Biology GCSE Flashcards
1
Q
Cell Cycle
A
interphase:cell grows in size, DNA and organelles replicate. Mitosis: replicated chromosomes line up along the centre of the cell and get pulled to opposite poles: nucleus divides.
Cytokinesis: cell membrane and cytoplasm divide to form 2 new identical daughter cells.
2
Q
Stem Cell
A
A cell that has not become specialised yet
3
Q
Advantages of embryonic stem cells: Advantages of adult stem cells
A
Embryonic: has the potential to transform into any type of cell/tissue. Used to treat human diseases. Painless
Adult: plentiful supply. no ethical issues in collection (consent can be given). Well tried/tested
4
Q
Hierarchy of living organism
A
cells->tissue->organ->organ system->organism
5
Q
carbohydrates
A
composed of long strains of simple sugars e.g. glucose molecules`
6
Q
proteins
A
composed of chains of amino acids
7
Q
How do enzymes work
A
Enzymes are protiens that speed up the rate of reaction
they all have specific shapes known as the active site.
The active site is complementary tothe shape of the substrate molecule similar to a “lock and key”.
There are random collisions between enzymes and substrates wen the substrate enters the active site of the enzyme it forms an substrate complex.
Bonds are broken
Products are formed
The enzyme can be reused
8
Q
The effect of temperature on enzymes
A
when the temperature is higher, both substrate and enzyme have more kinetic energy creating more frequent collisions thus creating more substrate complex’s=more product
Over 40 degrees the enzyme starts to become denatured and no longer functions
9
Q
Effect of pH on Enzymes
A
each enzyme has an optimum pH. Lower/higher pH’s cause the enzymes to become denatured
10
Q
Enzyme types and where they form
A
Protease production: stomach, small intestine, pancreas
Protease working site: stomach, small intestine
Lipase Production site: pancreas, small intestine
Lipase Working site: small intestine
Carbohydrase Production site: salivary glands, pancreas, small intestine
Carbohydrase Working site: mouth, small intestine
11
Q
Bile
A
A green alkaline liquid produced by the liver and stored in the gall bladder. it neutralises stomach acids and emulsifies fat (giving a larger surface area for enzyme lipase to act.
12
Q
Where is food absorbed into the bloodstream?
A
The small intestine
13
Q
Where is water reabsorbed back into the blood stream?
A
Large intestine
14
Q
Blood Plasma
A
a pale yellow liquid which transports dissolved substances around the body e.g. Carbon dioxide, urea, glucose, antibodies, waste etc
15
Q
How is oxygen carried around the body?
A
Oxygen blinds to the haemoglobin (on the red blood cells) forming oxyhaemoglobin which is carried to all cells for respiration
16
Q
What is meant by humans having a double circulatory system?
A
the heart is an organ that pumps blood around the body in a double circulatory system. the right ventricle carries deoxygenated blood to the lungs where gas exchange takes pace. the right ventricles carries oxygenated blood around the body to the cells that require it.
17
Q
Structure of an Artery
A
Thick outer wall
Small lumen
thick layer of muscular and elastic fibres
18
Q
Structure of a Capillary
A
very small lumen
walls made of a single cell
19
Q
Structure of a vein
A
thin layer of muscle and elastic fibres
large lumen
fairly thin outer wall
20
Q
Function of an Artery
A
transports (usually) oxygenated blood under high pressure away from the heart
21
Q
Function of a vein
A
Transports (usually) deoxygenated blood to the heart
22
Q
Function of a Capillary
A
allows fast exchange/diffusion of substances e.g. glucose, oxygen-out of the blood into the body cells/tissues
23
Q
coronary arteries
A
these are the arteries that supply the heart muscle with oxygen and glucose for respiration
24
Q
coronary heart disease
A
in coronary heart disease layers of fatty material build up in the coronary arteries, narrowing the lumen
this reduces the flow of blood through the coronary arteries resulting in a lack of oxygen and glucose for the heart muscle
25
Pacemaker
the 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
26
Statins
drugs taken to reduce cholesterol levels, which slows down the rate of fatty deposit build up in the coronary arteries
27
Stents
wire mesh "balloon" which is inserted into a (blocked) artery to widen the artery and allow more blood to flow
28
valves
valves in the heart prevent back-flow of blood. if the valve becomes faulty this could prevent the valve from opening fully or leaking. they can be replaced with mechanical or biological valvess
29
advantages of heart disease treatments
Stent:minor operation doesn't require anaesthetic
Statins: do not require surgery+reduces the risk of arteries narrowing
Artificial valve: high success rate
Transplant: can treat several heart conditions and increases life expectancy
Artificial pacemaker: long lasting devices
30
disadvantages of heart disease treatments
Stent: risk of infection
Statins: may increase the risk of type 2 diabetes
Artificial valve: risk of infection and need to take blood thinners
Transplant: risk of rejection and 3 year waiting list for compatible donor
Artificial pacemaker: doesn't treat heart disease, patients need to avoid magnetic and electromagnetic fields of energy.
