Biology a Flashcards
0
Q
What is a partially permeable membrane ?
A
A membrane with very small holes in, only small molecules can pass through them
1
Q
What is osmosis ?
A
The movement of water molecules across a partially permeable membrane from a region I high concentration to low concentration
2
Q
How does water move in and out of cells ?
A
Through osmosis. Human cells have a semi permeable membrane - cell membrane
3
Q
What is tissue fluid ?
A
It is what surrounds the cells in the body, it supplies the cells with everything it needs - water, oxygen, glucose, etc.
4
Q
What three ways can substances move ?
A
Diffusion
Osmosis
Active transport
5
Q
What is an exchange surface ?
A
It is what substances have to pass through, in osmosis, diffusion and active transport, in life processes. Like partially permeable membranes
6
Q
How are exchange surfaces adapted for maximum effectiveness ?
A
- They are thin so the substance only has to pass a short distance
- Large surface area so more substances can pass through
- Good blood supply
7
Q
What has the structure of a leaf adapted to do ?
A
Let gases diffuse in and out of cells
8
Q
How has a leaf adapted to optimise gas and liquid exchange ?
A
- It has air gaps so carbon dioxide can diffuse into cells
- Underside of leaf covered with stomata
- Water vapour and oxygen diffuse out through stomata
- Flat shape of leaf increases area of exchange
9
Q
How do guard cells affect stomata ?
A
They control stomata. They close if the stomata is losing too much water. Without guard cells the plant would wilt.
10
Q
What is the thorax ?
A
The top part of your body
11
Q
What separates the thorax from the abdomen (lower body) ?
A
The Diaphragm
12
Q
How does the air you breath get into your lungs ?
A
It goes down the TRACHEA and is split into two tubes called BRONCHI. Each BRONCHUS progressively becomes smaller into tubes called BRONCHIOLES. They take the air to ALVEOLI where the gas exchange takes place.
13
Q
What is ventilation ?
A
The movement of air in and out of the lungs
14
Q
What are the intercostal muscles ?
A
Muscles between ribs
15
Q
How do you breath in ?
A
As air goes in, intercostal muscles and the diaphragm contract. The thorax volume increases which lowers pressure in the lungs which draws the air in.
16
Q
How do you breathe out ?
A
The intercostal muscles and the diaphragm relax which increases the pressure in the lungs which forces air out.
17
Q
What do artificial ventilators do ?
A
They help people to breathe
18
Q
What are villi ?
A
They are projections that line the surface of the small intestine. The increase surface area to absorb as much food as possible into the blood.
19
Q
How are alveoli specialised to maximise diffusion ?
A
- A large surface area
- A moist lining for dissolving gases
- Very thin walls
- Good blood supply
20
Q
What is the job of the lungs ?
A
To transfer oxygen into the blood and to remove waste carbon dioxide from it. They have millions of alveoli which are like little air sacks where gas exchange takes place.
21
Q
What are cells on the surface of a plant’s root called and what do they do ?
A
Root hair cell. It sticks out into the soil which increases it’s surface area. As a result they are great at absorbing water and minerals
22
Q
How are minerals taken in to the root hair cells ?
A
Through active transport
23
Q
When does active transport take place ?
A
When the concentration of a substance in the area you want the substance to go to is high, diffusion cannot take place. This is when active transport is needed
24
What does active transport need for it to happen ?
Energy
25
Where does active transport take place in the human body ?
One example is When glucose is taken from the gut into the blood
26
What does phloem transport ?
Food
27
How do phloems work ?
They transport food substances from the leaves to growing regions like shoots. They do this by allowing the dissolved sugars to pass through small holes in the end
28
What do the xylem tubes transport ?
They transport water and minerals from the roots to the stem and leaves.
29
What are xylem constructed out of ?
Dead cells joined end to end
30
What is transpiration ?
The loss of water from a plant
31
How does transpiration work ?
When water evaporates from the leaf the new demand for water is met by the xylem vessels. This means that more water is drawn up from the soil by the root hair cells. It is a constant system.
32
What type of circulation system do humans have ?
Double circulatory system
33
How does the double circulatory system work ?
It is comprised of two circuits. One pumps deoxygenated blood to lungs to take in oxygen in. The second pumps oxygenated blood to cells
34
Where does the blood first enter the heart ?
In the atria (left and right atrium), coming from the vena cava and the pulmonary vein
35
How does the blood get from the atria to the ventricles ?
The atria contract, pushing the blood into the ventricles through a valve
36
What is the job of the valves in the heart ?
They stop blood from moving in the wrong direction in the heart
37
How does blood get from inside the ventricles to around the body ?
