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AQA Biology: 2 Organisation > 2.2 Animal Tissue, Organs and Systems > Flashcards

2.2 Animal Tissue, Organs and Systems Flashcards

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1
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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1
Q

What are the pancreas and the salivary gland and what is their role in the digestive system?

A

They are glands which produce digestive juices containing enzymes which digest food.

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2
Q

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

A

Produces hydrochloric acid which:

  • Kills any bacteria present .
  • Provides the optimum acidic pH for the protease enzyme to function.
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3
Q

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

A

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

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4
Q

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

A

Produces bile (stored in the gallbladder) which:

  • Emulsifies lipids
  • Allows the lipase enzyme to work more efficiently.
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5
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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6
Q

What is the role of enzymes in the digestive system?

A

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

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7
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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8
Q

What is metabolism?

A

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

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9
Q

What types of metabolic reactions do enzymes catalyse? (3)

A
  • Breaking down larger molecules into smaller molecules eg. carbohydrates to glucose.
  • Building larger molecules from smaller molecules eg. glucose to starch.
  • Changing one molecule to another eg. glucose to fructose.
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10
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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11
Q

How does temperature affect enzyme action? (3)

A
  • Up to a certain point, increasing temperature increases enzyme action, as molecules have a higher kinetic energy.
  • Above the optimum temperature, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction.
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12
Q

What is the optimum temperature for enzyme action?

A

Around 37°

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13
Q

How does pH affect enzyme function?

A

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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14
Q

What is the optimum pH for most enzymes? What is the exception? (2)

A

The optimum pH for most enzymes is 7 (slightly alkali conditions) apart from proteases in the stomach which is 2 (acidic conditions).

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15
Q

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

A
  • Carbohydrases: salivary gland and pancreas (amylase); small intestine (maltase).
  • Proteases: stomach (pepsin); pancreas and small intestine (others).
  • Lipases: pancreas and small intestine.
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16
Q

What is the role of carbohydrases ( in the digestive system? What are the role of amylase and maltase?

A

To break down carbohydrates into monosaccharides and disaccharides (simple sugars).

  • Amylase breaks down starch into maltose (made up of two glucose molecules).
  • Maltase breaks down maltose into glucose.
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17
Q

What is the role of proteases in the digestive system?

A

To break down proteins into amino acids.

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18
Q

What is the role of lipases in the digestive system?

A

To break down lipids into fatty acids and glycerol.

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19
Q

How are the products of digestion used? (2)

A
  • To build bigger molecules such as carbohydrates and proteins.
  • Glucose is used as a substrate in respiration.
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20
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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21
Q

What is the role of bile in the digestive system? (3)

A
  • Neutralise the hydrochloric acid secreted by the stomach (it is an alkaline substance).
  • Emulsify lipids to form droplets, increasing the surface area for the lipase enzyme to work on.
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22
Q

What is the heart?

A

An organ that pumps blood around the body.

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23
Q

What is the purpose of the circulatory system? (2)

A
  • Carries oxygen and other useful substances to bodily tissues.
  • Removes waste substances.
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24
Q

How does the double circulatory system work? (2)

A
  • One pathway (right) carries blood from the heart to the lungs, which is where the gaseous exchange of oxygen and carbon dioxide takes place.
  • One pathway (left) carries blood from the heart to the tissues.
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25
Q

Where does blood pumped by the right ventricle go?

A

The lungs

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26
Q

Where does blood pumped by the left ventricle go?

A

Body tissues

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27
Q

Why is the double circulatory system important; how? (2)

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 around the whole body.

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28
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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29
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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30
Q

What are the four main blood vessels associated with the heart and what are their roles?

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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31
Q

What is the purpose of valves in the heart?

A

Prevent the backflow of blood.

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32
Q

What is the purpose of coronary arteries?

A

To supply the heart muscle with oxygenated blood.

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33
Q

Describe the process of blood flow through the heart.

A
  1. Blood enters the right atrium through the vena cava, and the left atrium through the pulmonary vein.
  2. The atria contract, forcing blood into the ventricles and causing valves to shut.
  3. 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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34
Q

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

A

70 beats per minute.

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35
Q

How is the heart rate controlled? (2)

A

It 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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36
Q

How can an abnormal (irregular) heart rhythm be treated?

A

Using an artificial pacemaker, which sends out electrical signals to correct the heart’s rhythm.

