B1-B6 Flashcards
(168 cards)
1
Q
Why can a body cell not grow into an embryo?
A
- body cells lost ability to differentiate as many genes are already switched off
- only embroynic cells are totipotent
2
Q
Why does a runner need to keep breathing quickly after a run?
A
- used anaerobic respiration as couldn’t get enough oxygen
- caused lactic acid to build up
- thus she needs extra oxygen to remove the oxygen debt by breaking down the glucose and remove the lactic acid
3
Q
How can DNA mutations lead to cancer?
A
- mutations to DNA effects the base sequence of DNA
- bases may be added,deleted or changed
- changes the amino acid sequence so they are read differently
- amino acids determine how protein folds thus different shaped proteins produced
- this means that proteins such as enzymes can’t catalyse reactions any more
- changes in enzymes (e.g active site), can cause harmful changes to call processes
4
Q
How does DNA replication occur?
A
- DNA unzips through the enzyme DNA helicase
- then DNA polymerase adds free complementary nucleotides to the exposed bases on both strands (A - T and C-G)
- strands now twist into a double helix
5
Q
Describe the steps of mitosis
A
- nuclear membrane breaks
- chromosomes lines up in centre and pulled apart by spindle fibres
- nuclear membrane forms
6
Q
What is the point of sieve plates in plants?
A
- found in phloem
- allow movement on sucrose
7
Q
How do our eyes dilate?
A
- pupils dilate when radial muscles contact
- allows more light into the eye
- this is a reflex action
8
Q
What part of a kidney tubule is affected by ADH?
A
- increases permeability of kidney walls
- thus collecting ducts
9
Q
What is the cerebrum in charge of?
A
- controls motor function, movement and conscious activities
10
Q
Why is adrenaline applied to wounds?
A
- reduces blood flow to the skin
- causes vasoconstriction in the skin
- less blood is lost
11
Q
Where is progesterone made?
A
- corpus lutuem
12
Q
Why is photosynthesis important in the rate of transpiration?
A
- photosynthesis happens in the guard cells not epidermal cells, thus sugars are found in the guard cells (less sugar)
- epidermal cells have higher w.p than guard cells and allows water to move into guard cells by osmosis
- more turgid = open stomata due to thicker inner cell wall
- opening of stomata affects the transpiration rate
13
Q
Why is the rate of reaction very slow at 20 degrees?
A
- particles have less kinetic energy
- particles move slower
- less frequent collisions
14
Q
How can you check colour change more accurately?
A
- with a colorimeter
- get same person to judge the colour change
15
Q
Why is using a gas syringe more accurate?
A
- more accurate as otherwise the bubbles might be diff sizes or chance of missing it
- instead gas syringe collects the total volume of gas
16
Q
Why is calculating percentage change useful with osmosis practicals?
A
- you can still compare even if the sizes are different shapes
17
Q
What is the purpose of the cell membrane?
A
- it controls what leaves and enters the cell
- has receptor molecules that allow cells to communicate
18
Q
What is the purpose of the vacuole?
A
- it contains cell sap - a solution of salt and sugar
- it keeps the cell rigid and upright
19
Q
What is the purpose of the cell wall?
A
- it is made of cellulose
- it supports the cell and keeps the cell walls rigid
20
Q
Why do we use stains?
A
- it creates contrast to help us see subcellular structures
21
Q
Why is a higher magnification bad?
A
- makes it harder to focus
- harder to see the whole organism
22
Q
How is DNA arranged?
A
- arranged in chromosomes and divided into genes
23
Q
Describe enzyme-substrate complexes:
A
- enzymes are biological catalysts
- they are specific to a reaction - speed up reactions
- never used up
- bind at the active site to form E-S complexes
- products are released by the enzyme
24
Q
How do you test for non-reducing sugars?
e.g. sucrose
A
- add dilute HCl at 75 degrees C in a water bath
- add sodium- hydrogen carbonate
- add benedict’s reagent
- if blue = no sugar but red = yes
25
How do you test for proteins?
- Biuret test:
- add NaOH
- add CuSO4
- If blue = no protein but purple = yes
26
What's the symbol for lactic acid?
2(C3H6O3)
27
How is starch broken down?
