Biology Paper One Flashcards
(167 cards)
1
Q
What’s the difference between prokaryotes and eukaryotes?
A
Eukaryotic Cells: Complex e.g animal/plant cells
Prokaryotic Cells: Simple and Smaller e.g bacteria
2
Q
Describe bacterial cells?
A
- They don’t have a true nucleus
- Contain small rings of DNA called plasmids
- Bacteria don’t have mitochondria
3
Q
What’s the equation for magnification?
A
image size ÷ real size
4
Q
How do you prepare a slide? Onions
A
- Add a drop of water to the middle
- Cut up an onion and separate it into layers. Use tweezers to peel off some epidermal tissue for the bottom.
- Using tweezers, place that tissue into the water.
- Add some iodine solution.
- Place a cover slip on top.
5
Q
What is meant by differentiation?
A
Differentiation: the process by which a cell changes to become specialised for its job.
6
Q
How are sperm cells specialised?
A
- It has a long tail and a streamlined head to help it swim
- There are lots of mitochondria to provide energy
- Carries enzymes to break down the eggs cell membrane
7
Q
How are nerve cells specialised?
A
- The cells are long (to cover more distance)
- Branched connections at their ends to connect to other nerve cells
8
Q
How are muscle cells specialised?
A
- Cells are long so they have space to contract
- Lots of mitochondria to generate the energy needed for contractions.
9
Q
How are root hair cells specialised?
A
- Large surface area for absorbing water and minerals from the soil
10
Q
How are phloem and xylem cells specialised?
A
- Cells are long and joined end-end
- Xylem cells are hollow
- Phloem cells have very few subcellular structures so things can flow through them
11
Q
Explain growth and mitosis?
A
- DNA doubles are forms an x-shaped chromosome.
- Chromosomes line up at the centre, the two duplicates go to opposite sides.
- Membranes form around each set and become the nucleus.
- The cytoplasm and membrane split.
- Two identical daughter cells are made.
12
Q
How do prokaryotic cells replicate?
A
Binary Fission
- The circular DNA and plasmids replicate.
- The cell gets bigger and the circular DNA strands move to opposite sides of the cell.
- The cytoplasm begins to divide and new cell walls begin to form.
- Cytoplasm divides and two daughter cells are produced.
13
Q
What is diffusion?
A
Diffusion: the spreading out of particles from an area of higher concentration to an area of low concentration.
14
Q
What is osmosis?
A
Osmosis: the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
15
Q
What is a catalyst?
A
A substance which increases the speed of a reaction without being changed or used up in the reaction.
Every enzyme has an active site that fits onto the substance involved in the reaction.
16
Q
What conditions do enzymes need?
A
- Generally 37 degrees, if they get too hot they denature.
- optimum pH level, normally pH of 7.
17
Q
How do you convert carbohydrates into simple sugars?
A
Starch →amylase enzyme→maltose
Amylase is made in: the salivary glands, the pancreas and small intestine.
18
Q
How do you convert proteins into amino acids?
A
Proteins→protease enzyme→amino acids
Proteases is made in: stomach, pancreas and small intestine.
19
Q
How do you convert lipids?
A
Lipid→lipase enzyme→Glycerol and Fatty Acids
Lipases are made in: the pancreas and small intestine.
20
Q
What is bile?
A
Bile: neutralises the stomach acid and emulsifies fats.
- Bile is produced in the liver and stored in the gall bladder.
- The hydrochloric acid makes it too acidic, bile is an alkaline so it neutralises it.
21
Q
What are the different types of pathogens?
A
Bacteria, viruses, protists and fungi
22
Q
What are viruses?
A
- They’re not cells
- The reproduce rapidly
- The live inside a host cell and use it to replicate
- The cell with then burst and release all the copies
- The cell damage makes you feel ill
23
Q
What are protists?
A
- They’re all eukaryotes, most of them are single-celled
- Some protists are parasites, they live in or on other organisms.
- They are often transferred to the organism by a vector
24
Q
What is fungi?
