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Biology Topic 8 > Topic 8 > Flashcards

Topic 8 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What do all organisms take in?

A

1) All organisms must take in substances that they need from the environment and get rid of any waster products

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2
Q

Give examples of how organisms take in substances from the environment and get rid of waste products:

A
  • Cells need oxygen for aerobic respiration, which produces carbon dioxide as a waste product. These two gases move between cells and the environment by diffusion
  • Water is taken up by cells osmosis. In animals, dissolved food molecules (the products of digestion, e.g. glucose, amino acids) and mineral ions diffuse along with it.
  • Urea (a waste product produced by animals from protein) diffuses form cells to the blood plasma for removal from the body by the kidneys.
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3
Q

Why can gases and dissolved substance diffuse directly into and out of single celled organisms?

A

In single- celled organisms, gases and dissolved substances can diffuse directly into (or out of) the cell across the cell membrane- it’s because they have a large surface area compared to their volume, so enough substances can be exchanged across the membrane to supply the volume of the cell.

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4
Q

Why is it more difficult for multi cellular organism to exchange substances?

A

Multicellular organisms (such as animals) have a smaller surface area compared to their volume. This makes it difficult to exchange enough substances to supply their entire volume across their outside surface alone. So they need some sort of exchange surface for efficient diffusion and a mass transport system to move substance between the exchange surface and the rest of the body.

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5
Q

How are exchanged surfaces adapted to maximize effectiveness?

A

The exchange surfaces have to allow enough of the necessary substances to pass through, so they are adapted to maximize effectiveness.

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6
Q

What does the exchange of substance with its environment depend on?

A

How easy it is for an organism to exchange substances with its environment depends on the organism’s surface area to volume ratio (SA: V)

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7
Q

How would you find the area of a surface?

A

length * width

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8
Q

How would you find the total surface area?

A

Find area of individual faces and add them all up

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9
Q

How would you find the volume?

A

Area of shape* lenth

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10
Q

Where does gas exchange take place?

A

Gas exchange takes place in the alveoli.

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11
Q

Why does blood arriving at the alveoli have more C02 than O2?

A

2) Blood arriving at the alveoli has just returned to the lungs from the rest of the body, so it contains lots CO2 and not much O2. This maximises the concentration gradient for the diffusion of both gases.

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12
Q

Where does the O2 diffuse to?

A

O2 diffuses out of the air in the alveoli (where the concentration of O2 is high) and into the blood (where the concentration of O2 is low).

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13
Q

Where does the CO2 diffuse to?

A

CO2 diffuses in the opposite direction to be breathed out.

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14
Q

How is the alveoli specialized to maximise the diffusion of 02 and CO2?

A

They have:
• A moist lining for dissolving gases.
• A good blood supply to maintain the concentration gradients of O2 and CO2.
• Very thin walls- minimising the distance that gases have to move
• An enormous surface area (about 75 m2 in humans)

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15
Q

Name the three factors that affect diffusion?

A

Distance
Concentration
Surface area

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16
Q

How does distance affect diffusion?

A

substances diffuse more quickly when they haven’t as far to move.

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17
Q

How does concentration affect diffusion?

A

substances diffuse faster if there’s a big difference in concentration between the area they are diffusing from and the area they are diffusing to. If there are lots more particles on one side, there are more there to move across.

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18
Q

How does surface area affect diffusion?

A
  • the more surface there is available for molecules to move across, the faster they can get from one side to the other.
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19
Q

Recall Ficks law:

A

rate of diffusion is proportional to the surface area* concentration/ thickness of membranes

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20
Q

What happens to the surface area/ concentration if the rate of diffusion doubles?

A

Doubles

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21
Q

What happens to the thickness of the membrane if the rate of diffusion doubles?

A

Halves

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22
Q

What is the job of red blood cells?

A

1) The job of red blood cells (also called erythrocytes) is to carry oxygen form the lungs to all the cells in the body.

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23
Q

How does the shape of the red blood cell make it more efficient?

A

They have a biconcave shape (they look like a doughnut) to give a large surface area for absorbing oxygen.

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24
Q

Why doesn’t a red blood cell have a nucleus?

A

They don’t have a nucleus- this allows more room to carry oxygen.

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25
Q

What pigment do they contain?

