Nutrition

Assimilation

Assimilation is the movement of digested food molecules into the cells of the body where they are used. For example: glucose is used in respiration to provide energyamino acids are used to build new proteins

Non reducing sugar (sucrose)

Benedict's solution (10%CuSO4, HCl, NaHCO3) blue to orange/red precipitatd

Proteins

Biuret reagant (alkaline CuSO4) blue to lilac/purple precipitate

Worded equation (note chemical eqn in nb)

Carbon dioxide + water-----> glucose + oxygen

Miconutrient examples

Copper -essential in respiration, photosynthesis Defficiency-early aging, lower levels of carbohydrates

2.1 distinguish among heterotrophic, autotrophic and saprophytic nutrition;

Heterotrophic nutrition is nutrition obtained by digesting organic compounds prepared by other plants or animal tissues. All animals and non-green plants cannot make their own food; hence they depend on others directly or indirectly for their food supply. They are called heterotrophs. They break down the complex compounds into simpler forms.

Molybdenum

Important in building amino acids and important in nitrogen metabolism Defficiency- general chlorosis and stunted growth.

Starch

Iodine solution yellow/brown to blue-black

Organic substances used by animals vs Inorganic substances used by plants

Organic substances used by animals include: carbohydrates, proteins, fats Inorganic compounds used by plants include: carbon dioxide, water

Cellulose

Schultze's solution yellow to purple

the role of teeth in the mechanical breakdown of food

Teeth are the organs of chewing, which is also known as mastication. Teeth cut, tear and grind food in the mouth, enabling it to be mixed with saliva (from the salivary glands) effectively and therefore swallowed more easily. The actions performed by the teeth are all mechanical - as opposed to chemical.

Sromach

Type of digestion- 1. Mechanical: churning/mixing of food by walls of stomach. 2. chemical ph- 1-2 Juice and enzymes 1. Gastric juice: HCl acid, mucus, pepsin (enzyme), renin (enzyme found in young mammals) Substrate/food broken down proteins-------------> polypeptides (pepsin) Note: HCl makes conditions acidic for enzyme to work; kills any bacteria present

Properties of Enzymes

1. Enzymes are protein in nature ie made of proteins (anything that affects proteins will affect enzymes) 2. Enzymes are sensitive to temperature. AS TEMPERATURE INCREASES, THE RATE OF ENZYME ACTIVITY ALSO INCREASES UP TO 40 DEGREES CELSIUS. Above this temperature, enzyme structure changes ie becomes denatured and can no longer catalyze reactions. 3. Enzymes are pH specific ie they can only work in a specific PH range e.g pepsin and renin work best in acidic environments of pH 1.5 - 2.0 4. Enzymes are substrate specific. That is the substances that are broken down (substrate) are unique to enzymes. e.g pepsin acts on proteins but not on starches. 5. Some enzymes are sensitive to poison e.g cyanide and arsenic. 6. Some enzymes require help ie. they do not work alone and require a vitamin or mineral. These 'helpers' are called CO-FACTORS.

Saprophytic Nutrition

A type of nutrition in which an organism obtains its food from decaying organic matter by absorption. eg dead plants or animals.

Autotrophic nutrition

Autotrophic nutrition means that simple inorganic substances are taken in and used to synthesise organic molecules. Energy is needed to achieve this. In photo-autotrophic nutrition light is the energy source. In most instances the light source is solar energy, the process being photosynthesis. Carbon dioxide and water are taken in by organisms and used to synthesise glucose, which can be broken down later during respiration to release the energy needed for life. By far the greatest energy supply to support food chains and webs is obtained from photo-autotrophic nutrition. Most producers use this nutritional method. Chemo-autotrophic nutrition can also supply energy needs to some organisms. Simple inorganic substances are taken in and synthesised into organic molecules.

Mastication

Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes.

Magnesium

Constituent of the chlorophyll molecule, effective activator in numerous enzyme reactions Defficiency- plants begin to degrade the chlorophyll in the old leaves; chlorosis.

Lipids

Emulsion test-ethanol (C2H5OH) and water clear to formation of a cloudy white emulsion.

2.8 explain the role and importance of enzymes;

Enzymes are biological catalysts I.e they speed up the rate of reactions without undergoing any change. They remain the same after the reaction is completed.

