B1-8 Key Things To Remember Flashcards
1
Q
Resolution
A
the ability to distinguish between two separate points in an image. A light microscope
can resolve to point approx 200nm apart, but an electron microscope can resolve two points only
0.2nm apart.
2
Q
Cell membrane
A
Controls what enter and leave the cell
3
Q
Cytoplasm
A
Site of chemical reactions
4
Q
Nucleus
A
Contains genetic material (DNA)
5
Q
Ribosome:
A
Site of protein synthesis
6
Q
Mitochondria
A
Site of respiration
7
Q
Cellulose wall
A
Strengthen and support the plant. It is fully permeable
8
Q
Chloroplast
A
Site of photosynthesis
9
Q
Large permanent vacuole
A
Contains cell sap
10
Q
Diffusion
A
the movement of substances from an area of high concentration to an area of low
concentration. E.g. oxygen molecules diffuse from the lungs into the blood stream.
11
Q
Osmosis
A
the movement of water molecules from an area of high concentration to an area of low
concentration across a partially permeable membrane.
12
Q
Active transport
A
the movement of substances from an area of low concentration to an area of
higher concentration. Against a concentration gradient, requires ATP energy and a carrier protein in
the cell membrane.
E.g. glucose is sometimes actively transported from your small intestine into the bloodstream.
E.g. mineral ions in water are actively transported from the soil into the root hair cells.
13
Q
Interphase
A
Cell grows in size, DNA and organelles replicate
14
Q
Mitosis
A
replicated chromosomes line up along the centre of the cell and get pulled to
opposite poles. Nucleus divides.
15
Q
Cytokinesis
A
cell membrane and cytoplasm divide to form 2 new identical daughter cells.
16
Q
What is a stem cell
A
An unspecialised cell that can differentiate into many other cell types
17
Q
Hierarchy of living organisms
A
cells ->tissues ->organs ->organ systems ->organisms
18
Q
Carbohydrate
A
composed of long chains of simple sugars e.g. glucose molecules
19
Q
Proteins
A
composed of chains of amino acids
20
Q
Fats
A
composed of 3 fatty acids & 1 glycerol molecule
21
Q
How enzymes work
A
Enzymes are proteins. They speed up the rate of chemical reactions.
- They have a specific shape called the active site
- The active site is complementary to the shape of the substrate molecule. Like a ‘lock and
key’.
- There are random collisions between the enzyme and the substrate molecule, when the
substrate enters the active site an enzyme – substrate complex is formed.
- Bonds are broken
- Produce are released.
- Enzyme can then be reused.
22
Q
Higher temperature
A
both the enzyme and substrate molecules have more kinetic energy,
therefore there are more frequent collisions, more enzyme substrate complexes are formed and
more products are released. Over 40°C the enzyme starts to become denatured and no longer
functions.
23
Q
pH
A
each enzyme has an optimum pH. They only work within a narrow range of pH. Higher/lower
pHs cause the enzyme to become denatured.
24
Q
Bile
A
a green alkaline liquid produced by the liver and stored in the gallbladder. It neutralises
stomach acid and emulsifies fats (which gives a larger surface area for the enzyme lipase to act).
25
Where is food absorbed into the bloodstream
Small intestine
26
Where is water reabsorbed back into the bloodstream
Large intestine
27
Blood plasma
```
a pale yellow liquid, which transports dissolved substances around the body e.g.
carbon dioxide (waste), urea (waste), glucose, antibodies etc.
```
28
How is oxygen carried around the body
Oxygen binds to haemoglobin (on red blood cells) forming
| oxyhaemoglobin which is carried to all cells for respiration.
29
Function of white blood cells
to fight disease. There are two types of white blood cells. i)
Phagocytes – engulf pathogens and digest them ii) Lymphocytes – produce antibodies which attach
the pathogen and destroy it.
30
What is meant by humans having a 'double circulatory system'
The heart is an organ that pumps
blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs
where gas exchange takes place. The left ventricle pumps blood around the rest of the body.
31
Function of an artery
transport (usually) oxygenated blood under high pressure away from the heart
(except the pulmonary artery which transports deoxygenated blood to the lungs).
32
Function of a vein
transport (usually) deoxygenated blood to the heart (except the pulmonary vein
which transport oxygenated blood into the left atrium).
33
Function of capillary
allow fast exchange/diffusion of substances e.g. glucose, oxygen - out of the
blood into the body cells/tissues.
34
Pathway of blood through the heart
(RHS) Vena cava -> right atrium -> right ventricle ->
pulmonary artery (pumps blood to the lungs) -> (LHS) Pulmonary vein -> left atrium ->left ventricle
->aorta (pumps blood all around the body)
35
What are the coronary arteries:
these are the arteries that supply the heart muscle with oxygen
and glucose for respiration.
