OCR Biology A Level- Biological Molecules Study Exam And Answers Graded A+ 2024.

What is the charge of oxygen in a H2O molecule? - Answer Slightly negative Draw a diagram of hydrogen bonding on paper - Answer Diagram of hydrogen bonding Why is ice less dense than liquid water? - Answer The hydrogen bonds between molecules in ice are slightly further apart than the average distance between liquid water molecules What is an advantage to living organisms of ice being less dense than water? - Answer Ice floats and forms an insulating layer on top of ponds, maintaining a constant temperature for organisms Why is water a good solvent? - Answer It's polar so other charged molecules are attracted to it Why is water's high specific heat capacity useful for organisms? - Answer It can be used as a coolant, to buffer temperature changes during chemical reactions and to provide a constant temperature for aquatic organisms Why is water cohesive and adhesive? - Answer Water is cohesive because the hydrogen bonds mean water molecules are attracted to one another. Water is adhesive because it can be attracted to other polar molecules. Why is it useful to organisms that water is cohesive and adhesive? - Answer Water acts as a good transport medium. These properties also mean that it can move upwards through narrow tubes via capillary action. What are 3 examples of hexose monosaccharides? - Answer Glucose, fructose, galactose What is a hexose monosaccharide? - Answer One with 6 carbon