EDEXCEL GCSE 9-1 COMBINED SCIENCE FOUNDATION BIOLOGY PAPER 1

name the two types of cell devision
mitosis and meiosis
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how many stages does mitosis take place in ?
several
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what is mitosis ?
mitosis is the cell division that happens in body cells
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what is a body cell ?
a body cell is any cell except those that produce gametes (sex cells)
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what is the cell that is dividing called in mitosis ?
the parent cell
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What is the two new cells called that are formed in mitosis ?
daughter cells
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The daughter cells are what to the parent cell, so if the parent cell is diploid then the daughter cells will be diploid too?
identical
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Name the Five Stages of Mitosis
Interphase, Prophase, Metaphase, Anaphase and Telophase
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What happens in Interphase?
At the end of interphase, chromosomes start to become visible. The DNA has already been copied.
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What happens in Prophase?
Each chromosome consists of two chromatids.
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What happens in Metaphase?
The nuclear membrane breaks down. Chromosomes line up along the middle of the cell.
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What happens in Anaphase?
The chromatids seperate and one chromatid from each pair is pulled to each pole of the cell. The chromatids can now be called chromosomes.
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What happens in Telophase?
The cell splits into two. This is called cytokinesis.
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What is Mitosis used for?
Mitosis is used for growth, repair and asexual reproduction. After growth, cells can then differentiate into specialised cells. Growth and differentiation happen in different ways in plants and animals
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When does mitosis happen?
Normally cells only divide by mitosis when new diploid cells are needed for: growth, repair (replacement of damaged cells) and asexual reproduction
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In animals, a fertilised egg, or zygote, divides by mitosis to produce what?
genetically identical daughter cells. These cells grow and divide by mitosis, and eventually differentiate into different types of cells to make up a whole organism.
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Differentiation creates specialised cells adapted to carry out what?
a particular function. examples of specialised animal cells include: red blood cells, egg+sperm cells, nerve cells, bone cells and smooth muscle cells
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Plant cells divide by mitosis, just behind the tips of shoots and roots. After this the cells grow by ?
enlarging. Young cells have small vacuoles which take in water by osmosis and enlarge, causing the cells to elongate. These cells can differentiate into specialised cell types.
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Most plant cells can continue to grow and differentiate throughout what?
life. examples of specialised plant cells include: xylem, phloem, mesophyll cells, root hair cells and stoma cells
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What is Growth?
Growth is a permanet increase in size
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What can Percentile charts show?
Percentile charts can help to show if a child is growing faster or slower than what is normal for their age
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What are Stem cells ?
are cells that can divide to produce many types of cell.
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What are the three kinds of Stem cells ?
Embryonic, Adult and Meristems
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Where are Embryonic Stem cells taken from and when?
they are taken from embryos at a very early stage of division
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give one use for Embryonic Stem cells
replacing or repairing brain cells to treat people with Parkinson's disease
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give one use for Embryonic Stem cells
replacing damaged cells in the retina of the eye to treat some kinds of blindness
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give one use for Embryonic Stem cells
growing new tissues in the lab to use for transplants or drug testing
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give an advantage of using Embryonic Stem cells
easy to extract from embryo
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give an advantage of using Embryonic Stem cells
they produce any type of cell
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give an disadvantage of using Embryonic Stem cells
embryo destroyed when cells removed- some people think embryos have a right to life
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Where are Adult Stem cells found and why do they divide?
found in differentiated tissue such as bone or skin and they divide to replace damaged cells
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give a use for Adult Stem cells
treatment of leukaemia
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give a use for Adult Stem cells
potentially growing new tissues that are genetically matched to the patient
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give an advantage of using Adult Stem cells
no embryo destroyed so not an ethical issue
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give an advantage of using Adult Stem cells
if taken from the person to be treated, will not cause rejection by the body
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give an disadvantage of using Adult Stem cells
they produce only a few types of cell
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give an advantage of using all stem cells
replace faulty cell with healthy cell, so person is well again
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give a risk of using all stem cells
stem cells may not stop dividing, and so cause cancer
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What are Neurones ?
Neurones are specialised cells that carry nervous impulses
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What are the three main types of neurones?
Sensory, Motor and Relay
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Stimuli are detected by what ?
sensory receptors that send impulses along sensory neurones to the central nervous system
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In a Sensory neurone what does the dendron do ?
carries impulses towards cell body
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In a Sensory neurone what does the axon do ?
carries impulses away from cell body
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In a Sensory neurone what does the myelin sheath do ?
insulates the neurone
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What do Motor neurones carry ?
impulses from the central nervous system to the effector organs
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In a Motor neurone what does the axon do ?
The axon carries the electrical impulses over long distances through the body
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In a Motor neurone what happens in the myelin sheath ?
The electrical impulse cannot cross the fatty myelin sheath
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In a Motor neurone what does the nerve ending do ?
The nerve ending transmits the impulse to an effector
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What is a synapse ?
The point where two neurones meet
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Reflex arcs involve what ?
only three neurones, and impulses pass to and from the spinal cord