A
- Some fungi are single-celled
- Others have a body, which is made up of hyphae
- These can grow and penetrate human skin or the surface of plants
- The hyphae can produce spores
25
How can pathogens be spread?
Water
Air
Direct contact
26
What are measles?
- Spread by droplets
- Develops a red skin rash and fever
- Can be very serious, sometimes fatal
- Most people are vaccinated against it
27
What is HIV?
- A virus is spread by sexual contact or exchanging bodily fluids (sharing needles)
- Causes flu-like symptoms
- Attacks immune cells
- Damages the immune system
28
What is TMV?
Tobacco Mosaic Virus
- Virus that affects plants
- Causes a mosaic pattern on the leaves, becomes discoloured
- Reduces photosynthesis
29
What is Malaria?
`- Carried by a vector (mosquitoes)
- Causes repeating episodes of fever
- People can be protected by insecticides and mosquito nets.
30
What are 2 examples of bacterial diseases?
```
Salmonella:
- Causes food poisoning
- Symptoms are fever, cramps, vomiting and diarrhoea
- Toxins are released
Gonorrhoea:
- STD
- Pain when they urinate, yellow/green discharge
- Originally treated with antibiotics
```
31
What are some body defence systems?
- Skin is a barrier
- Hairs and mucus trap particles
- Trachea and bronchi secrete mucus and are lined with cilia.
- Stomach produces hydrochloric acid
32
What are the 3 lines of attack for pathogens?
1, Consuming them - WBC engulf and digest them (phagocytosis)
2. Producing Antibodies - The pathogens have antigens, the WBC recognise these as foreign and begin to produce antibodies to lock onto these. These then kill the pathogens.
3. Producing antitoxins - These counteract the toxins produced by bacteria.
33
What are the 3 main stages in drug testing?
1. Preclinical testing - drugs are tested on human cells and tissues.
2. Preclinical testing - tested on animals to see if the drugs are toxic and the dosage.
3. Clinical trial - it is firstly tested on healthy humans to make sure it has no harmful sound effects. Then they are testing on volunteers suffering from the illness. Tested with a group, some are given the drug and others are given a placebo.
34
What are monoclonal antibodies?
They are identical antibodies. Antibodies are produced by B-lymphocytes ( a type of WBC). They are produced from lots of clones of a single WBC. Tumour cells don't produce antibodies but they divide lots. You can fuse a B-lymphocyte with a tumour cell to create a cell called a hybridoma. These cells can be cloned.
35
How are monoclonal antibodies used in pregnancy tests?
If you're pregnant:
- The hormone binds to the antibodies on the blue beads.
- The urine moves up the stick, carrying the hormone and the beads.
- The beads and hormone bind to the antibodies on the strip.
- So the blue beads get stuck on the strip, making it blue.
If you're not pregnant:
- The urine still moves up the stick, carrying the blue beads.
- There's nothing to stick the blue beads onto so it doesn't go blue.
36
How can monoclonal antibodies be used to treat diseases?
1. Different cells in the body have different antigens on the surface, so you can make monoclonal antibodies that bind to specific cells.
2. Cancer cells have antigens on their cell membrane called tumour markers.
3. In the lab they make monoclonal antibodies that bind to the tumour markers.
4. An anti-cancer drug can be attached to these monoclonal antibodies.
5. These are given to the patient through a drip.
6. The antibodies target specific cells.
7. The drug only kills the cancer cells.
37
What is the equation for photosynthesis?
carbon dioxide + water → glucose + oxygen
38
How do plants use glucose?
1. Respiration
2. Making Cellulose
3. Making Amino Acids
4. Stored as oils or fats
5. Stored as Starch
39
What are limiting factors for photosynthesis?
- Light
- Carbon Dioxide
- Temperature
40
What is respiration?
Respiration: the process of transferring energy from glucose, which goes on in every cell.
41
What is meant by metabolism?
Metabolism: all the chemical reactions in an organism.