- broken down by carbohydrase in animals
| - broken down by amylase in plants
28
How is H2O2 broken down?
- by catalyse
| - found in potatoes
29
Why does photosynthesis allow organisms to do?
- increase their biomass
| - allows respiration as it releases oxygen
30
What are the advantages of being a multi called organism?
- can grow larger
| - can have specialised organs and tissues
31
What is a cardiac muscle?
- no nerve impulse is needed from the brain for the heart to contract
32
What are valves used for in the heart?
- prevents back flow from the atrium to the ventricle
| - stops oxygenated and deoxygenated blood from mixing
33
How are fat cells specialised?
- can expand to x1000
- store fat
- small nucleus
- small cytoplasm
34
Why are adult stem cells useful?
- can differentiate into some cells and can repair damage such as reverse paralysis or cure arthritis
- pluripotent
35
How are the lungs adapted to exchange?
- constant ventilation and good blood supply = higher cont gradient
- alveoli have a spherical shape = high SA
- thin walls = shorter distance for diffusion
- moist lining for dissolving gasses
36
What are the adaptions of plant exchange surfaces?
- broad leaves for high SA
- thin = less distance
- intercellular spaces for gas exchange
- lower leaves with stomata for CO2 and O2 change and water to escape in transpiration
- root hair cells = high SA to get H20 and mineral ions
37
What are the advantages of a double circulatory system?
- diffusion occurs quickly
- blood pumped at high Pa = more oxygen to cells a
- this maintains the body temp
38
Where does the body send blood to?
- organs and tissue
- body and brain
- except for the lungs, O2 diffuses out and CO2 diffuses into the blood
39
What are the features of arteries?
- oxygenated blood
- blood away from the heart at high Pa
- small lumen
- thick elastic muscular walls that contract and expand (pulse)
- collagen allows it not to burst under high Pa
40
What are the features of capillaries?
- exchange between blood and tissues/cells
- small lumen
- 1 cell thick = shorter distance = higher diffusion
- medium Pa
- semi-permeable wall allows it to supply O2 and diffuses out CO2
41
What type of muscle is the heart?
- myogenic muscle
- contracts without receiving nerve impulses from the brain
- thus needs lots of mitochondria
42
Where are vascular bundles found in leaves?
- form networks to support tissue
43
What are the features of xylem?
- made from dead cells = no lignin
- transport h2o and mineral ions
- lignin supports the outside
44
Where are sugars made from photosynthesis used?
- used in meristems to make new cells
- roots to store tissue
- is an energy store
45
How is water lost through stomata in the transpiration stream?
- in light = photosynthesis happens
- thus in the light, photosynthesis makes sugars in the guard cells
- guard cells have a low w.p
- epidermal cells (next to the guard cells) have a high w.p as no sugars are made there (as they have no chloroplasts)
- thus water moves into the guard cells by osmosis = turgor pressure = inner wall thicks and stomata 'opens'
- water moves out of leaves into the air due to steep cont gradient
- BUT in dark = less water loss as less sugar in G cells = high w.p and water moves out into the epidermal cells = flaccid and 'close' the stomata
46
What are the advantages of the transpiration stream?
- keeps plants cool
- allows plants to keep turgor pressure and stay rigid and stop wilting
- water for photosynthesis
- mineral ions also taken into the plant from the soil along with h20
47
What do eukaryotic cells have that prokaryotic don't?
- eukaryotic cells have mitochondria but prokaryotic cells don't have mitochondria
- they get energy other ways
48
What happens when you enter a dimly-lit room vs a very brightly-lit room?
- dimly lit = pupils dilate = circular muscles relax and radial muscles contract
- brightly lit = pupils constrict = circular muscles contract and radial muscles relax
49
What is the function of the brain?
- the brain processes all information by receptor cells about the internal and external changes in the environment and hormones to make a coordinated response
50
What are CT scans?
- X-rays of the inside of the brain are compared for odd behaviour
- disadvantages = risk of cancer and can't see the brain
- advantages = can see 3D structures and need no surgery (thus less chance of infection and damage)
51
What is negative feedback?
- type of control mechanism in homeostasis
52
How does the cycle of the menstrual cycle begin again?
