Biology is a branch of science that studies the nature of life from the smallest parts of living things to the largest plants and animals. Ask and answer questions about the living world and its wonderful inhabitants in this category!
Asked in Biology
Why is the tonicity of a solution important?
TONICITY describes the degree to which a solution can exert an osmotic pressure on a membrane. Particles which can freely cross a membrane do NOT affect tonicity. This is because they will freely move in order to achieve equilibrium. Therefore, tonicity is dictated by the particles than can't cross the membrane (such as proteins, which are usually too large to cross, or highly charged particles). Non-permeable particles will therefore force water to cross the membrane towards them in order to achieve equilibrium - they can therefore be said to exert an osmotic pressure on the membrane. Solutions can be HYPERTONIC (i.e. the surrounding solution contains a larger concentration of these non-permeable particles than inside the cell, causing water to LEAVE the cell) or HYPOTONIC (i.e. the opposite, where water moves INTO the cell). They can also be ISOTONIC (there is equilibrium of the non-permeable particles, so no water moves). There is a very important distinction between tonicity and OSMOLARITY: osmolarity ALSO takes into account the particles that CAN cross the membrane (the permeable ones). So a solution could be both HYPEROSMOLAR and ISOTONIC at the same time - one set of particles will be able to freely cross the membrane, so there will no net change in cell volume.
Asked in Biology
What is the advantage of having perforated walls among the vessel elements?
Asked in Biology
What is the shape of the apical and marginal cells of hydrilla?
Asked in Biology, Chemistry, Biochemistry
Why does catalase elute in a wider range of fractions than glucose oxidase does?
What are organisms called that cannot make their own food?
Asked in Biology, Microbiology, Bacteria
What are the features of bacteria that enable them to survive in a wide variety of habitats?
Asked in Biology, Botany or Plant Biology, Genetics
At what temperature do human enzymes work best at?
The optimum temperature for human enzymes is around 40 degrees Celsius, hence the normal body temperature of a human is 37.5 degrees Celsius. If the temperature decreases then the enzymes will not catalyze the chemical reactions in our bodies fast enough to sustain life. If the temperature increases above that then the enzymes will start to denature and can no longer catalyze reactions.
Who was Rosalind Franklin?
Rosalind Franklin was a distinguished scientist whose research played a pivotal role in discovering the structure of DNA. However, she wasn’t widely credited for that discovery until fairly recently. She earned her PhD in physical chemistry from Cambridge University in 1945, and she did her pivotal DNA research at King’s College between 1951 and 1953. The controversy over her role in the discovery of DNA’s structure stems from the fact that Maurice Wilkins, another researcher at King’s College, showed Franklin’s images of DNA to James Watson, another scientist trying to create a DNA model. Watson and his research partner Francis Crick published a paper about it shortly after, and Wilkins, Watson, and Crick all went on to receive a Nobel Prize for the double helix DNA model. Franklin was not recognized. She spent the rest of her career studying viruses at Birkbeck College, and she passed away in 1958.