42
What is the equation for anaerobic respiration in plants and yeast?
Glucose → Ethanol + Carbon Dioxide
43
How can embryonic cells be used to cure diseases?
1) Make insulin-producing cells for people with diabetes
| 2) Nerve cells for people with paralysed by spinal injuries
44
What is the maximum temperature at which microorganisms in a school lab should be grown?
25 degrees
45
What are the 2 main differences between active transport and diffusion?
Diffusion: high concentration to low
Active transport: low concentration to high
Diffusion doesn't require energy, active transport does.
46
What does it mean when an enzyme has been denatured?
When the shape of the enzymes active site changes so it can't fit properly
47
What is the role of alveoli?
Carry out gas exchange
48
Why is the circulatory system is described as a 'double circulatory system'?
Two circuits are joined together.
First circuit: right ventricle pumps deoxygenated blood to the lungs to take in oxygen, the blood then returns to the heart.
Second circuit: left ventricle pumps oxygenated blood around all the organs in our body, the deoxygenated blood then returns to the heart.
49
What is the role of the vacuole?
Contains cell sap which helps maintain rigidity of the cell (only in plants)
50
Anaerobic respiration in humans?
Glucose --> lactic acid + CO2 and energy.
51
How small is a bacteria cell compared to a regular body one?
1/100th of the size.
52
Why does bacteria presence in your body make you feel ill?
They produce toxins that damage cells and tissue.
53
How large is a virus compared to a bacterium?
1/100th of the size (smaller).
54
How does a virus replicate?
It inserts its DNA into a cell and uses its machinery to create copies.
55
Why does a virus make you feel ill?
Cell damage occurs during reproduction using a host cell as it 'bursts' open.
56
What are pathogens?
Micro-organisms that cause infectious disease.
57
How do you calculate rate?
amount of products / time
58
How do you calculate percentage change?
difference between percentages / old percentage x 100
59
How do you calculate the percentage of a factor?
amount / total x 100
60
How do you use a light microscope to view your slide? PRACTICAL
1. Clip the side onto the stage
2. Select the lowest-power objective lens
3. Use the coarse adjustment knob to move the stage up or down.
4. Look down the eyepiece
5. Adjust focus with the fine adjustment knob
6. For greater magnification use a higher-powered objective lens.
61
Which of the following subcellular structures would you not expect to find in a prokaryotic cell?
- Plasmid
- Nucleus
- Cell Wall
- Cell Membrane
Nucleus
62
What is the function of a chloroplast?
Absorbs light which is needed for photosynthesis
63
What are the differences between adult stem cells are embryo stem cells?
- Adult stem cells are found in the bone marrow
- Can only turn into certain cells eg red blood cells
- Embryo stem cells are found in embryos and can turn into any type, they can also be grown in a lab to produce clone cells.
64
Why are some people against stem cell research? (4)
1. Unethical
2. Curing patients who already exist and are suffering is more important
3. Scientists should focus on developing other sources rather than embryos
4 Cell research is banned in some countries
65
How are stem cells used to produce identical plants?
1. Stem cells are found in the meristems
2. These tissues can differentiate at any time
3. Produce clones quickly and cheaply
4. Can be used to produce more plants of a rare species
5. Can also be used to grow crops of identical plants that have desired features for farmers eg. disease resistance
66
Describe the structure of chromosomes
Chromosomes are coiled up lengths of DNA molecules. Each chromosome carries a large number of genes, these control the development of different characteristics. Body cells have 2 copies of each chromosome.
67
Describe how stem cells could be used to treat disorders?
Can be grown into any type of cell, which could then replace the faulty cell
68
Where are adult stem cells found?
Bone marrow
69
A bacterial cell has a mean division time of 30 minutes. How many cells will it have produced in 3 hours?
3 hours = 3 x 60 = 180
180/30 = 6 = 6 divisions
2x2x2x2x2x2=64 cells
70
Culturing Microorganisms PRACTICAL
1. Bacteria are grown in a culture medium which contains the carbohydrates, minerals, proteins and vitamins they need to grow.