- if pregnant = high progesterone levels, thus uterus lining maintained and high progesterone inhibits FSH and LH
- if not pregnant = low progesterone levels and thus uterus lining sheds (menstruation) and low progesterone stimulates the production of FSH and LH
53
How does the kidney absorb necessary molecules from the blood?
Ultrafiltration:
- blood enters the kidney through the renal artery leading to the glomerulus
- high Pa due to narrow blood vessels leads small molecules to pass out of glomerulus to the Bowman's Capsule
- larger molecules remain in the blood
Selective Reabsorption:
- filtrate passes through the kidney tubule
- glucose, salts and water absorbed
- passes through Loop of Henle and collecting ducts
- extra water and salts are reabsorbed and waste is sent to the bladder for excretion
54
What is the cerebrum, cerebellum and medulla in charge of?
Cerebrum:
- consciousness, intelligence, memory, language
Cerebellum:
- balance, muscle coordination
Medulla:
- unconscious activities (breathing, the beating of the heart)
55
What is oxygen debt?
- the amount of oxygen needed if all the energy
| released was from aerobic respiration (1)
56
What chemical is released in the body after an organism starts respiring anaerobically?
- lactic acid
- produced during exercise (because of anaerobic
respiration) and removed after exercise / when
resting (1)
57
Who would produce more urine? Someone, who drank isotonic drinks after (Sanchez) a run or someone who drank just water after a run (Leroy)?
- Leroy produces more urine
- as this dilutes his blood more than Sanchez’s
- high water level is detected by the hypothalamus
- less ADH released from the pituitary gland
- decreases the permeability of the nephron/kidney
- less water reabsorbed (in kidney tubules)
- produces urine that is more dilute
58
How could it be tested if the spring is behaving elastically with only one mass?
- remove mass
| - check if it's still the same - has it deformed?
59
How can lower frequency waves be made with a spring?
- add masses
| - use spring with smaller spring constant
60
What are the reasons for higher anomalous results for spring oscillations in 10 seconds?
- timed too many oscillations
| - misread stopwatch
61
What is the minimum number of atoms in a molecule?
- 2, because you cannot have a molecule with only one atom, as this is an atom.
62
Why is foil used on a test tube in a photosynthesis experiment?
- foil doesn't allow light through
| - this causes the rate of photosynthesis to be 0
63
What happens to the CO2 concentration in someone's blood if their rate of respiration increases?
- concentration in blood increases
| - as CO2 is a product of respiration
64
Where are the glomerulus and Bowman's Capsule found?
- glomerulus- renal cortex
| - Bowman's Capsule - renal cortex
65
Where are the Loop of Henle and collecting ducts found?
- Loop of Henle - renal cortex, dips into the medulla, then renal cortex again
- collecting ducts - medulla
66
Describe hormonal methods of contraception:
- progesterone + oestrogen pill = o inhibits FSH and thickens cervical mucus and thins uterus lining so egg can't implant and prevents ovulation
- patch/ injection/ implant release o and p
- IUD = releases progesterone
67
Describe non-hormonal methods of contraception:
- IUS = kills sperms through a copper coil
- diaphragm = covers cervix (only works with spermicide)
- condom = barrier (prevents against STIs)
68
Resolution is...
- measure of the smallest object using an instrument
| - resolution is the ability to distinguish two objects from each other.
69
Give two advantages and disadvantages of CT scans?
Advantages:
No surgical operation is required –- so reduced risk of infection / brain damage.
Allows 3D structures to be seen – enabling accurate identification of abnormalities.
Other acceptable suggestions with explanation.
Disadvantages:
Requires use of several X-rays – which have the potential to cause cancer.
Only still images produced – cannot see brain functioning, so cannot always link problem
to source.
70
What is negative feedback?
- detecting a change
| - reversing that change
71
What causes red-green colourblindness?
- genetics
| - missing cones
72
Why might a scientist publish his work?
- to inform other scientists (who might be
working on the topic)
- to see if other scientists can replicate the
work/ to have it peer-reviewed
- to allow recognition for their work✓
73
How do you add an air bubble to a capillary tube?