31
What are the adaptations of the alveoil in the lungs for efficient gas exchange?
Alveoli have a very large surface area which provides maximum diffusion of gases
Each alveolus is surrounded by a network of capillaries near the surface which helps maintain a steep concentration gradient, this means a faster rate of diffusion
The aleoli have thin moist walls which provides short (and quicker) diffusion pathways for gases
32
internal structure of a leaf
waxy cuticle, upper epidermis, chloroplasts, palisade mesophyll layer, spongy mesophyll layer, xylem, phloem, airspace, epidermal cell, guard cell.
33
What is transpiration
Transpiration is the loss of water vapour (by evaporation) from the surface of the leaf.
34
What is translocation?
the movement of dissolved sugars from the leaves(where they are made) to the rest of the plant
35
Xylem (specialised cell)
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.
36
Phloem(specialised cell)
a plant tissue which transports dissolved sugars from the leaves to the rest of the plant. the plant can use the sugars immediately or store them as starch
37
More on Phloem
phloem is composed of tubes of elongated cells. cell sap (sugars) can move from one phloem cell to the next through the pores in the end walls
38
What are stomata?
they are tiny pores on the surface 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 leaf. water vapour can also leave through the stomata. they control gas exchange and water loss. Remember water never enters through a leaf, it only leaves.
39
Explain 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 enters the leaf and the oxygen and water vapour that leave the leaf by diffusion.
40
Where are most stomata found?
on the lower surface of the leaf
41
For effect on traspiration
see showbie
42
Root Hair Cell Function and Adaptation
Function: to absorb water(by osmosis) and mineral ions e.g. K by active transport. Adaptation: there are many hairs which give an increased surface area so the plant can absorb more water by osmosis
43
Xylem Function and Adaptation
To transport water from the roots to the leaves. Adaptation: dead hollow cells, Thick lignified walls which give strength.
44
Phloem Function and adaptation
To transport food from the leaves to the rest of the plant for use or storage. Adaptation: tubes of elongated cells, Cell sap can move from one phloem cell to the next through pores in the end walls.
45
Health
The state of physical and mental wellbeing
46
Pathogen
a microorganism that causes a disease e.g. fungus, bacteria, virus, protist
47
Communicable diseases
A disease caused by a microorganism that can be transmitted from one person to an another
48
Non-Communicable Disease
a disease not caused by a microorganism that cannot be transferred from one person to another.
49
Factors that have effects on physical/mental health
Stress
diet
life situations
50
Risk Factors For disease
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Smoking
exposure to radiation
excessive alcohol use
carcinogens
obesity
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51
What is cancer?
it is a (usually) non-communicable disease which develops as a result of changes in the cells that lead to their uncontrollable growth and division forming tumours
52
Benign tumour
growths of abnormal cells which have not yet invaded the body
53
malignant tumour
growths of abnormal cells which have invaded neighbouring tissues and have spread to different parts of the body in the blood where they form secondary tumours
54
How do 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.
55
Measles
caused by a virus. they cause fever, red skin rash. they can be very serious. they are spread in an air-borne fashion(coughing , sneezing etc) Vaccination in early childhood can be done to prevent it from oocuring.
56
HIV
caused by a virus. it have fly type symptoms. the virus attacks the bodies immune cells to the point they can no longer fight diseases. they are spread by sexual contact or exchange of bodily fluids e.g. blood (STI/STD)
57
Tobacco mosaic virus
it is caused by a virus and the symptoms of a mosaic patter of discolouration on the leaves which affects the growth of the plant due to the lack of photosynthesis.