2. This can be a nutrient broth solution or solid agar jelly
3. Bacteria grown on agar plates will form visible colonies on the jelly.
4. In the lab at school, these cultures are not kept above 25 degrees because harmful pathogens are more likely to grown then.
71
How do you make an agar plate?
- Hot agar jelly is poured into a shallow round plastic dish called a petri dish
- When the jelly is cooled and set. inoculating loops can be used to transfer microorganisms to the culture medium.
72
How should you store the petri dish? (4)
1. Petri dish and culture medium must be sterilised before (eg heating) to kill any unwanted microorganisms
2. Sterilize the inoculating loop by heating
3. Petri dish lid should be lightly taped on
4. Stored upside down, to stop drops of condensation falling on the surface
73
How do you test the action of antibiotics on cultures of bacteria? PRACTICAL
1. Place paper discs soaked in different types or concentrations of antibiotics onto an agar plate that has an even layer of bacteria on the surface. Leave space between the discs
2. The antibiotic should diffuse into the agar jelly, antibiotic-resistant bacteria will grow around the discs, but non-resistant bacteria will die.
3. Use a control, place a paper disc soaked in sterile water, to clearly show the effect antibiotics have
4. Leave the plate for 48 hours at 25 degrees
5. The most effective antibiotic is the one with the largest inhibition zone.
74
Describe a control that should be used in a culturing microorganisms investigation? and why a control should be used.
1. A disc soaked in sterile water
| 2. To show that any difference in the growth of the bacteria is only due to the effect of the antiseptic
75
Osmosis PRACTICAL
1. Cut up a potato into identical pieces and get some beakers with different sugar solutions. One should be pure water and another should be a very concentrated sugar solution.
2. Measure the mass of the potato pieces, then leave them in a solution for 24 hours
3. Take them out and dry them, then measure their masses again
4. If water has been drawn in, the mass will increase
If water has been drawn out their mass will have decreased. Calculate their percentage change
76
What is the dependant/independant variable in the osmosis practical?
Dependant: Chip mass
Independent: Concentration of sugar solution
77
Active Transport
Substances absorbed against the concentration gradient, so from a lower to a higher concentration, needs energy from respiration for this.
78
How do root hair cells use active transport?
They take in minerals and water.
- Each branch of a root will be covered in millions of microscopic hairs, which gives the plant a large surface area]
- Plants need mineral ions for healthy growth
- The concentration is normally higher in the plant than the soil
79
How does active transport stop us from starving?
used when there is a lower concentration of nutrients in the gut but a higher concentration in the blood.
1. When there's a high concentration of glucose and amino acids in the gut they diffuse naturally into the blood.
2. But, sometimes there's a lower concentration.
3. Active transport allows nutrients to be taken into the blood, despite the fact that the concentration gradient is going the wrong way.
80
How have alveoli specialised to maximise diffusion?
- Enormous surface area
- Moist lining for dissolving gas
- Very thin walls
- Good blood supply
81
How do villi provide a really big surface area?
Villi cover the small intestine with millions and millions of tiny projections. These increase the surface area so digested food is absorbed much more quickly into the blood.
They have:
- a single layer of surface cells
- very good blood supply to assist quick absorptiom
82
How have the structure of leaves increased diffusion?
1. The underneath of the leaf is an exchange surface, its covered in holes called stomata, which co2 diffuses in through.
2. Oxygen and water vapour also diffuse out through stomata.
3. The size of the stomata is controlled by guard cells, these close the stomata if the plant is losing water faster than it is being replaced.
4. The flattened shape of the leaf increase the area of this exchange surface so that its more effective
5. Walls of the cell inside the leaf provide another exchange surface. The air spaces inside the leaf increase the area of this surface so more CO2 gets in.
83
How do gills help gas exchange?
1. Water enters the fishes mouth and leaves through the gills, as this happens oxygen diffuses from the water into the blood in the gills and carbon dioxide diffuses from the blood into the water.
