, explain what is meant by selective permeability - Leaving Cert Biology - Question c - 2010
Step 1
In relation to membranes in cells, explain what is meant by selective permeability.
Answer
Selective permeability refers to the ability of a membrane to allow certain substances to pass through while restricting others. This characteristic is crucial for maintaining homeostasis in cells, as it enables the cell to control its internal environment by regulating the entry and exit of various ions, molecules, and compounds. For example, essential nutrients can enter the cell, while waste products can be removed.
Step 2
Step 3
What is diffusion?
Answer
Diffusion is the process involving the movement of molecules (or substances) from an area of high concentration to an area of low concentration. This movement occurs until equilibrium is reached, where the concentration of the molecules is uniform throughout the space. Diffusion is a passive process and does not require energy.
Step 4
In the case of a named molecule, give a precise location at which it diffuses in the human body.
Answer
Oxygen diffuses from the alveoli in the lungs into the bloodstream. This process occurs during respiration, allowing oxygen to enter the blood where it is transported to tissues and organs.
Step 5
Explain the biological basis for the use of high sugar or high salt concentrations in the preservation of food.
Answer
High sugar or high salt concentrations create an environment that is hypertonic compared to the cells of microorganisms. This leads to osmosis, where water is drawn out of the microbial cells, causing them to lose water. As a result, the microbes become inactive or die, effectively preventing spoilage and extending the shelf life of food.