36
Coronary heart disease
layers of fatty material build up inside the coronary arteries, narrowing
them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for
the heart muscle.
37
Treatment for cardiovascular disease by drugs, mechanical devices or transplant
Drugs- e.g. statins
Mechanical devices- stents, artificial valves, artificial pacemakers
Heart transplant
38
Pacemaker
The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a
pacemaker. Artificial pacemakers are electrical devices used to correct irregularities in the heart
rate.
39
Statins
drugs taken to reduce blood cholesterol levels, which slows down the rate of fatty
deposit build up in the coronary arteries.
40
Stents
```
wire mesh (‘balloon’) which is inserted into a (blocked) artery to widen the artery
and allow more blood to flow.
```
41
Artificial valves
valves in the heart prevent backflow of blood. If the valve becomes faulty
this could prevent the valve from opening fully, or the heart valve might develop a leak.
Faulty heart valves can be replaced using biological or mechanical valves.
42
What are the adaptions of the alveoli in the lungs for efficient gas exchange?
Structure: alveoli have a very large surface area
Function: this provides maximum diffusion of gases
Structure: each alveolus is surrounded by a network of capillaries near the surface
Function: to maintain a steep concentration gradient, this means a faster rate of diffusion.
Structure: the alveoli have thin moist walls
Function: this provides a short (& quicker) diffusion pathway for gases
43
What is transpiration
Transpiration is the loss of water vapour (by evaporation) from the surface of
the leaf.
44
What is translocation
the movement of dissolved sugars from the leaves (where they are made) to
the rest of the plant.
45
Xylem
is a plant tissue which transports water and mineral ions from the roots to the stems and
leaves. It is composed of hollow tubes strengthened by lignin.
46
Phloem
Is a plant tissue which transports dissolved sugars from the leaves to the rest of the plant.
The plant can either use the sugars immediately or store them (as starch).
Phloem is composed of tubes of elongated cells. Cell sap (sugars) can move from one phloem cell to
the next through pores in the end walls.
47
What are stomata
They are tiny pores on the surfaces of leaves, which can open or close. Guard
cells surround the stomata and control the opening and closing of the stomata. They allow the
exchange of gases in and out of the leave. Water vapour can also leave through the stomata. They
control gas exchange and water loss.
48
Water enters through
Only the roots by osmosis
49
How stomata control gas exchange and water loss
Guard cells open and close the stomata and in this way control the levels of carbon dioxide that
enter the leaf and the oxygen & water vapour that leave the leaf by diffusion. i.e. Stomata control
gas exchange and water loss.
In low light the guard cells lose water and become flaccid, causing the stomata to close. They would
normally only close in the dark when no carbon dioxide is needed for photosynthesis.
50
Where are the most stomata found
On the lower surface on the leaf
51
How do mineral ions enter the plant
Mineral ions are dissolved in water in low concentrations. Therefore the mineral ions (e.g.
magnesium, potassium etc) enter the plant via the root hair cells by active transport.
52
How guard cells open and close
Guard cells have an unevenly thickened (cell) wall
| • This enables them to, change shape / bend when they gain water by osmosis.
53
What conditions cause stomata to open
Stomata open during the day and close during the night.
• High water potential outside the stomata
• Light causes stomata to open
54
Health
Is the state of physical and mental well-being
55
Pathogen:
Is a microorganism that causes a disease e,g. Bacteria, viruses, fungi, protists
56
Communicable disease
disease caused by a microorganism that can be transmitted from one
person to another.
57
Other factors other than disease that can have an effect on physical/mental health?
Diet, stress and life situation
58
Risk factors for disease
Smoking
- Exposure to radiation
- Excessive alcohol
- Carcinogens
- Obesity
59
How different types of diseases can interact with each other
Problems with the immune system mean that an individual is more likely to suffer from
infectious diseases.
- Viruses living in cells can be a trigger for cancers.
- Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and
asthma.
- Severe physical illnesses can lead to mental illnesses like depression.
60
Compare how bacteria and viruses cause illness
Bacteria and viruses both reproduce rapidly once inside the body. However whereas bacteria
reproduce in the bloodstream (where they may produce toxins that damage tissues) and make us
feel ill, viruses live and reproduce inside cells causing cell damage and eventually entering the
bloodstream.
61
How ion deficiencies could affect a plant by a range of conditions, MAGNESIUM
Lack of magnesium: magnesium is needed to make chlorophyll. Lack of magnesium causes
chlorosis. If there isn’t enough chlorophyll plants cannot trap sunlight energy therefore lack
of magnesium affects the rate of photosynthesis.