2, Each gill is made of thin plates called gill filaments which give a big surface area.
3. Each gill filament are covered in lamellae which increase the surface area even more.
4. Lamellae have lots of capillaries which speed up diffusion
5. Thin surface layer to minimise the diffusion gap
6. Blood flows one way and water flows the other which maintains a large concentration gradient.
84
What are the 3 types of tissues in humans + their functions?
Muscular tissue - contracts to move
Glandular tissue - makes and secretes chemicals like enzymes and hormones
Epithelial tissue - which covers some parts of the body eg the gut
85
How do the different tissues work in the stomach?
Muscular tissue - moves the stomach wall to churn up the food.
Glandular tissue - makes digestive juices to digest the food
Epithelial tissue - covers the outside and inside of the stomach
86
Investigating Enzymatic Reactions PRACTICAL
1. Put a drop of iodine solution into every well of the spotting tile.
2. Place a bunsen burner on a heat-proof mat and a tripod and a gauze over the burner. Put a beaker of water on top of the tripod, heat this water until 35 degrees
3. Use a syringe and add 1cm3 of amylase solution and 1cm3 of buffer solution with a pH of 5 to a boiling tube. Using test tube holders put the tube into the beaker of water and wait 5 minutes.
4. Use a different syringe to add 5cm3 of starch solution into a boiling tube.
5. Mix the contents and start stopwatch
6. Use continuous sampling to record how long it takes for the amylase to break down all the starch, keep adding this into a well until the iodine solution remains brown/orange.
7. Repeat the whole experiment with solutions of different pH values.
87
How do you test for sugars?
Benedict's Test:
1. Prepare the food sample and transfer 5cm3 to a test tube.
2. Prepare a water bath so that it's set to 75 degrees.
3. Add some Benedict's solution to the test tube (10 drops) using a pipette.
4. Place the test tube in the water bath and leave it for 5 minutes, make sure it's pointing away from you.
5. Colour will change from blue to green, yellow or red, depending on how much sugar was present.
88
How do you test for starch?
1. Make a food sample and transfer 5cm3 of your sample to a test tube.
2. Add a few drops of iodine solution and gently shake. If starch is present then it will change from browny-orange to black or blue-black.
89
How to test for proteins?
Biuret Test:
1. Prepare a sample of your food and transfer 2cm3 to a test tube.
2. Add 2cm3 of biuret solution to the sample and mix the contents by shaking it.
3. If proteins are present the solution will change from blue to pink or purple.
90
How to test for lipids?
Sudan III:
1. Prepare a sample of food. Transfer around 5cm3 into a test tube.
2. Use a pipette and add 3 drops of Sudan III stain solution and gently shake.
3. If lipids are present 3 layers will be present, top will be bright red.
91
How does bile need to have an alkaline pH and outline how it helps with digestion?
It neutralises the hydrochloric acid from the stomach. It emulsifies fats to give a much bigger surface area of fat for the lipase enzyme to work on.
92
Explain what effect a low pH has on the activity of an enzyme?
It would break the bonds in the enzyme and change the shape of the enzyme's active site/denatures the enzyme. This would mean the substrate would no longer fit into it so the enzyme wouldn't work anymore.
93
Describe the structure of arteries?
- Walls are thick
- Small lumen
- Carries blood at high pressure
- Walls are strong elastic
94
Describe the structure of capillaries?
- Really tiny
- Carry blood really close to every cell to easily exchange substances
- Permeable walls for diffusion
- Supply food and oxygen and take away waste like CO2
- One cell thick
95
Describe the structure of veins?
- Blood carried at low pressure so has valves to prevent backflow
- Bigger lumen
- Thinner walls
96
What is the function and structure of red blood cells?
Their job is to carry oxygen from the lungs to the cells in our bodies.
- Biconcave disc gives them a large surface area for absorbing oxygen.
- They don't have a nucleus so more room to carry oxygen.
- Contain a red pigment called haemoglobin.
