Biology paper 2

Question 1

What is Homeostasis ( do we keep levels of everything exactly the same

Answer 1

Homeostasis is the regulation of conditions inside our body to maintain a stable internal environment in response to both internal and external conditions. even though we regulate everything we do not keep levels of everything exactly constant as temperature and glucose levels do fluctuate but only within small bounds

Question 2

what does the automatic control system do
(What are its components and how do they communicate)

Answer 2

the automatic control system can detect if levels have derived from optimal conditions and send a signal to reverse and counteract this change so levels return to normal again.
Receptors detect the change
the central nervous system interprets the change and figures out what it needs to do
the effectors carry out the change
The components of the Automatic control system communicate through the nervous system and endocrine system

Question 3

what are the brief differences between the nervous system and endocrine system

Answer 3

the nervous system allows us to send very fast and precise electrical impulses through nerves which allows our body to respond quickly
the endocrine system relies on hormones which are small chemical molecules that are secreted into the blood and transported around the body via the blood stream. Although these hormone chemicals only effect certain cells with receptors specific to the hormone molecule. these hormones are transported around the body slower although their effects last longer and these act more generally as they span the entire body.

Question 4

what does a negative feedback loop do (give an example)

Answer 4

a negative feedback loop will detect if levels of something in our body is to high and bring about changes to bring our levels back down to normal (same is true for converse)
using temp as example -
if our body temperature is to low then receptors will detect this change in optimal conditions and send a signal the central nervous system to counteract this change. the CNS does this by interpreting this change and sending signals to the effectors to bring about this change by for example causing our erector muscles to contract as to make our hairs stand up and trap a layer of insulating air to reduce heat energy lost to surroundings

Question 5

what are the adaptations/function of the nerve cell

Answer 5

Nerve cells have adapted to carry electrical impulses from one location to another
they are long and thin. they also have many branched connections which enables them to pass messages to other neurones.

Question 6

What is the synapse

Answer 6

the synapse acts as the interconnected nerve pathway between neurones to allow communication. When an electrical impulse reaches the end of the long axon it causes the neurotransmitter vesicles to release neurotransmitters in order to diffuse across the synaptic gap in the form of chemical energy to bind to the receptor on the second neurone and stimulate an electrical impulse

Question 7

what is reflex arc and its benefits

Answer 7

the reflex arc is a nerve pathway that allows us to respond to danger rapidly and automatically

Question 8

what happens if you were to touch a needle/ hot pan

Answer 8

first receptors would detect stimuli and stimulate the sensory neurone to carry an electrical impulse to the spinal chord of the CNS. this would then transfer to the relay neurone that then passes this information to the motor neurones which are fired out to transport the impulse to the effectors such as the bicep to contract

Question 9

what are the components of our brain and their functions

Answer 9

the cerebral cortex is responsible for controlling our consciousness, memory, language , senses and intelligence
the cerebellum is responsible for controlling our balance and muscle coordination
the hypothamalous is responsible for regulating our body temperature and sending signals to the pituitary gland
the medulla is found in the brain stem and controls our unconscious activities such as breathing and beating of our hearts

Question 10

How do scientists study the brain

Answer 10

1) studying those with brain damage. for instance if someone had suffered a stroke and lost their hearing for instance by seeing what area of the brain was affected we can deduce that section of the brain is associated in some way with that sense
2) electrical stimulation of different parts of the brain. This is done by planting an electrode in different sections of the brain and observing the effects it has on the patient
3) scanning the brain ( least invasive ) .
CT scans use XRAYS to see what areas of the brain had been damaged
PET scans use radioactive chemicals to measure underlying activity of the brain
MRI scans use magnetic fields to measure underlying activity of the brain

Question 11

why is studying the brain so difficult

Answer 11

there is a wide range of things that can go wrong
Trauma, mental health problems, infections, tumours

because our brain is encased in our skull and is surrounded by a layer of fragile brain tissue it makes it difficult to fix anything physically

also because our brain is so complex it makes it difficult to treat with drugs and chemicals as we don’t fully understand underlying processes