A

The contain a red pigment called haemoglobin, which contains iron,

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26
Q

What do the red blood cells do in the lungs?

A

In the lungs, haemoglobin binds to oxygen to become oxyhaemoglobin

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27
Q

What do the red blood cells do in the body tissue?

A

In body tissues, the reverse happens- oxyhaemoglobin splits up into haemoglobin and oxygen, to release oxygen to the cells.

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28
Q

What are are phagocytes?

A

Phagocytes are white blood cells that can change shape to engulf unwelcome microorganisms- this is called phagocytosis.

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29
Q

What are lymphocytes?

A

2) Lymphocytes are white blood cells that produce antibodies against microorganism. Some also produce antitoxins to neutralise any toxins produced by the microorganisms. When you have an infection, your white blood cells multiply to fight it off- so a blood test will show a high count of white blood cells.

30
Q

What are platelets?

A

These are small fragments of cells. They have no nucleus

31
Q

How do they stop blood from pouring out of wounds?

A

They help the blood to clot at a wound- to stop all your blood pouring out and to stop microorganisms getting in. (So platelets kind of float about waiting for accidents to happen.)

32
Q

What can lack of platelets lead to?

A

Lack of platelets can cause excessive bleeding and bruising.

33
Q

What is plasma?

A

Plasma is the liquid that carried everything in blood.

34
Q

What does plasma carry?

A

Plasma carries:

1) Red and white blood cells and platelets.
2) Nutrients like glucose and amino acids. These are the soluble products of digestion which are absorbed form the gut and taken to the cells of the body.
3) Carbon dioxide form the organs to the lungs
4) Urea from the liver to the kidneys.
5) Hormones.
6) Proteins.
7) Antibodies and antitoxins produced by the white blood cells.

35
Q

Why are the artery walls strong and elastic?

A

1) The heart pumps the blood out at a high pressure so the artery walls are strong and elastic.

36
Q

Are the artery walls thick or thin?

A

The walls are thick compared to the size of the hole down the middle (the lumen).

37
Q

What do the thick layers of muscle do to the artery?

A

3) They contain thick layers of muscle to make them strong, and elastic fibres to allow them to stretch and spring back.

38
Q

What do arteries branch into?

A

1) Arteries branch into capillaries.

39
Q

Are capillaries small or big?

A

Capillaries are really tiny too small to see.

40
Q

Why can capillaries carry blood close to each cell in the body?

A

They are very narrow, so they can carry the blood really close to every cell in the body to exchange substances with them

41
Q

Why can substances diffuse in and out of the capillaries?

A

They have permeable walls, so substances can diffuse

in and out.

42
Q

What do capillaries do?

A

They supply food and oxygen and take away waste like CO2

43
Q

Why is the rate of diffusion faster in capillaries?

A

Their walls are usually only one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs.

44
Q

How are veins formed?

A

Capillaries eventually join up to form veins.

45
Q

Why don’t the veins walls have to be thick as artery walls?

A

The blood is at lower pressure in the veins so the walls don’t need to be as thick as artery walls.

46
Q

What helps the blood flow in the veins?

A

They have a bigger lumen, than arteries to help the blood flow despite the lower pressure,

47
Q

What makes sure that the blood flows in the right direction?

A

They also have valves to help keep the blood flowing in the right direction.

48
Q

How does the heart pump blood in two circuits?

A

The heart pumps blood around the body in two circuits. In the first circuit, the heart pumps deoxygenated blood to the lungs to take in oxygen. Oxygenated blood then returns to the heart. In the second circuit, the heart pumps oxygenated blood around all the other organs of the body to deliver oxygen to the body cells. Deoxygenated blood then returns back to the heart.

49
Q

How many chambers does the heart have?

A

The heart has four chambers and four major blood vessels:

50
Q

Describe how the heart processes the blood:

A

1) The right atrium of the heart receives deoxygenated blood form the body (through the vena cava)
2) The deoxygenated blood moves through to the right ventricle, which pumps it to the lungs (via the pulmonary artery).
3) The left atrium receives oxygenated blood from the lungs (through the pulmonary vein).
4) The oxygenated blood then moves through to the left ventricle, which pumps it out round the whole body (via the
aorta) .

51
Q

Why does the left ventricle have a thicker wall?

