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AQA Biology Paper 1: Combined Science > Topic 2: Organisation > Flashcards

Topic 2: Organisation Flashcards

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1
Q

What is a cell?

A

The basic building block of a living organism. Cells make up living things.

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2
Q

What is a tissue?

A

A group of cells with a similar structure and function working together. For example, muscular tissue contracts to bring about movement.

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3
Q

What is an organ?

A

A collection of tissues working together to perform a specific function. For example, the stomach contains glandular, muscular and epithelial tissues.

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4
Q

What is an organ system?

A

A group of organs working together to perform specific functions. For example, the digestive system contains organs such as the stomach, the small intestine and the large intestine.

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5
Q

What is the main function of the digestive system?

A

To digest food and absorb the nutrients obtained from digestion.

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6
Q

What is the role of the pancreas and the salivary gland in the digestive system?

A

The pancreas and the salivary gland are glands which produce digestive juices containing enzymes.

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7
Q

What is the role of the stomach in the digestive system?

A

Produces hydrochloric acid - which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function.

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8
Q

What is the role of the small intestine in the digestive system?

A

The small intestine is the site where soluble food molecules are absorbed into the bloodstream.

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9
Q

What is the role of the liver in the digestive system?

A

Produces bile (stored in the gallbladder) which emulsifies lipids and allows the lipase enzyme to work more efficiently.

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10
Q

What is the role of the large intestine in the digestive system?

A

Absorbs water from undigested food, producing faeces.

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11
Q

What is the role of enzymes in the digestive system?

A

Enzymes act as biological catalysts which speed up the rate of biological reactions (the breakdown of food) without being used up.

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12
Q

How does the shape of an enzyme affect its function?

A

Enzymes have a specific active site which is complementary to their substrate.

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13
Q

What is metabolism?

A

The sum of all the reactions in a cell or an organism.

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14
Q

What types of metabolic reactions do enzymes catalyse?

A

● Building larger molecules from smaller molecules eg. glucose to starch.
● Changing one molecule to another eg. glucose to fructose.
● Breaking down larger molecules into smaller molecules eg. carbohydrates to glucose.

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15
Q

What is the lock and key hypothesis of enzyme function?

A

The shape of the enzyme active site and the substrate are complementary, so can bind together to form an enzyme-substrate complex.

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16
Q

How does temperature affect enzyme action?

A

Up to a certain point, increasing temperature increases enzyme action, as molecules have a higher kinetic energy. Above a certain temperature, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction. The optimum temperature is around 37°.

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17
Q

How does pH affect enzyme function?

A

The optimum pH for most enzymes is 7 (apart from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.

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18
Q

Where are carbohydrases, proteases and lipases produced in the body?

A

● Carbohydrases: amylase - salivary gland and pancreas; maltase - small intestine.
● Proteases: pepsin - stomach; others - pancreas and small intestine.
● Lipases: pancreas and small intestine.

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19
Q

What is the role of carbohydrases in the digestive system?

A

Carbohydrases break down carbohydrates into monosaccharides and disaccharides. Amylase breaks down starch into maltose, and maltase breaks down maltose into glucose.

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20
Q

What is the role of proteases in the digestive system?

A

Proteases break down proteins into amino acids.

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21
Q

What is the role of lipases in the digestive system?

A

Lipases break down lipids into fatty acids and glycerol.

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22
Q

How are the products of digestion used?

A

They are used to build bigger molecules such as carbohydrates and proteins. Glucose is used as a substrate in respiration.

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23
Q

Where is bile made and stored in the body?

A

Bile is made by the liver and stored in the gallbladder

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24
Q

What is the role of bile in the digestive system?

A

● Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach.
● Bile emulsifies lipids to form droplets - this increases the surface area for the lipase enzyme to work on.

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25
Q

What is the heart?

A

An organ that pumps blood around the body

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26
Q

What is the purpose of the circulatory system?

A

Carries oxygen and other useful substances to bodily tissues, and removes waste substances.

