Nutrition Flashcards
photosynthesis
the process by which plants manufacture carbohydrates from raw materials using energy from light
describe what happens during photosynthesis
-energy from sunlight is absorbed by chlorophyll inside chloroplasts
-green plants use this energy to make carbohydrates glucose from the raw materials CO2 and water
-oxygen is released as a waste product
autotrophs meaning
organisms that can make complex molecules from simple molecules
what are producers
organisms that are able to make their own food and so are the first organism at the start of all food chain
how do plants use glucose they make as a source of energy
-produce starch for storage
-synthesise lipids for an energy source in seeds
-form cellulose to make cell walls
-produce amino acids when combined with nitrogen and other mineral ions absorbed by roots
word equation of photosynthesis
CO2 + water ->(light) glucose + oxygen
chemical equation of photosynthesis
6CO2 + 6H2O → C6H12O6 + 6O2
limiting factor meaning
something present in the environment in such short supply that it restricts life processes
3 main factors affecting the rate of photosynthesis
-temperature
-light intensity
-carbon dioxide concentration
(also number of chloroplasts)
why is water not considered a limiting factor for photosynthesis
the amount needed is small compared to amount transpired from a plant so rarely is there not enough water for photosynthesis
how is temperature a limiting factor for photosynthesis
-surrounding temp affects how much kinetic energy all particles have so temp affects the speed at which carbon dioxide and water move through a plant
-higher temperature = higher KE, resulting in more successful collisions over a period of time. Also higher KE increases the likelihood of collisions between reactants and enzymes resulting in the formation of products
-eventually enzymes denature, reducing the rate of photosynthesis
describe the graph of temp against rate of photosynthesis
-increases until optimum temp, where is quickly decreases
how is light intensity a limiting factor
-it affects the amount of energy plants have so photosynthesis happens at a slower rate
-more light = faster rate of photosynthesis
describe the graph of photosynthesis against light intensity
straight diagonal line proportional, until light intensity is no longer the limiting factor and the line becomes flat
how is carbon dioxide concentration a limiting factor
-CO2 is a raw material required for photosynthesis
-more CO2 = faster rate of photosynthesis
describe the graph of carbon dioxide concentration against photosynthesis
straight diagonal line proportional, until CO2 concentration is no longer the limiting factor and the line becomes flat
how is chlorophyll a limiting factor for the rate of photosynthesis
-chloroplasts absorb light energy, so more light energy can be used in the reaction when more chlorophyll are present
-more chlorophyll = faster rate of photosynthesis
what affects the number of chlorophyll in a plant
- diseases (tobacco mosaic virus)
- lack of nutrients (magnesium)
- loss of leaves
4, genetic factors such as variegated leaves
features of wax cuticle
protective layer on top of the leaf that prevents water from evaporating
features of upper epidermis
thin and transparent to allow light to enter palisade mesophyll layer underneath it, (protects leaf and prevents some water from evaporating)
features of palisade mesophyll
-column-shaped cells tightly packed with chloroplasts to absorb more light, maximising photosynthesis
features of spongy mesophyll
contains internal air spaces that increase the surface area to volume ratio for the diffusion of gases (mainly CO2)
lower epidermis features
-contains guard cells and stomata
guard cell
absorbs and loses water via osmosis to open and close the stomata to allow carbon dioxide to diffuse in and for oxygen to diffuse out
stomata
-where gas exchange take place, opens during the day and closes during the night
-evaporation of water takes place as well
-in most plants there is a greater concentration on the underside on the leaf to reduce water loss, as it is not exposed to the sun
vascular bundle
contains xylem and phloem to transport substances to and from the leaf
xylem
-transports water into the leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
-on the inside of the stem
phloem
transports sucrose and amino acids around the plant
adaptations of the plant
-leaves have large surface area to increase diffusion area and for absorption of light
-leaves are thin to allow CO2 to diffuse to palisade mesophyll cells quickly
-epidermis is thin and transparent, allowing more light to reach the palisade cell
-spongy layer contains air spaces that allow carbon dioxide to diffuse through the leaf, increasing the surface area it has so more gas exchange
-stomata in the leaf allow CO2 to diffuse into the lead and oxygen to diffuse out