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Reflex arcs are what ?
immediate, involuntary (brain not needed), innate (not learned) and invariable (always exactly the same)
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What is Meiosis ?
type of cell division that produces four daughter cells, each with half the number of chromosomes
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Meiosis only happens in what ?
gamete-producing cells, producing genetically different haploid gametes
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What is DNA ?
DNA is the genetic material found in the chromosomes in the nuclei of cells
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The nucleus contains what ?
chromosomes
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What does a Chromosome consists of what?
a string of genes
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What is a gene?
a short piece of DNA that codes for a specific protein
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Each gene is a length of DNA. DNA is a long, coiled molecule formed from two strands. The strands are twisted in what ?
a double helix
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The two strands of the double helix are joined by pairs of what ?
bases
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give the 1st base in DNA
A= adenine
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give the 2nd base in DNA
C= cytosine
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give the 3rd base in DNA
T= thymine
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give the 4th base in DNA
G= guanine
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What does the "A" base always pair with?
T
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What does the "C" base always pair with?
G
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Weak hydrogen bonds between what holds the DNA strands together?
the base pairs
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What is the genome?
is all the DNA in an organism
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DNA is a polymer made of many what?
monomers, called nucleotides, joined together
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DNA can be extracted by fruit by:
grinding the fruit with sand, using a pestle and mortar, to separate the cells
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DNA can be extracted by fruit by:
adding a detergent to break open the membranes
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DNA can be extracted by fruit by:
adding ice-cold alcohol so that the DNA precipitates out
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When gametes fuse at fertilisation, they form what ?
a diploid zygote.
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Each zygote inherits different alleles (genetic variants) of their genes from their parents. What does this produce?
This produces variation in inherited characteristics between different individuals
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There are two copies of each chromosomes in what ?
body cells- each copy has the same genes in the same order along its length (except chromosomes that determine sex)
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What is a gene?
A gene is a short piece of DNA at a particular point on a chromosome- a gene codes for a characterisitc
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A gene may come in different forms called what?
alleles, that produce different variations of the characteristic
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What does heterozygous mean?
different alleles of the same gene
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What does homozygous mean ?
genes that have the same allele on both chromosomes
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Chromosomes of the same pair have the same genes in what?
the same order
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What does Genotype show?
the alleles (forms of the genes) in the individual
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What does Phentotype mean?
the characteristics that are produced, including what the individual looks like
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The effect of the dominant allele will show when ?
at least one copy is present in the genotype
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The effect of the recessive allele will only show when?
two copies are present in the genotype
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Monohybrid inheritance can be explained using what?
genetic diagrams and punnett squares
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What is a Punnett square ?
A Punnett square is a different way of showing the same information about how genotype is inherited and what effect this has on the phenotype
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Genetic diagrams and Punnett squares only show what ?
possible offspring, not the actual offspring from the parents
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What is a Cystic fibrosis ?
is a genetic condition caused by a recessive allele
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You can use what to show the inheritance of a genetic condition within a family , and to predict the chance that someone will inherit the faulty allele?
family pedigree
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The sex of humans is determined at fertilisation and can be expressed using what ?
genetic diagrams and punnett squares
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The sex of humans is controlled by one pair of what?
sex chromosomes
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What does the genotype ** produce ?
the female phenotype
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What does the genotype XY produce ?
the male phenotype
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Causes of variation that influence phenotype include?
genetic variation and environmental variation
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Most phenotypic features in humans are caused by genes. Each of these genes may have what?
several alleles, so the phenotype is the result of the combination of different alleles for different genes. This combination of alleles that an organism inherits is the result of sexual reproduction
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What is a mutation?
A mutation or genetic variant is created if the sequence of bases in a gene is changed.
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A mutation in the gene's coding DNA can affect the what of an organism?
phenotype
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If the amino acid sequence is altered, the activity of the protein produced may also be what?
altered
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However most genetic mutations have what?
no effect on the phenotype
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However some mutations have what ?
a small effect on the phenotype
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However a single mutation can ?
rarely, significantly affect the phenotype
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A mutation may cause a large change in what ?
the protein produced
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A mutation may cause a small change in what ?
the protein
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A mutation may cause no change at all in what ?
the protein produced
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What is the Human Genome Project?
is a collaboration between scientists to decode the human genome (the order of bases on all human chromosomes)
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Why was the Human Genome Project completed quickly?
because so many scientists worked on it at the same time
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When was the work of the Human Genome Project published ?
in 2003 and made freely available to scientists all over the world