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27
Q

How does the double circulatory system work?

A

● One pathway carries blood from the heart to the lungs - where the gaseous exchange of oxygen and carbon dioxide takes place.
● One pathway carries blood from the heart to the tissues.

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28
Q

Where does blood pumped by the right ventricle go?

A

The lungs

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29
Q

Where does blood pumped by the left ventricle go?

A

Body tissues

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30
Q

Why is the double circulatory system important?

A

It makes the circulatory system more efficient - for example, oxygenated blood can be pumped around the body at a higher pressure by the left ventricle.

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31
Q

How many chambers does the heart have and what are they called?

A

4 - right atrium, right ventricle, left atrium, left ventricle.

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32
Q

Why is the wall of the left ventricle thicker?

A

The left ventricle has to pump blood at a higher pressure around the whole body.

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33
Q

What are the four main blood vessels associated with the heart?

A

● Aorta (left) - carries oxygenated blood from the heart to the body.
● Pulmonary vein (left) - carries oxygenated blood from the lungs to the heart.
● Vena cava (right) - carries deoxygenated blood from the body to the heart.
● Pulmonary artery (right) - carries deoxygenated blood from the heart to the lungs.

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34
Q

What is the purpose of valves in the heart?

A

Prevent the backflow of blood

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35
Q

What is the purpose of coronary arteries?

A

Coronary arteries supply the heart muscle with oxygenated blood.

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36
Q

Describe the process of blood flow through the heart

A

● Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
● The atria contract, forcing blood into the ventricles and causing valves to shut.
● After the ventricles contract, blood in the right ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricle enters the aorta (to the body).

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37
Q

What is the approximate value of the natural resting heart rate?

A

70 beats per minute

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38
Q

How is the heart rate controlled?

A

Heart rate is controlled by a group of cells in the right atrium which act as a pacemaker. They release waves of electrical activity which cause the heart muscle to contract.

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39
Q

How can an abnormal heart rhythm be treated?

A

Irregular heart rhythms can be treated using an artificial pacemaker, which sends out electrical signals to correct the heart’s rhythm.

40
Q

What are the three types of blood vessel in the body?

A

● Arteries
● Veins
● Capillaries

41
Q

How are arteries adapted for their function?

A

● Function: carry blood away from the heart.
● Thick muscle layer - adds strength to resist high pressure.
● Thick elastic layer - allows arteries to stretch and recoil - in order to withstand high pressure.

42
Q

How are veins adapted for their function?

A

● Function: carry blood towards the heart
● Wide lumen - enables low pressure
● Valves - prevent backflow of blood

43
Q

How are capillaries adapted for their function?

A

● Function: enable transfer of substances between the blood and tissues.
● Walls are one cell thick - short diffusion path.
● Permeable walls - substances can diffuse across.
● Narrow lumen - blood moves slowly - more time for diffusion.

44
Q

How would you calculate the rate of blood flow?

A

Volume of blood / number of minutes

45
Q

Where are the lungs found in the body?

A

The lungs are located in the thorax (within the chest). They are protected by the ribcage and separated from the rest of the abdomen by the diaphragm.

46
Q

What tissues make up the gas exchange system?

A 
●	Trachea
●	Intercostal muscles
●	Bronchi
●	Bronchioles
●	Alveoli
●	Diaphragm
47
Q

Explain how the lungs are ventilated by the action of intercostal muscles

A

● Intercostal muscles contract
● Ribcage moves upwards and outwards
● Diaphragm flattens and volume of the chest increases
● Increased volume results in decreased pressure
● Air is drawn into lungs down pressure gradient

The inverse occurs when air moves out of the lungs.

48
Q

Describe how gas exchange occurs at the alveoli

A

● Oxygen diffuses from the alveoli into the capillary bloodstream down its concentration gradient.
● Carbon dioxide diffuses from the capillary into the alveoli down its concentration gradient.

