1
Q
communicable diseases
A
- caused by pathogens: bacteria, viruses, protoctista and fungi
- pathogens cause harm through directly damaging tissue or through the release of toxins
2
Q
tuberculosis
A
- bacterial disease
- can infect humans, deer, cows, pigs and badgers
- transmitted through airborne droplets and more prevalent where people live im cramped conditions
- causes harm by damaging lung tissue and suppressing immune system
- cured using antibiotics and prevented through vaccination
3
Q
ring rot
A
- bacterial disease
- infects potatoes, tomatoes and aubergines
- damages leaves, tubers and fruit
- transmitted through infected tubers and micropropagation of plantlets from infected plants
- reduces crop of the plant and affects livelihood of farmers
4
Q
viruses
A
- non-living and aceullular
- smaller than bacteria
- consist of genetic material (DNA or RNA), a capsid (layer of protein surrounding genetic material) and attachment proteins
- viral replication occurs inside host cells and involves injection of nucleic acid into cell
- e.g. bacteriophage- virus that affects bacteria
5
Q
HIV/AIDS
A
- viral disease
- transported around in blood until it attaches to protein on T helper cells
- HIV positive is when person infected with HIV
- AIDS is when replicating viruses in T helper cells interfere with normal functioning of immune sustem
- with T helper cells being destroyed by virus, host is unable to produce and adequate immune response to other pathogens and is left vulnerable to infections and cancer
- HIV transmitted through direct contact through sharing/mixing of bodily fluids
6
Q
influenza
A
- viral disease
- infect the ciliated cells lining gas exchange surfaces
- young chilren, the elderly and anyone with a lowered immune system are at a higher risk of having severe symptoms or dying
- transmitted by airborne droplets when coughing and sneezing
7
Q
tobacco mosaic virus
A
- viral disease
- infects plants, mainly tobacco plants
- causes damage to leaves, resulting in mosaic pattern on them
- damages flowers and fruits
- damage prevents plant from growing
- transmitted when infected leaves touch healthy leaves or gardener’s use contaminated tools
- no cure, but resistant strains have been developed
8
Q
protoctista
A
- eukaryotes that exist as single-celled organisms or cells grouped into colonies
- very few are pathogenic, but the few that are cause extremely dangerous symptoms to hosts they infect
- pathogenic protoctista are parasites and are transmitted via a vector
9
Q
malaria
A
- protoctista diseases
- caused by Plasmodium and is spread to humans through mosquitoes
- reproduces both sexually and asexually, within mosquitoes and within human hosts
- passed from mosquitoes to humans when mosquitoes bite and take blood from humans
- in humans, infects red blood, liver and brain
- some preventative medicines but no vaccine or cure
10
Q
potato blight
A
- protoctista disease
- caused by fungus-like protoctista
- causes potato blight and tomato late blight
- has hyphae which enter plant and cause damage to leaves and fruit
- transmitted by spores which travel on wind or are transferred by animals and insects from one plant to another
- no cure, resistant strains have been developed
11
Q
fungi
A
- eukaryotes that cause many plant diseases
- can be either multicellular or single-celled
- pathogenic fungi are parasitic, releasing enzymes to digest host’s tissue (animals or plants)
12
Q
black sigatoka
A
- fungal disease
- infects bananas
- fungal hyphae cause damage to leaves, causing them to turn black preventing plant growth
- transmitted by spores from one plant to next through wind
- fungicides can kill fungus, and resistant strains have been developed
13
Q
athlete’s foot
A
- fungal disease
- only affects humans
- a type of ring worm that thrives in warm, damp regions between the toes
- causes skin to crack and to become scaly, causing itchiness and soreness
- transmitted by direct contact, e.g. wearing the same socks or shoes as an infected person
- cured using antifungal creams
14
Q
living conditions that make transmission more likely
A
- hot climates- increased heat provides more kinetic energy for chemical reactions and reproduction
- social factors (poverty/developing countries)- could result in poorer sewage infrastructure, a lack of fresh water and food, poorer sanitation and overcrowded living quarters. Medicines and vaccines being less readily available to prevent the spread
15
Q
2 modes of transmission
A
- direct
- indirect
16
Q
3 examples of direct transmission in animals
A
- direct contact- touching, kissing, contact with cuts in skin and sexual contact
- inoculation- animal bites, sharing needles and cuts in skin
- ingestion- drinking and eating contaminated water and food
17
Q
3 examples of indirect transmission in animals
A
- vectors- usually animals that pass the pathogen to humans, such as mosquitoes transmitting malaria
- droplets- pathogens transmitted in droplets of water, e.g. saliva and mucus expelled when sneezing
- fomites- dirty bedding, socks, and cosmetics are examples of inanimate objects that can carry and transmit pathogens
18
Q
example of direct transmission in plants
A
- direct contact- between different plants, e.g. ring rot, TMV, black sigatoka & blights
