How is the reducibility of sugar different in high school biology and chemistry?

Glucose is a polyhydroxyaldehyde and fructose is a polyhydroxy ketone. Tautomerism occurs at 70 degrees Celsius under alkaline conditions, that is, two sugars exist at the same time, and fructose at room temperature is mixed with glucose at this time. In fact, according to the book, there are 3 kinds of biology and 2 kinds of chemistry, and our two teachers have communicated, and high school chemistry will not ask this controversial question in the college entrance examination.

We also came through this contradiction, and in real chemistry, there is not even a question about the homework we usually do, but many provinces of biology have tested this question, and there are 3 undisputed kinds, which is clearly pointed out in the book.

Fructose itself is not actually reducible, because it has been converted to glucose under acidic conditions and is reducible. Each discipline has its own convenient statement, chemistry and biology have their own emphasis, as long as you understand it.

Fructose is a polysaccharide, there is no aldehyde group, and only the aldehyde group can react with the feilin reagent, strictly speaking, chemistry is right, but we should still focus on the exam, that is, temporarily separate biology and chemistry, and it is not too late to talk about it later.

The reducibility of sugar in chemistry is the reductiveness of the carbonyl in the sugar, such as the silver mirror reaction, the sugar in biology is to decompose the sugar into lactic acid, so that the valence of the carbon increases, reflecting the reductivity.

Fructose itself is not reducible and is reductive after isomerization in water.

The reducing sugars in high school biology mainly include glucose, fructose, galactose, lactose, maltose, etc.

Reducing sugars refer to sugars that have reducing properties. In sugars, monosaccharides containing free aldehyde groups or ketone groups and disaccharides containing free aldehyde groups are present in the molecule.

Properties: It can reduce Fehling reagent (Benedict reagent) or Torrance (the sugar of the reagent is called reducing sugar, and all monosaccharides (except dihydroxyacetone), regardless of aldose and ketose, are reducing sugars. Most disaccharides are also reducing sugars, with the exception of sucrose.

Filin reagent is a solution containing Cu2+ complex, which is reduced to obtain a brick-red Cu2O precipitate. When the Torrens reagent is reduced, it can produce elemental silver, which undergoes a "silver mirror reaction".

The reducing sugar of high school biology is often tested for glucose, fructose, maltose, galactose and so on. Other sugars, such as sucrose, are non-reducing sugars, cellulose, and many polysaccharides do not belong to them.

The reducing sugars of high school biology only require mastery of these three types: maltose, glucose, and fructose, and other reducing sugars are not required to be mastered.

There are only five and there are not eight, and these five are glucose, galactose, fructose, lactose and maltose. To judge reducing sugar, we mainly look at whether the reagent can be reduced, and the commonly used reagents are Feilin reagent and Benedict reagent, and the method of use is to put these two kinds of aldose and ketose together in a water bath to heat it to see if it reacts and produces brick-red precipitate.

1. Reducing sugars refer to sugars with reducing properties. Among the sugars, monosaccharides containing free aldehyde groups or ketone groups in the molecule and disaccharides containing free aldehyde groups are both reducible. Reducing sugars mainly include glucose, fructose, galactose, lactose, maltose, etc.

2. Feilin reagent and Benedict reagent (Ban's reagent) prepared by citric acid, copper sulfate and sodium hydroxide are often reacted with aldose and ketose under the condition of water bath heating to produce cuprous oxide brick red precipitate, and the reagent is reduced in this banquet, so all sugars that can react with the above reagents are called reducing sugars, and the sugars that cannot react with the above reagents are called non-reducing schizosacks, and glycosides cannot undergo the above reactions. The glucose molecule contains free aldehyde groups, the fructose molecule contains free ketone groups, and the lactose and maltose molecules contain free aldehyde groups, so they are all reducing sugars.

3. Non-reducing sugars include sucrose, starch, cellulose, etc., but they can all be hydrolyzed to produce corresponding reducing monosaccharides.

