B1- Specification



Fitness: The ability to do physical activity

Health: Being free from disease.

Different ways of measuring fitness:

  • strength
  • stamina
  • flexibility
  • agility
  • speed and cardiovascular efficiency
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Parasite: Organisms that live off other organisms (malaria)

Host: where vectors live (human)

Vector: carries parasite (mosquito). Spread of malaria limited to the mosquito.

1. Mosquito sucks blood from human

2. Malaria parasites (in the blood) mate and move from mosquitos gut to salivary glands.

3. Mosquito bites another person, passes malaria on.

4. Move to the liver and reproduce

5. Migrate to blood and replicate in red blood cells, bursting them open.

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Blood Pressure

Consequences of high blood pressure:

  • blood vessels weaken and eventually burst
  • brain damage
  • stroke
  • kidney damage

Consequences of low blood pressure:

  • some parts of the body deprived of glucose or oxygen
  • dizziness
  • fainting
  • cold hands and feet
  • kidney failure
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Smoking increases blood pressure:

  • Carbon monoxide reduces the oxygen carrying capacity of the blood so heart rate increases to compensate.
  • nicotine increases heart rate.
  • Carbon monoxide reduces the carrying capacity of red blood cells, the carbon monoxide combines with haemoglobin preventing oxygen transport.
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Balanced Diet

Kwashiorkor: Protein deficiency

  • overpopulation
  • limited investment in agricultural techniques  

EAR = 0.6 x body mass in kg - change age, pregnancy (need nutrients for baby as well) and lactation (need to produce more milk so need more protein)

BMI = mass (kg)/height in m squared

Low self esteem, poor self image and desire for perfection can lead to a poor diet can lead to damaging the body. No balence of nutrients to function, reproduction system affected and damage to bones.

First class proteins: from animals, contain essential amino acids cannot be made.

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Diet can increase the risk of heart disease:

  • saturated fats lead up to a build of cholesterol (a plaque) in the arteries
  • high levels of salt elevate blood pressure
  • narrowed arteries and thromobosis (blood clots) increase the risk of heart attack because the pressure of blood increases, putting strain on the heart.
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Reducing the risk of cancer:

  • dont smoke
  • dont drink excess alcohol
  • avoid sunburn
  • eat a healthy diet

Benign - a tumour that grows in one place

Malignant - a tumour that starts to grow in other places in the body

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The Eye

Parts of the eye:

  • Cornea - refracts light
  • Iris - controls how much light enters the pupil
  • Lens - focuses light onto the retina
  • Retina - contains light receptors, some sensitive to light of different colours
  • Optic nerve - carries impulses to the brain

The rays of light are refracted by the cornea and come together at a single point and produce a clear image on the retina. Light-sensitive receptor cells on your retina then cause nerve impulses to pass along sensory neurones in the optic nerve to your brain.

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Immune System

Pathogens cause the symptoms of an infectious disease by damaging cells or producing toxins. Each pathogen has own antigens so specific antigens are needed.

Antibodies lock on to antigens leading to the death of the pathogen.

Passive immunity - the body in injected with antibodies for a quick responce

Active immunity - the body makes it's own antibodies and are remembered in the future.

Antibiotics: kill bacteria and fungi

Anitviral: treat diseases caused by viruses only

Use of antibiotics needs to be careful. If over-prescribed bacteria can become resistant. All bacteria except for resistant ones killed. The resistant bacteria spread, making the antibiotic useless. Eg. MRSA  

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Blood Pressure

Blood Pressure

Diastolic and systolic data in mmHg

Factors increasing blood pressure:

  • being overweight
  • stress
  • high alcohol intake
  • smoking

Factors decreasing blood pressure:

  • regular exercise
  • balanced diet
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Process of immunisation:

1. Harmless pathogen injected carrying antigens

2. Antigens trigger immune system responce to produce antibodies

3. Memory produced and immunity remains.


  • Protects against disease which could kill or cause a disability
  • If everyone is vaccinated, the disease will finallu die out (small pox)


  • Could have a bad reaction to the immunisation
  • No vaccination is 100% safe.

Benefits outway the risks.

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Treatment of Diseases

A drug can be tested using:

  • Computer models - predicts how will affect cells
  • Animals - affects living organisms
  • Human tissue - (in laboratory) affects human cells.

Objections to testing:

  • Animal cruelty - not treated correctly, they dont have freedom etc
  • Human tissue - inhuman, unnatural and wrong

Blind trial - the volunteers do not know if they are given a new drug or a placebo (cancels out any pyschological factors)

Double blind trial - neither the doctors or the volunteers know whether they have been giving the drug or placebo. (doctors cannot influence the volunteers' responces)

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The Eye

Near objects:

  • ciliary muscles contract
  • suspensory ligaments relax
  • lens short and fat to refract light alot

Far objects:

  • ciliary muscles relax
  • suspensory ligaments contract
  • lens is thin and long to refract a small amount of light

Ciliary muscles - change shape of lens

Suspensory ligaments - attach the lens to the ciliary muscles

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Balanced Diet

  • Carbohydrates are made up of simple sugars such as glucose.
  • fats are made up of fatty acids and glycerol
  • proteins are made up of amino acids

A balanced diet will vary depending on age (older people need less food, less calories than young people), gender (males need to have more calories due to being larger and having more muscle), activity (physical exercise), personal choice (veggies and vegans), religion and medical conditions (allergies).

  • carbohydrates are stored in the liver as glycogen or converted to fats
  • fats are stored under the skins and around organs as adipose tissue
  • proteins are not stored
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Binocular: Predators

  • Limited field of view
  • Measure distance and speed

Monocular: Prey

  • Wide field of view
  • Cannot judge speed or distance accurately

Long (convex) and short (concave) sight cause by the lens being the wrong shape, light rays not accurately focused on the retina.