19
Q
2 examples of indirect transmission
A
- contaminated soil- pathogens and their spores can remain in the soil and infect the roots of subsequent plants
- vectors- wind, water, animals and humans can all carry pathogens and spores from one plant to another
20
Q
plant responses
A
- barriers to prvent entry, such as bark or waxy cuticles
- antibacterial chemicals and proteins as a defence against bacterial infections. Can repel insects (vectors) and kill pathogens
- physical defences to prevent pathogens from spreading between their cells, such as producing callose
21
Q
animal responses
A
- have primary and secondary line of defence against pathogens
- primary line of defence is non-specific
- secondary line of defence is a specific response to antigens
22
Q
primary defences in animals
A
- skin is a physical barrier and contains skin flora (healthy microorganisms), which outcompete pathogens for space and resources on the skin
- blood clots will form if the skin is cut to form a new barrier
- mucous membranes line many body tracts. The mucus produced traps pathogens and the cilia sweep the mucus away from the lungs
- lysozymes are hydrolytic enzymes which digest pathogens
- expulsive reflexes, such as sneezing, coughing and vomiting, are mechanisms to force pathogens out of the body
- inflammation occurs in localised areas where damage to cells is detected. It causes the area to become red, hot, sore, itchy and swollen. When cells are damaged, this triggers mast cells to release histamines and cytokines
- histamines cause blood vessels to dilate and therefore more blood is flowing in this area. The increased temeperature from blood can kill pathogens. Histamines also make the walls of blood vessels more permeable so more white blood cells can be delivered to the site of damage
- cytokines attract phagocytes, which can engulf and destroy pathogens
23
Q
phagocytosis
A
- phagocytes (macrophages and neutrophils) travel in the blood and squeeze out of capillaries to engulf and digest pathogens
- non-specific response
24
Q
process of phagocytosis
A
- damaged cells and pathogens release cell-signalling chemicals (cytokines) that attract the phagocytes to the site of infection
- an opsonin protein can attach to pathogens to mark them and make it easier for neutrophils and macrophages to engulf them
- phagocytes have receptors which can attach onto chemicals on the surface of pathogens
- tha phagocyte then engulfs the pathogen into a vesicle to create a phagosome
- withing the phagocytes, there are lysosomes whcih contain hydrolytic lysozyme
- the lysosome fuses with the phagosome to expose the pathogen to the lysozyme. The lysozyme hydrolyses the pathogen and any soluble useful molecules are abosrobed into the cytoplasm of the phagocyte
- the phagocytes will present the antigen of the digested pathogen on their surface- they are then called antigen-presenting cells
25
2 types of lymphocytes involved in second line of defence
- B lymphocytes (B cells)
- T lymphocytes (T cells)
- both are created by bone marrow stem cells, but B cells mature in bone marrow whereas T cells mature in thymus
26
cell-mediated response (T-cells)
- receptors on T cells bind to antigens on antigen-presenting cells (APCs)
- causes T cell to divide rapidly by mitosis (clonal expansion)
- APCs are cells that present a non-self antigen on their surface
27
examples of antigen-presenting cells
- infected body cells- presenting viral antigens on their surface
- macrophage- engulfed and destroyed a pathogen presenting the antigens on their surface
- cells of a transplanted organ- different shaped antigens on their surface compared to your self-cell antigens
- cancer cells- abnormal-shaped self-antigens
28
process of cell-mediated response
1. once a pathogen has been engulfed and destroyed by a phagocyte, the antigens are positioned on cell surface- this is now called an APC
2. T helper cells have receptors on their surface which can attach to antigens on APC
3. once attached, interleukins are produced which activates T helper cells to divide by mitosis to replicate and make large number of clones
4. cloned T helper cells differentiate into different cells:
- T helper cells and produce interleukins to activate B lymphocytes
- some produce interleukins to stimulate macrophages to perform more phagocytosis
- T memory cells for that shaped antigen
- T killer cells (cytotoxic T cells)
- T regulator cells which suppress immune response to ensure cell-mediated response only occurs when pathogens are detected
29
T killer cells
* destroy abnormal or infected cells
* release a protein, perforin, which embeds in the cell surface membrane and makes a pore (a hole) so that any substances can enter or leave the cell and this causes cell death
* most common in viral infections because viruses infect body cells. Body cells are sacrificed to prevent viral replication
30
humoral response (B cells)
- T helper cells stimulate B cells by producing interleukins
- this initiates the humoral response, which involves antibodies
31
antibodies
- globular, quaternary proteins that have binding sites complementary in shape to antigens
- made up of 4 polypeptide chains, 2 heavy polypeptide chains and 2 ligh polypeptide chains