Question 12

explain the structure of the eye

Answer 12

When light comes into contact with the eyes it first hits the cornea which is both transparent and has no blood vessels to allow all light to pass through. As the cornea has no blood vessels all oxygen supplied to it has to diffuse from the outside of the cell. The cornea bends/ refracts light.
the iris is the coloured part of your eye and controls the size of your pupil
the pupil is the gap in the iris which allows light to pass through to the lens
the lens also refracts/bends light however can change shape to alter its refractive power as so light is always directly converged onto the retina
the retina is made up of two cone cells. The cone cells are sensitive to the colour of light itself but don’t work well in low light conditions whereas the rod cells are sensitive to light but can only see in black and white. The fovea is a spot on the retina which only contains cone cells.
the optic nerve takes electrical impulses generated by receptor cells and transport this the CNS ( brain )

Question 13

how does your eye respond to low light and bright light conditions

Answer 13

in low light conditions your pupil dilates to let as much light in as possible
in order for this to happen the circular muscles relax so they can be stretched and the radial muscles contract in such a way they exert force on the iris causing it to be stretched from the centre causing the pupil to open more

in bright light conditions your pupil constricts so your eye is not damaged
in order for this to happen your circular muscles contract pulling the pupil inwards and the radial muscles relax so they can be stretched

Question 14

what are mutations

Answer 14

mutations are simply changes in the sequence of bases making up our DNA

Question 15

what increases risk of mutations

Answer 15

carcinogens which contain toxic chemicals
certain types of radiation such as x-rays or gamma rays

Question 16

how does a mutation work

Answer 16

if a Mutation occurs it could potentially change the amino acids that codons/triplets code for and have a knock on effect as the sequence of amino acids as a whole would be different and therefore when folded up and combined with other polypeptides it could form a different protein with a different shape and function.

Question 17

what could happen if a mutation occurred in an enzyme

Answer 17

if a mutation occurred in an enzyme it could alter the shape of the active site such that the substrate would no longer be complementary to that active site therefore wouldn’t be able to bind to it to form an enzyme substrate complex and so would be unable to catalyse reactions

Question 18

where do most mutations occur

Answer 18

most mutations don’t actually have any significant effect as even if they change the physical appearance of a protein slightly it will still for the most part have the same shape and be able to perform its function its dedicated to
also most mutations occur in the non - coding part of the DNA which even though it plays an important role in the expression of genes as they do not code for any amino acid it has no potential to have a knock on effect on the protein formed although a mutation here could alter the way genes are expressed and cause minor problems

Question 19

how do animals, plants and bacteria reproduce

Answer 19

animals rely on sexual reproduction
plants rely on sexual and asexual reproduction
bacteria rely on asexual reproduction

Question 20

how does sexual reproduction work

Answer 20

sexual reproduction involves the fusion of both male and female gametes in the process of fertilisation.
as in sexual reproduction we have two parents there will be a mixing of genetic material and therefore the offspring will for this reason be genetically different and have variation

Question 21

what are gametes and how are they made

Answer 21

gametes are sex cells (sperm in men)(egg cells in women) gametes are haploid cells as they contain half the genetic material of a normal human cell of 23 chromosomes such that when fused into a fertilised egg cell they form a diploid cell with 46 chromosomes

Question 22

what does Asexual reproduction involve

Answer 22

Asexual reproduction only involves one parent and therefore there will be no mixing of genetic material so the offspring will have no genetic variation allowing us to produce genetically identical clones
eukaryotic cells such as plants and fungi undergo Asexual reproduction via mitosis
while prokaryotic cells such as bacteria undergo Asexual reproduction via binary fission

Question 23

what are the benefits of Asexual reproduction

Answer 23

• Asexual reproduction only requires one parent is a very quick process
• Asexual reproduction allows a single organism to quickly colonise a new area. same applies to plants if conditions are right

Question 24

what are the drawbacks of Asexual reproduction

Answer 24

• because Asexual reproduction produces genetically identical clones this means there will be no variation in the population
  this makes the entire population more susceptible to being wiped out by a single event such as a new disease because if one organelle is affected this means the rest will be to which could cause the entire population of plants/ offspring to be wiped out
  Also offspring from Asexual reproduction are less likely to adapt to newly changing conditions such as climates and new competitors

Question 25

what are the Benefits of Sexual reproduction

Answer 25

main benefit of sexual reproduction is that there is genetic variation within the population in the short term this means that the population is less likely to be wiped out by a single event such as a new disease as some organisms will be more resistant than others in the long term this means that the population will be able to adapt to newly changing conditions through the allowance of evolution which describes the change of a species overtime which is significant because the most favourable traits are the most likely to be passed on

