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GCSE AQA TRIPLE SCIENCE - Biology > AQA GCSE Biology - Topic 2 - ORGANISATION > Flashcards

AQA GCSE Biology - Topic 2 - ORGANISATION Flashcards

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1
Q

What is a tissue?

A

A tissue is a group of cells with a similar structure and function.

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2
Q

What is an organ?

A

An organ is a group of tissues working together for a specific function.

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3
Q

What are organ systems?

A

Organ systems are groups of organs which work together to form organisms.

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4
Q

What is the function of the digestive sytem?

A
  • break down large molecules of food into smaller, soluble ones so that they can be absorbed into the bloodstream
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5
Q

What is the function of the mouth in the digestive sytem?

A
  • food is chewed - amylase enzymes released by the salivary glands begin to digest starch
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6
Q

What is the function of the stomach in the digestive sytem?

A
  • protease enzymes begin the digestion of proteins - contains hydrochloric acid which provides the optimal pH conditions for the protease - churning turns the food into a fluid which increases the SA for enzymes to digest
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7
Q

What is the function of the pancreas in the digestive sytem?

A
  • pancreas releases amylase and protease enzymes into the SI which continue the digestion of starch and protein, and begin the digestion of lipids
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8
Q

What is the function of the liver and gall bladder in the digestive sytem?

A
  • releases bile into the SI - gall bladder stores bile
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9
Q

What is the function of the SI in the digestive sytem?

A
  • walls of the SI release enzymes to continue the digestion of protein and lipids - here, small food molecules are absorbed into the bloodstream
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10
Q

What is the function of the LI in the digestive sytem?

A
  • here, water is absorbed into the bloodstream
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11
Q

What is the function of the rectum and anus in the digestive sytem?

A
  • rectum stores faeces - faeces is released from anus
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12
Q

What happens to the products of digestion after?

A
  • products used by the body to build new carbohydrates, lipids, and proteins - some of the glucose produced is used in respiration
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13
Q

What is the function of enzymes?

A

Enzymes catalyse (speed up) chemical reactions.

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14
Q

What are enzymes?

A

Enzymes are protein molecules.

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15
Q

How do enzymes work?

A

Enzymes have an active site where only a specific substrate fits into. The enzyme then breaks down the subtrate into the products. Enzymes lower the activation energy.

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16
Q

What is the enzyme and substrate theory called?

A

The ‘lock and key theory’ shows that enzymes are specific and the substrate must fit perfectly into the active site.

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17
Q

What are proteins broken down into? What happens after the products are absorbed into the bloodstream?

A

Proteins (chains of amino acids) are broken down into amino acids by protease. When the amino acids are absorbed by the body cells, they are joined together in a different order to make human proteins.

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18
Q

What are carbohydrates broken down into? What is the specific case for starch?

A

Carbohydrates (chain of simple sugars) are broken down by carbohydrases into simple sugars. Starch is broken down by amylase.

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19
Q

What is the structure of lipids? What are lipids broken down into?

A

A lipid molecule consists of a glycerol molecule attached to 3 fatty acid molecules. Lipids are broken down by lipase enzymes into glycerol and fatty acids.

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20
Q

What are the 2 functions of bile?

A
  • bile emulsifies lipids (increase SA => increase rate of lipid breakdown) - the alkaline bile also neutralises the HCL to provide the optimum conditions for lipase enzymes => increases rate of lipid digestion
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21
Q

What happens if we increase the temperature for enzymes? Why?

A
  • activity of the enzyme increases and the reaction is faster because the enzyme and the substrate are moving faster, colliding more frequently
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22
Q

What happens at the optimum temperature?

A

enzymatic reactions occurring at maximum possible rate - maximum frequency of successful collisions

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23
Q

What happens if we increase the temperature past the optimum? Why?

A
  • enzyme activity rapidly decreases to zero and active site is denatured - at high temperatures, enzyme vibrates and the shape of the active site changes so substrate no longer fits
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24
Q

How can we test for starch?

A
  • Take the food sample and grind with distilled water using a mortal & pestle; transfer paste to a beaker, add more distilled water, stir to dissolve; filter 1) Add 2cm3 of food solution to test tube. 2) Add a few drops of iodine solution. 3) If starch, iodine: orange => blue-black
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25
Q

How can we test for reducing sugars?