- binding site is variable region, where antibody binds to a complementary-shaped antigen
- rest of antibody is constant region
- when an antigen binds to an antibody it is described as an antigen-antibody complex
- the hinge region of the antibody gives it flexibility when binding to mutliple pathogens
32
3 ways antibodies work in the humoral response
- agglutination
- marking pathogens
- acting as anti-toxins
33
agglutination
the clumping together of pathogens to make it easier for phagocytes to locate and engulf them
34
marking pathogens
* act as an opsonin when an antibody-antigen complex has been formed
* the antibodies are marking the antigen making them more susceptible to phagocytosis
35
acting as anti-toxins
antibodies can bind to toxins, preventing them from entering cells and causing harm
36
humoral response process
- activated T helper cells bind to B cells with complementary antibody to antigen- clonal selection
- this B cell is activated by the release of interleukins from the T helper cell
- the B cells rapidly divide by mitosis to make clones which differentiate into either memory B cells or plasma cells- clonal expansion
- the plasma cells produce antibodies which attach to the antigens on the pathogen to help destroy them by agglutination and marking them for phagocytes
- this is the primary immune response ( the first time the body has encountered this pathogen/antigen)
- the B memory cells remain in the blood after infection and can rapidly produce large amounts of antibodies if there is reinfection with the same pathogen
37
primary immune response
- first exposure to a pathogen
- it can take a few days for the lymphocytes to create enough of the complementary antibodies to help destroy the pathogen, therefore you suffer from symptoms before pathogen is destroyed
38
secondary immune response
- when you are re-infected with the same pathogen
- B memory cells can help produce large amounts of antibodies rapidly, so pathogen is destroyed before causing any symptoms
- active immunity
39
passive immunity
- antibodies are introduced into body
- pathogen doesn't enter body, so plasma cells and memory cells are not made
- no long-term immunity
40
example of natural passive immunity
antibodies passed to a foetus through the placenta or through breast milk to a baby
41
example of artificial passive immunity
transfusion or injection of antibodies as part of medical treatment of a disease, e.g. hepatitis B
42
active immunity
immunity is created by your own immune system following exposure to the pathogen or its antigen
43
example of natural active immunity
following infection by a pathogen
44
example of artificial active immunity
following the introduction of a weakened version of the pathogen or antigens via a vaccine
45
cell recognition
- cells are labelled with proteins to allow recognition
- to prevent your lymphocytes from destroying your own body cells, each of your body cells is labelled a unique shape protein that your lymphocytes recognise as 'self' cells
- any other type of protein detected on the surface of a cell is recognised as a 'non-self' and is destroyed
46
antigen
- a protein molecule on the cell-surface of a membrane of non-self cells
- the presence of antigens triggers an immune response and the production of antibodies
47
autoimmune diseases
* your immune system identifies your own body cells as non-self and therefore potentially harmful
* the body recognises antigens on some body cells/tissues as non-self and produces antibodies against these antigens
* the cells are then attacked and damaged, causing the symptoms of the disease
* sometimes the immune system responds abnormally to healthy 'good' microorganisms within the body or overreacts to mild pathogens
* other times, the T regulator cells do not work properly, so the immune response isn't regulated
48
# example of an autoimmune disease
rheumatoid arthritis
* the immune system attacks the cartilage in joints
* this can cause inflammation and pain in the affected joints
* there is no cure but anti-inflammatory drugs, steroids, pain relief and immunosuppressant drugs can be taken to relieve the symptoms
49
disease prevention (immunisation)
- can induce passive or artificial active immunity
- passive immunity is when antibodies are injected directly into you to help destroy the pathogen
- artificial active immunity is when antigens or small amounts of an attenuated pathogen are injected or taken orally. These trigger a primary immune response but with a few symptoms. Therefore, if you are re-infected with the same pathogen you will rapidly produce antibodies as it is the secondary immune response. In this way, vaccines provide protection for individuals and populations against disease
50
vaccines
- not always effective in long term
- pathogens' genetic material can mutate, resulting in a pathogen producing a different shaped antigen
- this is antigen variability
- booster vaccines need to be taken
51
epidemic
when disease spreads rapildly on a national level
52
pandemic
disease spreads rapidly on global level
53
mass vaccination programmes
* prevent further spread of pathogen causing disease, vaccines frequently updated to account for antigen variability
* if large enough proportion of population are vaccinated, herd immunity arises
