nucleus- contains DNA and controls the actions of the cell
cytoplasm- where chemical reactions, controlled by enzymes take place.
cell membrane- controlls what comes in and out of the cell
mitchondria- where respiration takes place
ribosomes- protein sytrhesis takes place here
cell wall- strengthens cells, made of cellulose
chloroplasts - made of chlorophyll, which aborbe light for photosythesis
permanent vacuole- filled with sap, keeps cell turgid
leaf cell-absorbs light for photosyntheisis, its packed with chloroplasts, the cells are a regular shape and are tightly packed so there is a continuous layer
root hair cell- absorbs water and ions in the soil, thin cell and a project give it a large surface area and make it a good site for transport.
sperm cell- fertalises an egg cell, gamete, head contains genetic information and an enzyme for fertalisation, the middle bit is packed full of mitchondria for respiration and energy. the flagela is the tail that helps power the cell.
red blood cell contain haemoglobin, to carry oxygen to the body cells, no nucleus so it can carry more haemoglobin.
this happenbs when cells spread out, its the net moverment of particles from high concentration to low concentration due to the random movement of particles.
the bigger the difference in concentration the faster the rate of diffusion.
a bigger surface area increases the rate too
an increas in temp will also increas rate.
osmosis is the net movement of water from a high water concentration to a low water concentration through a partiallaly permeable membrane.
the cell membrane is a partially permeable membrane so osmosis can take place in a cell.
equilibrium is reached when both soultions have the same concentration of water. not when there is the same volume of solution there.
carbon dioxide +water (+light energy) ---> oxygen +glucose
the chlorophyll absorb the light needed
some of the glucose is used immediately but some is also turned into starch
iodine solution turns blue in the presence of starch.
plants are adapted for photsynthesis
- they have a broad leave so lots of light falls on it
- they have lots of chloroplasts
- they have air spaces in the leaves, for CO2 and O2 to move about in
- they have an xylem to take water to the plant
light intensity increases the rate a untill another limiting factor takes effect
carbon dioxide increases the rate a untill another limiting factor takes effect, in a green house, a tropical forest or dense vegetation there could be a lack of CO2
temperature increases the rate untill optimum, after which is will decrease the rate because enzymes have become dentaured.
how plants use glucose
plants photosythesise at a much higher rate in the day than they do at night they respire at a constant rate all the time. they respire, to get energy from the glucose
some of the glucose is stored as starch, because it is insoluable
they use some of the energy to combine with nutrients from the soil in order to make amino acids and later on proteins which get built into cells.
the enegry is also used to build up a store of oils and fats for food stores and seeds.
the phloem transports sugars around the plant
the xlyem transports water and mineral ions from the roots upwards
why do plants need minerals?
the minerals are taken up in the roots by active transport
the root hair cells have a larg surface area
nitrate. is used for making proteins and without it a plant will have stunted growth
magnesium. is used to make chlorophyll and without it it will have pale yellow leaves
a new way of growing plants is through hydrophnics, the plants are grown in water which has plenty of minerals in it.
the crops are also grown in a greenhouse with the other limiting factors controlled
this is an expensive way to farm and is done on a large scale but in the end the crops fetch a high price
pyramids of biomass
the enrgy for ALL living organisms comes indirectly from the sun.
biomass is the amount of living material in an animal or a living thing.
it is often measured as dry mass in grams
you can represents food chains on pyramids of biomass or pyramids of number
the pyramid of biomass shows us the amount of biological material involved at each trophic level in a way simple numbers do not.
the engergy from one trophic level to the other is always less than the one before it this is because:
not all of the food eaten can be digested so some energy is lost as faeces
some of the enegry is used in respiration for movement and controlling body temperature and only a very small amount is used for growth.
energy in food production
meat comes from animals which eat plants so because energy is lost by the animal eating plants is more efficient than eating animals.
so in theory if we all became vegaterians there would be more food to go around because less of the energy would be wasted and the energy produced by the plant would go directly to us.
every time we add another trophic level we lose more biomass
factory farming limits the amount of energy lost by controlling temp and movement
this raises moral concerns beacuse the animal welfare is not being considered
when a plant takes up minerals from the ground, they are passes on the food chain,
when an organism dies and falls to the ground they get recyled and reused. detritus feeders start the deacy process by eating the waste material,
then decomposers, microorganisms including bacteria and fungi, they break down the matter and digest some they also produce watse products including, carbon dioxide water and minerals which plants use
the decomposers work best in warm, moist, oxygenated conditions as they respire.
this process is used in sewage plants and in composte heaps
the carbon cycle
farming, intensive or extensive?