Question 26

what are the drawbacks of Sexual reproduction

Answer 26

the problem with sexual reproduction is that its very time and energy consuming as finding a mate is time consuming and actually impressing a mate is energy consuming in a way

Question 27

what are the stages of meiosis

Answer 27

- first is the replication of DNA in which chromosomes all gain extra arm - these two armed chromosomes then line up down the centre of the cell in their corresponding pairs however the number of chromosomes in the left to right ratio always changes - then these two armed chromosomes are pulled apart to each end of the cell and the cell divides into two. However the number of maternal and paternal chromosomes will be randomly distributed between the two cells meaning that the DNA in each will be different in each - next the two armed chromosomes are lined up down the centre of the cell again and their corresponding copy is pulled apart (arm) to each end of the cell ready for the second division forming 4 genetically unique cells as during mitosis/meiosis mutations happen spontaneously and therefore will differ slightly genetically -these will form gametes each with 23 chromosomes. in men these will develop into sperm and in females will develop into egg cells. These gametes can then fuse in the process of fertilisation to form a fertilised egg cell/ diploid cell that can then undergo mitosis to form an embryo that when implanted in the uterus lining can develop into a foetus and eventually a fully grown organism

Question 28

what does a genetic diagram show

Answer 28

a genetic diagram shows the different combinations of alleles from 2 parents

Question 29

what is polydactyly

Answer 29

polydactyly is a condition where a baby is born with extra fingers/ toes and is caused by a dominant allele

Question 30

what is cystic fibrosis

Answer 30

cystic fibrosis is a essentially a condition which is a disorder of the cell membranes causing there to be a build-up of thick mucus in the air pathways of the lungs and the pancreas causing respiratory issues and digestive problems. this is caused by homozygous recessive alleles however vectors of the disease are heterozygous

Question 31

what is embryonic screening

Answer 31

new advances in microscope technology has allowed us to remove single cells from an embryo which we can screen to identify genes that cause or increase risk of genetic disorders such as polydactyly and cystic fibrosis

Question 32

what are the pros and cons of embryonic screening

Answer 32

the pros of embryonic screening is that it reduces overall suffering as fewer people in the world will have health problems and it also saves money as treating those with genetic disorders is very expensive however this creates the idea that those with genetic disorders are undesirable which links to prejudice and also creates the risk of designer babies if people start screening for other traits like gender, height and eye colour which creates moral strain

Question 33

what did Mendel do and discover

Answer 33

Mendel experimented on pea plants with the colours of their pods and flowers and also their height. Mendel first cross bred green pea plants with green pods with a yellow pea plant with yellow pods and found that from all the offspring only yellow pea plants with yellow pods were produced / made. He then crossbred these offspring of yellow pea plants with yellow pods with each other and found that 3/4 were yellow but 1/4 was green which he deduced to be the result of "something" being passed down through the population across the generations. He called these "things" hereditary units which could either be recessive or dominant with the recessive unit only being expressed if two copies were found in offspring

Question 34

what is the brief entire history of DNA

Answer 34

in the late 1800s scientist's discovered chromosomes and observed how they behaved in cell division in the early 1900s scientists found similarities between Mendel's hereditary units which we call genes/alleles today with chromosomes and chromosomes actually contained these "units" in the 1950s scientists uncovered the structure of DNA in which were polymers which are long chains made up of smaller molecules called monomers in DNAs case called nucleotides which are made up of one 4 bases adenine, cytosine , guanine and thymine and that each contained a sugar molecule and phosphate molecule which binds together to form the sugar phosphate backbone forming complementary base pairs with the polymer chain its linked to as it coils up in the structure of a double helix for protection In 2003 scientists discovered the entire sequence of the human genome meaning they uncovered the entire sequence of genetic bases making up our DNA allowing us to identify genes that increase risk/ cause disease for example the gene BRCA as this only increases risk of breast cancer and has also allowed us to track ancestors migration patterns by observing small differences within DNA

Question 35

why does a population look "different"

Answer 35

the reason why a population looks different is due to genetic variation in which everyone's phenotypes is different. the phenotype is the observable characteristics/traits we get from the genotype which is our collection of alleles. These traits however are also determined by how multiple different genes interact with each other and external environmental factors. Everyone in the world has a unique genome which means we will form slightly different combinations of proteins making us look different.