Corrected by corneal sugery, reshaping the cornea.

Colour blindness - lack of specialised cells in the retina.

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Cigarette smokes affects:

  • Ciliated epithelial cells  - prevents the cilia from being able to remove mucus, tar and dirt from the lungs, leading to smokers cough as the body tries to cough up mucus.

Cancer of the:

  • mouth
  • throat
  • oesophagus
  • lungs

Heart disease, emphysema and bronchitis.

Tar contains chemicals that are irritants and carcinogens (cancer causing chemicals). Particulates in cigarettes smoke accumulate in living tissue.

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Shoots are positively phototrophic and negatively geotrophic.

Roots are negatively phototrophic and positively geotrophic.


  • move through the plant in solution
  • involved in the responce to light (phototrophism) and gravity (geotrophism)
  • made in the tip
  • unequally distributed in responce to light.

1. Hormones in direct sunlight are destroyed

2. Hormones on the shaded side continue to function, causing the cells to elongate (lengthen)

3. The shoot bends towards light.

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Class A - most dangerous, heaviest penalties

Class C - least dangerous, lightest penalties

Depressants (bind with the receptor molecules in the membrane of the next neurone blocking the transmission of the impulses) - alcohol, solvents and tamazepam.

Painkillers - aspirin and paracetamol

Stimulant (cause more neurotransmitter to cross the synapse) - nicotine, ecstacy and caffeine.

Performance enhancers - anabolic steroids.

Hallucigens - LSD

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Long term effects:

  • The liver can be damaged as it removes alcohol. The liver contains enzymes which break down alcohol. The products are toxic though.
  • Brain damage from dehydration

Short term effects:

  • lack of balance and muscle control
  • blurred vision and slurred speech
  • poor judgement and drowsiness
  • vasodilation - blood vessels widen, increasing blood flow to the skin and heat loss.
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Hormones and Insulin

Insulin controls blood sugar levels - Converts excess glucose into glycogen in the liver.

Type II - controlled by diet (affects cells that respond to insulin)

Type I - treated by insulin dosage (pancreas fails to produce insulin)

Type I: have alot of food containing alot of sugar they need a high dose of insulin. If they are doing exercise and need more glucose, a lower dose is taken as requires more energy.

Responces controlled by hormones are usually slower than responces controlled by the nervous system because they travel through the blood. The nervous system's responces are alot faster because they are electrical messages relayed directly to the target organs.

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Homeostasis - maintaining a constant internal environment and balancing bodily inputs and outputs. These include temperature (37 degrees), water content and carbon dioxide.

Controlling Temp: Sweating increases the heat transfer to the environment by evaporation of sweat whihc requires heat, so removing heat from the skin.

High temperatures:

  • Heat stoke
  • dehydration (water lost through sweating)
  • death

Low temperatures:

  • hypothermia
  • unconciousness and death
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Commercial Uses of Plant Hormones

Selective weedkiller - disrupt the growth patterns of their target platns without harming other plants. The broad leaved weeds recieve a larger dose due to having a larger surface area compared to the narrow leaved crop plants, so they die.

Rooting powder - encourages growth of roots in stem cuttings

Fruit ripening (delay or acceleration) - causes fruit to ripen or delayed if required for transportation or storage.

Control of dormancy - hormones can be used to speed up or slow down plant growth and bud development.

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Knowing the life cycle of the disease is very important to help control the disease. For example, you can find out where they breed (warm, stagnant water) and also what they are attracted to (humans), to prevent the spread.

Limiting spread:

  • sleep under mosquito nets
  • use insect repellent
  • killing mosquitoes with insecticide
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Causes of genetic variation can be caused by mutations (changes in the genes), differences between gametes or the randon nature of fertillisation.

Environmental causes of genes:

  • language
  • scars

Genetic causes of genes:

  • nose shape
  • eye colour


  • intelligence
  • height and body shape
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Motor neurone: Axon (long thin part of the cell), cell body, shealth.

Axon (make connections from one part of the body to another), Insulating shealth (speed up nerve impulses) and dendrites (allows a single neurone to act on many muscle fibres)

Reflex arc (action): Stimulus - receptor - sensory neurone - relay neurone  - motor neurone - effector - responce

Voluntary action: Stimulus - receptor - sensory neurone - brain - motor neurone - effector - responce

Gap between neurones = synapse

Impulse triggers the release of a transmitter substance in a synapse and it diffuses across to bind with receptor molecules in the membrance of the next neurone causing the impulse to continue.

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Dominant: chacteristic if only one chromosome in a pair

Recessive: characteristic only shown without dominant.

When a characteristic is only determinded by one pair of alleles (eye colour or rolling tongue) it's called monohybrid inheritance.

  • Homozygous - 2 indentical alleles
  • Hetrozygous - 2 different alleles
  • Genotype - the genetic makeup
  • Phenotype - the characteristic expressed.


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Inherited Disorders

Inherited disorders are caused by faulty genes (faulty alleles - most are recessive)

Issues raised: whether to have the child or to abort the foetus


  • red-green colour blindness
  • sickle cell anemia
  • cystic fibrosis

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Most body cells have the same number of chromosomes but this varies between species. Humans have 23 pairs.

Alleles are different versions of the same gene.

Sex in mammals is determined by sex chromosomes: ** female and XY male

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Negative Feedback (Homeostasis)

Negative feedback is the automatic reversal of a change in condition


  • Heat lost by radiation
  • Blood vessels dilate
  • Sweating cools the skin


  • Blood vessels constrict so less heat lost through radiation.
  • Sweating stops

Enzymes work best at 37 degrees, if it is hotter then they denature and if it is too cold they will not be active enough.

Temperature monitered by brain - nervous and hormonal systems

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