A

1) Add 2cm3 of food solution to a test tube. 2) Add 10 drops of Benedict’s solution. 3) Place tube into beaker and half-fill with hot water from kettle, leave for 5min. 4) If sugar, Benedict’s solution: blue => green/yellow/brick-red

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26
Q

How can we test for proteins?

A

1) Add 2cm3 of food solution to a test tube. 2) Add 2cm3 of Biuret solution. 3) If protein, Biuret solution: blue => purple/pink

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27
Q

How can we test for lipids?

A
  • but without filtering 1) Add 2cm3 of food solution to a test tube. 2) Add 3 drops of Sudan III. 3) Shake test tube gently to mix. 4) If lipids: red-stained oil layer will separate out and float on surface
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28
Q

Why should no naked flames be present when testing for lipids?

A

Sudan III contains ethanol which is flammable.

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29
Q

Describe a method to investigate the effect of pH on amylase.

A

1) Place 1 drop of iodine solution into each well of a spotting tile. 2) In the first test tube, add 2cm3 of starch solution. 3) In the second test tube, add 2cm3 of amylase solution. 4) In the third test tube, add 2cm3 of pH5 buffer solution. 5) Place all 3 test tubes in a water bath (30°C) for 10min to allow the solutions to reach the correct temperature. 6) Combine the 3 solutions into 1 test tube and mix with a stirring rod. Return test tube to the waterbath and start a stopwatch. 7) After every 30s, use the stirring rod to transfer 1 drop of solution into a spotting tile well. 8) Iodine should turn blue-black if starch is present. 9) Stop transferring when the iodine remains orange. (reaction complete). record this time. 10) Repeat whole experiment with different pH buffers.

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30
Q

What are some problems with thi method and how could we solve this issue.

A
  • samples taken every 30s (only have an approximate time for when the reaction is complete) => take samples every 10s - not obvious when iodine does not turn blue-black => ask several people to look at the spotting tile to decide the time => mean
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31
Q

How is the small intestine adapted for absorption of food molecules?

A
  • length of 5m => very large SA - interior covered with millions of VILLI => increase SA - microvilli on the surface of villi - very good blood supply from capillaries => rapidly removes the products of digestion (maintains high concentration gradient) - thin membrane (short diffusion pathway)
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32
Q

What is the problem of having a single circulatory system?

A

Blood loses a lot of pressure so blood reaches organs relatively slowly => cannot deliver a great deal of oxygen

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33
Q

What is advantageous about a double circulatory system?

A

Blood passes through the heart twice which repressures it so it reaches organs quickly.

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34
Q

What is, and what is the function of the heart?

A

The heart is an organ, consisting mainly of muscle tissue, that pumps blood around the body.

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35
Q

What is the order of the 4 chambers in the heart? (left to right on a diagram)

A

Right Atrium > Left Atrium > Right Ventricle > Left Ventricle

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36
Q

How are the atria separated from the ventricles?

A

By atrioventricular valves

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37
Q

What is the flow of blood through the heart?

A

The vena cava brings in deoxygenated blood from the body. The blood passes from the heart to the LUNGS in the pulmonary Artery, where the blood becomes oxygenated. Oxygenated blood passes from the LUNGS to the heart in the pulmonary veIN. Oxygenated blood is pumped from the heart to the body in the aortA

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38
Q

What is the role of valves?

A

Valves prevent the backflow of blood.

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39
Q

Why does the left side of the septum have a thicker muscular wall than the right side?

A

The left ventricle has to pump pump to the entire body so it requires a greater force from the thicker muscular wall.

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40
Q

What is the function of coronary arteries?

A

The coronary arteries branch out of the aorta to supply the heart muscle with oxygen so it can be used in repiration to provide the energy for contraction.

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41
Q

How is the natural resting heart rate controlled? What happens if this stops working correctly?

A

By a group of cells located in the right atrium that act as a pacemaker. If the pacemaker becomes faulty, docotrs can implant an artifical pacemaker to correct irregularities in the heart rate.

