2 structure and functions in living organisms E (nutrition in humans) Flashcards
2.7, 2.8, 2.9, 2.24, 2.25, 2.26
what chemical elements are present in carbohydrates?
- carbon
- hydrogen
- oxygen
what chemical elements are present in proteins?
- carbon
- hydrogen
- oxygen
- nitrogen
what chemical elements are present in lipids?
- carbon
- hydrogen
- oxygen
what are carbohydrates made up from?
starch and glycogen from simple sugars
what are proteins made up from?
amino acids
what are lipids made up from?
three fatty acids and glycerol
food test for glucose:
- heated Benedict’s solution
- will turn from blue to brick red
food test for starch:
- iodine
- will turn from browny orange to blue/black
food test for protein:
- biuret solution
- will change from blue to pink/purple
food test for fat:
- ethanol solution
- turns from colourless to cloudy
what should a balanced diet contain?
- carbohydrate
- protein
- lipids
- vitamins
- minerals
- water
- dietary fibre
sources and function of carbohydrate:
- grains, bread, pasta
- quick release energy
sources and function of protein:
- meat, fish, pulses
- growth and repair
sources and function of Vitamin A:
- carrots, sweet potato
- healthy skin and hair and improves eyesight
sources and function of Vitamin C:
- citrus fruit
- prevents scurvy
sources and functions of Vitamin D:
- fish, cheese, sunlight
- absorbs calcium
sources and functions of calcium:
- yoghurt, cheese
- healthy bones + teeth
sources and functions of iron:
- red meat, leafy green vegetables
- makes haemoglobin for blood
sources and functions of fibre:
- celery, wholemeal foods
- healthy gut movement
sources and function of lipids:
- dairy, lard
- energy store + insulation
how do energy requirements vary with activity levels, age and pregnancy?
AGE - younger children are growing, need more energy
ACTIVITY LEVELS - more active, more energy needed, burning more calories
PREGNANCY - more energy required, sharing between woman and baby
what is the role of bile?
neutralising stomach acid and emulsifying lipids
where is bile produced and stored?
- PRODUCED- liver
- STORED- gall bladder
how is the small intestine adapted for absorption?
- has many folds- large surface area
- has many villi- short diffusion distance as villi are one cell thick
- villi have a high concentration gradient- provided by capillary network and lacteals removing absorbed molecules
what do amylase and maltase do and where are they produced?
- AMYLASE- break down starch to maltose- produced in the salivary glands and pancreases
- MALTASE- break down maltose to glucose- produced in the lining of the duodenum
what do pepsin, trypsin and peptidase do and where are they produced?
- PEPSIN- breaks down proteins to peptides- produced in gastric glands in stomach wall
- TRYPSIN- breaks down proteins to peptides- produced in pancreas
- PEPTIDASE- breaks down peptides to amino acids
- produced in lining of duodenum
what does lipase do and where is it produced?
- breaks down lipids to fatty acids and glycerol
- produced in the pancreas
structure of the alimentary canal:
forms a tube through the centre of the body- a. bit like a bagel
function of the alimentary canal:
food is ingested, digested, absorbed and egested from this canal for the purpose that the food can be assimilated
what is ingestion?
taking food in through the mouth and swallowing
what is digestion?
- PHYSICAL- breaking down large insoluble molecules in food into smaller pieces
- CHEMICAL- breaking down smaller pieces into smaller, soluble molecules
what is absorption?
movement of small soluble molecules out of the gut and into the blood by diffusion and active transport
what is egestion?
passing out undigested food through the anus
what is assimilation?
building larger biological molecules from the small soluble molecules in all cells
structure and function of the mouth:
- the first structure in the alimentary canal
- where ingestion takes place
- digestion also begins here:
1. MECHANICAL- food is broken up into smaller pieces in the mouth by chewing which increases the surface area for enzymes and prevents discomfort when swallowing
2. CHEMICAL- saliva is released into the mouth by the salivary glands, this makes food easier to swallow, also contains the. enzyme amylase. Amylase breaks down starch to maltose and works best at neutral pH.
structure and function of the oesophagus:
- long tube which connects the mouth to the stomach
- food is pushed down by peristalsis
- two sets of muscles push the food down the oesophagus, the CIRCULAR muscles contract behind the bolus pushing it along. When the LONGITUDINAL muscles contract they make the oesophagus wider.
structure and function of the duodenum:
- digestion occurs here
- contains trypsin, amylase and lipase
- duodenum wall contains glands which secrete maltase and peptidase
- contains bile which is produced by the liver and stored in the gall bladder:
1. it neutralises stomach acid because enzymes in the duodenum work best at a pH 7-8
2. it emulsifies lipids and breaks down larger droplets into smaller droplets, increasing the surface area for lipase to digest the fats
structure and function of the large intestine:
- broken down into two sections:
1. COLON- site or all reabsorption of water
2. RECTUM- where faeces is stored and then egested by the ANUS
structure and function of the pancreas:
- makes trypsin, amylase and lipase and secrets them into the duodenum
what is peristalsis?
- how food is moved through the gut
- muscular contractions
how does swallowing work?
- food is shaped into a ball by the tongue which is called a bolus
- there is a flap called the epiglottis which blocks the food from entering the trachea
structure and function of the stomach:
- contraction of the stomach wall causes mixing of the contents of the stomach, maximising cantata between enzymes and food
- the gastric glands of the stomach wall secrete pepsin which begins the process of digesting proteins into peptides
- pepsin’s optimum conditions are an acidic pH
- the conditions in the stomach are acidic due to the release of HYDROCHLORIC acid by the gastric glands
- acid also kills bacteria and fungi which may be present in the food we eat
structure and function of the ileum:
- digestion occurs and absorption begins here
- ileum has many fold sand is covered in finger like projections called villi
- some molecules are absorbed by diffusion and some are absorbed by active transport
- rate of diffusion is increased by:
1. large surface area- folding of ileum and many villi and microvilli
2. short diffusion distance- villi are one cell thick
3. high concentration gradient- provided by capillary network in the lacteals
P2 investigate the energy contents in a food sample:
Measure 25cm3 of water into a boiling tube;
Measure and record the starting temperature of the water;
Measure the mass of the crisp;
Set the crisp alight using a Bunsen burner;
Hold the crisp under the boiling tube of water until it goes out;
Relight and repeat until the crisp will not catch fire;
Measure the final temperature of the water;
Calculate energy content: temperature change x volume of water x 4.2/ mass of crisp