54
sources of medicine
- many medicines have been sources from microorganisms and plants
- therefore maintaining biodiversity is key
55
examples of sources of medicine
- microorganisms- many antibiotics including penicillin and vancomycin
- plants- aspirin (from willow bark), digitoxin (from foxglove) and quinine, an antimalarial drug (from cinchona tree)
56
importance of maintaining biodiversity
- many drugs have originated from plants and microbes
- by maintaining biodiversity, it increases the chances of finding more new drugs
- we need to make sure we maintain the genetic resource for the future
- many modern drugs have been made using knowledge of traditional remedies
- once a species is extinct, its genetics and potential medicines would be lost forever
57
antibiotic resistance
- due to random mutations that occur in bacterial genetic material
- a mutation could code for a new protein that provides the bacteria with a selective advantage
- the widespread use, and misuse, of antibiotics strengthened the selection pressure and results in antibiotic resistance spreading rapidly amongst bacteria
- the antibitotics will only kill the non-resistant bacterial in a host, which leaves the bacteria with the mutated resistance gene able to survive with no competition for resources
- the mutated gene for antibiotic resistance is found in the plasmid (loop of DNA) which can be exchanged between bacteria
- resistant bacteria can also reproduce rapidly until a resistant strain of bacteria has been created
58
personalised medicines
by analysing your DNA, it can be possible to identify drugs that individuals will respond better to
59
synthetic biology
* using cells as medicine factories
* combines gene sequencing, bioinformatics and computational biology to find out the base sequence of a protein, store the data digitally and make 3D models and simulations before physically producing a medicine in a laboratory
60
# c
species diversity
the number of different species and individuals within each species in a communty
61
species richness
the number of different species in a particular area at the particular time
62
species evenness
the relative abundance of each different species within the community
63
genetic diversity
the variety of genes amongst all the individuals in a population of one species
64
habitat diversity
the range of different habitats
65
measuring genetic diversity
- calculated by examining polymorphic genes within isolated populations, such as zoos (captive breeding), rare breeds and pedigree animals where selective breeding has be used
66
polymorphic gene
has more than on allele
67
genetic diversity equation
proportion of polymorphic gene loci= number of polymorphic gene loci / total number of loci
higher proportion of polymorphic gene loci, larger the genetic diversity within the population
68
simpson's index of diversity
D= 1- (Σ(n/N)^2)
values closer to 0 have lower biodiversity, closer to 1 have higher biodiversity
## Footnote
N- total number of organisms of all species
n- total number of organisms of a particular species
D- Simpson's diversity index
69
random sampling
- lay out 2 tape measures at right angles to each other to create a gridded area
- use a random number generator to generate 2 numbers to serve as coordinates on the grid
70
3 types of non-random sampling
* opportunistic
* stratified
* systematic
71
opportunistic sampling
- unlikely to result in a sample that accurately represents population
- involves sampling organisms which are conveniently available, therefore involves bias
72
stratified sampling
- some populations or habitats can be separated into groups to sample from (strata)
- e.g. a pond- surface, shallo, deep-water regions
- take random samples within each group
73
systematic sampling
- identifying different areas within a habitat to sample
- used when there is a change in the distribution of species within the habitat and you want to investigate impact of change on biodiversity
- often involves belt transect- place single tape measure along sample area, at regular set distance along tape measure place quadrat and record data
74
quadrats
- used to sample plants and slow-moving organisms
- point quadrat- horizontal bar with holes along it at set intervals that long pins can be placed through. The pin is pushed through to touch the ground and any species touching the pin are recorded
- frame quadrat- square frame of a known size, typicall 0.5m x 0.5m
75
3 different methods of using a quadrat
- density- count individuals present
- frequency- quick method, requires gridded frame with 100 squares- count how many squares species is present in, if present in 25/100 = 25%
- percentage cover- estimate percentage of entire quadrat covered with species, quick but subjective so lower accuracy
76
# sampling techniques for animals
sweeping nets
nets that can be used to capture insects with long grass
77
# sampling techniques for animals
pitfall traps
- hole is dug in the ground and a pot is placed within it
- small inveterbrates may crawl into the trap and will be unable to crawl out
- roof-like structure is placed on top to prevent the trap from filling with rainwater and investigators will return daily to collect results and release the animals
78