49
Q

Describe how alveoli are adapted for gas exchange

A

● Small and arranged in clusters - larger surface area.
● Rich blood supply - maintains concentration gradient.
● Thin alveolar wall - short diffusion pathway.

50
Q

How would you calculate the breathing rate

A

Number of breaths / number of minutes

51
Q

What substance carries the different components of blood around the body?

A

Plasma

52
Q

What substances are transported by plasma?

A 
●	Red blood cells
●	White blood cells
●	Platelets
●	Carbon dioxide
●	Urea
●	Products of digestion
53
Q

What is plasma?

A

A yellow liquid within blood that transports substances around the body.

54
Q

What is the purpose of red blood cells in blood?

A

Transport of oxygen around the body

55
Q

How are red blood cells adapted for their function?

A

● Biconcave shape - increased surface area to volume ratio.
● No nucleus - more room for haemoglobin to bind to oxygen.
● Contain haemoglobin - binds to oxygen.

56
Q

What is the purpose of white blood cells in blood?

A

They form part of the immune system, which protects the body from invading pathogens.

57
Q

How are white blood cells adapted for their function?

A

● Have a nucleus - contains DNA which codes for proteins
● Can produce antibodies
● Can produce antitoxins
● Can engulf and digest pathogens (phagocytosis)

58
Q

What is the purpose of platelets in blood?

A

Platelets are small cell fragments which aid the clotting of blood at the site of a wound.

59
Q

Why is the function of platelets important?

A

● Platelets aid in the process of blood clotting (conversion of fibrinogen to fibrin). As a result, red blood cells are trapped in the fibrin network, forming a clot which prevents excessive bleeding. Scab formation (after the clot has dried) prevents bacteria from entering the wound.

60
Q

What is coronary heart disease?

A

Coronary heart disease occurs when the coronary arteries that supply the heart muscle become blocked with a buildup of fatty material. This restricts the supply of oxygen to the heart, possibly leading to a heart attack or death.

61
Q

What is a stent and how does it work?

A

A stent is a metal mesh tube that is inserted into a blocked artery so that it remains open. The stent is inflated using a balloon, which is later removed to allow blood to flow freely.

62
Q

What are the advantages of stents?

A

Advantages
● Insertion can be carried out without general anaesthetic
● Quick recovery time
● Lower the risk of a heart attack

63
Q

What are the disadvantages of stents?

A

Disadvantages
● Risk of postoperative infection
● Risk of blood clots at site of stent

64
Q

What are statins?

A

Statins are drugs which reduce the level of LDL (bad) cholesterol which contributes to the development of coronary heart disease

65
Q

What are the advantages of statins?

A

Advantages
● Reduce risk of strokes, coronary heart disease and heart attacks
● Increase level of HDL (good) cholesterol

66
Q

What are the disadvantages of statins?

A

Disadvantages
● Have to be taken continuously
● May have side effects
● Effect may not be immediate

67
Q

What is a heart bypass surgery?

A

A surgery where blocked coronary arteries are replaced with sections of veins taken from other parts of the body.

68
Q

What are the consequences of leaky heart valves?

A

Blood flows in the wrong direction, causing the heart to become less efficient. Patients may become breathless and die as a result.

69
Q

What types of valves can replace leaky valves?

A

● Mechanical - made of metal or polymers

● Biological - taken from animals (pigs, sometimes humans)

70
Q

What are the advantages of mechanical valves?

A

Advantages

● Last for a very long time

71
Q

What are the disadvantages of mechanical valves?

A

Disadvantages

● Need to take medication to prevent blood clotting around valve

72
Q

What are the advantages of biological valves?

A

Advantages

● Work very well - no medication required

73
Q

What are the disadvantages of biological valves?

A

Disadvantages

● Only lasts 12-15 years

74
Q

What is the purpose of an artificial heart?

A

Artificial hearts are intended to support a patient’s heart while they wait for a suitable donor heart.

75
Q

What are the advantages of artificial hearts?

A

Advantages
● Less likely to be rejected by immune system
● Allows damaged heart to rest to help recovery

76
Q

What are the disadvantages of artificial hearts?

