Biological Molecules and Tests

Which of the following are among the MOST important functions of Calcium, biologically? Check all that apply.

[blank_start]Cohesion[blank_end] describes the phenomenon of when water molecules to stick together. [blank_start]Surface tension[blank_end] is what describes when water is more attracted to itself than to surrounding media.

Why is water's state at room temperature so essential to life? Check all that apply.

Water's high thermodynamic stability is illustrated in its [blank_start]high[blank_end] specific heat [blank_start]capacity[blank_end], which means it heats up [blank_start]slowly[blank_end], and [blank_start]latent[blank_end] heat of [blank_start]vaporisation[blank_end], meaning it has a [blank_start]high[blank_end] boiling temperature.

Which of the following are among the MOST important functions of Sodium, biologically? Check all that apply.

Which of the following are among the MOST important functions of hydrogen ions, biologically? Check all that apply.

Water molecules are held together by [blank_start]hydrogen bonds[blank_end]. This is thanks to oxygen's [blank_start]electronegativity[blank_end], which means that the oxygen region of the molecule is slightly more [blank_start]negative[blank_end] than the hydrogen regions. Water is said to be a [blank_start]polar[blank_end] molecule. [blank_start]Hydrogen bonding[blank_end] is the attraction between [blank_start]slightly negative oxygen[blank_end] atoms and [blank_start]slightly positive hydrogen[blank_end] atoms, and explains why water is a [blank_start]liquid[blank_end] at room temperature, despite its small size.

Which of the following are among the MOST important functions of ammonium ions, biologically? Check all that apply.

Which of the following are among the MOST important functions of nitrate ions, biologically? Check all that apply.

Water is at its most dense at 4 degrees C.

Not all [blank_start]disaccharides[blank_end] are reducing sugars, but no non-reducing sugars are [blank_start]monosaccharides[blank_end].

Which of the following are among the MOST important functions of chloride ions, biologically? Check all that apply.

Benedict's Solution is commonly used to test for reducing sugars.

When testing for a reducing sugar with alkaline copper(II) sulphate, the reducing agent is [blank_start]the reducing sugar[blank_end]. At a temperature of [blank_start]80[blank_end] degrees C, for a duration of [blank_start]3 minutes[blank_end], [blank_start]Cu2+[blank_end] is is reduced to [blank_start]Cu+[blank_end], by gaining [blank_start]an electron[blank_end]. The new, reduced ion forms [blank_start]copper oxide[blank_end], which precipitates. The colour change is from [blank_start]blue[blank_end] to [blank_start]red[blank_end], and the degree of colour change is proportional to the concentration of reducing sugar.

You have a biological sample, which has been ground up into a uniform consistency. You then add iodine solution in potassium iodide, and notice that the mixture goes from a yellow colour to a dark blue/black. What conclusions can you draw from the reaction?

Which of the following are among the MOST important functions of phosphate ions, biologically? Check all that apply.

A biuret test is used to detect the presence of...

Lipids are tested for by the [blank_start]emulsion[blank_end] test.

Before testing for non-reducing sugars, you should test for [blank_start]reducing sugars[blank_end]. Next, boiling the sample [blank_start]with hydrochloric acid[blank_end] ensures [blank_start]hydrolysis[blank_end] of the sugars. Then, cool and neutralise with [blank_start]sodium hydrogen carbonate[blank_end] solution. If there were any non-reducing sugars in the sample, they will have been converted into [blank_start]reducing sugars[blank_end], which you can now test for. A [blank_start]positive[blank_end] result will indicate the presence of non-reducing sugars in the original sample.

A colorimeter works by...

To test for lipids, first mix thoroughly with [blank_start]ethanol[blank_end]. Then, after [blank_start]filtering[blank_end], pour the mixture into [blank_start]water[blank_end]. A positive result is indicated by a [blank_start]cloudy white[blank_end] emulsion.

The two reagents needed to test for proteins are [blank_start]sodium hydroxide[blank_end] and [blank_start]copper sulphate[blank_end]. The goal is to see whether [blank_start]copper[blank_end] ions form a complex with [blank_start]peptide[blank_end] bonds. A colour change from [blank_start]blue[blank_end] to [blank_start]purple[blank_end] indicates a positive result.