AQA GCSE Combined Science- Higher notes
,Biology
Keeping Healthy - Key Points
7 Food Groups
Carbohydrates To release energy
Fats To keep warm and release energy
Protein For growth and cell repair & replacement
Fibre For a healthy digestive system
Vitamins (small amounts) For healthy functioning of the body
Minerals (small amounts) For healthy functioning of the body
Water To stay hydrated
Metabolic rate - The speed at which chemical reactions occur within
the body
1) Resting metabolic rate can vary:
- proportion of muscle to fat in body, muscle needs more energy than fatty
tissue
- size, more cells
- gender, men have a higher rate (due to the reasons given above)
- regular exercise – builds muscle
2) Metabolic rate can be increased by: (a) exercise and (b) activity levels
Malnourished – not having a balanced diet
Obesity – 20% over recommended body mass
Caused by: eating excess carbohydrate/fats, lack of exercise, hormone
problems (rare)
Leads to: arthritis (inflammation of joints), type II diabetes (cannot control
blood sugar), high blood pressure, heart disease, high blood cholesterol (due to
high saturated fat in diet) and increased risk of certain cancers.
Salt - Too much salt can also lead to high blood pressure and heart disease.
Lack of food – e.g. developing countries
Can cause: slow growth (children), fatigue, poor resistance to infection,
irregular periods
Deficiency diseases – due to lack of vitamin/mineral e.g. vitamin C deficiency
disease is scurvy, causes skin/joints/gum problems
,Regular exercise/active lifestyle
- increases energy used, decreases fat stored, builds muscle – increases
metabolic rate
Inherited factors – e.g.:
-underactive thyroid gland – lowers metabolic rate, causes obesity
-increased blood cholesterol (fatty substance, essential), increased risk of heart
disease
Slimming programmes – claim to help people lose weight, may be true but
misleading
- Should be based on published scientific studies (in reputable journals),
written by a qualified person, carried out with a large sample size (reliable),
and other studies have found the same thing (reproducible)
- Successful slimming if people eat less fat/carbohydrates and do more
exercise
Pathogens, Disease & Immunity
Pathogens – microorganisms that cause diseases (Infectious diseases –
easily spread)
- Bacteria – very small cells, reproduce rapidly, damage cells, produce toxins
- Viruses – not cells, extremely small, invade & reproduce inside body cells –
cells burst Mutate often, takes time to produce antiviral drugs/vaccines –
pandemic can kill many
Defence to prevent pathogen entry/disease
skin, hairs, mucus (traps pathogens), platelets (cell fragments) – help blood
clotting
Natural immune system (white blood cells) – (during time taken - can get
symptoms)
– engulf & digest pathogens
– produce antibodies that recognise specific antigens (on surface of
pathogen), kills it
– produce antitoxins – neutralises the toxins produced by pathogenic
bacteria
Vaccinations (acquired immunity)
- injection of dead/inactive pathogen that have antigens on surface, may need
booster
, - antibodies produced by white blood cells in response to dead/inactive
pathogen
- if same pathogen infects, more antibodies produced faster to kill it before get
symptoms
Pros - control lots of infectious diseases, some totally eradicated
like smallpox
- epidemics (outbreaks) prevented, fewer people catch &
pass on disease
Cons - not always effective
- bad reactions possible – swelling/fever/seizures
Drugs
- Reduce symptoms (e.g. painkillers, cold remedies)
- Antibiotics – kills/prevent growth of different types of bacteria (don´t kill
viruses)
- Difficult to develop antiviral drugs without damaging cells (viruses
reproduce inside)
Antibiotic drug resistance (an example of natural selection - evolving)
- Antibiotic resistance arises due to a mutation in a bacteria occurring (new
strain)
- Only non-resistant bacteria killed by antibiotic
- Resistant bacteria survive and reproduce
- Superbugs (resistant) becoming more common (e.g. MRSA bacteria)
- Not killed by that antibiotic – infection no longer treated and spread easily
and could cause an epidemic –big disease outbreak
- Avoided by doctors not over-prescribing antibiotics
Investigating microorganisms
- Grow microorganisms in a culture medium (agar jelly that contains
carbohydrates, proteins, minerals and vitamins) in a petri dish
- Inoculating loops used to transfer microorganisms to petri dish
- Paper discs containing antibiotics are placed onto surface, bacteria die near
disc
- Aseptic techniques are used to prevent contamination – equipment (petri
dishes, culture medium) sterilised e.g. inoculating loops in flame, lids taped
on
- Incubated at 25o to avoid growth of harmful pathogens (that like body
temp. 37o)
,Biology
Keeping Healthy - Key Points
7 Food Groups
Carbohydrates To release energy
Fats To keep warm and release energy
Protein For growth and cell repair & replacement
Fibre For a healthy digestive system
Vitamins (small amounts) For healthy functioning of the body
Minerals (small amounts) For healthy functioning of the body
Water To stay hydrated
Metabolic rate - The speed at which chemical reactions occur within
the body
1) Resting metabolic rate can vary:
- proportion of muscle to fat in body, muscle needs more energy than fatty
tissue
- size, more cells
- gender, men have a higher rate (due to the reasons given above)
- regular exercise – builds muscle
2) Metabolic rate can be increased by: (a) exercise and (b) activity levels
Malnourished – not having a balanced diet
Obesity – 20% over recommended body mass
Caused by: eating excess carbohydrate/fats, lack of exercise, hormone
problems (rare)
Leads to: arthritis (inflammation of joints), type II diabetes (cannot control
blood sugar), high blood pressure, heart disease, high blood cholesterol (due to
high saturated fat in diet) and increased risk of certain cancers.