58
salmonella
it is a Bacteria. it has symptoms of food poisoning, fever, abdominal cramps. it is spread through food or food prepared in unhygienic conditions. it can be prevented in ways such as the uk poultry are vaccinated against salmonella to control the spread of the bacteria.
59
Gonorrhoea
it is a bacteria. symptoms: Thick yellow/green discharge from the vagina or penis and pain when urinating. it is an STD. it is easily treated wit the antibiotic penicillin.
60
Rose Black Spot
It is a fungi. a fungal disease where purple or or black spots develop on the leaves. affects the growth of the plant as photosynthesis cannot take place.
61
malaria
it is a protist. it causes recurrent episodes of fever, can be fatal. It is a vector-mosquito. prevented through using nets and stopping them breeding.
62
How can plant diseases be detected
```
stunted growth
spots on leaves
areas of decay(rot)
growths
Malformed stems or leaves
discolouration
the presence of pests
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63
how can someone identify a plant disease
use a reputable gardening manual or website
taking infected plants to a laboratory to identify the pathogen
using testing kits that contain monoclonal antibodies
64
How do ion deficiencies could affect a plant?
stunted growth caused by nitrate deficiency. nitrates are needed to make proteins. therefore lack of nitrates cause poor plant growth.
chlorosis caused by magnesium deficiency. magnesium is needed to make chlorophyll. therefore a lack of magnesium will affect the rate of photosynthesis.
65
Physical plant defences
cellulose cell walls
tough waxy cuticle on leaves
layers of dead cells around stems (bark on trees) which fall off.
66
Chemical plant defences responses
antibacterial chemicals, poisons to deter herbivores
67
Mechanical adaptations
thorns and hairs deter animals, leaves which droop or curl when touched, mimicry to trick animals.
68
The human defence system
the human defence system is made up of two main parts,
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.
The immune system: or the "specific" defence system: the white blood cells (phagocytes and lymphocytes)
69
how do white blood cells recognise pathogens?
Pathogens have receptors on their surface known as antigens. this is how the white blood cell identifies them as "foreign".
70
Pathogens
they reproduce quickly and produce toxins
71
Phagocytes
they engulf pathogens and digest them making them harmless.
72
Lymphocytes
they produce antibodies in response to foreign antigens. the antibodies attach to the antigens and destroy them. they can also produce antitoxins which cancel out the effect of the pathogen's toxins.
73
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 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.
74
What i herd immunity?
vaccinating a large proportion of the population against a certain pathogen (e.g. flu vaccine). this is to reduce the number of people getting the disease and avoids an outbreak.
75
What are monoclonal antibodies?
monoclonal antibodies are antibodies that are produced from a single clone of cells, consisting of identical antibody molecules.
The antibodies are specific to one binding site on one protein antigen and so are able to target a specific chemical or specific cells in the body.
76
How are monoclonal antibodies formed?
1) lymphocytes make specific antibodies but do not divide.
2) tumour cells that do not make antibodies but divide
these are both combined.
they form a hybridoma cell (makes specific antibodies and divides) next the cells are cloned. the monoclonal antibodies are separated, purified, and can be used.
77
Monoclonal antibody facts to remember
B lymphocytes can produce the specific antibody but cannot divide. tumour cells can divide rapidly but cannot produce antibodies.
78
Monoclonal antibodies procedure.
1) inject the specific antigen into mice or rats
2) The rats own B lymphocytes (e.g. from the spleen) start to produce specific antibodies.
3) The B lymphocytes are then removed from the animal.
4) these lymphocytes are fused with tumour cells called myeloma cells.
5) The resulting hybridoma cell can divide rapidly and produce the specific antibody.
6) These purified monoclonal antibodies are collected and used in a number of ways.
79
Use of monoclonal antibodies
Pregnancy tests
diagnosis of disease
measuring and monitoring (e.g. measuring the levels of hormones or other chemicals in the blood). or to detect the presence of pathogens.
Research-to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye
80
Origins of certain drugs
Digitalis
Aspirin
Penicillin
The hear drug digitalis orginates from foxgloves
The painkiller aspirin originates from willow
Penicillin was discovered by Alexander Fleming from the penicillium mold
81
Drugs need to be tested to ensure...
