nutrients Flashcards
what is the function of water?
it regulates temperature.(sweat in animals and transpiration in plants). It is a medium for chemical reactions to occur. It is a key component of tissues e.g protoplasm, lubricants,digestive juices and blood. It transports dissolved substances. For humans, it transports digested food products(from small intestine), excretory products(from cells) and hormones from one part of the body to another.
Why is water needed in plants?
(continuation from last card). It is essential for photosynthesis, it is needed to help maintain the turgidity of the cell. It is needed to transport mineral salts(up the xylem) and food substances(down the phloem).
what are carbohydrates?what is the chemical formula of carbohydrates?
C6H12O6. They are organic molecules made up of the elements carbon, hydrogen and oxygen.
What can carbohydrates be classified as?
monosaccharides(single sugars, cannot be broken down further), disaccharides(double sugar), polysaccharides(many sugars).
what sugars are under polysaccharides?
starch, cellulose and glycogen.
What sugars are there under monosaccharides?(atoms are arranged differently within the molecules.) this gives them different chemical and biological properties.
glucose(found in plants and animals), fructose(common in plants, rare in animals), galactose(present in milksugar in mammals)
what sugars are there under disaccharides?(different arrangement of atoms)
two molecules of single sugars bonded together. maltose(occurs in germinating grains),sucrose(not a reducing sugar btw), lactose.
What is a condensation reaction?
A reaction in which two simple molecules combine to form a larger molecule removing one molecule of water
What is hydrolysis?
A reaction in which a water molecule is needed to break up a complex molecule into smaller molecules.
How do we test for reducing sugars?
- Cut sample into smaller pieces
2.mix 2 cm3 of solid sample with 2 cm3 of water - Add 2 cm3 of benedicts solution to food sample.
- shake the mixture and place the tube in a boiling water bath for 2-3 mins.
Results of Benedict’s Test
Blue solution → no reducing sugar.
Green/blue precipitate → traces of reducing sugar.
Orange/yellow precipitate → moderate amounts of reducing sugar.
Brick red precipitate → large amount of reducing sugar.
What are polysaccharides?
starch- made up of several thousand glucose molecules joined together(storage carbohydrate in plants)(straight glucose chains)
cellulose- made up of many glucose molecules joined together. The bonds between glucose units are different from that in starch.(cellulose cell wall prevents cell from bursting or damage, they serve as dietary fibres that prevent constipation)
glycogen- made up of many glucose molecules joined together.(storage carbohydrate in mammals)(refer to structure in tb pg 57)(branched glucose chains)
How do we test for starch?What is the process?
Iodine test. Add 1-2 drops of iodine on sample. Blue-black means starch is present. Brown means starch isn’t present.
Why are glycogen(animal) and starch (plant)suitable storers of glucose?
They are insoluble in water so they don’t change the water potential of the cells. They are large molecules which cannot diffuse through the cell membranes, so they will not be lost from the cell.They can easily be hydrolysed into glucose. They have compact shapes so they occupy less space than the individual glucose molecules.
What is the function of carbohydrates?
-substrate for respiration, to provide energy for cellular activities.
-to form supporting structures, i.e cell wall.
-for the formation of nuucleic acid eg dna.
-to synthesise lubricants, for example mucus.
-to synthesise nectar in flowers.
