Structure and Functions in Living Organisms - Nutrition Flashcards
what is photosynthesis?
Production of Glucose in plant cells using light energy from the Sun
what is the equation for photosynthesis?
Carbon Dioxide + Water → Glucose + Oxygen
what happens during photosynthesis?
- Light energy from the sun is absorbed by chlorophyll to produce glucose which is stored as starch for growth, and oxygen as a waste product
- Glucose produced in photosynthesis is passed down the food chain from one organism to another
- Photosynthesis only occurs under the presence of sunlight
what factors affect the rate of photosynthesis?
carbon dioxide concentration, light intensity and temperature
how does carbon dioxide concentration affect the rate of photosynthesis?
- As the concentration of carbon dioxide increases, the rate of photosynthesis will increase
- Carbon dioxide is a reactant in photosynthesis, an increase in concentration will allow more photosynthesis to occur
- However, as the concentration increases beyond a certain point, the rate of photosynthesis with plateau as another factor will be the limiting factor
how does temperature affect the rate of photosynthesis?
- As temperature increases towards optimum, the rate will increase
- This is because the increase in temperature towards optimum will allow optimum enzyme activity
- However, as temperature increases above optimum, enzymes involved in Photosynthesis will denature, therefore causing so rate decreases
how does light intensity affect the rate of photosynthesis?
- As light intensity increases, the rate will increase
- Photosynthesis can only occur under the presence of light, an increase in light intensity will therefore allow more Photosynthesis to occur
- However, as light intensity increases beyond a certain point, the rate will plateau as another factor is the limiting factor
what are the layers of a leaf?
waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis
what is the waxy cuticle?
The outermost protective layer that prevents water loss via evaporation
what is the upper epidermis?
A thin and transparent layer of cells that allows light to enter palisade mesophyll
what is the palisade mesophyll?
Layer tightly packed with chloroplasts to maximise light absorption for photosynthesis
what is the spongy mesophyll?
Layer containing internal air spaces to increase surface area to volume ratio for the diffusion of gases
what is the lower epidermis?
Layer containing:
- Guard cells: cells that control the opening and closing of stomata by absorbing and losing water to regulate gas exchange and prevent water loss
- Stomata: mouth-shaped opening controlled by guard cells
how is the leaf adapted for photosynthesis?
- large surface area
- thin
- a large amount of chlorophyll
- a large network of veins
- stomata
how does the large surface area of a leaf increase the rate of photosynthesis?
Increases surface area to volume ratio for diffusion
how does the thinness of a leaf increase the rate of photosynthesis?
Short diffusion length which increases the rate of diffusion
how does the large amount of chlorophyll increase the rate of photosynthesis?
present in large amounts in the palisade mesophyll to maximise light absorption
how does the large network of veins increase the rate of photosynthesis?
- supports the leaf
- transports water for photosynthesis and transpiration (via Xylem)
- transports carbohydrates produced by Photosynthesis (via Phloem)
how do the stomata increase the rate of photosynthesis?
Regulates gas exchange by allowing carbon dioxide to diffuse into the leaf for use and Oxygen to diffuse out as a waste product
what mineral ions do plants require for growth?
magnesium ions and nitrate ions
what do magnesium ions do in plants?
to build chlorophyll for growth
when plants are magnesium deficient leaves turn yellow
what do nitrate ions do in plants?
to produce Amino acids to build Protein and DNA
when plants are nitrate deficient eaves turn yellow and stunted growth
how would you investigate the effect of light intensity on photosynthesis in pondweed?
- place pondweed in a beaker of water
- change the light intensity
- leave for 5 minutes to allow pond weed to adapt to the environment
- count the number of air bubbles produced in a fixed period of time
- increase or decrease the light intensity by a fixed increment
- repeat process to obtain a range of data
what does a balanced diet consist of?
appropriate proportions of carbohydrates, proteins, lipids, vitamins, minerals, water and dietary fibre
what are carbohydrates found in?
pasta, rice, sugar
what are the functions of carbohydrates?
provide energy
what are lipids found in?
butter, oily fish
what are the functions of lipids?
provide energy, act as an energy source and provide insulation
what are proteins found in?
meat and fish
what are the functions of proteins?
growth and repair and to provide an emergency energy store
what is vitamin A found in?
liver
what is the function of vitamin A?
helps to improve vision
what is vitamin C found in?
fruit, e.g. oranges
what is the function of vitamin C?
needed to prevent scurvy
what is vitamin D found in?
eggs
what is the function of vitamin D?
needed for calcium absorption
what is calcium found in?
milk, cheese
what is the function of calcium?
needed to make bones and teeth
what is iron found in?
red meat
what is the function of iron?
needed to make haemoglobin for healthy blood
what is water found in?
food and drink
what is the function of water?
to replace water lost through urinating, breathing and sweating
what is fibre found in?
wholemeal bread and fruit
what is the function of fibre?
aids the movement of food through the gut (peristalsis)
how does activity level affect energy requirements?
more active people need more energy
how does age affect energy requirements?
children and teens need more energy as they need energy to grow
how does pregnancy affect energy requirements?
pregnant women need more energy to provide the energy their babies need to develop
what does the alimentary canal contain?
mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine
(colon and rectum) and pancreas
what happens in the mouth?
- salivary glands in the mouth produce amylase enzymes in the saliva
- teeth break down food
what is the oesophagus?
the muscular tube that connects the mouth and the stomach
what happens in the liver?
bile is produced
what happens in the gallbladder?
bile is stored
what happens in the large intestine?
excess water is absorbed from food
what is the rectum and what happens in it?
- the last part of the large intestine
- where faeces are stored before they leave through the anus
what happens in the stomach?
- food is pummeled with the stomachs walls
- produces the protease enzyme, pepsin
- produces HCl to kill bacteria and to give the optimum pH for the protease enzyme
what happens in the pancreas?
produces protease, amylase and lipase enzymes. it releases them into the small enzyme
what happens in the small intestine?
- produces protease, amylase and lipase enzymes to complete digestion
- this is where nutrients are absorbed out of the alimentary canal into the body
what are the two parts of the small intestine?
- duodenum
- ileum
what is peristalsis?
wave-like muscle contractions that push food bolus down the oesophagus from mouth to anus - occurs in stomach and gut
what is the purpose of peristalsis?
- as food bolus is pushed only a few centimetres at a time, progression through the intestine is slow, allowing time for digestion
- this allows the churning of semi-digested food as they mix food bolus with enzymes, increasing the rate of digestion
what does amylase do?
digest starch into maltose
what does maltase do?
digest maltose into glucose
what does protease do?
digest protein into amino acids
what does lipase do?
digest lipids into fatty acids and glycerol
where is bile produced?
in the liver
where is bile stored?
in the gallbladder
what are the functions of bile?
- neutralising stomach acid:
- enzymes in the small intestine function optimally in alkaline conditions
- the churning of food in the stomach by hydrochloric acid creates an acidic environment
- bile will neutralise hydrochloric acid to maintain alkaline conditions - emulsifying lipids
- the breakdown and digestion of lipid molecules require a long period of time, bile is used to emulsify large lipid molecules into small droplets
- lipid droplets will have a larger surface area to volume ratio, allowing faster breakdown
how are the villi adapted for absorption?
- thin cell wall
- larger surface area to volume ratio
- dense capillary network
how do thin cell walls help the villis absorption?
thin cell wall (one cell thick) to minimise the distance of diffusion
how does the large surface area of a villi help absorption?
increase surface area to volume ratio for the diffusion
how does the dense capillary network of a villi help absorption?
a dense capillary network provides a rich blood supply, creating a strong concentration gradient for the diffusion