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42
Q

What do arteries do? How are they adapted for this?

A

Arteries carry very high pressure blood Away from the heart to the organs in the body. - very thick muscular walls to withstand the very high pressure - elastic fibres which stretch to cope with the blood surges pass through (then recoil in between to keep the blud moving)

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43
Q

What do capillaries do? How are they adapted for this?

A

Capillaries are where substances such as glucose and oxygen diffuse out to the cell in the organs (carbon dioxide diffuses back into the blood). - very thin walls (short dffusion pathway for rapid substance diffusion)

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44
Q

What do veins do? How are they adapted for this?

A

VeINs carry low pressure, slow-moving blood back to the heart. - have valves to prevent backflow of slow-moving blad - thin wall (thick = unecessary)

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45
Q

What is the plasma? What is its function?

A

The plasma is the liquid part of the blood. The blood plasma transports dissolved substances around the body, such as: - soluble digestion products (small intestine => other organs) - carbon dioxide (organs => lungs) - urea (liver => kidneys)

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46
Q

What is the function of red blood cells?

A

Red blood cells transport oxygen from the lungs to the body cells.

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47
Q

How are red blood cells adapted to their function?

A
  • contain haemoglobin which binds to oxygen in the lungs - no organelles => more room for haemoglobin - biconcave disc shape => increase surface area => oxygen diffuses in and out rapidly
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48
Q

What is the function of white bood cells?

A

White blood cells form part of the immune system.

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49
Q

What features help white blood cells to carry out their function?

A
  • do have a nucleus (contains DNA which encodes the instructions for their job)
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50
Q

What is the function of the platelets?

A

Platelets are tiny fragments of cells that help the blood to clot.

51
Q

What can donated blood be used for in medicine?

A
  • to replace blood that has been lost during an injury - platelets are extracted to help patient with blood clotting - proteins that are extracted from blood can be useful, e.g. antibodies
52
Q

What are some problems with donating blood?

A
  • in a blood transfusion, the donated blood has to be the same blood type as the patient’s (otherwise the patient’s immune system could reject the blood) - risk of infection (different diseases could be transmitted via blood)
53
Q

What are cardiovascular diseases?

A

Diseases of the heart and blood vessels.

54
Q

What does it mean if cardiovascular diseases are non-communicable?

A
  • they are not infectious (cannot be passed from person to person)
55
Q

What happens if someone has coronary heart disease?

A

Layers of fatty material build up inside the coronary arteries, narrowing them, and therefore, reduce the flow of blood through the coronary arteries. -> heart muscle receives less oxygen to use in respiration -> muscle cannot contract efficiently

56
Q

What are statins? - pros? - cons?

A
  • STATINS ARE DRUGS which reduce the level of cholesterol in the blood - they slow down the rate that fatty materials build up - reduce the risk of coronary heart disease - do have some unwanted side-effects, e.g. liver problems
57
Q

What are stents? - pros? - cons?

A

A STENT is a tube which can be inserted into to the coronary artery to keep it open - blood can flow normally throught the coronary artery - stent will not prevent other regions of the coronary arteries from narrowing - does not treat the underlying causes of the disease

58
Q

What happens if heart valves are faulty and do not fully open?

A

The heart has to pump extra hard to force the blood through -> causes heart to enlargen

59
Q

What happens if heart valves are leaky?

A

If the heart valves are leaky, the patient can feel weak and tired

60
Q

What 2 treatments are used for faulty heart valves?

A
  • replacement with an artificial, MECHANICAL valve (made from metal) - replacement with a biological valve from an animal, e.g. piggy
61
Q

What are the pros and cons of mechanical valves?

A
  • can last a lifetime - may increase the risk of bloodclots -> patients have to take anticlotting drugs
62
Q

What are the pros and cons of biological valves?

A
  • do not need to take drugs - do not last as long and may need to be replaced
63
Q

What is heart failure?

A

Heart failure is the inability of the heart to pump sufficient blood to meet the needs for oxygen and nutrients.

64
Q

What are the 2 problems associated with a donated heart to treat heart failure?

A
  • not enough donated hearts available - patient must take drugs to stop the donated heart from being rejected by the immune system
65
Q

What is an artifical heart used for?