97
What is the function and structure of white blood cells?
Lymphocytes and Phagocytes
| Defend against infection
98
What is the function and structure of platelets?
Help blood clot.
- Small fragments of cells, no nucleus
- Help blood to clot at a wound.
99
What is the function and structure of plasma?
```
Liquid that carries everything in blood.
Carries everything:
- White and Red blood cells
- Platelets
- Glucose and amino acids
- Carbon dioxide
- Urea
- Hormones
-Proteins
- Antibodies
```
100
Describe the function of the left ventricle?
It pumps blood around the body.
101
What is the function of the valves in the heart?
Prevent backflow of blood.
102
Describe how deoxygenated blood from the body passes through the heart to reach the lungs?
Deoxygenated blood enters the right atrium through the vena cava. The right atrium then contracts and the blood passes into the right ventricle. Again this contracts which forces the blood through the pulmonary artery and out of the heart, which then takes it to the lungs.
103
What is coronary heart disease?
Coronary heart disease is when the coronary arteries that supply the blood to the muscle of the heart get blocked by layers of fatty material. This causes the arteries to become narrow so blood flow is restricted and there's a lack of oxygen, this can result in a heart attack.
104
What are the 2 solutions for coronary heart disease?
Stents:
- Tubes inserted in the arteries, keep them open
- Effective and long term solution
- Risk of infection in surgery.
- Risk of blood clot near the stent
Statins:
- Too much cholesterol leads to a build up in fatty acids
- Statin reduces amount of bad cholesterol
- Daily tablets
105
What are the advantages and disadvantages of statins?
+ Reduces risk of strokes, coronary heart disease and heart attacks.
+ Increased amount of beneficial cholesterol
+ Prevents other diseases
- Long term drug which is taken regularly
- Negative side effects e.g headaches
- Takes time to kick in.
106
What is an artificial heart?
An artificial heart is a mechanical device to pump blood around the body. This is only a temporary fix until a correct donor has been found.
107
What are the + and -'s
+ Less likely to be rejected
- Bleeding and infection
- Don't work as well as healthy ones
108
How can faulty hearts be replaced?
Valves are weakened by heart attacks, infection or old age.
These can be replaced by taking one from another human or mammal.
Biological or man-made
109
What are the 2 types of valves?
Biological or Man-Made
110
What are the 2 types of tumours?
Benign and Malignant
111
What is the difference between the 2 tumours?
Malignant tumours are cancerous
112
Explain how secondary tumours form in the body?
Tumour cells can break off and spread to other parts of the body by travelling in the bloodstream. The malignant cells then invade healthy tissues elsewhere in the body and form secondary tumours
113
What are the different types of plant tissues?
```
Epidermal Tissues
Palisade mesophyll Tissue
Spongy mesophyll Tissue
Xylem and Phloem
Meristem Tissue
```
114
What are the different functions of plant tissues?
Epidermal Tissues - covers the whole plant
Palisade mesophyll Tissue - photosynthesis happens
Spongy mesophyll Tissue - big air spaces for gases to allow gases to diffuse
Xylem and Phloem - transport water, minerals and food
Meristem Tissue - found at the growing tips of shoots and roots and is able to differentiate into different plant cell types.
115
Phloem Tubes
- Transport food substances
- This goes in both directions
- This is called translocation
116
Xylem Tubes
- Made of dead cells with no end walls and a hole down the middle.
- They carry water and mineral ions from the roots to the stem and leaves
- Movement of water from the roots through the xylem and out of the leaf is called the transpiration stream
117
What is transpiration?
Transpiration: loss of water from the plant
118
What causes transpiration?
Evaporation and diffusion of water from a plant's surface. Most of this happens from the leaves.
119
What happens to a plant from transpiration?
A slight shortage of water in the leaf and so more water is drawn up from the rest of the plant through the xylem vessels to replace it. This in turn means more water is drawn up from the roots and so there is a constant transpiration stream of water through the plant.
120
How is transpiration rate affected?