# sampling techniques for animals
pooters
- used to capture very small insects
- 2 tubes are connected to a closed pot
- investigator sucks on one tube and places other tube over insect
- creates suction and draws insect into pot
79
# sampling techniques for animals
tullgren funnel
- used to extract small organisms from within soil samples
- soil samples dried using heat lamp- causes animals to move in opposite direction (downwards) where a collecting dish is placed
80
# sampling techniques for animals
kick sampling
- used to sample organisms within river beds
- one investigator will gently kick river bed to distrub earth and organisms within it
- second investigator stands behind them with a net to capture any organisms that are released
81
factors affecting biodiversity
- increase in human population- increased need of space for housing, farming and industry (deforestation)
- increase in agriculture- to feed everyone, results in destruction of habitats, chemical pesticides or fertilisers added to land
- increase in climate change- increase in global temperatures is metling polar ice caps, sea levels rising (flooding), lower rainfall, xerophytes becoming dominant species in some areas as outcompeting other species
82
ecological reasons to maintain biodiversity
* agriculture reduces biodiversity as it removes natural habitats
* all organisms are interdependent on each other, loss of one species impacts all others
* removal of habitat removes food sources for many animals
83
economic reasons to maintain biodiversity
* deforestation can result in soil erosion and monocultures can result in soil becoming deficient in particular minerals that the crop absorbs a lot of
* both results in soil depletion and can negatively impact a country's ability to grow crops
* tourism often relies on people visiting areas of natural beauty and observing animals in their natural habitat- extinction of habitats, plants and animals could reduce tourism and impact economy
* many medicines have been based on chemicals naturally occuring in plants, so plant species going extinct could have potentially held the molecules needed to cure diseases in humans
84
aesthetic reasons to maintain biodiversity
* being in nature around animals and plants enriches people's lives and this is why people may choose to visit different environments like the rainforest and beaches
* nature is a creative inspiration for art, music and writers
* being amongst nature has been shown to improve people's mental health
85
# methods of maintaining biodiversity
In situ
| within the natural habitat
- as conservation happens with the habitat, genetic diversity is maintained as individuals are not bred captively
- another advantage is, because all organisms are interdependent, putting measures in place in situ to prevent the extinction of one species will have a positive impact on all other species dependent on it
- e.g. marine conservation zones- designated for wildlife to recover and repopulate (areas where fishing and tourism aren't allowed), wildlife reserves
86
# methods of maintaining biodiversity
Ex situ
| not within the natural habitat
* removing organisms from their natural habitat to try and protect them, usually used in addition to in situ measures
* e.g. botanical gardens, seed banks, captive breeding
87
# example of ex situ maintenance
seed banks
- like a store of genetic material
- seeds of variety of plants species are stored in water and temperature-controlled environments to keep them viable for longer
- stored as a backup for potential plant species that may go extinct
88
# example of ex situ maintenance
captive breeding programmes
* reproducing animals in zoos and aquariums
* aim is to increase number of endangered species, these individuals can then be reintroduced into the wild
89
# international and local conservation agreements
convention on international trade in endagered species (CITES)
- stared in 1973 with 145 countries signing up
- treaty that regulates international trade of endangered animals, plants and their products
- regulation of international trade requires cooperation and agreememnt between countries
- not always been successful as it drives price of banned substance up through illegal trading, e.g. ivory
90
# international and local conservation agreements
rio convention on biological diversity (CBD)
* began in 1992 when 172 nations met in Rio and came up with several agreements
* countries must come up with strategies for sustainable development
* to stabilise greenhouse gas emissions and concentrations within the atmosphere
* to prevent destruction of fertile land into desert and reduce effects of drought
* share access to scientific knowledge and technology
91
countryside stewardship scheme (CSS)
* specifically in UK
* setup to protect and enhance natural environment
biology
flashcards
Decks in class (14)
# Cards
-
Biological molecules key words54
-
Enzymes key words15
-
Nucleic acids key words23
-
Water & inorganic ions key words7
-
Cells key words34
-
Mitosis key words16
-
Cell membrane key words17
-
Genes and protein and the genetic code key words41
-
Meiosis key words11
-
Chapter 11 biodiversity flashcards18
-
chapter 10 classification and evolution flashcards1
-
Module 2 notes182
-
Module 3 notes84
-
Module 4 notes91