Question 36

why is there so much genetic variation

Answer 36

the actual reason why there is so much genetic variation is due to mutations which happen spontaneously within our cells. most of these mutations will not have any significant effect and occur in the non - coding part of the DNA which plays an important role in expression of genes meaning that this would not alter the amino acid that these codons/triplets code for and therefore when the sequence of amino acids folds up the protein formed will be the same and therefore the phenotype will remain unchanged however sometimes these mutations do actually alter the amino acid transcribed from these codons/triplets and such the sequence of amino acids will alter so will form a different protein when folded up with a different shape and function and such changing the phenotype slightly. Most of the times this change is bad but very occasionally can lead to beneficial mutations which could for example increase resistance to certain diseases or give us enhancements in physical attributes allowing us to run quicker. These people with these beneficial mutations are more likely to survive and therefore more likely to reproduce and pass of their traits to offspring for generations to come.

Question 37

what are the three main concepts Charles Darwin believed in and what does this imply

Answer 37

Darwin for one believed in survival of the fittest in which he noticed that traits were passed down from parent to child and the most favourable traits were the most likely to be passed on to the offspring which ties into his idea of natural selection in which the fittest individuals would be selected to survive. Another main concept is the idea of evolution which states that through the inheritance of certain characteristics within a population across multiple generations could lead to a change in a whole species or development of an entirely new different species. This implies that all living species today evolved from simple life forms first developed more than three billion years ago.

Question 38

what provides evidence for evolution

Answer 38

anti - biotic bacteria resistance fossil records

Question 39

what is a summary to be made of evolution

Answer 39

evolution in summary is the process of natural selection of different genetic changes that gives rise to the phenotypes best suited for the environment

Question 40

how do we class stuff as a "new species"

Answer 40

we can class something as a new species when the phenotype of these animals/species becomes so different that interbreeding is no longer possible to produce fertile offspring

Question 41

what did Lamarck's theory state

Answer 41

Lamarks theory stated that an organism could acquire certain characteristics during its lifetime and pass these traits onto their offspring

Question 42

According to Lamarck's theory how do giraffes have longer necks

Answer 42

giraffe's started with short necked adapted to low vegetation as these Giraffes stretch their neck to reach higher branches for food, they acquire certain characteristics during their lifetime of a long neck this acquired long neck trait is then passed down to offspring, for successive generations will all have a long neck to reach higher leaves

Question 43

what are the three observations Charles Darwin made

Answer 43

Charles Darwin discovered that organisms of an individual species show a wide range of variation for a specific trait Charles Darwin also observed variation in species that are adapted to survive in different environments Charles also found that older layers of rock contain fossil records of less complex organisms however more recent layers of rock show fossil records of more complex organisms

Question 44

what was Charles and Wallace's reasoning for how Giraffes got longer necks

Answer 44

- some Giraffes have longer necks than other due to genetic variation among the species. we get this variation from mutations. - these Giraffes are better adapted and suited to the environment as they can reach leaves from higher trees - therefore these Giraffes are more likely to survive and reproduce to pass on the favourable traits to offspring as these are the most likely to be passed on - this process as a result is the reason why modern Giraffes look the way they do now and all have very long necks

Question 45

why did it take so long for Charles and Wallace's theory to be accepted

Answer 45

religious reasons lack of evidence DNA hadn't been discovered

Question 46

what is selective breeding

Answer 46

Selective breeding is the process of selecting the best animals or plants within a population and breeding them together to produce the best offspring possible across multiple generations

Question 47

what are the drawbacks of selective breeding

Answer 47

However selective breeding reduces the gene pool within a population. (gene pool just refers to the entire collection of alleles within a population) As in selective breeding we are simply just selecting certain alleles that code for the desirable traits we want this can also lead to a risk of inbreeding as the animals/plants that express the best alleles are most likely closely related as they look similar meaning that offspring will be more at risk/susceptible to diseases or genetically inherited disorders. Also as we mentioned because selective breeding reduces the gene pool which refers to the collection of alleles within a population and in selective breeding we are simply selecting for certain alleles that code for the traits we so desire we will also get a smaller pool of alleles meaning that the population will have less genetic variation making them prone to being wiped out by a single catastrophic event like a new disease since if one of the plants/animals were affected greatly by this event then the rest are likely to experience the same fait due to the reduced gene pool or reduced pool of alleles