A
  • temporary solution to heart failure while waiting for a heart transplant - allow damaged heart to rest
66
Q

What are the disadvantages of using an artifical heart?

A
  • increase the risk of blood clotting, not a long-term soltuion to heart failure
67
Q

What is the pathway of air in the gas exchange system?

A

Air passes into the lungs through TRACHEA > trachea now splits into two smaller BRONCHI (one bronchus to each lung) > bronchi dubdivide into many smaller bronchioles > alveoli

68
Q

What is one key feature of the trachea?

A
  • contains RINGS OF CARTILAGE prevent the trachea from collapsing during inhalation
69
Q

What is the function of the alveoli?

A

Alveoli are the tiny air sacs within our lungs where oxygen diffuses in and carbon dioxide diffuses out from the bloodstream.

70
Q

How are alveoli adapted for gas exchange?

A
  • millions of alveoli (huge SA) - very thin walls (short diffusion pathway) - very good blood supply (maintains steep concentration gradient) - moist (gases have to be dissolved to diffuse) - ventilation brings in fresh oxygen ad removes carbon dioxide (maintains steep concentration gradient) —> rapid rate of gas diffusion
71
Q

What is key about the control of mitosis?

A
  • extremely tightly controlled (genes tell cells when to divide and when to stop dividing)
72
Q

How are cancers formed?

A

Changes take place in the genes -> uncontrolled growth and division -> produces a tumour (aka growth)

73
Q

What is the difference between benign and malignant tumours?

A

-> Benign tumours: - benign tumours are the growths of abnormal cells found in one area, usually contained within a membrane. - They do not invade other parts of the body- they stay in one place. - A benign tumour isn’t normally dangerous, and the tumour isn’t classed as a cancer (isn’t cancerous). -> Malignant tumour: - Malignant cells invade neighbouring tissues and move into the bloodstream. - Once in the bloodstream, malignant tumours spread to different parts of the body, forming new, secondary tumours. - Malignant tumour are dangerous and can be fatal. They are classed as a cancer.

74
Q

What are the risk factors linked to cancer?

A
  • genetics - lifestyle - exposure to carcinogens
75
Q

What is radon?

A

Radon is a radioactove gas which increases your risk of developing lung cancer

76
Q

Why is radon a carcinogen? (how is it capable of causing cancer)

A

Radon is a carcinogen because it releases ionising radiation which damages the DNA in our cells - causing the cells to undergo uncontrolled cell division, leading to cancer.

77
Q

What is a communicable disease? Give an example.

A

A communicable disease can be spread from person to person, e.g. measles. Communicable diseases are spread by pathogens such as bacteria or viruses.

78
Q

What is a non-communicable disease? Give an example.

A

A non-communicable disease cannot be spread from person to person, e.g. coronary heart disease.

79
Q

What is health?

A

Health is the state of physical and mental well-being.

80
Q

What can ill health be caused by?

A

Ill health can be caused by: - both communicable and non-communicable diseases - poor diet - high levels of stress - life situations

81
Q

What is Tubercolosis (TB)?

A

Tubercolosis (TB) communicable lung disease. Tubercolosis (TB) can be fatal.

82
Q

Why may some people be unable to fight off the bacteria that cause TB?

A

In most people, the immune system can fight off Tubercolosis (TB). However, some people have a defective immune system, for e.g. people with HIV. People with a defective immune system are much more likely to suffer from infectious diseases.

83
Q

What is HPV?

A

Human papilloma virus (HPV) is extremely common. In most people it is essentially harmless.

84
Q

What can HPV cause?

A

In some people, HPV can cause cervical cancer. Most cervical cancers are caused by the human papilloma virus which infects the cells of the cervix, triggering cancer.

85
Q

How can allergies be caused by a pathogen?

A

Allergies, such as asthma or dermatitis, can be triggered by immune reactions initially caused by a pathogen, which the immune system fights off, but the person left with an allergy.

86
Q

Give an example where a mental illness can be caused by a physical illness?

A

Depression can be caused by arthritis.

87
Q

What is epidemiology?

A

The study of the patterns of disease to determine risk factors.

