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41 Cards in this Set
- Front
- Back
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why is it advantageous that humans have an extended childhood?
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- ensures do not become parents until advanced social skills are learnt |
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what process causes the release of testosterone at the start of puberty?
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- hypothalamus releases GnFR which stimulates release of FSH and LH, these stimulate release of testosterone |
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give 3 main secondary sex characteristics in males as a result of puberty
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- growth of penis and testes - growth of pubic hair - growth of underarm, facial, chest and body hair - growth of larynx - voice deepens - general body growth and muscle development - increased activity of sweat and sebaceous glands |
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how does GnRF affect females during puberty?
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- caused release of FSH and LH bringing about menstrual cycle |
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give 3 main secondary sex characteristics in females as a result of puberty
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- growth of sex organs (ovaries, vagina, uterus..) - breast growth - pubic hair growth - underarm hair growth - increased cartilage in pelvic girdle which causes widening of the hips 'carrying angle' of arms and legs changes so they're at a slight angle - accumulation of fat on breasts hips and thighs - increased activity of sweat and sebaceous glands |
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describe 2 effects of ageing
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- cardiac output drops as we have less/smaller cardiac muscle cells - especially if min exercise - nerve cells die so fewer neurones in brain - neurone impulse speed decreases bcos myelin sheath becomes thinner so more ions leak and synapses produce less transmitter substance - females undergo menopause which is caused by a lack of follicles - infertile - lack of oestrogen increases chd risk and reduces bone density - oesteoporosis |
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what does a mutation in a proto-oncogene cause?
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what does a mutation in a tumour suppressor gene cause?
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may result in cells with damaged DNA to replicate rapidly |
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describe the placement of the prostate gland
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- lies just below urinary bladder - surrounds upper part of urethra |
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what is benign prostate hyperplasia and how can it be treated?
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can be treated by removing some of the prostate gland |
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why do many cases of prostate cancer go untreated?
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- surgery could cause damage to urethra, rectum, nerve supply, bladder or penis |
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give 3 factors that increase the risk of developing breast cancer
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- alcohol consumption - sedentary lifestyle - oral contraceptives - using HRT for longer than 5 years - genetic factors |
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what happens in the brains of alzheimers sufferers?
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- neurones develop twisted fibres called tangles -plaques of amyloid protein build up between neurones |
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give 3 symptoms of Alzheimer's
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- difficulty finding correct word - confusion, forgetting names and appointments, where they are, recent events - mood swings - frustration due to the memory loss - become withdrawn due to inability to communicate and hit to confidence |
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what factors can increase the risk of developing alzheimers
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- severe head/whiplash injuries - boxers - smoking, high BP, high cholesterol |
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how does the fault in the CFTR allele cause CF?
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- without it, CFTR folds up into a different tertiary structure resulting in a protein that wont function |
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in what case will a recessive allele be expressed in an organisms phenotype?
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if the two copied of the allele are identical |
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how does haemoglobin s differ from normal haemoglobin and what does this cause?
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- makes it less soluble and crystallises in low oxygen concentrations meaning red blood cells become sickle-shaped when oxygen levels are low |
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what affects do the sickle-shaped blood cells have on a person?
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- can block blood flow to lungs causing tissue damage and sever pain in arms chest legs and abdomen - if parts of brain tissue die it can cause strokes as the cells did not receive enough oxygen - can cause damage to most organs |
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how is anaemia caused by sickle-shaped blood cells?
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- can be easily damages and rapidly broken down meaning person has fewer red blood cells to carry oxygen in their blood |
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how is sickle cell anaemia treated?
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- intravenous fluids - antibiotics - painkillers |
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give an example of a condition caused by codominant alleles
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blood groups - a and b co-dom |
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why is sickle-cell so common in parts of Africa and india?
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- people with normal haemoglobin are more likely to die from malaria - people with a sickle cell trait (heterozygous) have some protection against malaria and are more likely to survive - means that people who are heterozygous are more likely to have children and pass on their genes |
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how is antigen D related to rhesus blood groups?