- lift the end of the capillary tube out of the (beaker) of
water
- after a short time / when some air has gone in, put it back into the water
74
What happens when a cell doesn't have enzymes or a cell wall?
- cannot digest food
- cannot release energy
- cannot carry out any other
- named vital cell process
- cell cannot grow
- cell cannot reproduce
75
What effect does blocking ADH have?
- blocking ADH makes the kidney tubule less
permeable/less water reabsorbed
- blocking ADH increases the volume of water lost
from the body/present in urine/urine becomes
more dilute
- blood concentration is increased / water potential
lowered / water would move out of cell/water will
not move into cells
- eventually, blood and cells are isotonic/same
concentration/same water potential/same sodium
ion concentration
76
What is tRNA?
- tRNA is a carrier molecule for amino acids / tRNA/carrier molecule brings (correct) amino acids into
place / tRNA reads the triplets on the mRNA
77
What is our cerebellum in charge of?
- coordinate voluntary muscle movements
| - maintain posture, balance, and equilibrium
78
What is oxygen debt?
- quantity of oxygen required to break down lactic acid in anaerobic respiration
79
Where are mitochondria involved in making enzymes?
- provide energy for translation in ribosomes
80
What is the function of carbohydrates?
- energy for the body
| - fat oxidation
81
What are the two types of lipids?
- fats and oils
82
What is a gene?
- Section of DNA that codes for a characteristic
83
Difference between animal and plant stem cells:
· Animal stem cells usually differentiate at the early stages of their life
· Stem cells in adult animals are mainly used for replacement or repair
· Plant cells differentiate throughout their life cycle
· Plant stem cells are grouped together in structures called meristems
84
What is the medulla oblongata in charge of?
- automatic actions such as heart and breathing rate
85
What is the cerebrum in charge of?
- complex behaviour such as memory, language and personality
86
What components of the blood transport what molecules?
```
Molecules carried
Oxygen/haemoglobin ( by red blood cell)
Carbon dioxide (by plasma/rbc)
Glucose/amino acids (plasma)
Hormones (plasma)
urea (plasma)
water (plasma)
Antibodies (plasma)
```
87
What is the role of the carbon cycle?
- maintain the flow of nutrients and habitats
88
Why happens when water evaporates and condenses?
- forms water droplets which help to make clouds
89
Why is not all of the energy of the sun transferred to the biomass of the plant?
- only 10% is converted to body tissue by consumers
- light availability, temperature and light reflected means that half of the energy is taken away
- rest of it adds to biomass
90
How is energy lost by the consumers?
- excretion - urine
- egestion - not all of it is digested such as waste faeces
- respiration - movement and transferred into the surroundings as thermal energy
- not all of the organism eaten - bones or roots
91
How does the temperature of an area affect the organisms in an area?
- Temperature affects enzymes that control metabolic reactions
- Plants develop more
rapidly in warmer temperatures (as their metabolism will be faster), as do cold-blooded
animals (ectotherms)
- Warm-blooded animals (endotherms) are less affected by their
external temperature
92
How are plants involved in the carbon cycle?
- take in carbon dioxide in photosynthesis
- give out carbon dioxide in respiration / when decay
- pass on carbohydrates / proteins / fats to animals / when eaten
93
What is the structure of a virus?
- protein coat / protein outer layer
| - (containing) genetic material
94
What is a variation?
- difference within a species
95
What is a parasite?
- lives on / off / in a host / living organism
| - causing it harm
96
How does smoking increase the risk of cancer?
- substances burnt increases the chances of mutation of the DNA sequence
97
What do start codons do?
- triggers transcription
| - in the non - coding section of DNA
98
Describe the history of genetics?
- Mendel - characteristics passed on from parents, by genes, Recessive and dom
- Meischer - Nuclien = acidic substances in nucleus (DNA)
- Avery - bacteria passed on disease-causing genes from one to another
- Chargaff - same no. of C-G and A-T
- Franklin and Wilkins - photographed DNA crystals
- Watson and Crick - discovered double helix shape of DNA
- 1953 to 2000 = genetic engineering and genetic diseases
- 2003 = genome project
- now = gene therapy
99
How do mutations occur?
- alters the base
| - inherited or spontaneous
100
How do plants produce seeds?