88
Q

What does a correlation do?

A

A correlation does not prove that a disease is caused by a risk factor; it only suggests that they might be linked.

89
Q

What is a causal mechanism?

A

A causal mechanism is evidence that a risk factor definitely leads to a particular disease.

90
Q

What is the correlation between cigarette smoking and lung cancer? What is the causal mechanism between cigarette smoking and lung cancer?

A

Cigarette smoking and lung cancer have a positive correlation; this shows that they may be linked. A causal mechanism between cigarette smoking and lung cancer is that cigarette smoke contains carcinogens which damage DNA and increase the risk of cancer.

91
Q

What do scientists do to investigate whether a disease is linked to a diet?

A

Scientists sample a group of people and then try to draw conclusions about the whole population.

92
Q

What is the problem of sampling a group of people from only one town? How can we avoid this bias when sampling?

A

If we select our sample (group of people) from only one town, it is possible that this does not represent the entire population of the country. So we say the sample is biased, for e.g. people in the town might take less exercise than average, or they might be exposed to a certain type of pollution only found in that town. That means we could not use the results to draw conclusions about the whole country. -> To avoid bias, you can: - take sample as LARGE as possible - take sample as RANDOM as possible

93
Q

What are the risk factors for cardiovascular diseases?

A
  • Diets are a major risk factor for coronary heart disease. For e.g. a diet high in fat and low in vegetables increases certain types of cholesterol in the blood, which increases the rate that fatty materials build up in the arteries. - A diet high in salt can increase blood pressure, increasing the risk of developing cardiovascular diseases. - Smoking also massively increases the risk of developing cardiovascular diseases. - However, regular exercise decreases your risk of developing cardiovascular diseases.
94
Q

What are the risk factors for lung cancer and other diseases of the lungs?

A

Smoking massively increases risk of lung cancer because cigarette smoke contains carcinogens (which damages our DNA, increasing the risk of cancer). Smoking is also a cause for other lung diseases like emphysema. These diseases (of the lungs) are extremely unpleasant and leads to a very poor quality of life.

95
Q

What is the effect of smoking during pregnancy?

A

The effect of smoking when pregnant is that it can harm an unborn baby as it increases risk of miscarriage & premature birth

96
Q

What is the effect of drinking alcohol on an unborn baby?

A

Drinking alcohol when pregnant can cause fetal alcohol syndrome. Children born with fetal alcohol syndrome can have learning difficulties and other mental or physical problems.

97
Q

What other diseases are also caused by drinking alcohol?

A

Adults who drink alcohol excessively increase their risk of liver cirrhosis & liver cancer. Alcohol can also affect the brain, leading to addiction and memory loss.

98
Q

What are the risk factors of type 2 diabetes?

A

Obesity and physical inactivity, increases your risk of developing type 2 diabetes.

99
Q

What can type 2 diabetes lead to?

A

Type 2 diabetes can lead to blindness or require the amputation of a limb.

100
Q

Give an example of how different risk factors can interact to cause a disease?

A

Different risk factors can interact to cause a disease. For e.g. drinking excess alcohol can lead to obesity and then that increases the risk of type 2 diabetes.

101
Q

What is a risk factor which is not linked to lifestyle?

A

The substances present in your environment can also be risk factors for a disease, e.g. radon is a radioactive gas which increases your risk of developing lung cancer.

102
Q

Leaf

A

The leaf is a plant organ. Just like any other organ, the leaf contains a group of tissues that work together for a specific function.

103
Q

What is the top and bottom of the leaf covered with? What is the function of both these layers?

A

The top and bottom of the leaf are covered with a layer of very thin epidermal cells which form epidermal tissue, these tissues are called the upper and lower epidermis. The epidermises protect the top and bottom surfaces of the leaf. So the upper epidermis protects the top surface of the leaf, and the lower epidermis protects the bottom surface of a leaf.

104
Q

What is the key adaptation of the upper epidermis?

A
  • The upper epidermis is transparent. This allows light to pass through to the photosynthetic cells below.
105
Q

Where is the waxy cuticle?

A

The upper epidermis is also covered with a thin layer of oily material called the waxy cuticle.

106
Q

What is the role of the waxy cuticle?