To improve high school biology scores, you can accumulate many years of practical experience in the college entrance examination, summarize, adjust and revise to formulate a suitable high school biology learning plan; On the other hand, grasp the biological basis. If high school students want to improve their high school biology test scores, I suggest that high school students should pay attention to returning to textbooks, consolidating basic knowledge, strengthening information transformation ability training and experimental skills training, and strengthening experimental program design in the process of reviewing biology.

The most important thing in high school politics is to memorize textbooks, and liberal arts subjects can only get high scores if you memorize the books thoroughly, especially there are many subjective political topics, and you will do it if you memorize the topics, and you won't even know where to start. Politics from the first year of high school to the third year of high school elective and compulsory textbooks must be memorized, and it is flexible to endorse, and the knowledge points of each chapter are integrated.

Bioreducing sugars include glucose, fructose, galactose, lactose, maltose, etc.

Chemical reducing sugars focus on the reducing properties of reducing sugars, and monosaccharides containing free aldehyde groups or ketone groups and disaccharides containing free aldehyde groups in the molecule are reducible.

Any sugar that can be oxidized by a weak oxidant such as Toulon reagent or Ferrin reagent is called reducing sugar, the former produces a silver mirror, and the latter produces a brick-red precipitate of cuprous oxide, and the aldehyde group of the sugar molecule is oxidized to a carboxyl group. So, fructose is also a reducing sugar.

The reason for the reduction of fructose: epimerization - fructose can undergo ketone-enol interchange in dilute alkali solution, and the ketone group continues to become aldehyde group (Toulon reagent and Feilin reagent are both alkaline test test jujube agents, so ketose can be oxidized by these two reagents).

For more information, please refer to:

It must be a reducing sugar.

The structural formula of fructose is 5 hydroxy ketone, but it can be structurally isomerized, that is, it can generate aldehyde groups in solution, so it is a reducing sugar.

Yes, reducing sugar refers to the sugar that can react with weak oxidants, monosaccharides are reducing sugars, fructose belongs to monosaccharides, although it is a ketose in a monosaccharide, but isomerization occurs in weak oxidants, and a part of fructose transforms into aldollose.

The reducing sugars mentioned in biology textbooks generally refer to glucose, fructose and maltose. Glucose and maltose have aldedo groups, fructose does not have aldehyde groups, but fructose can be converted to glucose very quickly in water, so it is also treated as reducing sugar. According to chemical terms, fructose is indeed a polyhydroxy ketone, without aldehyde groups, and is not a reducing sugar.

The reason why fructose is treated as a reducing sugar in biology textbooks is probably considered from the perspective of experimental phenomena, and another reason is that the analogy of sugars in biology textbooks is earlier than that in chemistry textbooks, and it is inconvenient for everyone to learn too much structural knowledge.

Reducing sugars include glucose, fructose, lactose, and maltose.

Fructose is a reducing sugar.

Reducing sugar, as the name suggests, is a sugar with strong reducing ability, generally referring to aldose and some ketose, such as glucose, fructose, etc. (fructose is ketose).

In addition, I learned that aldehydes are more reducible than those of ketones, so glucose can undergo a silver mirror reaction with silver ammonia solution (in this reaction, glucose is oxidized to gluconic acid and Ag+ is reduced to Ag), and fructose can be isomerized to glucose under alkaline conditions, so this reaction can also occur. Generally, film reagent is used to test whether it is a reducing sugar.

Total sugars mainly refer to reducing glucose, fructose, pentose, lactose and sucrose, maltose and starch that may be partially hydrolyzed under the determination conditions that can be hydrolyzed into reducing monosaccharides.

Reducing sugars: Generally speaking, sugars that can be oxidized as reducing agents.

In terms of structure, sugars containing reducing groups (such as free aldehyde groups, hemiacetal hydroxyl groups or free carbonyl groups) in the molecular structure are called reducing sugars. Carbonyl carbon is not involved in the formation of glycosidic bonds.

Functionally: it can reduce the sugar of Fehling reagent or Torrance reagent. All monosaccharides (except dihydroxyacetone), whether aldose or ketose, are reducing sugars. Most disaccharides are also reducing sugars, with the exception of sucrose.