- pollen (male) fuses with the egg cell in the ovule
101
How does meiosis occur?
- DNA unzips, free nucleotides join, replicates
- homologous chromosomes pair together, crossed and genes swapped
- pair lines up in the centre and splits = 2 diploid cells
- 2nd div = line up and split as each arm pulled = 4 haploid gametes
- genetically varied
102
Where does meiosis occur?
- in gonads (testes or ovaries) = 23 from male and 23 from females
103
How did Darwin's theory lead to The Theory of Evolution?
- travelled to the Galapagos Islands
- noticed that different islands had different finches
- birds were closely related, but their beaks and claws had different shapes and size
- observations = realised that the design of the finches’ beaks was linked to the food available on each island
- concluded= bird born with a beak more suited to the food available would survive longer than a bird whose beak was less suited.
- Therefore, it would have more offspring, passing on its characteristic beak.
- Over time the finch population on that island would all share this characteristic
- Darwin called this process natural selection
104
What is classification?
- sorting organisms into groups with similar features depending on their similarities and differences
105
What is the reason for using bacteria to produce hormones?
- bacteria reproduce rapidly
| - can quickly produce many bacteria containing the new gene
106
How is malaria caused?
malaria is caused by protist, and mosquitos at as vectors and they pick it up when they feed on infected animals, every time mosquito feeds = infects by inserting protists to animal’s blood vessels = malaria can cause repeating episodes of fever and can be fatal
107
How do wbc eat microorganisms?
- phagocytes have a flexible membrane and have lots of enzymes
- enables them to engulf foreign cells and digest them-
- phagocytosis
108
How do wbc produce antibodies?
- done by B-lymphocytes
- every invading pathogen has unique antigens on its surface
- wbc comes across foreign antigen = produce proteins called antibodies to lock onto the invading cells
- antibodies are specific to that type of antigen
- antibodies are produced rapidly and carried around the body to lock on to similar pathogens
- antibodies help the phagocytes find pathogens so they can engulf them
- some wbc are called memory cells - stay around in the blood after pathogen is gone so if the person is infected with the same pathogen again = the white blood cells rapidly produce the antibodies to destroy it - naturally immune to that pathogen
109
What are monoclonal antibodies?
- produced from lots of clones of a single white blood cell = identical and will only target one specific protein antigen
- produced in the lab by using hybridomas (fusion of lymphocyte and tumour cell)
110
How are monoclonal antibodies produced?
- genetically modified mice injected with chosen antigen
- body produces antibodies to specific antigen (using lymphocytes)
- lymphocytes collected and fused with myeloma cells to make hybridoma (can’t survive out of body)
- myeloma cells reproduce indefinitely
- as hybridoma cells reproduce = form clones
- each clone will produce required antibody which is harvested = monoclonal antibodies
111
How do vaccinations work?
- they involve injecting dead, inactive or weakened pathogens into the body
- they carry antigens so even though they are harmless, they still trigger an immune response
- the wbc (lymphocytes) produce antibodies to attack them
- some of theses wbc remain in the blood as memory cells so if live pathogens of the same type ever appear, the antibiotics help destroy them will be produced immediately before symptoms show = immunity
112
What are drugs?
- substances which alter the way the body works (some medically used - penicillin and some dangerous if misused)
- this is why some can’t be bought over the counter and only on prescription
113
What are antibiotics?
- drugs that kill bacteria without killing your own body cells (diff types for each range of bacteria)
- many produced naturally by fungi or other microbes (penicillin = mould)
- grown at large scale and useful for clearing up bacterial infections but don’t kill viruses (not all microbes are harmful)
- some bacteria are naturally resistant to antibiotics so misuse has increased the rate of development of resistant strains and MRSA is the best-known antibiotic resistant strain
114
What are antivirals?
- drugs that destroy viruses (specific so act on 1 type of virus) and most stop them from reproducing
- might kill virus by = blocking virus from entering host cell, prevent virus from releasing its genetic material and prevent virus from inserting its genetic material in to host DNA
- difficult to produce as virus use the host cell to replicate so hard to target virus without damaging cells
115
What are antiseptics?