A

The waxy cuticle reduces the evaporation of water from the surface of the leaf. This helps prevent leaf from drying out.

107
Q

Where is the stomata?

A

The lower epidermis has tiny pores called stomata.

108
Q

What are the functions of the stomata?

A

Stomata allow carbon dioxide to enter the leaf and oxygen to leave. Stomata also help to control the amount of water vapour that can pass out of the leaf.

109
Q

Where do we find guard cells?

A

On either side of the stomata we find guard cells.

110
Q

What does the palisade mesophyll consist of? What is the role of the palisade mesophyll?

A

The palisade mesophyll consists of palisade cells which are packed full of chloroplasts. Chloroplasts contain chlorophyll which absorb the light energy needed for photosynthesis.

111
Q

What is the role of the spongey mesophyll?

A

The spongey mesophyll is full of air spaces, which allow CO2 to diffuse from the stomata through the spongey mesophyll to the palisade cells to then be used in photosynthesis. The air spaces in the spongy mesophyll also allow oxygen to diffuse from the palisade cells through the spongy mesophyll to the stomata.

112
Q

What is the function of the xylem?

A

Xylem tissue transports water from the roots to the stem and leaves. Some of the water is then used in photosynthesis. The xylem also transports dissolved minerals ions. These include magnesium which is used to make chlorophyll.

113
Q

What is the function of the phloem?

A

Phloem tissue transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant. This is known as Translocation. The sugars can then be used immediately, e.g. glucose is used in respiration. The sugars can also be stored for e.g. as starch

114
Q

!!!!! Make sure you can label a cross section diagram of a leaf !!!!!

A

!!!!! Make sure you can label a cross section diagram of a leaf !!!!!

115
Q

What is a meristem tissue?

A

Meristem tissue is a plant tissue.

116
Q

Where can meristem tissue be found?

A

We find meristem tissue at growing tips e.g. in shoots and roots.

117
Q

What is the function of the meristem tissue?

A

The meristem tissue contains stem cells which can differentiate into different types of plant tissue.

118
Q

What does water enter the leaf through?

A

Water enters the leaf through root hair cells.

119
Q

What is translocation?

A

The movement of sugars through a plant in phloem

120
Q

What is transpiration?

A

Transpiration is the constant evaporation of water from the surfaces of leaves.

121
Q

What is the transpiration stream?

A

Transpiration starts with the evaporation of water from cells inside the leaf. The water vapour then diffuses through the air spaces in the spongy mesophyll and out of the leaf through the stomata. Now, water passes from the xylem into the leaf to replace the water that has been lost. Finally, water is drawn into the root hair cells and up the xylem vessels to the leaf. Scientists call this whole process the transpiration stream.

122
Q

Why is transpiration important?

A
  • Transpiration brings water to the leaf; water is needed for photosynthesis. - The transpiration stream transports dissolved mineral ions such as magnesium, which play important roles in the plant. - The evaporation of water from the leaf cools the leaf down, especially in warm weather.
123
Q

Factors affecting the rate of transpiration

A
  1. Temperature- rate of transpiration is greater at higher temperatures. That is because evaporation is faster when temperatures are higher. 2. Humidity- transpiration is also faster under dry conditions, when the air is not humid. That is because evaporation takes place more quickly under dry conditions. 3. Wind- the rate of transpiration increases in windy conditions. That is because wind removes any water vapour, allowing more water to evaporate. 4. Light intensity- the rate of transpiration increases when the light intensity increases. That is because high light intensity increases the rate of photosynthesis. So, the stomata now open to allow carbon dioxide to enter. Once The stomata have opened, water vapour can now pass out of the leaf.
124
Q

How does the stomata work?

A

Stomata are surrounded by two guard cells. When the light intensity is high for example during the day, the guard cells swell and change their shape. This causes the stomata to open. Now, carbon dioxide can diffuse into the leaf and be used in photosynthesis. Under hot conditions, the plant closes it’s stomata to reduce water loss by transpiration. That now means that the plant cannot photosynthesise as carbon dioxide can no longer enter the leaf.

GCSE AQA TRIPLE SCIENCE - Biology (9 decks)

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