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What are the results of the Human Genome Project being used for ?
to develop new medicines and treatments for disease
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state a advantage of the Human Genome Project
Alerting people they are at particular risk of certain diseases. The person may be able to make lifestyle changes to reduce the chances of the disease developing
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state a advantage of the Human Genome Project
Distinguishing between different forms of diseases such as leukemia or Alzheimer's disease, as some drugs are beneficial in some forms of these diseases but not in others
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state a advantage of the Human Genome Project
Allowing doctors to tailor treatments for some diseases to the individual, where specific alleles affect how a person will respond to treatment
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state a disadvantage of the Human Genome Project
People who are at risk of certain diseases, e.g. cancer, may have to pay more to obtain life insurance
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state a disadvantage of the Human Genome Project
It may not be helpful to tell someone they are at risk of a condition for which there is currently no cure
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Who developed a theory of evolution by means of natural selection ?
Charles Darwin
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Individuals of a species show variation. This can mean some individuals will be better able to survive in their environment and produce more healthy offspring than others. what is this?
natural selection, where the environment (including climate and other organisms) selects which individuals pass on their alleles to the next generation.
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The theory of evolution is very important in modern biology:
It helps us understand the relationship between different species of organisms
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The theory of evolution is very important in modern biology:
It explains how new species evolve
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The theory of evolution is very important in modern biology:
It explains how different species adapt to changes in their environment
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What are the five kingdoms ?
Plants, Animals, Fungi, Protists and Prokaryotes
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What is selective breeding ?
is when plants or animals with certain desirable characteristics are chosen to breed together, so that offspring will be produced that inherit these characteristics. This produces new breeds of animals and new varients of plants
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state a reason for selective breeding
disease resistance
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state a reason for selective breeding
increased yield
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state a reason for selective breeding
better ability to cope with difficult conditions
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state a reason for selective breeding
faster growth
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state a reason for selective breeding
better flavour
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What is genetic engineering?
is changing the genome of an organism, often by introducing genes from another to create genetically modified organisms
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GM crop plants have been genetically modified to give what?
them new characteristics
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What does health mean?
a state of complete physical, mental and social well-being
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Diseases may be what ?
communicable or non-communicable
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What does communicable mean?
can be passed from one person to another
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What does non-communicable mean?
not passed between people
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What is a pathogen ?
is an organism that causes an infectious disease
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Physical barriers make it what ?
hard for pathogens to enter the body
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Chemical defences are chemicals that are what?
produced to kill or make pathogens inactive
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The immune system helps to what ?
protect the body by attacking pathogens if they manage to enter the body. Lymphocytes are part of this immune system
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Each pathogens has unique what on its surface?
antigens
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The antibodies produced by a lymphocyte are what?
specific for one particular kind of pathogen. means they can only destroy that kind of pathogen. can't destroy another kind of bacterium or virus
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Why is the Secondary response much faster?
Because memory cells are already present,and can secrete specific antibodies immediately
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What is immunisation?
is when you give a person a vaccine to prevent them becoming ill from a disease
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What are Antibiotics ?
are medicines that kill bacteria inside the body
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How does genes increase the risk of developing non-communicable diseases
different alleles of a gene may be more prone to mutation or how well you absorb nutrients. These factors may be more common in particular ethnic groups
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How does age increase the risk of developing non-communicable disease
the older the body, the more likely that cells may develop mutations which lead to cancer
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How does sex increase the risk of developing non-communicable diseases
The female hormone oestrogen has protective effects that men do not get
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How does environmental affect the risk of developing non-communicable diseases
Air pollution can cause lung diseases; poisons in food and drink can damage the body
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How does lifestyle factors affect the risk of developing non-communicable diseases
The way we live, including diet, alcohol, smoking and excise, can affect our risk of developing many diseases
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Lifestyle factors including drinking alcohol and smoking increases the risk of what?
non-communicable diseases by changing how the body works and increasing the levels of toxins in your body
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When does malnutrition happen?
when a person eats too much or too little of a nutrient. Too little of some nutrients can lead to deficiency diseases
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How do you calculate BMI
BMI= weight in kilograms/ (height in metres)^2
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How do you calculate waist:hip ratio
waist:hip ratio= waist measurement/ hip measurement
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How can cardiovascular disease be treated?
medication, surgery or by making life style changes
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how many stages does mitosis take place in ?

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several

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what is mitosis ?

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what is a body cell ?

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what is the cell that is dividing called in mitosis ?

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