- chemicals that destroy microorganisms or stop them from growing and don’t harm human tissue (alcohol and iodine) = diff antiseptics for diff microorganisms
- used in external living surface (to kill/ neutralise any type of pathogen) to help clean wounds and surfaces (prevent infection rather than treat it) and kills pathogens on non-living surfaces =disinfectant (household products)
- used in hospitals and surgeries to try to prevent the spread of infections like MRSA
116
What happens after a potential drug is identified?
- drugs are developed further by preclinical tests in the lab to see how it behaves
- preclinical tests = test on live cells, bacteria and tissue culture
- but you can’t use human tissue to test drugs that affect whole/ multiple body systems
- e.g testing drug for blood pressure must be done with a whole animal (one with intact circulatory system)
- many fail as this stage as may damage cells or not work
117
What happens after clinical trials?
- Animal testing =must pass with 2 species before human trials (some think it’s cruel and others think it’s the safest way)
- 3 Rs principal:
- reduction = use a small number of animals present
- refinement = improve experiments to avoid unnecessary suffering and improve animal care
- replacement = replace animals with other techniques (e.g cell cultures)
118
What are the two groups of people testing drugs?
- one is given new drug and other is given a placebo (substance that looks like the real drug but doesn’t do anything)
- this is done so scientists can see actual difference the drug makes, allowing the placebo effect
- they are double blind trials so the patient and scientist/ doctor don’t know if they’re getting the drug or the placebo until the all the results have been gathered
- this is so doctors monitoring the patients and analysing the results aren’t subconsciously influenced by their knowledge
- to allow for the placebo effect in patients (where people start to feel better just because they expect the treatment to work even though the treatment isn’t doing anything)
119
What are the chemical defences of plants?
- produce antimicrobial chemicals or kill pathogens/ inhibit their growth (antibacterial chemicals)
- antimicrobials are chemicals that act against microbes
- produce saponins (destroys cell membrane of fungi/other pathogens)
120
What are the 2 lab techniques to find pathogens of plant diseases?
DNA analysis (PCR)
- all living things have a unique genome
- use DNA fingerprinting to identify the pathogen we have based on the DNA present
- parts of the DNA complementary to the pathogen are used as primers (template) and any dna that matches is copied over and over again and if the pathogen is present lots of its dna will be made and it will show up on images
- match the bands from bottom up for known viruses and unknown pathogens
Antigen identification (ELISA test)
- antigens are unique molecules on cell’s surface and can be detected using antibodies (proteins that bind to specific antigen)
- antigens from pathogen = present if infected by it
- in ELISA = antibodies for the pathogen’s antigens are used as they have enzymes on them which react with substrate = colour change
- antibodies are added to sample tested and watched, but if bind to antigen, stay in sample so colour change when substrate is added = antigen (and so the pathogen) is present
121
What are the chemicals produced by plants and what do they do?
- citronella: insect repellents
- pine resin: insect repellents
- phenols: disrupts cell wall - anti bad compounds
- defensins: disrupts cell membrane - anti bac compounds
- pyrethrins: insecticide
- caffeine: toxic to fungi or insecticides - antifungal compounds
- chitinases: breaks down fungal call wall - antifungal compounds
122
How can you stop the spread of diseases in plants?
- biological control
- chemical control
- crop-rotation
- destroy infected plants
- no contact between infected and not infected plants
123
How can bacteria be spread?
- E. coli in unpasteurised milk
- Salmonella in unwashed vegetables
- Campylobacter in raw meat
124
What is a virus?
- attacks cells and replicates itself inside oranism
- burst and releases virus
- very small - 1/100th of a bac
- not cells
125
What is a fungi?
single celled
- made of hypahe
- can penetrate skin or plant surface and cause diseases
- can produce spores to other animals and plants
126
Describe HPV?
- virus transmitted bodily fluids and sexually
- no symptoms mostly and clears in a few months
- BUT can cause cell changes resulting in certain types of cancer (thus cervical)
127
Describe HIV?
- enters lymph nodes and attack immune cells
| - reproduces inside wbc and it can't prevent infections and cancers
128
What are the adaptations of white blood cells?
- lymphocytes have a large nucleus to make antibodies
- phagocytes have a flexible loped nucleus so that they can move around and engulf germs
- both flexible so they can change their shape to pass out of capillaries
129
How does plant piece affect decomposition rates?