2.7 relate the structures of the human alimentary canal to their functions; Simple diagrams of the alimentary canal and internal structure of a tooth required. (look in folder for pics)

Mouth Type of digestion -mechanical (teeth), chemical ph- 7-8 juice and enzymes- salive-mucus, salivary amylase, (enzyme produced by salivary glands) Substrate/food broken down- starch is converted to maltose starch-----------> maltose (salivary amylase) Note: bile and saliva are not enzymes End product- maltose

2.5 discuss the importance of minerals in plant nutrition using nitrogen and magnesium as examples;

Nitrogen- Constituent of chlorophyll,makes up 40-50% of dry matter of protoplasm. Constituent of amino acids, building blocks of proteins Defficiency- Accumulation of anthocynanin pigments lead to*** yellow leaves

10 describe what happens to the products of digestion after their absorption

Once nutrients are absorbed by the intestine, they pass into the blood stream and are carried to the liver. The liver has the job of processing all the nutrients, vitamins, drugs, and other things we ingest and absorb each day. It will turn protein, sugar, and fat into energy which, with the help of pancreatic hormones like insulin, will feed the cells of our body. The liver also gets rid of the byproducts of drugs and the nutrients we don't need in bile. In fact, bile is the primary way the body gets rid of excess cholesterol and heavy metals such as copper.

2.2 describe the process of photosynthesis in green plants;

Photosynthesis is an enzyme controlled reaction which involves the conversion of solar energy to chemical energy by green plants ie. The conversion of simple inorganic molecules to complex organic molecules in the presence of molecules**. It is done by organisms which contain chlorophyll eg. alagae, bacteria, flowering plants.

2.6 perform tests to distinguish among food substances;

Reducing sugars eg fructose glucose maltose Benedict's solution (10% CuSO4) blue to orange/red precipitate

Candidates may be asked to deduce from tables and graphs the effects of temperature and pH on enzyme activity.

See notebook for now

role of digestive enzymes in the mouth, stomach and pancreatic enzymes in the small intestine.

See previous slides for now

Note the necessity for hydrolysis and neutralisation in testing for non-reducing sugars.****

The difference between dehydration synthesis and hydrolysis is that in one, bonds are being formed, while in the other bonds are being destroyed. Dehydration synthesis bonds molecules together by removing water. In hydrolysis, water is added to the molecules in order to dissolve those bonds. Dehydration synthesis and hydrolysis perform two different jobs when it comes to macromolecules or polymers. Polymers are molecules linked together covalently.

Villi ( see folder for diagram)

The function of the plicae circulares, the villi, and the microvilli is to increase the amount of surface area available for the absorption of nutrients. ... The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries ( amino acids and carbohydrates) and lacteals (lipids).

Light Inpendent stage-(dark reaction)

The hydrogen from hydrogen from the light-dependent stage reduces the carbon from the carbon dioxide to produce sugars (C6H12O6). Thus process is called carbon fixation.(Has nothing to with night or day; light is not needed for this)

Liver

The liver is important in assimilation. For example, it converts glucose intoglycogen (a complex carbohydrate used for storage) and amino acids into proteins.The liver is involved in the process of deamination. This is the removal of the nitrogen-containing part of amino acids, to form urea, followed by therelease of energy from the remainder of the amino acid.

Egestion

The small intestine absorbs most of the water in the contents of the gut. By the time the contents reach the end of the small intestine, most of the digested food has also been absorbed. The remaining material consists of: waterbacteria (living and dead)cells from the lining of the gutindigestible substances - such as cellulose from plant cell walls The colon is the first part of the large intestine. It absorbs most of the remaining water. This leaves semi-solid waste material called faeces. The faeces are stored in the rectum, the last part of the large intestine. Egestionhappens when these faeces pass out of the body through the anus.

Duodenum (small intestines)

Type of digestion Chemical ph- 10-12 Juices and Enzymes 1. Liver secretes bile into the duodenum 2. Pancreas secretes pancreatic juices: amylase, lipase trypsin. and also sodiumbicarbonate Note: pancreas and liver are accessory organs Bile is stored in the gallbladder Substrates/food broken down emulsify 1. Bile-----------> break fats into fat droplets fats amylase 2. maltose------------> glucose lipase 3. fats/lipids-----------> fatty acid + glycerol trypsin 4. proteins--------------> amino acids/polypeptides

Oesophagus (gullet)

Type of digestion- mechanical: muscular contractions and relaxations of wall (peristalsis) pushes food to the stomach

2.11 discuss the importance of a balanced diet in human.

Visit various websites

How enzymes work (see notebook v important)

enzyme + substrate--> enzyme substrate complex --> product + enzyme . enzyme does not change . active site- where enzyme and substrate meet . The enzyme interacts with the substrate by a lock and key mechanism; the substrate fits exactly into the active site of the enzyme. .inhibitor- prevents real substrate from interacting with enzyme; does not fit perfectly

Fats

grease spot test Place small sample in a piece of paper Soak in water for 1-2 minutes then dry over Bunsen burner hold paper up to light If paper is translucent fat is present

Photosynthesis stage 1- Light dependent stage (light t reaction)

splits water molecules (photolysis of water) to produce hydrogen ions and oxygen gas.