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people who have antigen D on their red blood cell are rhesus pos those who don't are rhesus neg |
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what can cause haemolytic disease of the newborn?
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- blood doesn't mix during pregnancy however can come into contact around time of brith - if this happens the antigen on babys blood cells causes immune response in mother - system will make antibodies against antigen D, unlikely to harm child as this happens at the end of pregnancy - if mother were to become preg with another rhesus pos baby the antibodies may pass across the placenta and attack the babys blood cells causing severe anaemia - this is haemolytic disease of the newborn |
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how does the severity of haemolytic disease of the newborn differ?
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mild - baby born with anaemia and jaundice severe - baby could develop repiratory arrest, heart failure or be stillborn |
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how can haemolytic disease of the newborn be prevented?
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- give preg women who are rhesus neg an injection of anti-rhesus globulin and repeating after birth of rhesus pos child |
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what are the 4 blood groups in the ABO system?
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-B -O - AB |
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what antigens are related to each group in the ABO system?
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- B - B antigens - AB - both A and B antigens - O - neither of these two antigens |
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why is the blood group used in a blood transfusion so important?
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- its important that the antigens in the transfusion are compatible with these antibodies as if the wrong blood group is used the antibodies can clump and block blood vessels |
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how is the sex of a baby determined?
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depends on what sex chromosome they inherit from their father, if they inherit an X from their mother and a Y from their father they will be born a boy but if they receive two X chromosomes they will be bon a girl. |
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what are some symptoms of Duchenne muscular dystrophy?
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- usually appear in boys under the age of 6 - loss of muscle tissue and weakness in arms and pelvis - progressive mobility difficulties will normally need a wheelchair from age 11 - by late teens/early 20s breathing muscles become affected and condition becomes life threatening |
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what causes DMD?
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- recessive allele on X chromosome - very rarely occurs in females as they have another X chromosome with the normal allele for the gene however in boys they only have the single recessive allele meaning they will become a sufferer. |
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how is amniocentesis carried out?
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- ultrasound used to locate baby - hypodermic needle inserted into the uterus through mother abdomen - amniotic fluid sample is removed into a syringe, will contain fetal cells - cells will either then be cultured so that the chromosomes can be examined or the DNA will be extracted from the cells and tested to see if it contains genes for a genetic disorder |
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what are the names of two tests that can be carried out to test an unborn baby?
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- amniocentesis - chorionic villus sampling (CVS) |
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how is a CVS carried out?
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- ultrasound used to guide catheter through a woman's vagina, through the cervix and close to the placenta - syringe on the other end of the catheter is used to remove small amount of tissue from the placenta - test is also sometimes done with the use of a needle through the abdomen |
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what are the miscarriage risks like when it comes to amniocentesis and CVS?
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- amniocentesis isn't usually carried out before 15 weeks of pregnancy because f the increased risk of miscarriage - CVS can be carried out from week 10 of pregnancy, it gives a 1-2% chance of miscarriage which is slightly higher than that of when an amniocentesis is carried out |
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how is karyotyping carried out?
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- fetal cells can be cultured in a medium which contains a chemical which stimulates cells to divide by mitosis - a spindle inhibitor is also used so that the cells will start to divide but will not complete mitosis - a photograph is take on the chromosomes and a computer is used to manipulate the images - chromosomes are arranged into their homologous pairs |
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what is a karyotype used for?
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detect any abnormalities of the chromosomes but not a disorder involving a single gene
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how is embryo screening carried out?
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- several embryos produced by IVF - allowed to grow to 8 cells stage - embryo held steady by a suction pipette whilst a smaller pipette breaks open the protein covering of the embryo and sucks out a single cell - DNA from cell is extracted and tested to see whether disease causing alleles are present. embryos that do not cause serious disease will be implanted into the uterus |
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what are the ethical issues related to embryo screening?
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very new technique so nobody born this way is yet old enough to have a child so the long term affects of this technique are still unknown - as this technique involves creating a number of embryos of which many aren't used some people don't agree its also believed that this type of selection allows couples to have 'designer babies' however this type of testing is regulated by the human fertilisation and embryology authority and is only allowed for the most serious genetic conditions |