- large size
- low SA to volume ratio
- fewer microorganisms as they reproduce slower and so respire slower
130
Why is decomposition important for ecosystems?
- idea of recycling in nature
- named example of a recycled substance e.g.
carbon/nitrogen
- example of reason why the recycling is important e.g. for photosynthesis/production of proteins in plants
131
What is an antibody?
- protein molecule made by the immune system
| - destroys/kills pathogens / clumps them together / attaches to antigens
132
How does more mRNA mean more protein?
- mRNA carries the code for proteins
| - more protein will be made
133
What is an antibiotic?
```
a chemical (usually) made by fungi / microbes (1)
that kills (other) microbes / kills bacteria (1)
```
134
What elements do all proteins contain?
- C
- O
- N
- H
135
What type of characteristics would we genetic engineering plants to have?
- drought resistance
- disease resistance
- pest resistance
- herbicide resistance
- insect resistant
136
How can fertilisers help plants make proteins?
- plants make proteins using nitrogen from nitrates or nitrogen ions in fertilisers
137
What are the disadvantages of hydroponics?
- lots of fertilisers needed
- cost of setting up is high
- diseases can spread very quickly and cause major damage
138
What does a flushing agent do?
- used to help the blood sample flow from one end of the stick to the other through the paper strip
139
How do antigen tests work?
- antibodies complementary to the pathogen antigens are stuck to the point of the line
- if disease = pathogen antigens get bound to dye-labelled antibodies flow through start to end of strip
- pathogen antibody binds to the antibodies stuck on the line of the strip
- dye-labelled antibodies at strip create a visible coloured line
140
Why is high amounts of salt bad?
- increases blood pressure
| - increases chance of heart disease and stroke
141
Why are stem cells used instead of foreign cells from donors?
- less chance of being rejected by the immune system as it has the same antigen
142
What virus can increase the chances of getting cervical cancer?
- HPV (not HIV)
143
Why are antibiotic-resistant markers used?
- to identify which bacteria have taken up the plasmid
144
Why did fossil fuel records show?
- a small change can result in larger changes
145
Why would minerals in the soil run out if there are no microorganisms in the soil?
- no microorganisms = no decomposers
| - no decay happens
146
How can fungal infections spread?
- spread through fungal spores through the wind
- enter leaves through the stomata
- but if burn plants = kills spores so no infection can spread
147
How are antibodies made?
- antigens are detected
| - triggers antibodies to be made by white blood cells
148
Why are placebos made?
- acts as a control
- can act as a comparison to check if the drug works
- identifying/eliminates any psychological effect
- placebo contains no active drug
149
What is a dominant allele?
- an allele is a form/version of a gene
- dominant means that it always expresses itself when
present
150
Why is informing people of their genetic disease good or bad?
- the person may decide not to have children
and therefore will not pass on the allele
- there is a wide range of ages that a person of a
certain age can first show symptoms
- it does not show how bad the symptoms are or
how long the person will live for
- some people would rather not know when, or if,
they are likely to become ill
- it’s useful to be aware and prepare for when
the first symptoms will show
- less useful/reliable/predictable test of when the
first symptoms will show with a lower number
of CAG repeats.
- less useful as there is no cure only limited
treatment for symptoms
151
Why will non-resistant alleles never die?
- Rr and Rr (heterozygous), would always make rr, a recessive allele, which may be not resistant
152
Why may people want to or not want to get tested for genetic diseases?
Ethical/moral/religious:
may or may not believe in testing
may or may not believe in terminations
may or may not be worried about discrimination against a
disabled child
may or may not believe there should be any interference in
nature (idea of playing God)
economic:
may or may not be able to afford care for child / treatment /
counselling (since medical services cost in some countries)
medical:
increased risk of miscarriage
risk to health of mother as a result of termination
risk to health of mother / fetus as a result of testing
false negative/positive test. Accuracy of the test.
plan for future medical treatment
circumstances:
may or may not have other healthy children to consider
may or may not have been trying for a baby for a long time
may or may not have had many miscarriages prior to this
baby
may or may not plan for the future
general:
can make decisions regarding termination
may, or may not, want to know whether the child has the
disease
couples will make different judgements about risks and
benefits of the test
idea that perception of risk is different to actual risk
the quality of life the child/parents will have
153
How can a gene determine the sex of a foetus?