Question 48

what is genetic engineering

Answer 48

genetic engineering is the process of taking an organism with desirable traits and extracting the gene that we want to copy to transfer it into an organism that we want to develop these same desirable traits essentially modifying the organelles genome in which we can then call them genetically modified

Question 49

what are some examples of genetic engineering

Answer 49

- for one we can genetically engineer sheep to produce drug like substances in their milk which we can then extract to treat diseases - another example is that we can genetically engineer bacteria so secrete hormones such as insulin that we can harvest to treat diabetes - another is that we can genetically modify crops/fruit so we can grow larger and overall better fruit and also increase resistance to diseases, herbicides and insects

Question 50

what is gene therapy potential problems and therefore solutions

Answer 50

in gene therapy we replace patients genes that cause diseases with healthy versions of that gene however this proves difficult as for instance if this patient was to have a genetically inherited/ caused /increased risk disorder then the faulty gene would be in all the patients cells therefore it would prove difficult to replace this faulty gene with the healthy version of that gene for each of the patients cells. A solution regarding this would be to replace the faulty gene at an early stage of development with this healthy version of the gene as if we did this for a fertilised egg cell or rather zygote/diploid cell then when this undergoes mitosis to develop into an embryo and eventually foetus and then fully grown organism the patients cells would all contain this healthy version of the gene as in mitosis we produce genetically identical cells henceforth fixing this condition however a problem we experience here is due to spontaneous mutations within our cells especially during mitosis or any kind of cell division this could alter the sequence of genetic bases making up our DNA and henceforth alter the amino acids transcripted by these codons/triplets in some versions of mutations completely altering the sequence of amino acids and therefore the healthy version of the gene that we replaced could undergo mutation and code for a different protein with a different shape and function. A way we can reduce risk of this would be to integrate therapeutic genes into sections of the DNA which are less prone to mutations or use AAV (adeno - associated viruses) which act as vectors for these healthy versions of the genes yet are external to the patients DNA and therefore wont modify patients genome eliminating risk partially of these mutations occurring

Question 51

what the pros and cons of genetically modified crops

Answer 51

pros : Genetically modified crops allows us to produce many crops with desirable characteristics such as more and larger fruit and increase resistance to disease, insects and herbicides - this is especially helpful in developing countries allowing us to produce more food for a cheaper price - another benefit is that we can integrate special nutrients into crops/fruit for example beta-carotene in golden rice aids in the presentation of bindless rather decreasing risk ]# cons : however we can not say with 100 percent certainty how these genetically modified crops affect our health at least in the long term yet there is no evidence supplies that talks of how these genetically modified crops would be bad otherwise Also if these genetically modified crops were to get out into the wild these crops would quickly outcompete other crops and predecessors altering the ecosystem and potentially reducing biodiversity however this is not likely seen as GM crops have been specifically modified to be in farmers fields rather than the wild however is non the less a possibility

Question 52

How do we transfer the gene from one organism to another in genetic engineering

Answer 52

firstly we isolate the section of DNA or the gene that codes for the desirable characteristics that we want using enzymes we then insert this isolated gene into a vector which could either be a bacterial plasmid or virus then we introduce vector to the organism we want to have this gene. the organism will take in this vector and gene simultaneously. The organism will then start producing this protein and seen as the gene codes for the protein that contains the properties of the desirable characteristics and traits the organism will start developing these features/traits

Question 53

Why is the human genome project important

Answer 53

- the human genome project has allowed us to understand how genetic disorders work so preventative steps can be taken. People can be screened for health risks early so they can start treatment sooner. also the human genome project has allowed us to diagnose and improve treatment of genetic disorder as it has allowed us to identify faulty genes quickly. new personalised drugs and therapeutics can be tailored to match a patients specific genetic makeup for the best results and avoid any health issues

Question 54

how does nucleus transplant cloning work

Answer 54

- take an egg cell from a female donor and remove its nucleus to form an enucleated egg cell - take an adult body cell (e.g. skin cell) from the organism you want to clone and remove its nucleus - fuse nucleus of adult body cell with enucleated egg cell - stimulate the cell via a small electric shock to make it act as a zygote which will then undergo cell division or mitosis to form an embryo - implant embryo into the uterus of a surrogate mother and birth will carry out as normal

