2.18 - 2. 33B (nutrition) Flashcards
what is the photosynthesis theory
it is an endothermic reaction in which energy from sunlight is transferred to the chloroplasts in green plants
what do plants use the products of photosynthesis for
plants use the products as a source of energy in respiration
they can also use it to
- produce starch for storage
- synthesise lipids for an energy source in seeds
- to form cellulose to make cell walls
- to produce amino acides
what are the raw materials needed for photosynthesis
carbon dioxide and water
what is the word equation for photosynthesis
carbon dioxide + water —-> glucose +
oxygen
and on the arrow there is light and chlorophyll
what are the main limiting factors of photosynthesis
- temperature
- light intensity
- carbon dioxide
what is the balanced chemical equation for photosynthesis
6 CO2 + 6 H2O —-> C6H12O6 + 6 O2
and on the arrow there is light and chlorophyll
what happens to the rate of photosynthesis when the temperature increases
as temp increases, so does the rate of photosynthesis due to an increase in kinetic energy
but once the optimum temperature is reached, any further increase in temp will cause the enzymes to denature
what happens to the rate of photosynthesis when light intensity increases
it has a linear increase until it reaches a certain point and then the rate of photosynthesis remains constant (does not go down)
what happens to the rate of photosynthesis when carbon dioxide concentration increases
it has a linear increase until it reaches a certain point and then the rate of photosynthesis remains constant
what are the main plant tissues in a leaf?
- epidermal
- palisade mesophyll
- spongy mesophyll
- xylem and phloem
what is the upper epidermis in a leaf
- a single layer of transparent cells to allow light through
- covered by a waxy cuticle that prevents water loss
what is the palisade mesophyll in a leaf
- column shaped cells with many chloroplasts
- most photosynthesis
what is the spongy mesophyll in a leaf
- loosely packed cells
- air spaces in between them
- maximise diffusion of gases
what is the lower epidermis in a leaf
- contains guard cells controlling opening and closing of stomata
- found mainly on underside of leaf to reduce water loss
what is the vascular bundle in a leaf
- composed of xylem and phloem
- xylem to transport water
- phloem to transport sucrose and amino acids
what adaptations make the leaf structure good for photosynthesis
- large surface area for diffusion of co2 and absorption of light
- network of veins for water transportation to the cells
- cells contain chlorophyll so light energy can be absorbed for energy for photosynthesis
- thin leave facilitates diffusion of co2 through the stomata
- air spaces increase SA for diffusion of co2
why do plants need mineral ions
for growth
why do plants need magnesium ions
for the production of chlorophyll
why do plants need nitrate ions
for the production of amino acids
what do plants store their glucose as
starch
what should a healthy diet include
- carbohydrates
- proteins
- lipids
- vitamins
- minerals
- water
- dietary fibre
sources and functions of carbohydrates
bread and pasta
it is quick energy
sources and functions of proteins
eggs, meat, nuts
used for growth and repair
sources and functions of lipids
fats, oil, butter
slow energy
sources and functions of vitamin A
vegetables and fish - healthy skin
red vegetables, fish oil - healthy vision
sources and functions of vitamin C
citrus fruits - heal wounds, growth and repair
sources and functions of vitamin D
fish, eggs- healthy bones, regulates cellular function
sources and functions of calcium
milk, eggs
strong bones and teeth
sources and functions of iron
red meat, lentils
makes hemoglobin in red blood cells to carry oxygen
sources and functions of water
leafy vegetables, whole grain wheat
prevents constipation and bowel cancer
sources and functions of diatery fibre
whole grain wheat , leafy legumes
prevents constipation
what may make dietary needs vary
pregnancy, activeness, sex, age, height
what is the digestive system an example of?
an organ system
what are the components of the digestive system in order from the mouth to the anus
mouth
salivary glands
oesophagus
stomach
liver
bile duct
gall bladder
pancreas
small intestine
large intestine appendix
rectum
anus
what is the purpose of the mouth and salivary glands
mouth- mechanical digestion
amylase enzymes in saliva digest starch into maltose
what is the purpose of the oesophagus
its the tube that connects the mouth to the stomach
peristalsis takes place to bring it down to the stomach
what is the purpose of the stomach
mechanical digestion - churning of the food
chemical digestion - protease enzymes digest proteins hydrochloric acids to kill the bacteria in the food
it creates the optimum pH for protease enzymes to work
what is the purpose of the small intestine
the duodenum - food coming out of
the stomach finishes to be digested
here by enzymes produced here and
also secreted from the pancreas
the pH of the small intestine is slightly alkaline (8-9)
the ileum - absorption of digested
food molecules take place
it is lined with villi to increase SA
what is the purpose of the large intestine
water is absorbed from remaining material
faeces is produces
it is stored in the rectum
what is the purpose of the pancreas
produces amylase, protease, and lipase
what is the purpose of the liver
it produces bile to emulsify fats (mechanical digestion)
what is the purpose of the gallbladder
it stores bile
what mechanism helps move food along the alimentary canal
peristalsis
what muscles control peristalsis
circular and longitudinal
what enzyme breaks down carbohydrates and what do they turn them into
carbohydrases (amylase is one)
simple sugars and glucose
amylase breaks down starch into maltose
and maltase breaks down maltose into glucose
what enzyme breaks down protein and what do they turn them into
proteases (pepsin is one)
protein and amino acids
pepsin breaks down proteins into smaller polypeptide chains
proteases made in the pancreas and small intestine break down peptides into amino acids
what enzyme breaks down lipids and what do they turn them into
lipases (lipase is one)
glycerol and fatty acids
lipase breaks down lipids into 1 glycerol and 3 fatty acids
what is bile
bile is an alkaline substance produced in the liver
what are the two roles of bile?
- neutralising the hydrochloric acid from the stomach
- breaking apart large drops of fat into smaller ones (emulsification)
what are the stages of food breakdown
- ingestion
- mechanical digestion
- chemical digestion
- absorption
- assimilation
- egestion
what are the adaptations of the small intestine that help with its purpose
- villi
- peristalsis
why are villi good at their purpose
- increasing surface area
- only 1 cell thick for easy diffusion
- they are connected to different structures which support the diffusion process
practical: energy content of a food sample
how do you carry this practical out?
- use a measuring cylinder to measure 25cm^3 of water and pour into a boiling tube
- record the starting temp of the water
- weigh the initial mass of the food sample
- set fire to the sample of food using a bunsen burner
- keep the food sample 2 cm under the water
- record the final temperature of the water
- once cooled weigh the mass of the remaining food and record it
- repeat the process with different food samples
practical: energy content of a food sample
what do the results tell you?
a larger increase in water temperature indicates larger amount of energy contained by the sample
practical: energy content of a food sample
how do we calculate the energy
energy transferred (J) = (mass of water (g) x 4.2 x temperature increase (°c) ) / mass of food (g)
practical: energy content of a food sample
how can we improve this practical
- relight the food sample to make sure everything is actually burnt
- heat energy is lost to the surroundings however, if the experiment is carried out the exact same way each time it should be fine