- gene on Y chromosome forms testes
| - absences of gene on Y chromosome form ovaries
154
What is a fair test?
- control all variables except the ones tested
| - more confident in results
155
How are observation and prediction linked?
The observation increases the likelihood /
confidence in the prediction;
But does not necessarily prove it is correct;
156
How can a heart attack be caused?
What causes a heart attack:
- increased fatty deposits/blood clots/plaques/atheroma
- narrowing/blocking of arteries supplying the heart or coronary arteries
- less/no oxygen/glucose reaches the heart muscle
- cells in the heart die
Increased risk for Leo due to:
-poor diet / diet high in salt / diet high in fat/obesity
- stress
- smoking
- misuse of drugs
- less exercise
-high blood pressure
-drinking alcohol
- diabetes
157
What does sustainability mean?
meeting the needs of the people today (1)
| without damaging the Earth for future generations (1
158
Explain why the carbon cycle is or is not an enclosed system?
For -
Carbon not (shown) entering / leaving the system;
Energy is not (shown) entering or leaving the system;
Idea of recycled / no waste;
Against -
Fossil fuels lock carbon away for a long time;
Carbon entering the atmosphere faster than leaving it;
Fossil fuels used up faster than replaced;
Sunlight / energy entering or leaving system;
159
How would scientists use genetic engineering to modify bacteria to make insulin and identify the successful ones?
Gene from a human
- Isolate / remove / cut out gene
- Use of enzymes
- Replicate gene
- (Put gene into) vector / virus / plasmid
INSERTION into bacteria may include:
- (DNA) incorporated into bacteria
- Replication of bacteria
- (Bacteria start) producing insulin
```
SELECTING bacteria include:
Either with a fluorescent marker
- Production of gene probe
- Addition of probe to DNA
- Probe attaches to correct gene
- Probe fluoresces under UV
Or with antibiotic resistant gene
- Antibiotic resistant gene attached to insulin
- Both genes taken up by bacteria
- Bacteria treated with antibiotic
- Bacteria with resistant gene and insulin gene
survive / others do not
```
160
How does artificial cloning work for animals?
```
transfer nucleus from (adult) body cell into (unfertilised)
egg cell (1)
idea that egg cell is empty / had its own nucleus removed
```
161
How is nitrogen removed from an ecosystem?
rabbit/animal leaves/removed/migrates; (1)
(nitrogen compounds/soil) maybe washed away; (1)
(crop) plants/timber may be harvested/taken away; (1)
162
What causes cancer?
changes to DNA/genes
uncontrollable cell division/ rapidly dividing cells/ cell
divides many times by mitosis
creates a tumour
163
How would you genetically engineer mosquitos?
```
isolate the gene
replicate/copy the gene
use of a vector/plasmid
to insert the gene into (mosquito) cells
select the modified cells
```
164
How are antigens destroyed by our body?
(antigens trigger) white blood cells release antibodies /
antitoxins (1)
antibodies / antitoxins lock on to antigens (and destroy
them) (1)
white blood cells engulf antigens (1)
165
How does cloning occur?
nucleus removed from an egg cell/enucleated egg
(ignore DNA / genetic material)
nucleus from the udder / body cell is inserted into the
egg cell
BUT
egg cell nucleus replaced with the nucleus from an
udder / body cell (covers the first 2 indicative scientific
points)
(allow a correct example of a named body cell, ignore
unqualified cell eg adult cell)
(egg cell) given an electric shock to make it divide /
multiply (ignore just grow)
embryo /Dolly is genetically identical to / a clone of the
sheep from which the udder/body cell came from
or udder/body cell taken from the sheep they want to
clone
166
Genetic engineering meaning:
- a process which involves modifying the genome of an organism to introduce desirable characteristics
167
What is a chromosome?
Strand of DNA containing genes
168
What are the indicator species for pollution?
Unpolluted - mayfly larvae
Low pollution - freshwater Shrimp
High pollution - water louse
Very high pollution - sludge worm