62
How ion deficiencies could affect a plant by a range of conditions, NITROGEN
Lack of nitrogen: nitrogen (in the form of nitrates) are required by plants to make proteins.
Lack of nitrogen causes poor plant growth.
63
Non-communicable disease:
disease not caused by a microorganism that can not be transferred
from one person to another.
Examples of non-communicable diseases: cancer, diabetes
64
What is a cancer
```
is a (usually) non-communicable disease which develops as a result of changes in cells that lead to
their uncontrollable growth and division forming tumours.
```
65
Benign tumour
Growths of abnormal cells which have not yet invaded other parts of the body.
66
Malignant tumour
Growths of abnormal cells which have invaded neighbouring tissues and spread to different parts of
the body in the blood where they form secondary tumours.
67
Human defence is made up of two parts :
| The general defence system
The general defence system or the ‘non-specific’ defence system: e.g. skin, hairs in nose,
cilia in trachea and bronchi, HCl acid in the stomach.
68
And the immune system:
The immune system or ‘the ‘specific’ defence system: the white blood cells (phagocytes and
lymphocytes).
69
Pathogens have receptors
called antigens on their surface. This is how the white blood
cells identify them as ‘foreign’.
Pathogens can reproduce rapidly and produce toxins.
70
Phagocytes
engulf pathogens and digest them making them harmless
71
Lymphocytes
produce antibodies in response to ‘foreign’ antigens. The antibodies attach to
the antigens destroy them. They also can produce antitoxins which cancel out the effect of
the pathogen’s toxins.
72
How does a vaccination provide immunity?
A dead/weakened/inactive pathogen is injected into the patient’s bloodstream. The
pathogen still retains the antigens.
- Specific lymphocyte recognises the specific antigens and 1) produces clones of itself and 2)
produce large amounts of the correct antibody.
- After the lymphocyte has destroyed the pathogen the antibodies are broken down, but the
clone of lymphocytes remain in the bloodstream as ‘memory lymphocytes’.
- This provides immunity to that specific pathogen.
- If the same pathogen re-enters the body the white blood cells respond (more) quickly to
produce large amounts of the correct antibodies, preventing infection.
73
What is herd immunity?
Vaccinating a large proportion of the population against a certain pathogen (e.g. flu vacci
74
Traditionally drugs were extracted from plants and microorganisms like:
* The heart drug digitalis originates from foxgloves.
* The painkiller aspirin originates from willow.
* Penicillin was discovered by Alexander Fleming from the Penicillium mould.
75
Nowadays drugs need to be rigorously trialled/ tested to ensure:
They are safe, do not have any toxic side affects, the correct dose is given and they are stable - can be taken under normal conditions and can be stored safely
76
Drugs trials have various different stages
Pre-clinical trials: this is where drugs are tested on cells, tissues and live animals
e.g. mice. This is to ensure there are no unwanted side effects.
Clinical trials: this is where the drug is tested on humans. There are 3 stages.
Phase 1: drug is tested on healthy volunteers. Low doses are used.
Phase 2: drug is tested on people who actually have the disease (i.e. the patient).
Double blind trial: Some patients are given the actual drug, some are given a
placebo (a ‘fake’ drug without the active ingredient). Neither the patient nor the
doctor knows who has been given the drug or placebo. This is to remove bias. At the
end of the trial the Scientists from the drug company can compare data.
Phase 3: larger numbers of patients are used. Patients are given the drug or placebo.
This is to verify the efficacy/effectiveness of the drug and to determine the co
77
What are antibiotics
Antibiotics are chemicals that kill (pathogenic) bacteria inside the body. Specific
antibiotics kill specific bacteria.
78
Why do antibiotics not kill viruses
They do not work against viruses because viruses live and reproduce inside cells.
79
Why is it difficult for scientists to develop drugs that kill viruses
is difficult to develop drugs that kill viruses as viruses reproduce inside cells. Therefore
it is difficult to just kill the virus and not the body’s tissues too.
80
How do bacteria become resistant to certain antibiotics
1. Antibiotics kill individual bacterial pathogens of the non-resistant strain.
2. Resistant/mutated pathogens survive and reproduce.
3. The population of the resistant strain of pathogens increases because they are not
affected/killed by the antibiotic.
4. The resistant strain will then spread because people are not immune to it and there is
no effective treatment.
81
How can we reduce the spread of antibiotic resistant bacteria?
Do not prescribe antibiotics for mild infections because they will get better due to
the body’s normal immune system
• Do not prescribe antibiotics for viral infections / colds / flu because antibiotics do
not kill viruses
• If you do prescribe antibiotics make sure the patient finishes the full course because
any bacteria left may develop resistance, survive and reproduce rapidly (due to lack
of competition)
• Prescribe the correct antibiotic for the particular bacterial strain because routine use
would lead to an increase in resistant bacteria
82
Photosynthesis:
Photosynthesis is the process by which green plants (and some bacteria) make their
food. They use raw substance (carbon dioxide and water) and light energy to combine
these substances to make glucose and oxygen.