-vascular bundles have think cell walls, which help to support the stem and leaf
-the thin wax cuticle protects the leaf without blocking sunlight since
-chlorophyll in the leaf absorbs light energy so that photosynthesis can take place
-network of veins in the leaves allows the transport of water to cells in leaves for photosynthesis and carbohydrates from the leaf
how do plants obtain elements required such as magnesium
absorb elements in the form of mineral ions from the soil by root hair cells using active transport
what mineral ions (elements do plants need)
nitrates
phosphates
potassium
magnesium
use of nitrates in plants
making amino acids to make proteins
nitrate deficiency symptoms
stunted growth of plants, older leaves turn yellow
use of phosphates in plants
making DNA, part of cell membrane
phosphate deficiency in plants
-poor root growth and younger leaves turn purple
use of potassium in plants
for enzymes of respiration and photosynthesis
potassium deficiency plants
leaves turn yellow with dead spots
use for magnesium in plants
needed to make chlorophyll
deficiency of magnesium in plants
leaves turn yellow
why is food needed/what are digested molecules used for
-to supply us with a ‘fuel’ for energy
-to provide materials for growth and repair of tissues
-help us fight diseases and keep our bodies healthy
-repair
-to grow
-function
necessary key food groups (8)
Carbohydrates
Proteins
Lipids
Dietary fibre
Vitamins
Minerals (mineral ions)
Water
Malnutrition
types of malnutrition caused by unbalanced diet
- starvation
- coronary heart disease
- constipation
- obesity
cause and effect of starvation
-taking in less energy than is used over a long period
-body starts to break down energy stores - first fat then muscle tissue, leading to severe weight loss and eventually damage to heart and immune system which increases the risk of diseases
cause and effects of coronary heart disease
-diet too high in saturated fat and cholesterol
-fat deposits built up in arteries supplying the heart, reducing flow of blood to the heart muscle cells which do not work properly due to lack of oxygen. Can lead to heart attacks and death
cause and effects of constipation
-lack of fibre in the diet
-food lacks bulk for muscles to push it through the alimentary canal. Hence, risk of diseases such as bowel cancer are increased
cause and effects of obesity
-taking in more energy than is used
-extra energy stored as fat, weight increases and contributes to development of diseases such as heart disease and type 2 diabetes
function and source of carbohydrates
-source of energy
-pasta, bread, rice, potatoes etc
function and source of protein
-growth and repair
-meat, fish and eggs
function and sources of lipids
-insulation and energy storage
-butter, oil
function and sources of dietary fibre
-provides bulk for the intestine to push food through it
-whole grains, vegetables
function and source of vitamin A
-making a chemical in the retina, protects surface of eye for vision
-liver
deficiency of vitamin A
-night blindness, damaged cornea
function and source of vitamin C
-form part of collagen proteins which makes up skin, hair, gums and bones
deficiency of vitamin C
scurvy
function and source of vitamin D
-helps the body absorb calcium for strong bones and teeth
-found in oily fish
deficiency of vitamin D
-rickets, poor teeth
function and source of iron
-needed to make haemoglobin in RBCs to carry oxygen
function and source of calcium
-strong teeth in bones and clotting of blood
-found in milk, cheese and eggs
deficiency of calcium
osteoporosis
function and source of water
-needed for chemical reactions to take place in the body
-water, juice, milk
how and why should the diet of young people vary
-more protein, more energy overall
-children need to grow so they need more protein
how and why should the diet of active people vary
-more energy required
-because muscles are contracting more and respiring faster
how and why should the diet of pregnant people vary
-energy requirements increase
-because energy is needed to support the growth of the developing fetus and the larger mass the mother needs to carry around
-extra calcium and iron needed to build bones, teeth and blood of the fetus
how and why should the diet of breastfeeding mothers vary
-energy requirements increase
-extra calcium needed to make high quality breast milk
how and why should the diet of males compared to females
-higher energy requirements for males
-larger proportion of muscle to fat (less insulation and muscle is living tissue and burns calories)
digestion
the process where large, insoluble molecules in food are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body
use of digested molecules such as glucose and amino acids in the body
-provide cells with energy
ingestion
when food enters the mouth
absorption meaning when describing digestion
