Unit 4 Flashcards
(86 cards)
1
Q
Role of PCR in DNA profiling?
A
Only small amounts of DNA can be collected so must amplify and make copies for there to be enough for gel electrophoresis.
2
Q
Explain how DNA profiling could show that these two lemurs originated from the lemurs on Madagascar?
A
- Use gel electrophoresis, take DNA from both lemeurs
- Find similar band pattern between the two indicating they have genetic similarities
- Base sequencing shows similar sequences
3
Q
Lemurs are endemic to Madagascar. There are many different species of lemur, all of which evolved from one common ancestor. This common ancestor is thought to be a primate that was carried across the sea from mainland Africa on a raft of vegetation. The diet of Sifakas is mostly seeds but also includes fruits, flowers and some types of leave. The diet of Indri is mainly leaves. Explain the types of speciation that have taken place is the evolution of Sifakas and Indri in this region of Madagascar.
A
- Allopatric speciation- the common ancestor of Lemur arrived to Madagascard but were geographically isolated, separating into two species
- Sympatric speciation- the common ancestor arrived however groups developed different food preferences and adaptations causing them to evolve into two different species, causing for instance Sifakas and Indri to live in the same habitat but have different diets.
4
Q
What do small error bars show?
A
Data points are closer so more precise and consistent measurement
5
Q
Evaluate the use of body temp of a corpse to estimate time of death?
A
- Body temp is readily available and easy to measure
- Many formulae and a calibration curve is available so scientists can work backwards and calculate time of death
-However body temp is influenced by many factors like ambient temp which could make estimated inaccurate e.g- (ambient temp) in cold environment body cools down faster in hotter environment body cools down slower - Hence using temp alone isnt always reliable better to use with something else like rigor mortis
6
Q
What is amylose produced by?
A
Plants (amylose is a component of starch, starch plants)
7
Q
Describe how the carbon present in sugars in the plant is returned to the atmosphere in the carbon cycle?
A
- Plants use some of their own sugar for energy via respiration emitting out CO2 back into the air
- Animals eat the plant, respire out CO2
- When plants/animals die, microbes decompose them and they also respire out CO2
8
Q
Climate change
A
Fluctuations in mean temperature and rainfall patterns
9
Q
Explain how the products of the light-independent reactions become NPP below the ground
A
- Light independent reaction produces glucose
- Glucose is needed to make sucrose and amino acids
- These are transported through the phloem to the roots
- When it reaches it makes biomass contributing to NPP
10
Q
How does sucrose and amino acids contribute to biomass
A
- Starch: Can convert into starch and make cellulose in cell walls and other carbohydrates- biomass
- Amino acids: can synthesise proteins for growth- biomass
11
Q
Why a combination of antibiotics has to be given for several months?
A
- Combination: different bacteria get resistant to different antibiotics
- Several months: ensures bacteria are exposed to drugs for long enough time to be killed
12
Q
A patient was given immunosuppressive drugs.
Immunosuppressive drugs weaken the immune system. Some of these drugs work by preventing DNA synthesis in the patient. As a result of the immunosuppressive drug treatment, the infection with Mycobacterium developed faster.
Explain why the infection with Mycobacterium developed faster when the patient was taking immunosuppressive drugs?
A
- If there’s no DNA synthesis, cells can’t divide by mitosis
- There’s no clinical expansion of T and B cells hence there’s not enough of them
- There’s less killer T cells so then can’t identify the infected host cell
- No B cells so they can secrete antibodies- no opsonisation
- So macrophages can’t eliminate the mycobacteria
13
Q
What is opsonisation and how does it help in the immune response in specific and non specific
A
- Opsonisation is the process where opsonin proteins bind to pathogens, marking them for destruction.
- In the non-specific response, this helps phagocytes like macrophages recognize and engulf the pathogen.
- In the specific response, antibodies (a type of opsonin) produced by plasma cells bind to antigens, enhancing phagocytosis.