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37
Q

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

A
  • Arteries
  • Veins
  • Capillaries
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38
Q

What is the role (function) of arteries?

A

To carry blood away from the heart.

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39
Q

How are arteries adapted for their function? (2)

A
  • Thick muscle layer adds strength to resist high pressure.
  • Thick elastic layer allows arteries to stretch and recoil (in order to withstand high pressure).
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40
Q

What is the role (function) of veins?

A

To carry blood towards the heart.

41
Q

How are veins adapted for their function? (2)

A
  • Wide lumen enables low pressure.
  • Valves prevent backflow of blood.
42
Q

What is the role (function) of capillaries?

A

To enable the transfer of substances between the blood and tissues.

43
Q

How are capillaries adapted for their function? (3)

A
  • One cell thick walls create a short diffusion path.
  • Permeable walls enables substances to diffuse across.
  • Narrow lumen enables blood to move slowly so that there is 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? (3)

A

In the thorax (within the chest), protected by the ribcage and separated from the rest of the abdomen by the diaphragm.

46
Q

What organs make up the gas exchange system? (6)

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

Explain how the lungs are ventilated by the action of intercostal muscles. (5)

A
  1. Intercostal muscles contract.
  2. Ribcage moves upwards and outwards.
  3. Diaphragm flattens and volume of the chest increases.
  4. Increased volume results in decreased pressure.
  5. Air is drawn into lungs down pressure gradient.

The inverse occurs when air moves out of the lungs.

48
Q

Explain the process of exhalation in the lungs by the action of intercostal muscles. (5)

A
  1. Intercostal muscles relax.
  2. Ribcage moves downwards and inwards.
  3. Diaphragm becomes a “dome” shape and volume of the chest decreases.
  4. Decreased volume results in increased pressure.
  5. Air is drawn out of lungs down pressure gradient.

The inverse occurs when air moves into the lungs.

49
Q

Describe how gas exchange occurs at the alveoli. (2)

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.
50
Q

Describe how alveoli are adapted for gas exchange

A
  • Small and arranged in clusters causes larger surface area.
  • Rich blood supply maintains concentration gradient.
  • Thin alveolar wall creates short diffusion pathway.
51
Q

How would you calculate the breathing rate?

A

Number of breaths / number of minutes

52
Q

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

A

Plasma

53
Q

What four components is the blood made out of?

A
  • Red blood cells
  • White blood cells
  • Plasma
  • Platelets
54
Q

What substances are transported by plasma? (6)

A
  • Red blood cells
  • White blood cells
  • Platelets
  • Carbon dioxide
  • Urea
  • Products of digestion
55
Q

What is plasma?

A

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

56
Q

What is the purpose of red blood cells in blood?

A

To transport of oxygen around the body.

57
Q

How are red blood cells adapted for their function? (3)

A
  • Biconcave shape causes increased surface area to volume ratio.
  • No nucleus creates more room for haemoglobin to bind to oxygen.
  • Contain haemoglobin which binds to oxygen.
58
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.

59
Q

How are white blood cells adapted for their function?

A
  • Nucleus contains DNA which codes for proteins.
  • Can produce antibodies.
  • Can produce antitoxins.
  • Can engulf and digest pathogens (phagocytosis).
60
Q

What are platelets and what is their purpose in blood?

A

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

61
Q

Why is the function of platelets important?

A
  • They aid in the process of blood clotting (conversion of fibrinogen to fibrin) which prevents excessive bleeding as red blood cells are trapped in the fibrin network forming a clot.
  • They cause scab formations (after the clot has dried) preventing bacteria from entering the wound.
62
Q

What is coronary heart disease? (3)

A

Occurs when the coronary arteries that supply the heart muscle with blood become blocked with a buildup of fatty material, restricting the supply of oxygen to the heart causing the heart muscle to weaken overtime.

63
Q

What can coronary heart disease lead to?

A

It could possibly lead to a heart attack or death.

64
Q

What is a stent and how does it work?

A

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

65
Q

What are the advantages of stents? (3)

A
  • Insertion can be carried out without general anaesthetic.
  • Quick recovery time.
  • Lower the risk of a heart attack.
66
Q

What are the disadvantages of stents? (2)

A
  • Risk of postoperative infection.
  • Risk of blood clots at site of stent.
67
Q

What are statins?