small digested food molecules move from the small intestine into the blood
assimilation/synthesis meaning
small molecules are used to build large molecules
egestion meaning
removal of undigested food/waste through the anus
what is the alimentary canal
-the passage in which food flows through the body, starting at the mouth and ending at the anus
-digestion occurs here
-accessory organs such as the liver produce substances for digestion but food does not pass through these organs directly
function of the mouth and salivary glands
-(chew) food to break it into smaller pieces and increase its surface area to volume ratio
-(amylase) enzymes digest (starch) into (maltose)
-food is shaped into a bolus and lubricated by saliva so it can be swallowed easily
() = in mark scheme
oesophagus function
-connects the mouth to the stomach
-wave-like contractions/peristalsis takes place to push the food down without relying on gravity
stomach function
-churning actions mechanically digests food
-protease (pepsin?) enzymes digest proteins
-HCl kills bacteria in food and provide optimum pH for protease enzymes to work
small intestine function
-in the duodenum: amylase, lipase and protease from the pancreas digest the food (alkaline conditions, 8-9)
-in ileum: absorption of water and digested food molecules takes place, lined with villi for higher SA of which absorption can take place
large intestine function
-water is absorbed from remaining material in the colon to produce faeces
-faeces are stored in rectum and exit the body via the anus
pancreas function
-produces amylase, protease and lipase
-secretes enzymes in alkaline fluid into duodenum for digestion, raises the pH of fluid coming out of the stomach
liver function
-amino acids not used to make proteins are broken down, producing urea
-produces bile to emulsify fats into smaller droplets to increase SA for enzymes. Bile also neutralises the stomach acid for enzymes in the duodenum
gall bladder function
stores bile to release into the duodenum
mechanical digestion
breakdown of food into smaller pieces without chemical change to the food molecules to increase the surface are for enzymes
chemical digestion
bonds holding large molecules are broken, leading to the breakdown of large, insoluble molecules into small, soluble molecules
how does peristalsis work
-responsible for moving food along the gut
-circular muscles contract and the longitudinal muscles relax behind the bolus, causing the the gut to become narrower behind it, and the circular muscles relax and then the longitudinal muscles contract ahead of the bolus, moving it forward through a wave of contractions
-prevents relying on gravity
what does carbohydrase do
breaks down carbohydrase into simple sugars like glucose
what does amylase do
breaks starch into maltose
what does maltase do
-breaks down maltose into glucose
where is amylase made
-salivary glands, pancreas and small intestine
where is amylase denatured and replaced
-amylase from salivary glands are denatured in the stomach
-replaced by amylase from the pancreas in the small intestine
what does protease do
a group of enzymes that break down proteins into amino acids
what is pepsin
an enzyme made in the stomach which breaks down proteins into smaller polypeptide chains
series of events for proteins to be broken down into amino acid
-protein molecules made in the stomach are broken down into smaller polypeptide chains in the stomach
-protease enzymes made in the pancreas and small intestine break the polypeptide chains into amino acids
lipase
-enzymes that break down lipids(fats) to glycerol and fatty acids
-lipase enzymes are produced in the pancreas and secreted into the small intestine
role of bile
- neutralise hydrochloric acid from stomach: bile is alkaline, allows enzymes in the stomach that have higher optimum pH to work
- breaking apart large drops of lipids into smaller ones: increases SA, known as emulsification
alkaline conditions and larger SA allows lipase to chemically break down lipids into glycerol and fatty acids at a faster rate
how are small, soluble digested molecules absorbed into the blood stream
-diffusion and active transport (sometimes)
how and where is water absorbed
-osmosis in the small intestine as well as large intestine
how is the small intestine/villi adapted for rapid absorption of substances
-there is a (large surface area)
-(microvilli) on surface of villi increase surface area available
-(one cell thick wall) of villus leads to shorter diffusion distance
-good blood supply from (capillaries) that transport glucose and amino acids maintain steep (concentration gradient)
-lacteal runs through centre of villus to transport fatty acids and glycerol away from small intestine
-enzymes produced in walls of villi assist with chemical digestion
-movement of villi helps to move food along and mix with enzymes
-it has both (diffusion) and (active transport)