Question 55

how does embryonic cloning work

Answer 55

- take a male and female with the most desirable characteristics - fuse the male gamete sperm cells with the female gamete egg cells via fertilisation to form a zygote - let the zygote undergo mitosis and divide to form an embryo - split the embryo into a bunch of smaller embryos - implant each embryo into the uterus of a surrogate mother - each one will produce genetically identical clones

Question 56

how do cuttings work

Answer 56

- take a plant with the most desirable characteristics and traits you want to clone - cut of a small piece of the plant ( ideally a growing shoot or branch - place cutting into the soil along with other nutrients and growth hormones such as rooting powder which contains auxins - this cutting will develop into a genetically identical clone of the original plant

Question 57

how does micropropagation work

Answer 57

- take a plant with the most desirable characteristics/ traits that you want to clone - cut of very tiny pieces of the plant tissue called explants using a scalpel from the tips of the stem - sterilise explant to remove microorganisms - transfer explant into a nutrient medium growth (agar) using forceps or tweezers and leave explants to develop into small masses of cells called calluses. The medium growth should also contain plant growth hormones like auxins and gibberellin - transfer calluses into the soil and leave to develop into platelets - transfer platelets into their own pot to develop into genetically identical adult plants

Question 58

give examples of nutrients used in nutrient medium

Answer 58

magnesium is used for chlorophyll phosphate is used for adenine - tri - phosphate glucose is used for respiration nitrates are used for amino acids

Question 59

define the term species

Answer 59

a species is a group of genetically similar organisms that can undergo interbreeding to produce fertile offspring

Question 60

what does speciation refer to

Answer 60

speciation is a term that refers to when a new species is formulated from a common ancestor

Question 61

explain how two different species of rabbits can be produced from a common ancestor

Answer 61

this even can first start to occur due to a combination of both natural selection and isolation. Isolation is a term that refers to a physical barrier separating two different populations of the same species. Usually within these two barriers there will be alternating/different environmental conditions. Essentially what this means is that the two different populations will undergo different selection pressure. Which simply refers to the fact that different characteristics/traits will be more favourable between the different populations due to these contrasting environmental conditions meaning that through the process of natural selection these characteristics will become more common within the populations swaying further away from genetic similarity. Effectively different mutations will occur among these organisms as certain alleles are selected to code for the characteristics/traits that is the most suited to the environment shall be selected through the process of evolution which simply put is the concept of natural selection of genetic changes that give rise to the phenotype best suited to the environment. Therefore after generations (long periods of time) these animals will develop differently in terms of genetic/behavioural/physical traits such that eventually interbreeding in order to produce fertile offspring will become impossible and therefore we can say "speciation" has occurred since this just describes the formulation of a new species from a common ancestor

Question 62

how does anti biotic resistance develop

Answer 62

- random mutation's occur in bacteria's DNA occasionally changing bacteria's characteristics - in some rare cases this mutation will cause the bacteria to become less affected by anti - biotics - seen as resistant bacteria has no more competition it will survive and undergo division to form a complete genetic copy of an antibiotic resistance strain that all contain the gene coding for anti - biotic resistance

Question 63

what is it called if a bacterium is resistant to lots of different anti - biotics an example of one and its "symptoms"

Answer 63

if a bacteria is resistant to lots of different anti - biotics is will be called a superbug. An example of one is MRSA that is relatively common due to its resistant strength most occasionally effecting those in hospitals which can he fatal in some cases

Question 64

why is it important to take the full course of anti - biotics

Answer 64

because bacteria developing resistance is relatively uncommon and even when they do its only classified as partial resistance and therefore by taking the full course you eliminate risk of this bacterium surviving and reproducing to form anti - biotic resistance strains and prevent passing it on to others with potentially weaker immune systems

Question 65

why has anti biotic resistance become so frequent

Answer 65

- because doctors frequently prescribe anti biotics in cases that they do not help such as viral illnesses and unserious minor events such as a tummy ache - Also two thirds of our one hundred thousand tonnes of anti - biotics that we produce goes to farm animals. As farmers place these anti - biotics into the food of already healthy animals in hopes to prevent them getting ill and so that the animals will grow faster however as one can imagine acts as a breeding ground for anti - biotic resistance