A

Disadvantages
● Risk of infection due to surgery
● Risk of blood clots
● Have to take blood-thinning drugs

77
Q

What is health?

A

Health is the state of physical and mental wellbeing

78
Q

What is a communicable disease?

A

A disease caused by a pathogen which can be transmitted from one person to another eg. the flu.

79
Q

What is a non-communicable disease?

A

A disease which can not be transmitted from person to person eg. cancer.

80
Q

How can diet affect health?

A

● Too little food / lack of nutrition - anaemia, vitamin deficiencies.
● Too much food / too much unhealthy food - obesity, type 2 diabetes.

81
Q

How can stress affect health?

A

Prolonged stress is linked to a wide range of health problems including heart diseases, cancers and mental health issues.

82
Q

How can life situations affect health?

A

Many life factors such as location, gender, financial status, ethnic group and healthcare provision can impact a person’s mental and physical health.

83
Q

Give examples of how health problems can interact

A

● Infection with certain viruses can lead to cancer eg. hepatitis infections can lead to liver cancer.
● A compromised immune system (eg. due to cancer) can lead to a higher risk of infection with communicable diseases.
● Immune reactions caused by a pathogen can trigger allergic reactions.
● Problems with physical health can lead to mental health issues.

84
Q

What is a risk factor?

A

A risk factor is an aspect of a person’s lifestyle or a substance found in the body or the environment which can increase the risk of a disease.

85
Q

What is a causal mechanism?

A

A mechanism which demonstrates how one factor biologically influences another.

86
Q

How do diet, smoking and exercise affect the development of cardiovascular disease?

A

● Diet: high levels of LDL cholesterol causes arteries to become blocked, increasing blood pressure and the risk of a heart attack.
● Smoking: nicotine increases heart rate; other chemicals damage the artery lining and increase blood pressure.
● Exercise: lowers blood pressure, reducing strain on the heart.

87
Q

How does obesity affect the development of type 2 diabetes?

A

● Obesity is strongly linked with the onset of type 2 diabetes - a disease in which the body stops responding to insulin.

88
Q

How does alcohol affect liver and brain function?

A

● Excessive long-term alcohol use may lead to liver cirrhosis (scarring of the liver).
● Increases risk of liver cancer.
● Damages brain tissue and nerve cells.

89
Q

How does smoking affect the development of lung disease and lung cancer?

A

● Tar in tobacco can damage the alveoli of the lungs, leading to chronic obstructive pulmonary disease (COPD).
● Tar also damages the cells which line the lungs, leading to lung cancer.

90
Q

How do smoking and alcohol affect unborn babies?

A

● Carbon monoxide from tobacco smoke reduces the amount of oxygen the foetus receives, which can lead to premature birth or stillbirth.
● Alcohol passes across the placenta and damages the developing foetus. Once born, the baby may have a number of deformities and health problems as part of foetal alcohol syndrome.

91
Q

How do carcinogens affect the development of cancer?

A

Ionising radiation is a type of carcinogen which can cause mutations in DNA, potentially leading to cancer.

92
Q

What is cancer?

A

Cancer is the development of a tumour as a result of uncontrolled cell division.

93
Q

What is a benign tumour?

A

● A tumour that is contained in one location, usually within a membrane.
● They are not cancerous and do not invade other parts of the body.
● Can grow large very quickly - may cause damage to another organ.

94
Q

What is a malignant tumour?

A

● A tumour that can spread around the body via the blood and lymphatic system.
● Can invade other tissues (metastasis).
● Cells divide more rapidly and have a longer lifespan.
● Disrupts healthy tissues and may lead to death.

95
Q

Give examples of factors which can lead to cancer

A

● Genetics - certain genes increase the risk of breast and ovarian cancer
● Smoking
● Obesity
● Ionising radiation - UV light and X-rays
● Viral infections - HPV and cervical cancer

AQA Biology Paper 1: Combined Science (7 decks)

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