They are safe
Do not have any toxic side effects
The correct dosage is given
They are stable-can be taken under normal conditions and be stored safely.
82
Stages of drug trials
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Pre-clinical trials
Clinical trials
Phase 1
Phase 2
Double blind trial
Phase 3
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83
Pre-clinical trials
This is where the drugs are tested on cells, tissues and live animals. E.g. mice. This is to ensure there are no unwanted side effects
84
Clinical trials
This is where the drug is tested on humans There are 3 stages
85
Phase 1
Drug is tested on health volunteers low doses are used
86
Phase 2
Drug is tested on people who actually have the disease e.g. a patient
87
Double blind trial
Some patients are given the actual drug, some are given a placebo. Neither the patient nor the doctors know who has been given the drug or the placebo. This is to remove bias. At the end of the trial the scientists from the drug company can compare data.
88
Phase 3
Larger numbers of patients are used. Patients are given the drug or the placebo. This is to verify the efficacy of the drug and determine the correct dose.
89
Respiration equation
Glucose+oxygen-->carbon dioxide + water (energy)
| C6H12O6 6O2. 6CO2. 6H2O
90
Respiration
Exothermic equation as it gives us energy
Takes place in the mitochondria of the cell
Mitochondria have 2 membranes, Inner and Outer
Inner membrane is highly folded to give a large surface area for the reactions of respiration to take place
Liver cells and muscle cells have large numbers of mitochondria due to their energy demands
91
Why do organisms need energy
Movement
Warmth
Chemical reactions
92
2 types of respiration and their differences
Aerobic (requires oxygen)
| Anaerobic (produces lactic acid)
93
Anaerobic respiration differs how in terms of energy release?
Anaerobic respiration lacks oxygen. Usually when oxygen is available, glucose molecules will be completely broken down to form 38ATP energy. When there is a lack, only around 2 ATP will be released.
94
Problems with lactic acid
Lactic acid builds up an oxygen debt that must be re-paid. This means that Anaerobic respiration is only sustainable for a short amount of time as it causes cramps and fatigue.
95
How to calculate the mean number of organisms in a field
Total area of field/area of qua-drat= mean # of organisms
96
Competition in animals and plants
Animals: territory, food, mating
Plants: sunlight, nutrients, water, space
97
Homeostasis
Homeostasis:is how the body regulates the internal conditions to keep a constant internal environment. It controls Temperature, water levels and blood glucose concentration.
98
Nervous system
Nervous system responds to changes in our environment known as stimuli
99
What is the nervous system divided into?
It is divided into the CNS (Central nervous system) which consists of the brain and the spinal cord, and into the PNS (Peripheral Nervous System) consisting of all other nerves.
100
How does the the nervous system transmit messages?
The nervous system transmits messages as electrical impulses which travel along nerve cells known as neurones.
101
3 Types of neurone
Sensory neurone
Relay neurone
Motor neurone
102
Path of an electrical impulse (conscience action)
Receptor(organ that detects the stimuli)---> sensory neurone---> CNS (Brain/spinal cord)---> relay neurone---> motor neurone--> effector (muscle/gland)---> response (--->=electrical impulse)
103
Reflex actions
Reflex actions are unconscious reactions. These actions are: Fast, Automatic, Protective Responses=(FAP Responses). They do not involve the conscious part of our brain.
104
Pathway of an electrical impulse (reflex action)
Receptor--->Sensory Neurone--->Spinal Cord--->relay neurone---> motor neurone--->effector--->response
105
Examples of reflex actions
Iris reflex: prevents too much light entering eye
| Pulling hand away from very hot plate
106
What is a synapses?
A synapses is a gap between 2 neurones
107
How do electrical impulses travel along neurones?
* Electrical impulse reaches the end of a neurone
* this stimulates the release of neurotransmitter chemicals
* the chemicals diffuse across the synapses
* they bind to receptors on the next neurone
* this generates a new impulse, same message, that can travel along the neurone which can then proceed along the next neurone.
108
The Brain
Cerebral Cortex:controls memory, intelligence, language and consciousness.
Cerebellum: Co-ordination of muscular activity
Medulla: Unconscious activity e.g. heart beating, breathing, etc.