Light Intensity
Temperature
Air Flow
Humidity
121
How do guard cells change?
1. They have a kidney shape which open and closes the stomata.
2. When the plants have lots of water the guard cells fill with it and go turgid, this makes the stomata open so gases can be exchanged for photosynthesis.
3. When the plant is short of water the guard cells lose water and become flaccid making the stomata close. This stops too much water vapour escaping.
4. Thin outer walls and thickened inner walls make the opening and closing work.
5. They are also sensitive to light.
122
Name the vessels that transport water and mineral ions from the roots of a plant to the leaves?
Xylem vessels
123
What type of transport vessel does the cell sap come from?
Pholem
124
Name the movement of cell sap through the plant transport vessels?
Translocation
125
Explain how the structure of these transport vessels is adapted to their function?
They are made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through.
126
What are the pros and cons of vaccinations?
+ Control communicable diseases that were once common.
+ Big outbreaks of disease called epidemics can be prevented.
-Vaccines don't always work
- You can sometimes have a bad reaction
127
Explain how drugs come from plants?
1. Plants produce a variety of chemicals to defened themselves
2. These can be used to treat a human disease
3. Lots of our current medicines are used.
4. Some drugs were extracted from microorganisms
128
What does a 'double blind' clinical trial mean?
In a double blind trial, neither the patient nor doctor know who is receiving the drug or placebo until all the results have been gathered.
129
What is the role of hairs and mucus in the nose?
They trap particles that could contain pathogens.
130
How do the cilia in the trachea and bronchi help defend the body?
They waft the mucus up to the back of the throat where it can be swallowed.
131
The results from drug testing are assessed by peer review, explain what this means?
Peer review is where other scientists check the work to make sure it is valid and has been carried out rigorously. It is done to prevent false claims being made about results.
132
Why do scientists research during drug testing?
Dosage
Efficiency
Toxicity
133
Suggest a drug that patients with rubella may be given to relieve their symptoms?
Painkiller
134
Why might it be difficult to develop a drug which destroys rubella in the body?
Rubella is a virus, these reproduce using your body cells, which makes it very difficult to develop drugs that destroy just the virus without killing the body's cells.
135
Explain how being vaccinated against rubella can prevent a person from catching the disease and suggest why vaccinating a large proportion of the population reduces the risk of someone who hasn't been vaccinated?
- When a person is vaccinated against rubella, they are injected with dead/inactive rubella viruses.
- These carry antigens, which cause the body to produce antibodies to attack them.
- If rubella attacks the body after this, then white blood cells rapidly produce antibodies to protect them.
- If a large population is injected then there is a low amount of people able to carry the disease.
- This means someone who hasn't been vaccinated is still unlikely to catch the disease.
136
Why might people may choose to not receive a vaccination?
- Vaccines don't always work
| - May get a bad reaction
137
Give three methods of physical defence used by plants to stop pathogens entering?
- Waxy cuticle on leaves
- Cellulose cell walls
- Layers of dead cells around stems
138
Explain why plants with a magnesium deficiency are less able to photosynthesise?
Magnesium ions are needed for making chlorophyll, which is needed for photosynthesis.
139
State signs which may indicate that a plant is diseased?
- Stunted growth
- Spots on the leaves
- Patches of decay
- Abnormal growths
- Malformed leaves of stems
140
What 3 things can be bound to a monoclonal antibody to treat cancer?
- Radioactive substance
- A toxic drug
- Chemical to stop cells growing and dividing
141
How do you measure the rate of photosynthesis? PRACTICAL
1. A source of white light is placed at a specific distance from pondweed.
2. This is left to photosynthesise for a set amount of time. The oxygen released will collect in the capillary tube.
3. At the end, the syringe is used to draw the gas bubble in the tube alongside a ruler and the length of the gas bubble is measure.
4. All variables should be controlled.
5. Experiment is repeated with light sources from different distances.
142
What happens to a cell when it becomes specialised?
Differentiation is the process by which a cell changes to become specialised for its job.
