Nutrition and Biological Molecules Flashcards
What is the chemical equation for photosynthesis?
6CO2 + 6H2O —> C6H12O6 + 6O2
What is required for photosynthesis to occur?
Light energy and chlorophyll
What does photosynthesis do?
Converts light energy to chemical energy
How does carbon dioxide concentration affect the rate of photosynthesis?
The higher the concentration of carbon dioxide the higher the rate of photosynthesis occurs
How does light intensity affect the rate of photosynthesis?
The higher the light intensity the higher the rate of photosynthesis
How does temperature affect the rate of photosynthesis?
Up to 30C temperature increases the rate of photosynthesis but after that the rate starts to decrease
What is a limiting factor?
The component of the reaction which is in short supply so it limits the rate at which the reaction can take place
What are Magnesium ions used for in plants?
Part of the chlorophyll molecule
What are nitrate ions used for in plants?
Making amino acids and proteins
What are phosphate ions used for in plants?
Part of the cell membrane and DNA
What are potassium ions used for in plants?
Needed for enzymes of respiration and photosynthesis to work
What does the cuticle of a leaf do?
Reduced water loss by evaporation and acts as a barrier to the entry of pathogens
How is the upper epidermis adapted for photosynthesis?
It is transparent to allow light to enter the leaf
How are palisade cells adapted for photosynthesis?
1) densely packed
2) lots of chloroplasts
3) absorb light
What is the role of spongy cells in photosynthesis?
Main gas exchange surface absorbing carbon dioxide and releasing oxygen and water vapour
What is the role of the air spaces in a leaf?
Allow gas exchange in and out of the leaf
How are guard cells adapted for photosynthesis?
Open and close the stomata as in light fill with water and bend out, opening (vice versa for dark)
Describe experiment to measure photosynthesis using pond weed
1) place pondweed in a beaker of water
2) place a lamp 10cm away from the beaker
3) record the number of bubbles produced per minute for 10 minutes
4) repeat each time moving the lamp 10cm further away from the beaker
How do you test leaves for starch?
1) kill leaf in boiling water for 30 seconds
2) remove colour in boiling ethanol for 2 minutes
3) wash with cold water to soften the leaf
4) spread out leaf on tile and ass iodine solution to test for starch
5) any parts of the leaf containing starch then blue black
Describe an experiment to investigate the effect of light in gas exchange by a leaf
1) put 10cm3 of hydrogencarbonate indicator in the base of 4 boiling tube
2) add a large leaf to 3 of the boiling tubes
3) cover one tube with silver foil and one with translucent material and place the other in bright light
4) after 3 hours heck the colour of the indicator
What is the colour of hydrogencarbonate indicator in low, normal and high concentrations of carbon dioxide?
Low=purple
Normal=orange
High=yellow
What should a balanced diet contain?
Carbohydrates, proteins, lipids, vitamins, minerals, water and dietary fibre
What is a source of carbohydrates?
Bread, pasta and rice
What is a source of protein?
Meat, fish and cheese
What is a source of lipid?
Butter, oil and eggs
What is a source of vitamin A?
Fish liver oils, butter and carrot
What is a source of vitamin C?
Citrus fruits and vegetables
What is a source of vitamin D?
Fish liver oils, butter and skin makes in sunlight
What is a source of calcium?
Milk, cheese and fish
What is a source of iron?
Red meat, eggs and spinach
What is a source of dietary fibre?
Fruit and vegetables
What is the function of dietary fibre?
Helps move materials through the gut
What is the function of vitamin A?
1) make chemicals in the retina
2) protect surface of the eye
3) part of connective tissues
What is the function of vitamin D?
Helps absorb calcium and phosphorous
What is the function of vitamin C?
Makes connective tissues that stick together cells lining surfaces of the body
What is the function of calcium?
Creates and strengthens teeth and bones
What is the function of iron?
1) part of hemoglobin in red blood cells
2) helps transport oxygen round the body for respiration
What causes energy requirements to vary?
Age, activity levels and pregnancy
What is the function of the mouth?
Breaks down food mechanically and begins to digest starch
What is the function of the oesophagus?
Carries food from the mouth to stomach and continues the digestion of starch
What is the function of the stomach?
Begin the break down proteins in acidic environment which also kills bacteria
What is the function of the small intestine?
Fully breaks down food and is the site for absorption of the products until the blood
What is the function of the large intestine?
Site of water absorption into the blood
What is the function of the pancreas?
Produces pancreatic juice which contains many digestive enzymes
What is ingestion?
Food entering the mouth
What is digestion?
The breaking down of large insoluble molecules into small soluble ones
What is absorption?
Small molecules moving from the small intestine into the blood
What is assimilation?
Small food molecules being used to build large molecules
What is egestion?
The removal of undigested food from the anus
What is digested in the mouth?
Starch to maltose via salivary amylase
What is digested in the stomach?
Proteins to peptides by pepsin
What is digested in the small intestine?
1) starch to maltose by pancreatic amylase
2) maltose to glucose by maltase
3) proteins to peptides by trypsin
4) peptides to amino acids by peptidases
5) lipids to glycerol and fatty acids by lipase
What enzymes are released from the salivary glands?
Salivary amylase
What enzymes are released from the stomach wall?
Pepsin
What enzymes are released from the pancreas?
Lipase, trypsin and pancreatic amylase
What enzymes are released from the wall of the small intestine?
Maltase and peptidases
What is peristalsis?