14
Q
What happens when macrophages detect a pathogen
A
- Macrophages detect pathogen thanks to opsonisation and surrounds and engulfs pathogen bringing it into phagosome
- Phagosome fuses with lysosomes which contains digestive enzymes breaking down pathogen into small bits
- After breaking down pathogen, macrophage presents small pieces of pathogen (antigen) onto its surface
- T helper cell recognises cells and the T cells are activated
- T cells activate B cells
15
Q
Plastics are carbon-based polymers made from repeating monomers.
Many plastics do not break down naturally and their disposal is causing a lot of
damage to the environment.
Plastics have been around for about 70 years.
Scientists think that microorganisms could evolve the ability to break down plastics to obtain nutrients.
Explain why scientists think that plastics could be broken down by microorganisms.
A
- Microorganisms are already involved in the carbon cycle / decomposition
- Because they produce enzymes for decomposition/ will be able to produce enzymes for break down of plastics
- Mutation occurs that results in the breakdown plastics
16
Q
Explain how microorganisms could evolve to break down plastics.
A
- Mutation occurs resulting in an enzyme that break down plastics
- Presence of plastics/lack of food acts as selection pressure
- These genes are passes onto next generation
17
Q
Condensation reaction
A
Joins 2 molecules together to form a larger molecule and water is removed
18
Q
Hydrolysis reaction
A
Breaks down larger molecules into smaller molecules, water is added to break bonds
19
Q
Explain why the width of tree rings produced in cooler months would be different from the width of tree rings produced in hotter months.
A
- During cooler months tree rings are narrower because mean temperatures are cooler
- The RUBISCO enzyme is working slower
- Photosynthesis is slower
- Less biomass would be produced
20
Q
A decrease in the area covered by rainforest results in both a decrease in biodiversity and a decrease in populations.
Explain why a decrease in the area covered by rainforest reduces both biodiversity and populations within the rainforest.
A
- Biodiversity could decrease as species become extinct due to loss of habitat or a decrease in food
- Biodiversity could decrease due to a decrease in genetic diversity within a species due to a loss of habitat or less food
- Populations could decrease as organisms of one species die as there’s not enough food/habitat/camouflage
21
Q
Whats to role of viral proteins?
A
It carries the genetic code for viral proteins like RNA polymerase
22
Q
A moth was seen and a specimen collected in 1887. It was not seen again in the rainforests of Malaysia until 2017.
The DNA of these recently rediscovered Oriental blue clearwings was compared with the DNA of the moth collected in 1887.
Describe how this comparison could be made.
A
- Amplify the DNA of both species using a PCR
- Use gel electrophoresis by applying agarose gel, apply a current, make wells, use of dye and a restriction enzyme
- Compare the DNA bands of the two moths
23
Q
Whats the role of glycoproteins
A
The allow the virus to bind to the receptor on the host cell
24
Q
The enzyme RNA polymerase is involved in RNA transcription. Explain why the structure of the Ebola virus includes RNA polymerase.
A
To make viral RNA because host cells dont have this enzyme
25
What is a virus assembly
A virus assembly is the process where newly made viral components (e.g- genetic material and proteins) come together to form a complete virus particle in a infected cell
26
How do interferons inhibit viral replication?
1) Stimulates production of protein kinase: interferons activate protein kinase an enzyme that blocks ribosomes, so it slows down the production of them
2) Destroys viral RNA: Some interferon activated proteins break down virus RNA- can’t make more copies
3) Kill infected cells: if a cell is to infected, interferons can make it self destruct to prevent it spreading
4) Helps immune system find infected cells: When interferons are released they increase the number of MHC l molecules which alert killer T cells which come and destroy the infected cell
27
What colour does chlorophyll a and b absorb and reflect?
- Chlorophyll a absorbs mostly blue (430nm) and red (665-680nm) and reflects green so it appears green
- Chlorophyll b is the same but not as high
28
What colours does carotenoids absorb and reflect?