As cells change, they develop different subcellular structures and turn into different types of cells.
143
When does differentiation often occur?
As an organism develops.
In most animal cells the ability is lost at an early stage once they become specialised.
However lots of plants cells do not ever lose the ability to differentiate.
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How is a sperm cell specialised? (differentiation)
The function of the sperm cell is to get the male DNA to the female DNA.
It has a long tail and a streamlined head to help it swim to the egg.
There are lots of mitochondria in the cell to provide the energy needed.
It also carries enzymes in its head to digest through the egg cell to the membrane.
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What affects the rate of photosynthesis?
Intensity of light.
Concentration of co2.
Temperature.
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What else do plants also need for photosynthesis other than the 3 factors?
Plants also need water for photosynthesis, but when a plant is so short of water that it becomes the limiting factor in photosynthesis, its already in such trouble that this is the least of its worries.
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Whats a limiting factor in photosynthesis?
A factor that prevents photosynthesis from happening any faster.
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What effect do limiting factors have on photosynthesis?
These factors have a combined effect on the rate of photosynthesis, but which factor is limiting at a particular time depends on the environmental conditions.
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How can chloroplast function affect the rate of photosynthesis?
The amount of chlorophyll in a plant can be affected by disease e.g tmv
Environmental stress such as lack of nutrients can also reduce the amount of chlorophyll.
These factors can cause chloroplasts to become damaged or to not make enough chlorophyll.
This means the rate of photosynthesis is reduced because they can't absorb as much light.
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How does light affect photosynthesis?
As the light level is raised the rate of photosynthesis increases steadily - but only up to a certain point before it levels off and is not longer a limiting factor.
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How does carbon dioxide affect photosynthesis?
Co2 is one of the raw materials needed for photosynthesis.
| The amount of co2 will only increase the rate of photosynthesis to a certain point before the level flattens off.
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What can you deduce from the limiting factor graphs surrounding photosynthesis?
As long as light and co2 are in plentiful supply then the factor limiting photosynthesis must be temperature.
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How does temperature affect the rate of photosynthesis?
The temp has to be just right.
Temperature affects the rate of photosynthesis because it affects the enzymes involved.
Usually if the temp is the limiting factor its because its too low - the enzymes needed for photosynthesis work more slowly at low temps.
But if the plant gets too hot, the enzymes it needs for photosynthesis and other reactions will become damaged. This happens at 45 degrees.
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When is a enzymes catalytic energy at its greatest?
This optimal temperature is usually around human body temperature (37.5 degrees centergrade) for the enzymes in human cells.
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What is metabolism?
The measure of all the chemical reactions in an organism. (The sum total)
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What is respiration?
The process of transferring energy from glucose, which goes on in every cell.
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Respiration is exothermic. What does this mean?
It transfers energy to the environment.
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Name the two types of respiration?
Aerobic and anaerobic respiration.
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Where do most of the reactions for aerobic respiration occur?
The mitochondria.
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Word equation for aerobic respiration.
glucose + oxygen --> carbon dioxide + water.
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When is anaerobic respiration used?
When there isnt enough oxygen.
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What is anaerobic respiration?
When your body cant supply enough oxygen to your muscles.
Anaerobic respiration is the incomplete breakdown of glucose making lactic acid.
Anaerobic respiration does not transfer nearly as much energy as aerobic, this is because the glucose isn't fully oxidised.
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Word equation for anaerobic respiration?
glucose --> lactic acid.
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Word equation for anaerobic respiration in plants and yeast?
Glucose --> ethanol + carbon dioxide.
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What is anaerobic respiration in yeast cells called?
Fermentation.
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Why does your pulse increase during exercise?
Your body needs to get more oxygen to the muscles and take more carbon dioxide away from the muscles.
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Other than 'oxygen debt' name one way your body copes with the high levels of lactic acid after aerobic respiration?
The blood that enters your muscles transports the lactic acid to the liver, in the liver, the lactic acid is converted back to glucose.