- Large amount produced very quickly and products cheaper than free range
- Not much land required
- Less people employed
- Chickens get really big quickly
- Heats itself as animals keep each other warm
- Restricted movement ensures more energy more energy goes into growth
- Stressed animals = poor quality meat
- Disease spreads quickly
- Increased food costs as no supplement with grubs and seeds
- Lighting costs and some heating costs
- Risk to all products if problem occurs in a barn
lost of reactions take place in your body and they all need to be controlled
they are controlles by biological catalysts, enzymes.
enzymes are made of proteins, each enzymes has its own shape because its active site is different so different substrates can be controlled with it.
they work by lowering the activation energy, or by providing a site for a reaction to take place on.
factors effecting enzymes
a rise in temperature can speed up the rate of reaction but too high and the enzymes shape will be deformed and it will become denatured.
the higher the concentration of enzymes the faster the rate of reaction untill there is a higher concentration of enzymes than substrate.
different enzymes work in different pH ranges but too acidic/alkaline and it will be denatured
oxygen + glucose --> carbon dioxide + water
C6H12 +O2 --> 6CO2 + 6H2O + energy
respiration takes place in the mitchondria
respiration has four main functions:
- breaking down the glucose from our food
- making new cell material
- to contract and relax muscles
- energy for homeostasis
enzymes in digestion
amylase- is produced in the salivary glands, pancreas and small intestine
protease- is produced in the pancreas stomach and small intestine
proteins---> amino acids
lipase is produced in the pancreas and the small intestine
lipids--> fatty acids and glycerol
speeding up digestion
the stomach is acidic
but the enzymes in the small intestine work best in slightly alkaline conditions
so we have bile which nuetralises the stomach acid and it emulsifies fats.
it is made in the liver
and it is stored in the gall bladder
making use of enzymes
protease- used to manafacture baby food, so the proteins are already pre-digested
lipase- used in biological detergents to break down (digest) the the substances in stanis into small soluble molecules.
carbohydrase- used to convert starch into sugar syrups which has more worth and is used in sports drinks
isomerase- used to convert glucose into fructose which is sweeter so lees needs to be used so it is often found in slimming foods.
controlling internal conditions
for your body to work the conditions around your body must stay constant.
excretion- carbon dioxide and water
amino acids are a form of urea and taken out the blood by the kidney
too much water can damage a cell.
controlling body temp
- heat from muscles in exersice
- fever from disease
- the external temp falling or rising
when your too hot
- you sweat
- metabolism slows down
when your too cold
- you shiver - this is contracting and relaxing of your muscles with creates heat from respiration
- hairs stand on end
controlling blood sugar levels
blood sugar levels are controlled by the pancreas
too high- the pancreas excretes insulin which tells the liver to convert glucose into glycogen
too high - pancreas excretes glucagon which tells the liver to convert glycogen into glucose which goes back into the blood.
diabetes is where your body cant control your blood sugar levels.
type 1- dont produce insulin so they have to inject, they have to check to make sure they inject the right amount
type 2- their cells dont respond to insulin so they have to controll blood sugar levels with diet and exercise
cell division and growth
mitosis occurs in all cells
it results in two cells identical to each other
when early enbryos are formed they are made of stem cells, these are un differentiated cells to can become anything.
by the time a human has been born the cells are specialised except some partially specialised cells in the bone marrow.
plants can be cloned so easily because the cells can become unspecialised and move around the plant to perform other jobs, because they never stop growing.
stem cells are not specialised and can become differntiated into many different types of cell when when required.
there are ethical issues surrounding the use of stem cells
stem cell research is slow and expensive but ultimately could save millions of lives
cell division in sexual reproduction
cells in reproductive organs divide to form gametes
the cell divides twice, to form four gametes
each gamete only contains one chromosome of the original pair
this process is known as meiosis
from mendel to DNA
gregor mendel was a sceintist that first thought about DNA by crossing pea plants..
DNA - deoxyribose nucleic acid
your genes are small strings of DNA
genes are codes for making proteins out of amino acids
inheritance in action
phenotype - physical appearance
homozygeous- same alleles
hetrozygeous- different alleles
recessive- the effect can be masked by a dominant allele, and can only take effect if the person has inherited both from both parents
dominant- this one can mask the effect of another allele and be the one that takes effect
it affects the cell membranes and is inherited from a recessive allele
it affects the nervous system and is a dominant allele, so only one parent need to have it for there to be a chance that the child inherits the condition.
embryo screening is doctors test the embryos for genetic disorders