Salt - Too much salt can also lead to high blood pressure and heart disease.
Lack of food – e.g. developing countries
Can cause: slow growth (children), fatigue, poor resistance to infection,
irregular periods
Deficiency diseases – due to lack of vitamin/mineral e.g. vitamin C deficiency
disease is scurvy, causes skin/joints/gum problems
,Regular exercise/active lifestyle
- increases energy used, decreases fat stored, builds muscle – increases
metabolic rate
Inherited factors – e.g.:
-underactive thyroid gland – lowers metabolic rate, causes obesity
-increased blood cholesterol (fatty substance, essential), increased risk of heart
disease
Slimming programmes – claim to help people lose weight, may be true but
misleading
- Should be based on published scientific studies (in reputable journals),
written by a qualified person, carried out with a large sample size (reliable),
and other studies have found the same thing (reproducible)
- Successful slimming if people eat less fat/carbohydrates and do more
exercise
Pathogens, Disease & Immunity
Pathogens – microorganisms that cause diseases (Infectious diseases –
easily spread)
- Bacteria – very small cells, reproduce rapidly, damage cells, produce toxins
- Viruses – not cells, extremely small, invade & reproduce inside body cells –
cells burst Mutate often, takes time to produce antiviral drugs/vaccines –
pandemic can kill many
Defence to prevent pathogen entry/disease
skin, hairs, mucus (traps pathogens), platelets (cell fragments) – help blood
clotting
Natural immune system (white blood cells) – (during time taken - can get
symptoms)
– engulf & digest pathogens
– produce antibodies that recognise specific antigens (on surface of
pathogen), kills it
– produce antitoxins – neutralises the toxins produced by pathogenic
bacteria
Vaccinations (acquired immunity)
- injection of dead/inactive pathogen that have antigens on surface, may need
booster
, - antibodies produced by white blood cells in response to dead/inactive
pathogen
- if same pathogen infects, more antibodies produced faster to kill it before get
symptoms
Pros - control lots of infectious diseases, some totally eradicated
like smallpox
- epidemics (outbreaks) prevented, fewer people catch &
pass on disease
Cons - not always effective
- bad reactions possible – swelling/fever/seizures
Drugs
- Reduce symptoms (e.g. painkillers, cold remedies)
- Antibiotics – kills/prevent growth of different types of bacteria (don´t kill
viruses)
- Difficult to develop antiviral drugs without damaging cells (viruses
reproduce inside)
Antibiotic drug resistance (an example of natural selection - evolving)
- Antibiotic resistance arises due to a mutation in a bacteria occurring (new
strain)
- Only non-resistant bacteria killed by antibiotic
- Resistant bacteria survive and reproduce
- Superbugs (resistant) becoming more common (e.g. MRSA bacteria)
- Not killed by that antibiotic – infection no longer treated and spread easily
and could cause an epidemic –big disease outbreak
- Avoided by doctors not over-prescribing antibiotics
Investigating microorganisms
- Grow microorganisms in a culture medium (agar jelly that contains
carbohydrates, proteins, minerals and vitamins) in a petri dish
- Inoculating loops used to transfer microorganisms to petri dish
- Paper discs containing antibiotics are placed onto surface, bacteria die near
disc
- Aseptic techniques are used to prevent contamination – equipment (petri
dishes, culture medium) sterilised e.g. inoculating loops in flame, lids taped
on
- Incubated at 25o to avoid growth of harmful pathogens (that like body
temp. 37o)