A

The left ventricle has a much thicker wall than the right ventricle. It needs more muscle because it has to pump blood around the whole body at high pressure whereas the right ventricle only has to pump it to the lings, Valves prevent the backflow of blood in the heart.

52
Q

What does respiration do?

A

Respiration goes in and out of every cell of all living organisms- and it happens continuously

53
Q

What is respiration?

A

It’s the process of transferring (Releasing) energy from the breakdown of organic compounds (usually glucose).

54
Q

What is the energy in respiration used for?

A

The energy is then used for things like:

  • Metabolic processes- such as making larger molecules from smaller ones (e.g. proteins form amino acids).
  • Contracting muscles (in animals)
  • Maintaining a steady body temperature (in mammals and birds)
55
Q

Why is respiration an exothermic reaction?

A

Because energy is transferred to the environment, respiration is an exothermic reaction. Some of this energy is transferred by heat.

56
Q

What are the two types of respiration?

A

There are two types of respiration, aerobic and anaerobi

57
Q

What is aerobic respiration?

A

1) Aerobic respiration is what happens when there’s plenty of oxygen available.
2) Aerobic means with oxygen and it’s the most efficient way to transfer energy from glucose.
3) This type of respiration goes on all the time in plants and animals

58
Q

What is the equation for aerobic respiration?

A

glucose + oxygen——> carbon dioxide +water

C6H12O6 + 6O2—–> 6CO2 +6H20

59
Q

What is anaerobic respiration?

A

1) When you do vigorous exercise your body can’t supply enough oxygen to you muscles for aerobic respiration –even though your heart rate and breathing rate increase as much as they can. Tour muscles have to start respiring anaerobically as well.
2) Anaerobic means without oxygen. It transfers much less energy than aerobic respiration so it’s much less efficient. In anaerobic respiration, the glucose is only partially broken down and lactic acid is also produced.
3) The lactic acid builds up in the muscles-It gets painful and leads to cramp.

60
Q

What is the word equation for anaerobic respiration in animals?

A

glucose—-> lactic acid

61
Q

What do plants produce during anaerobic respiration?

A

1) Plants can respire without oxygen too, but they produce ethanol (alcohol) and CO2 instead of lactic acid.

62
Q

What is the word equation for anaerobic respiration for plants?

A

glucose—-> ethanol + carbon dioxide

63
Q

How can the rate of respiration be calculated in aerobic respiration?

A

In aerobic respiration organisms, use up oxygen form the air. Yopu can calculate the rate of respiration by measuring the amount of oxygen consumed byu the organism in a given time.

64
Q

Describe the experiment which allows you to measure the effect of temperature on the rate of respiration?

A

1) Firstly, some soda lime granules are added to two test tubes. Soda lime absorbs the CO2 produced by the respiring woodlice ion the experiment.
2) A ball of cotton is placed above the soda lime in each tube. Woodlice are placed on top of the cotton wool in one tube. Glass beads with the same mass as the woodlice are used in the control tube.
3)The respirometer is then set up.
4) The syringe is used to set the fluid in the manometer to a known level.
The apparatus is left for a set period of time to 15 degress
6) During this time there will be a decrease in the volume of the air in the test tube containing the woodlice. This is because the woodlice use up oxygen in the tube as they respire. (The CO2 is absorbs by the soda lime so it doesn’t affect the experiment)
7) The decrease in the volume reduces the pressure in the test tube causing the coloured liquid in the manometer to move towards the test tube containing the woodlice.
8) The distance moved by the liquid is the given time. This value can then be used to calculate the volume of the oxygen taken in by the woodlice per minute.
9) Repeat steps 1-8 with different water bath temperature

65
Q

How is the experiment set up?

A

Refer to the textbook for picture of equipment

66
Q

What can be used instead of woodlice?

A

Germinating peas or beans as they respire to provide energy for growth.

67
Q

What is cardiac output?

A

The total of volume of blood pumped by a ventricle every minutw

68
Q

How can you calculate the cardiac output?

A

Cardiac put put= heart rate *stroke volume

69
Q

What is the heart rate?

A

The number of beats per minute.

70
Q

What is the stroke volume

A

The volume if blood pumped by one ventricle each time it contracts

Biology Topic 8 (1 decks)

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