- Aborbs light in blue and green (450-490nm) and reflects orange, yellow so appears reddish
29
What is a plant had both pigments what would it look like
Brown
30
Describe how GALP, produced in chloroplasts, is converted into protein.
1) GALP is converted to glucose
2) Amino acids are more from glucose and nitrates: Glucose provides carbon skeletons for amino acids and nitrates are absorbed from the soil and make amino acids
3) Amino acids are joined by peptide bonds through condensation reactions to form proteins
4) Glucose is also respired to produce ATP, which is used in protein synthesis: Some of the glucose made from GALP is broken down in cellular respiration to produce ATP
31
What antigens are present to T helper cells and T killer cells
1) Macrophages present antigens to T helper cells
2) Infected body/host cell present antigen to T killer cell
32
What does optical density do?
How much light doesn’t go through a sample
33
Suggest why using optical density to measure the concentration of microorganisms is more accurate at lower concentrations of cells.
1) More cells present, there is more reflection of light from the cells: At high concentrations, the cells block a large portion of the light, which can lead to inaccurate readings.
2) Some light is reflected away from the detector: When there are many cells, some of the light that is scattered by the cells is reflected away from the detector, leading to a lower reading of the optical density than the actual concentration of cells.
3) Some light is reflected towards the detector:
However, in a sample with fewer cells, the scattered light is more likely to be directed towards the detector, giving a more accurate reading because the light scattering is more predictable at lower concentrations.
34
Where does light independent and dependent happen?
Dependent: Thylakoid membrane
Independent: Stroma
35
Action spectrum
Shows how the rate of photosynthesis changes with diff wavelengths of light
36
Absorption spectrum
Shows how much light a pigment absorbs at diff wavelengths of light
37
Where should temp of a dead. Body be taken
Rectum or liver
38
How does body cool in cooler environment
- A body cools much faster in a colder environment
- This is because there’s a greater difference between the surrounding temperature and the body temperature
39
Explain why using body stiffness only, is insufficient to estimate the time since death accurately.
- Because temperature and other factors e.g- exercise, body shape, body fat… affects rigor mortis (gets stiff for different amounts of time depending on temperature)
- Because deceiving whether its stiff or not is subjective
- If body is stiff time of death can only be estimate from 3-36 hours
- If body is not stuff we dont know if threats before 3 hours or after
40
How does temperature affect rigor mortis
High temp:
- Theres a faster start and shorter duration of rigor mortis
- Enzyme activity increases at higher temperatures, which accelerates the biochemical processes leading to rigor mortis.
Cold temp:
- Slower start and longer duration of rigor mortis
- Muscle rigidity can last longer because the lower temperature slows down the metabolic and enzymatic processes responsible for muscle breakdown
41
Where in chloroplast is glucose bonds made
Stroma
42
Explain why amino acids cannot be produced from glucose alone.
Because dlucose doest have nitrogen which is needed to synthesis amino acids. Glucose has only C H O nitrogen is obtained from mineral ions nitrates in soil
43
Explain how attaching the gene for TNF to the viral gene results in TNF being displayed on the outside of the capsid.
- When the gene is attached to the virus the virus reads the gene and transcribes into mRNA
- The mRNA is then translated into the TNF protein which is fused and encoporated into the capsid of the virus
44
Tumour necrosis factor (TNF) is a protein that can be released by several types of cell. It plays an important part in the immune response.
This protein binds to specific receptors on the surface of cell membranes stimulating chemical reactions inside the cell. As a result, a number of responses may occur that include inflammation and the stimulation of phagocytosis
by macrophages.
Antibodies to TNF are used to treat rheumatoid arthritis. Explain why antibodies to TNF are used in the treatment of rheumatoid arthritis?
- Antibodies bind to TNF preventing TNF binding to receptors on cell membranes
- Inflammatory response not triggered
45
Tumour necrosis factor (TNF) is a protein that can be released by several types of cell. It plays an important part in the immune response.
