Human Nutrition

Define a balanced diet

food intake in appropriate proportions to sufficiently provide the body with energy for growth and other factors like repair and fighting diseases

importance of carbs?

provide energy/glucose

importance of protein?

repair of muscles

importance of lipids?

stores energy/glucose

Importance of vitamins, minerals and water?

vits and mins: required in small quantities to support health. Water needed to conduct chemical reactions in cells.

Define an enzyme

Enzymes are proteins which break down macro nutrients so they they can be absorbed into the body. They can break break down larger molecules into smaller molecules or smaller molecules into larger molecules. Also, they are biological catalysts; speed up digestion.

Example of vitamin A and function

eggs, liver, to fight infections, for better vision and healthy skin

Example of vitamin C and function

citric fruits, for skin and blood vessel health, balances pH levels

Example of vitamin D and function

red meat, helps calcium absorption

Example of calcium and function

milk, leafy greens, healthy and strong bones, muscles, helps blood clotting

Example of iron and function

beans, nuts, make red blood cells

Example of fibre and function

whole grains, greens, help digestion(break down food)

Investigation link

reagent and positive results for following food samples: starch, reducing sugar/glucose, protein, fat &oil

starch- iodine: from dark yellow to dark blue

glucose/reducing sugar- Benedict’s solution: from blue to a red-ish precipitate

protein- Biuret’s solution: from blue to lilac

fat & oil/lipids- Ethanol: from colorless to a white precipitate

Define digestion

break down of food from large, insoluble molecules into small, soluble ones for absorption of nutrients

Define an enzyme and describe its structure

a protein made up of amino acids and biological catalyst(speeds up reaction without being used up itself) to help digestion

made of chains of amino acids that are joined into a long chain and folded into a unique 3D structure

role of amalyse

to break down starch into sugar(MALTOSE)

role of protease

to break down proteins into amino acids

role of lipase

to break down fats into glycerin/glycerole/fatty acids

Explain why enzymes are so specific about which reaction they catalyze

Each enzyme has an active site that is uniquely shaped/complementary to a specific substrate. Their shapes are determined by the sequence of amino acids in their structure.

Factors that affect enzyme activity

• Temperature(if it’s too hot, exceeding an enzyme’s optimum, it will denature/active site isn’t functional)

• pH(if the pH is too low or high, beyond an enzyme’s optimum, the enzyme’s shape irreversibly alters)

• Enzyme concentration(the denser the enzyme concentration, the quicker enzymes will break it down)

• Substrate concentration(the more substrates there are to break down, the more active enzymes become)

explain this graph (impacts of temp on enzyme activity)

At the start, the temperature is increasing, resulting in more kinetic energy, thus successful collisions, meaning this is an increase in the rate of reaction. Eventually, the temp exceeds the enzymes’ optimum, so the amino acids in its structure break(enzymes denature) and can’t form an enzyme-substrate complex anymore.

explain this graph (impacts of pH on enzyme activity)

at the ranges of 6-7 pH, it shows that it’s the enzyme’s optimum pH, as that’s when enzyme activity is the highest, compared to too acidic or alkalic pHs which result in denaturing of an enzyme, meaning it can’t for enzyme-substrate complexes anymore.

How does food pass down the oesophagus?

via peristalsis, which is a mechanism of waves of muscular contractions

What’s the alimentary canal

tube of organs including the esophagus, stomach, and intestines

P.S: stomach is a muscular bag which mixes food and drinks with acid (mechanically and chemically breaks it down)

Role of small and large intestines

small- digests macronutrients which then are absorbed into the bloodstream

large- where fiber(food that can’t be broken down) passes through and absorbs water from it into the blood

P.S: rectum stores foeces or undigested food whilst anus is the opening through which foeces exits

Roles of pancreas, liver and gall bladder

Liver- produces bile

Pancreas- secretes enzymes into small intestine

Gall Bladder- releases bile

Role and source of bile

Bile is a fluid that is made and released by the liver and stored in the gallbladder. Bile helps with digestion; it breaks down fats into fatty acids, which can be taken into the body by the digestive tract

Name two diseases: one’s caused by calcium deficiency, one’s caused by vitamin c deficiency

calcium deficiency- Rickets

vitamin c deficiency- Scurvy

How can the energy in food be experimentally tested?

by recording the energy burnt from a food sample (finds the energy content)

Define emulsification and what purpose it serves for the body?

it’s the break down of large droplets into smaller droplets.

Bile emulsifies fats, which increases their surface area so that lipase enzymes break them down easier and quicker

How is the small intestine adapted to absorbing nutrients quickly?

It has thin walls which means the diffusion pathway is short, has a large surface area:volume ratio and gets good blood supply which means a high concentration gradient, resulting in a higher rate of nutrient diffusion.

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