Glucose is needed in the plant, oxygen is released (some is used up in respiration).
83
What type of reaction is photosynthesis
Photosynthesis is an endothermic reaction. It requires light energy which is trapped by
the chlorophyll in the chloroplasts.
84
Photosynthesis word equation
Carbon dioxide+ water -sunlight-chlorophyll->glucose+oxygen
85
Photosynthesis chemical equation
6CO2+6H2O->C6H12O6+6O2
86
What does a plant use the glucose made in photosynthesis for?
Used for respiration to release energy
- Converted into insoluble starch for storage until it is needed
- Used to produce fat, or oil for storage
- Used to make other carbohydrates e.g. cellulose which strengthens the cell wall
- Used to produce amino acids for protein synthesis.
87
Explain the effects of temperature, light intensity, carbon dioxide concentration and the
amount of chlorophyll on the rate of photosynthesis.
The rate of photosynthesis is how quickly photosynthesis takes place (or how quickly
a plant converts water and carbon dioxide to glucose and oxygen)
• The rate depends on a few factors being present.
• If one or more of these factors are in limited supply the rate will not increase. These
are called limiting factors.
88
What is a limiting factor?
When a process (e.g. photosynthesis) depends on two or more factors (/substances), the
rate of that process is limited by the factor which is in shortest supply
89
Which factors could limit the rate of photosynthesis?
-Light intensity
-Availability of water
-Temperature
-Carbon dioxide concentration
-Amount of chlorophyl
These factors all interact and any one of them may become the factor that limits
photosynthesis.
90
Required practical
to investigate the effect of light intensity on the rate of photosynthesis
using an aquatic organism such as pondweed.
91
What is respiration?
Respiration is an exothermic reaction (releases energy) which releases energy from glucose.
**Do not say energy is formed or created or made...
There are two types of respiration that can release energy. Aerobic (requires oxygen) and
anaerobic (without oxygen).
92
Aerobic respiration equation:
Glucose+oxygen->energy+carbon dioxide+ water
93
Chemical equation for aerobic respiration
C6H12O6+6O2->6CO2+6H2O
94
Anaerobic respiration equation (in muscles of animals):
Glucose ->lactic acid
95
Anaerobic respiration (in plants):
Glucose->ethanol+ carbon dioxide
96
Anaerobic respiration in yeast cells:
Anaerobic respiration in yeast cells is called fermentation and has economic importance in
the manufacture of bread and alcoholic drinks.
97
How the body responds to exercise:
When exercising the body needs MORE energy. This means it needs MORE glucose and
MORE oxygen to carry out MORE respiration to release MORE energy.
*You must use the word more!
98
The heart and lungs have to work harder therefore:
-Breathing rate increases (supplies more oxygen to your exercising muscles
and removes excess carbon dioxide being produced).
• Heart rate increases, and the arteries supplying blood to muscles dilate (widen), this
delivers more Oxygen & glucose to the muscles.
• It also increases the rate of carbon dioxide & lactic acid removal from your muscles.
• Glycogen stored in the muscles is converted back to glucose to increase the rate of
respiration.
- Higher rate of respiration occurs as more ATPenergy is needed
99
What happens if there isn’t enough oxygen being supplied e.g. during hard, strenuous
exercise like a 100m sprint race?
If insufficient oxygen is supplied anaerobic respiration takes place in muscles.
The incomplete breakdown of glucose causes a build up of lactic acid and this
creates an oxygen debt.
During long periods of vigorous activity muscles become fatigued and stop
contracting efficiently
After the intense exercise the oxygen debt needs to be ‘paid back’ to remove the
excess lactic acid built up.
The person starts panting to take in extra oxygen, and the blood flowing through the
muscles transports the lactic acid to the liver where it is converted back into glucose
100
What is oxygen debt?
Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the
accumulated lactic acid and remove it from the cells.
101
What is metabolism
Metabolism is the sum of all the reactions in a cell or the body.
The energy transferred by respiration in cells is used by the organism for the continual
enzyme controlled processes of metabolism that synthesise new molecules.
102
Examples of metabolic reactions in the body
Metabolism includes:
• Conversion of glucose to starch, glycogen and cellulose
• The formation of lipid molecules from a molecule of glycerol and three molecules of fatty
acids
• The use of glucose and nitrate ions to form amino acids which in turn are used to
synthesise proteins
• Respiration
• Breakdown of excess proteins to form urea for excretion.