This protein binds to specific receptors on the surface of cell membranes stimulating chemical reactions inside the cell. As a result, a number of responses may occur that include inflammation and the stimulation of phagocytosis
by macrophages.
Antibodies to TNF are used to treat rheumatoid arthritis. Patients being treated with antibodies to TNF are more susceptible to tuberculosis (TB), which can be fatal.
Explain why patients being treated with antibodies to TNF can die from TB.
- Antibodies to TNF enhance phagocytosis so responses stimulated by TNF like phagocytosis and inflammation wont occur
- Without phagocytosis mycobacterium which causes TB wont be engulfed or destroyed
- Antigens wont be present on cell by macrophages for T helper cells
- Primary response wont happen, T cells wont release cytokines, stimulate b cells, form plasma cells, produce antibodies
- Without antibodies agglutination and opsonisation wont occur
- Bacteria spreads to lungs destroying gas exchange surface so person wont get sufficient oxygen and bacteria spreads to other organs
- No inflammation, no increased blood flow to area so no WBC and antibodies
46
Some viruses that infect bacteria cause the production of molecules called holins.
Holins form protein channels in the cell membranes of bacteria. This allows polar molecules called lysins to reach the cell wall by facilitated diffusion. Explain how the primary structure and the tertiary structure of holins determine the properties of these channel proteins.
- A primary structure is chain of amino acids and the order determines the tertiary structure
- These determine bonds
- Because they allow polar molecules through the amino acids w polar R group faces into Chanel and non polar faces outwards
47
Lysins break down the cell wall of bacteria.
Explain the role of lysins in the lytic cycle.
- Lysins break bond between peptidoglycan molecules
- So virus leaves bacteria cell wall
48
Explain what will happen if a person with blood type A is given a transfusion of blood type AB.
- If blood type AB is given to A the B antigen is detected as foreign
- Causes humoral immune response, macrophage engulfs and becomes APC
- T cell with complementary receptors bind and divides
- B cells are active by cytokines
- The differentiate into plasma cells making antibodies
- Causes agglutination and cell lysis
49
Both the molecules on the membranes of the cells lining our intestines and the antigens on red blood cells have sugars attached to protein molecules.
Bacteria living in our intestines secrete an enzyme that separates the sugars from the protein molecules.
Suggest why bacteria living in our intestines secrete this enzyme.
Because they can absorb this sugar and use this in respiration to produce ATP
50
Characteristics of inflammation
- Swelling
- Redness
- Pain
- Temp rise
51
Why does temp rise during inflammation
- Warmth speeds up chemical reactions/division/phagocytosis rising rate of enzyme activity
52
Difference between bactericidal and bacteriostatic
- Bactericidal: It kills the bacteria
- Bacteriostatic: It stops the bacteria from multiplying
53
How does vaccine result. In active immunity?
- When you are given a vaccine it contains some of a inactive pathogen
- Macrohpage engulfs and displays the antigen on its surface
- Macrophage presents antigen to T helper cells
- T cell activates B cells and T killer cells by T cells releasing cytokines giving signal for b cell to divide and differentiate into plasma cells and memory b cells
- T/B memory cells produces
54
The more people in a population who are vaccinated against a disease, the less likely it is for non-vaccinated people to become infected.
Suggest why vaccination is more successful when a greater proportion of people are vaccinated.
- Because when more individuals are vaccinated its less likely for the disease to spread as individuals are vaccinated so can’t get the disease
- Herd immunity- when enough people are immune to a disease so it can’t spread easily protecting people who aren’t immune
55
Photosynthesis consists of the light-dependent reactions and the light-independent reactions.
In the light-dependent reactions, light energy is converted into energy stored in ATP.
Explain why light energy is converted into energy stored in ATP.