The process by which food is moved through the gut via muscle contractions (independently of gravity)
How is food moved through the gut via peristalsis?
Circular muscles contract behind the bolus and longitudinal muscles relax pushing the bolus forward
Where is bile produced, stored and released into?
Produced in the liver and stored in the gall bladder and released into the small intestine
What does bile do?
1) neutralises stomach acid
2) emulsified fats to increase the surface area to volume ratio so there is more surface area for the enzymes to act on
How is the small intestine/ileum adapted for absorption?
1) very long
2) lining is folded
3) covered in villi
How are is a villus adapted for absorption?
1) covered in microvilli
2) surface is one cell thick
3) good blood supply
4) lacteal for absorption of the products of lipids
Name 5 factors which affect the rate of photosynthesis
1) sunlight
2) temperature
3) water
4) minerals
5) carbon dioxide concentration
what are the chemicals present in carbohydrates?
Carbon, hydrogen and oxygen
what are the chemicals present in lipids?
Carbon, hydrogen and oxygen
what are the chemicals present in proteins?
Carbon, hydrogen, oxygen, nitrogen (and sometimes sulphur)
What is the structure of starch?
Starch polymer made up of smaller glucose units (glucose)
What is the structure of proteins?
Polymer made up of chains of amino acids
What is the structure of lipids?
Large molecule made up of fatty acids and glycerol
What is a polymer?
A large biological molecule made up of smaller biological molecules in chains
What is the test for glucose?
1) Add Benedict’s reagent and heat
2) if glucose is present it will turn from blue to brick red
What is the test for starch?
1) add iodine solution
2) if starch is present it will turn from oranges brown to blue black
What is the function of carbohydrates in the body?
Energy source for respiration
What is the function of proteins in the body?
1) growth and repair of tissues
2) form enzymes
What is the function of lipids in the body?
1) insulation
2) energy store
3) forms cell membranes
What are enzymes?
Biological catalysts which speed up metabolic reactions (reactions taking place in cells)
How does an increase in temperature affect the rate of enzyme activity up to 36C?
1) enzyme activity increases
2) more movement of particles/particles have more kinetic energy
3) more collisions
Describe an investigation to find out the affect of temperature on enzyme activity
1) spots of iodine are placed on the spotting tile
2) 5cm3 of starch suspension is placed in a boiling tube and 5cm3 of amylase solution in another tube
3) beaker is filled with water at 20C and both boiling tubes placed in it for 5 minutes
4) amylase solution added to the starch
5) using pipette place one drop of the solution in a spotting tile contains iodine and record the colour
6) repeat every 30 seconds until 10 minutes have elapsed
7) repeat experiment but this time heating the water to 30C, then 40C, then 50C, then 60C
Describe an experiment to demonstrate that chlorophyll is needed for photosynthesis
1) use variegated leaf
2) draw pattern of chlorophyll and compare results
3) test for starch
Describe an experiment to demonstrate that carbon dioxide is needed for photosynthesis
1) add sodium hydroxide (NaOH)
2) to absorb carbon dioxide
3) test for starch
Which organ does hepatitis affect?
The liver
What is the function of the oesophagus?
Carries food from the mouth to the stomach
How are enzymes effected by pH?
Optimum pH is neutral (7) and then enzyme activity decreases either side as the active site becomes denatured
Describe an experiment to investigate the energy content in a food sample
1) Weight food to determine its mass
2) Place 20cm3 of water in a boiling tube
3) Measure temperature of water using a thermometer
4) Burn food sample and hols under the tube containing water
5) burn the food sample completely
6) measure temperature of water after burning
7) Use equation:
Energy (J/g) = ((final temperature-initial temperature) × mass of water (g) × SHC of water(J/˚C))) ÷ (mass of food (g))
what is the equation used to work out the energy in food?
Energy (J/g) = ((final temperature-initial temperature) × mass of water (g) × SHC of water(J/˚C))) ÷ (mass of food (g))
what is the specific heat capacity of water?
4.2 J/˚C
In the experiment to work out the energy in food why might the result be lower than the value on the packet?
1) heat energy lost from tube
2) not all food sample burnt
3) incomplete combustion
4) no insulation
suggest why cows absorb a lower percentage of energy from the food they eat than fish?
1) eat more plants
2) food difficult to digest/less food digested
3) cellulose
suggest how the productivity of cow farming could be improved?
1) keep indoors;
2) less heat loss
OR
3) restrict movement
4) less respiration/less energy used
OR
5) more digestible food
6) so more energy absorbed;
explain the effect that the level of activity has on someone’s energy requirements
1) more muscle contractions
2) more respiration
3) more energy required
4) more glucose
how does an increase in temperature affect enzyme activity after 36C?
1) decrease in enzyme activity
2) denatured
3) active site shape altered
4) substrate no longer fits
Suggest how spending time outdoors can reduce the chance of getting rickets
Sun light makes vitamin D
Suggest why vitamin D deficiency is more of a problem for children than adults
Children are still growing bones
Suggest why snacking on crisps and chocolate is an unsuitable diet for children who are not very active
1) high in sugar and fat (calories)
2) not needed
Suggest the health problems that might develop if children have too much fat
1) obesity
2) diabetes
3) heart disease/attack
4) blocks arteries
5) stroke
suggest two reasons why a pregnant woman needs more energy than a non-pregnant woman
1) more mass
2) growth and development of fetus