A

Drugs that reduce the level of LDL or “bad” cholesterol which contributes to the development of coronary heart disease.

68
Q

What are the advantages of statins? (2)

A
  • Reduce risk of strokes, coronary heart disease and heart attacks.
  • Increase level of HDL (good) cholesterol.
69
Q

What are the disadvantages of statins? (3)

A
  • Have to be taken continuously.
  • May have side effects.
  • Effect may not be immediate.
70
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.

71
Q

What are the consequences of leaky heart valves? (2)

A

The heart to becomes less efficient because blood flows in the wrong direction, leading patients to possibly become breathless and die as a result.

72
Q

What types of valves can replace leaky valves? (2)

A
  • Mechanical - made of metal or polymers.
  • Biological - taken from animals (pigs, sometimes humans).
73
Q

What are the advantages of mechanical valves? (1)

A
  • Last for a very long time.
74
Q

What are the disadvantages of mechanical valves? (2)

A
  • On-going medication needed to prevent blood clotting around valve.
  • Risk of haemorrhage and blood clotting.
75
Q

What are the advantages of biological valves? (1)

A
  • Work very well - no medication required (risk of medication removed).
76
Q

What are the disadvantages of biological valves? (1)

A
  • Replacements needed - only lasts 12-15 years.
77
Q

What is the purpose of an artificial heart?

A

To support a patient’s heart while they wait for a suitable donor heart.

78
Q

What are the advantages of artificial hearts? (2)

A
  • Less likely to be rejected by immune system.
  • Allows damaged heart to rest to help recovery.
79
Q

What are the disadvantages of artificial hearts? (3)

A
  • Risk of infection due to surgery.
  • Risk of blood clots.
  • Have to take blood-thinning drugs.
80
Q

What is health?

A

The state of physical and mental well-being.

81
Q

How can different health problems interact? (4)

A
  1. One disease may increase the risk of contracting another disease (e.g. HIV increases risk of TB)
  2. Infection from one disease may cause another disease (e.g. HPV → cervical cancer).
  3. Immune reactions caused by a pathogen can trigger allergic reactions.
  4. A mental illness can be triggered by a physical illness (e.g. arthritis → depression).
82
Q

What may cause ill health; include examples? (3)

A
  • Communicable disease: Measles
  • Non-communicable diseases: HIV
  • Lifestyle factors: poor diet, high levels of stress, environmental impacts (e.g. high pollution).
83
Q

How can diet affect health? (2)

A
  • Too little food / lack of nutrition - anaemia, vitamin deficiencies.
  • Too much food / too much unhealthy food - obesity, type 2 diabetes.
84
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.

85
Q

How can life situations affect health? (5)

A

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

86
Q

What is a risk factor?

A

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.

87
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.
88
Q

What is a causal mechanism?

A

A mechanism which demonstrates how one factor biologically influences another.

89
Q

How does obesity affect the development of type 2 diabetes?

A
  • Obesity is strongly linked with the onset of type 2 diabetes as it causes insulin resistances and β-cell dysfunction.
90
Q

What are type 2 diabetes?

A

A disease in which the body stops responding to insulin.

91
Q

How does alcohol affect liver and brain function? (3)

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.
92
Q

How does smoking affect the development of lung disease and lung cancer? (2)

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.
93
Q

How does smoking 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.

94
Q

How does alcohol affect unborn babies?

A

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.

95
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.

96
Q

What is cancer?

A

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

97
Q

Give examples of factors which can lead to cancer. (5)

A
  • Genetics - certain genes increase the risk of cancer (e.g. breast and ovarian cancer).
  • Smoking
  • Obesity
  • Ionising radiation (e.g. UV light and X-rays).
  • Viral infections (e.g. HPV causes cervical cancer).
98
Q

What are the characteristics of a benign tumour?

A
  • Non-cancerous.
  • Cannot invade other tissues.
  • Contained in one location, usually within a membrane (cannot spread around the body) so can easily be removed.
  • Grows slowly.
99
Q

What are the characteristics of a malignant tumour?

A
  • Cancerous
  • Can invade and disrupt other tissues.
  • Can spread to other parts of the body in the bloodstream and lymphatic system.
  • Secondary tumours can form from cancer cells detaching as the tumour grows, in other parts of the body (metastasis).
  • Grows rapidly (cells divide more rapidly).

AQA Biology: 2 Organisation (5 decks)

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