- ATP converts GP —> GALP
- ATP is a source of energy for plants/all living organisms
- Light energy can’t be used directly
56
Simple sugars have the formula CnH2nOn.
Name the inorganic molecule from which each element in a simple sugar originated.
C
H
O
C- Carbon dioxide
H- Water
O- Carbon dioxide
57
Explain why the use of an enzyme to cut the DNA results in fragments, of different lengths, that can be separated by gel electrophoresis.
- Enzyme identifies specific base sequences called recognition sites
- Recognition sites are evenly space out
- Enzyme hydrolyses phosphodiester bond
- Different sized fragments more diff distances
58
Circular DNA moves at a faster rate through the gel than linear DNA.
Give two examples of circular DNA found in cells.
- Plasmids
- Bacterial chromosomes
- Mitochondrial DNA
59
Give two differences between the structure of circular DNA and that of linear DNA, other than their shapes.
- Linear DNA (3’ to 5’) end, circular doesn’t
- Linear has more association with histone proteins than circular
- Linear has a phosphate group
- Linear has one less phosphodiester bond
60
61
Compare and contrast the structure between the thylakoid membrane and the cell membrane?
Similarities:
- They both have a phospholipid bilateral
Differences:
- Thylakoid membrane has chlorophyll/PSII/PSI but cell membrane doesn’t
- Thylakoid membrane has a ATP synthase channel but cell membrane doesn’t
- Thylakoid membrane has a electron protein embedded but cell membrane doesn’t
62
Whats different about replication of chloroplast?
Replication of chloroplast is independent of mitosis/cell cycle meaning they can replicate their DNA anytime not just during the cell cycle or mitosis
63
What viruses have an envelope
- Ebola virus
- HIV virus
- Rabies virus
64
What are the structure of the:
- Ebola virus
- HIV virus
- Lambda phage
- Tobacco mosaic virus
- Ebola virus- Helical structure
- HIV- Polyhedral structure
- Lambda phage- Complex capsid structure
- Tobacco mosaic virus- Helical structure
65
Which of these viruses are DNA and which are RNA?
- Ebola virus
- HIV virus
- Lambda phage
- Tobacco mosaic virus
- Ebola: RNA
- HIV virus: RNA
- lambda phage: DNA
- Tobacco mosaic virus: RNA
66
A person was bitten by a lemur.
This person did not receive any treatment for rabies until 18 days after being bitten.
Explain why doctors were worried that this person had left it too long for the treatment to be successful.
- Because during 18 days new viruses are produced
- The virus bursts out of the host cell and infects others
- It takes time for immune system to be stimulated
- Person may be ill before immune system is stimulated
67
What type of artificial immunity occurs when:
- Antibodies are injected into the person
- B cells differentiate into plasma cells
- Memory cells are formed
Types of artificial immunity:
- Both active and passive
- Active only
- Passive only
- Neither active nor passive
- Antibodies are injected into the person: passive only
- B cells differentiate into plasma cells: Active only
- Memory cells are formed: Active only
68
Explain why both T helper cells and T killer cells are needed in the immune response to a virus?
- T helper cells stimulate B cells to divide
- Because antibodies will be needed for opsonisation
- T helper cells stimulate T killer cells to divide
- Because T killer cells destroy virus infected cells
- So that virus can be engulfed by macrophages
69
How cab core samples of trees determines how old a tree is?
- Because it shows the gaps between the rings
- The larger the ring the charter its been there because each year a new ring grows
- Thickness of ring changes each year as its affected by weather conditions
- Rings in different samples can line up ring pattern
- Only count a ring once if it overlaps in terms of dates
70
How can the growth of a tree be calculated?
- Measure the height of a tree
- Divide by number of rings
71
Describe how a 1 in 2 dilution plating method would have been carried out to achieve the dilution in this well.
- Adding equal volumes of anti microbial substance and broth together
- Repeat using diluted solution form the previous steps
72
An investigation tested eight antimicrobial substances on one type of bacteria, E. coli using a MIC assay (rows and column). Explain why an antimicrobial substance that affects E. coli only was included in this assay (row H).