The ventricles contract which forces blood out via the pulmonary artery and the aorta which travel around the body
38
What do arteries do ?
Carry blood AWAY from the heart
39
What does a vein do ?
They carry blood TO the heart
41
What is the hole in the middle of blood vessels called ?
Lumen
42
Why do veins have large lumen ?
To help blood flow despite the low pressure
43
Thick muscles around the lumen are on veins or arteries ?
Arteries - the muscle makes them strong, the elastic fibres allow them to stretch and spring back under pressure.
44
What is the capillary ?
The third type of blood vessel. They are involved in the exchange of material at the tissues. They branch out from arteries
45
Why are capillaries needed ?
They carry blood really close to every cell in the body to exchange substances. They supply food and oxygen and remove waste
46
How do the substances exchange between cells and capillaries ?
They have partially permeable walls, so substances can diffuse in and out
47
How thick are capillary walls ?
Around one cell thick. This increases the rate of diffusion by decreasing the distance over which it travels
48
What is blood ?
A tissue that acts as a huge transportation system
49
What are the four main elements of the blood ?
Red blood cells
White blood cells
Platelets
Plasma
50
What is the job of the red blood cell ? How are they adapted to maximise this ?
They carry oxygen from the lungs to all cells in the body. They have a concave shape which increases the surface area to absorb as much oxygen as possible, they also don't have a nucleus which saves space
51
How do red blood cells absorb oxygen ?
A red pigment called haemoglobin combines with oxygen in the lungs to form oxyhaemoglobin. The reverse of this reaction takes place at the cells, forming oxygen (used by the cells) and haemoglobin.
52
How do high levels of red blood cells help people in high altitudes ?
There is less oxygen so people who live there produce more red blood cells. Athletes do altitude training to try and make their body make more red blood cells.
53
What are white blood cells in the blood for ?
They fight against disease.
54
In what three ways do white blood cells protect against disease ?
* Change shape to engulf microorganisms
* Antibodies formed to fight microorganisms
* Antitoxins which counteract toxins excreted by bacteria
55
What are platelets and what do they do ?
They are small fragments of cells that help blood to clot. This prevents blood pouring out of wounds or microorganisms getting in.
56
What does a lack of platelets cause ?
Excessive bleeding and bruising
57
What is plasma ?
A pale, straw-like liquid which carries everything in the blood
58
Why are artery walls thick and vein walls thin ?
The blood is pumped at a higher pressure in the artery, it is lower in the vein. The thicker the wall the stronger it is.
59
When is artificial blood needed ?
Wen someone loses a lot of blood, their heart can still pump the remaining red blood cells around as long as the volume of their blood can be topped up
60
What can be used as artificial blood ?
It is a blood substitute like a salt solution. It replaces the lost volume of blood.
61
Even if a patient loses 2/3 o their red blood cells they can be kept alive, this gives the patient time to make more. If the patient can't produce the cells quick enough, what happens ?
A blood transfusion is needed. This tops up the red blood cells
62
What would the perfect artificial blood be able to do ?
Replicate red blood cells, so there would be no need for blood transfusions. They are currently being developed but scientists are having problems with side affects.
63
What is an artificial heart ?
A mechanical device that pumps blood around the body if the individual's heart fails.
64
What is the main advantage an artificial heart has over donor hearts ?
The artificial heart is not rejected by the body because it is made out of metal and plastic. The body doesn't recognise them as foreign
65
What are the disadvantages of artificial hearts ?
* The surgery is dangerous (infection)
* They don't work as well as healthy, natural hearts
* Parts can break
* Blood doesn't flow as smoothly so patients have to take drugs to thin their blood.
66
How do mechanical valves work ?
If a heart valve is defective then it can be replaced by a mechanical one. It is a much less drastic operation than a heart transplant (still major surgery).
67
What is coronary heart disease ?
When the arteries that supply blood to heart muscle are clogged by fatty deposit.
68
What does coronary heart disease lead to ?
The arteries become narrow and restrict blood flow. This can result in a heart attack
69
How do stents help blocked arteries ?
Stents are tubes that are inserted into arteries. They keep them open so that blood can pass through the heart muscle, keeping the person's heart beating
70
What are the disadvantages of stents ?
The artery can narrow over time, which irritates the person and can cause scar tissue to grow. The patient also has to take drugs to stop blood clotting
71
What is homeostasis ?
The maintenance of a constant internal environment
72
What are the six main things that need to be controlled ?
```
Temperature
Water content
Ion content
Blood sugar
Carbon dioxide levels
Urea
```
73
Why does body temperature have to be regulated ?
