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Title: GCSE Biology Exam 1
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) Topics are also sold separately.
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) Topics are also sold separately.
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‘Lock and key’ modelling
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Temperature and enzyme activity
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Increased temperature results in increased collisions between enzymes and
substrates
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2: Respiration and the respiratory system in humans
Aerobic respiration
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a process that occurs in cells with oxygen is available
a series of enzyme-controlled reactions within the cell that use glucose and oxygen to
release energy (in the form of ATP) and produce carbon dioxide and water
glucose + oxygen → carbon dioxide + water + ATP
Anaerobic respiration
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a process that occurs in the absence of oxygen
when glucose is being broken down to release energy and lactic acid
causes oxygen debt
less efficient than aerobic respiration because of the incomplete breakdown of glucose,
producing less ATP per molecule of glucose
glucose → lactic acid + ATP
Lactic acid
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harmful
must be removed from cells and broken down following the resumption of aerobic
respiration (to repay the oxygen debt)
The respiratory system
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required by large organisms in order to obtain a sufficient volume of oxygen to maintain a
high level of aerobic respiration and to remove an equivalent volume of waste carbon
dioxide
The structure of the respiratory system
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Mucus and cilia
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help protect the respiratory system
Particles and bacteria stick to mucus and cilia move the mucus out of the respiratory
system to the back of the throat
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The bell jar is unable to move, unlike the chest cavity, which moves upwards and
outwards
The balloons have large open spaces, unlike the lungs, which have millions of alveoli
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The structure of an alveolus
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The adaptations of alveoli for gas exchange
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large surface area
thin wall
moist lining
rich blood supply
The percentage composition of inspired air
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oxygen: 21%
carbon dioxide: 0
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Cigarettes
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increase the risk of disease in the respiratory system
contain nicotine, which is addictive
(smoke) have chemicals that paralyse cilia and have particles that clog mucus, which
prevents their function
(smoke) destroy lung tissue, leading to emphysema
(tobacco smoke) has tar, which contains carcinogens, which lead to lung cancer
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It has a rich blood supply which maintains a steep diffusion gradient
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Balanced diet
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proteins
carbohydrates
fats
minerals (such as iron, to produce haemoglobin)
vitamins (such as vitamin C, to maintain healthy tissue)
fibre (to provide bulk in the digestive system)
water (as it is essential part of many bodily functions and processes)
Energy content of food eaten
•
must be balanced with energy needs as excess energy will be stored as fat by the body,
leading to obesity
Excess sugar
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can lead to obesity, type 2 diabetes and tooth decay
Excess fat
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can lead to obesity, heart disease, circulatory disease
Excess salt (sodium)
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can lead to high blood pressure
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The heart
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made of muscle that contracts to pump blood around the body
Coronary vessels
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supply the heart muscle with blood
Valves
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prevent the backflow of blood
Arteries
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contain blood flowing towards the
organs
have high pressure
have small lumens
have thick walls
do not contain valves
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Veins
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contain blood flowing towards the
heart
have low pressure
have large lumens
have thin walls
contain valves
•
Capillaries
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very small blood vessels
have thin walls (an advantage for
diffusion)
form extensive networks so that every
cell is near to a capillary carrying
blood
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Risk factors of cardiovascular disease
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high levels of fat in the diet
high levels of salt in the diet
high blood pressure
high blood cholesterol
smoking
genetic factors
a lack of exercise
Atheroma
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plaque that causes the narrowing of a coronary artery
Statins
• a daily medication
+ controls blood cholesterol levels
− may cause side effects
Angioplasty
•
surgery to place a small balloon in a blood vessel that is inflated to remove a
blockage
+ improves blood flow (such as in coronary vessels)
− sometimes only a temporary remedy
Changes to diet/lifestyle
• include stopping smoking, taking up regular exercise and eating more healthy food
+ reduce risk and lower high blood pressure
− need a high level of self-discipline to maintain these long-term changes
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4
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Use ethanol to decolour the leaf
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Test the leaf with iodine
Title: GCSE Biology Exam 1
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) Topics are also sold separately.
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) Topics are also sold separately.