- To see if the culture is contaminated or contains other bacteria
- Because it wouldn’t kill growth of the other bacteria
- To check that the E. coli has not changed resistance so it still is affected to the antimicrobial substance (no mutation)
73
An investigation tested eight antimicrobial substances on one type of bacteria, E. coli using a MIC assay (rows and column). Explain why there was one column that had no antimicrobial substance added to it (column 12).
- It shows that E.coli is still viable and it can row and replicate
- If there is no growth you wouldn’t know is it was dead or the antimicrobial killed it
74
Suggest why different concentrations of chlorophyll were obtained using two different solvents.
- Chlorophyll have different solubility in different convents, maybe chlorophyll dissolves better in some than others
- The chlorophyll has different structures which affects how they will dissolve
- Solvent must break through membrane to reach chlorophyll
75
Why do some graph points have both a horizontal and a vertical error bars plotted with it
They were mean values
76
Whats the term biomass
Amount of organic matter in a organism
77
Suggest why the scientists studied the distribution of biomass in groups of organisms and not the number of individual organisms.
- because there are so many of each and it would be too time consuming
- There are different sized organisms
78
Why’s it good to have a high carbon store and low decomposition rate?
- More carbon retained in the ecosystem (soil, plants, trees) so less CO2 released so less global warming
- Low decomposition so less CO2 released so less global warming
79
What are some aseptic techniques which can be carried out
- Bunsen burner- creates a updraft to move microorganisms in the air away so they dont fall into the culture
- Disinfect work area
- Sterilise equipment
- Wash hands
- Close doors and windows
80
Name the enzyme, found in some types of virus, that can synthesise DNA from an RNA template.
Reverse transcriptase
81
Human cells contain several types of DNA polymerase. One type of DNA polymerase, found in some cancer cells, has been shown to synthesise DNA from an RNA template.
Suggest why this DNA polymerase may be a target for drugs used to
treat cancer.
- Normally we synthesise DNA from DNA however some cancer cells synthesise DNA from RNA using the reverse transcriptase.
- If we made a drug preventing the enzyme from functioning, cancer cells will be affected but human cells wont as they dont have it
82
If you had mud in a cup the bottom was from 2700 years ago and the top was present day and there was different pollen grain A B C, A was closes to the bottom the B then C explain the distribution on these.
- The type of pollen disposed shows which plants grew at different times based on different conditions
- Type A first appeared as conditions were suitable for F back them and it lasted long so maybe F could withstand different conditions and had little competition
- Conditions changed as B and C gré as the conditions potentially favoured them
- A may of disappeared as they found it hard to survive in that climate or there was more competition for light and space
83
Describe the information that had to be collected by scientists before a drug could be approved.
- if it causes side effects
- if it actually does what it says it does
- An effective dose of the drug
- Best method to administer drug
- How long to administer drug
84
Reforestation is one way to repair the damage caused to forests by climate change.
Explain why the changes to the environment caused by climate change need to be considered when selecting the species of trees to use in reforestation.
Change to consider:
1) Temperature: As climate change leads to warmer temp trees have to be selected so they are suitable for the mew conditions due to enzymes etc
2) Drought: It’s important to choose trees that are drought resistant so they dont dehydrate and die
3) Needs of animals: It’s important to choose trees that provide suitable habitats and food for animals as it can lead to loss of biodiversity
4) Native trees: Some of the previous native trees may not be adapted for the new conditions so must not be grown again
85
Describe how GALP, produced in the leaves, becomes incorporated into biomass
in the roots.
- GALP is converted into glucose
- Glucose and fructose make sucrose
- Sucrose and amino acids move to roots in phloem
- Glucose/sucrose/amino acids make organic molecules
- e.g calcium ions for formation of calcium p-e tâte in cell walls
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