Enzymes work best at around 37 degrees Celsius in the human body. If it gets too hot or cold them the enzymes won't work properly and some really important reactions won't take place.
74
Where in the brain is temperature regulated ?
Thermoregulatory centre
75
How does the thermoregulatory centre work ?
It contains receptors that are sensitive to the temperature of blood flowing through the brain. It also receives impulses from the skin to give it information about skin temperature
76
Why do your hairs stand on up when you are cold ?
They trap an insulating layer of air
77
Why is sweat produced when you are hot ?
It evaporates from the skin, this removes heat by taking energy from the skin
78
Why do blood vessels dilate when you are warm ?
This makes the blood flow closer to the skin. This makes it easier for heat to be transferred from blood to the air
79
What is the opposite of blood vessels dilating ?
Blood vessels constricting
80
Why do you shiver when you are cold ?
Shivering is when your muscles contract automatically. This needs respiration which releases energy and warms the body
81
What three main roles do the kidneys perform ?
Removal of Urea
Adjustment of Water
Adjustment of ion content
82
What do the kidneys do ?
filter the blood
83
How is urea produced ?
Because proteins can't be stored in the body they are converted into days and carbohydrates. This process occurs in the liver and produces urea as a waste product.
84
Why does urea need to be removed ?
It is poisonous
85
Why does ion content and water content have to be monitored ?
If the balance of the two is upset then too much mater can be absorbed into cells during osmosis. This causes cell damage or mean they don't work as normal.
86
Are all ions removed by the kidneys ?
No, some is removed in sweat. BUT the balance between ions and water is always maintained by the kidneys
87
What are the three main ways water is removed from the body ?
Urine
Sweat
Breath
88
The body cannot control the amount of water breathed out, so what is the water balance between ?
1. How much water is consumed
2. Amount sweated out
3. Amount excreted by the kidneys in urine
89
Why is urine usually pale and dilute on a cold day ?
Because you don't sweat as much
90
Why are sports drinks used during exercise ?
The ions and water in them replace those lost in sweat. The sugar replaces the sugar used up by the muscles
91
What is ultrafiltration ?
High pressure is built up which squeezes water, urea, ions and sugar out of the blood (acts as the filter). Large molecules like proteins and blood cells are too big to pass out of the blood
92
What is reabsorbtion ?
This is when useful substances are reabsorbed back into the blood.
93
What what substances are reabsorbed ?
All of the sugar
Sufficient ions
Sufficient water
94
How are ions and sugar reabsorbed ?
Through active transport so they go against the concentration gradient
95
What happens to the waste ?
It passes out of the kidney through the ureter, into the bladder as urine
96
Why are your kidneys so important ?
If they don't work properly waste substances build up in the blood and ion and water levels are not balanced. Eventually this leads to death
97
What is dialysis ?
When machines filter the blood instead of the kidneys
98
How do dialysis machines work ?
Partially permeable barriers block blood cells and proteins from leaving the blood. The same substances that are removed by the kidneys diffuse into dialysis fluid and are removed.
99
What are the disadvantages of dialysis ?
* Patients have to have a dialysis session 3 times a week for 3-4 hours
* Can cause blood clots and infections
100
What is the only known cure for kidney disease ?
A kidney transplant. Healthy kidneys are transplanted into ill patients to give them a working kidney.
101
Why are some transplanted organs rejected ?
The patients immune system attack the foreign antigens because they think they are dangerous.
102
What precautions are taken to prevent organs being rejected ?
1. A tissue that closely matches the donors is chosen. Tissue type is based on antigens which are proteins on the surface of most cells.
2. The patient takes drugs which suppress the immune system
103
What two hormones control blood glucose levels ?
Insulin and glucagon
104
What happens when glucose levels are too high ?
Insulin is secreted by the pancreas. Insulin makes the live turn glucose into glycogen therefore removing it from the blood
105
What happens when the glucose level is too low ?
Glucagon is secreted from the pancreas. Glucagon makes the liver turn glycogen into glucose
106
What is diabetes ?
When the pancreas produces little or no insulin. The blood sugar levels can therefore rise high enough to kill them.
107
How can the problem be controlled ?
* Avoid eating food rich in carbohydrates and exercise to use up as much of the energy as possible
* Inject insulin into the blood which will remove the insulin.
108
How is insulin produced ?
It used to be extracted from pigs or cows but now human insulin is produced through genetic engineering.
109
What is a cure for diabetes ?
A pancreas transplant. However as with any transplant the body can reject the organ. Immunosuppressive drugs can be taken but they have serious side affects and are expensive.
110
What new ways of curing diabetes are they investigating ?
Artificial pancreases and stem cell research may eliminate organ rejection but try need more research
