UNIT 4 - Biodiversity and Natural resources Flashcards
(131 cards)
1
Q
What is the plant cell wall mainly made out of?
A
Cellulose
2
Q
What is the main function of the plant cell wall?
A
Support plant cells.
3
Q
What is the main function of the midlle lamella and where is it found?
A
It is the outermost layer of the cell and acts as an adhesive, sticking adjacent plant cells together.
4
Q
What are plasmodesmata and what is their function?
A
Channels in cell walls that link adjacent cells together for transport of substances and communication between cells.
5
Q
What are pits and what is their function?
A
Regions where the cell wall is very thin (in both adjacent cells). It allows transport of substances between cells.
6
Q
What is an amyloplast and what is its function?
A
Small organelle enclosed by a membrane. It contains starch granules for starch storage.
7
Q
What is the function of the vacuole and tonoplast?
A
The vacuole contains the cell sap (water, enzymes, minerals, water).
Keep the cells turgid - stopping plants from wilting.
Also involved in the breakdown and isolation of unwanted chemicals.
The tonoplast is the surrounding membrane and it controls what enters or leaves the vacuole.
8
Q
In which two places inside the chloroplast does photosynthesis occur?
A
Grana and stroma
9
Q
What is A?
A
Stroma
10
Q
What is B?
A
Thylakoid
11
Q
What is C?
A
Granum (plural grana)
(it’s a stack of thylakoid)
12
Q
What is D?
A
lamella (plural lamellae)
13
Q
What is A?
A
Middle lamella
14
Q
What is B?
A
Plasmodesmata
15
Q
What is C?
A
Pits
16
Q
What is the function of xylem vessels?
A
Transport water and mineral ions and to provide support.
17
Q
What is the structure of the xylem vessels?
A
Long, thin structures formed by cells with hollow lumen and no end walls.
This makes uninterrupted tubes thickened with lignin, which adds support.
Water and mineral ions move in and out through pits in the walls where there’s no lignin.
The tubes are found together in bundles.
18
Q
What is the function of sclerenchyma fibres?
A
To provide support (not involved in transport).
19
Q
What is the structure of sclerenchyma fibres?
A
Like xylem vessels, they are also made of dead, hollow, long cells.
But these cells do have end walls.
Cell walls are thickened in lignin but they don’t contain pits.
They have more cellulose.
20
Q
What is the function of the phloem?
A
To transport organic solutes (such as sucrose) from where they are made to where they are needed. (translocation). Isn’t used for support (only transport).
21
Q
What is the structure of phloem vessels?
A
Made out of tubes of cells.
Made out of 2 cells: sieve tube elements and companion cells.
Sieve tube elements have sieve plates at the end walls which contain holes to allow solutes to pass through. They have no nucleus, a very thin layer of cytoplasm and few organelles.
There’s 1 companion cell for every sieve tube element - they carry out livng function for both themselves and their sieve cells.
22
Q
This is a transverse cross section of a stem.
What is A?
A
Phloem
23
Q
This is a transverse cross section of a stem.
What is B?
A
Xylem
24
Q
This is a transverse cross section of a stem.
What is C?
A
Schlerenchyma
25
This is a longitudinal cross section of a stem.
What is A?
Xylem
26
This is a longitudinal cross section of a stem.
What is B?
Phloem
27
This is a longitudinal cross section of a stem.
What is C?
Sclerenchyma
28
How would you dissect plants in order to identify xylem vessels, sieve cells (phloem) and sclerenchyma fibres?
1. Cut a thin cross section of the stem (transverse or longitudinal).
2. To prevent drying out, use tweezers to place the cut sections in water.
3. Stain your cross section with toluidine blue O (TBO) and leave it for 1 minute.
4. Rinse off with water and mount it onto a slide.
5. Observe through the microscope. TBO stains lignin blue-green so the xylem and sclerenchyma would appear blue-green while the phloem and other tissues without lignin will appear pinkish purple.
29
What is the chemical structure of starch and how does it relate to its function?
It's made from amylose and amylopectin - two alpha glucose chains. (cells get energy for glucose)
Amylose is a long, unbranched chain - this makes it compact, so good for storage.
Amylopectin is a branched chain - the side branches allow enzymes to release glucose quicker.
Starch is insoluble, so it won't cause water to enter cells by osmosis, preventing them from swelling.
30
What is the chemical structure of cellulose and how does it relate to its structure?
Long, unbranched chains of beta-glucose, joined by 1,4 straight glycosidic bonds.
Hydrogen bonds join between 50 and 80 cellulose chains together, forming microfibrils.
They are strong so provide structural support.
31
What are the two main reasons why plant fibres are strong?
* The net-like arrangement of cellulose microfibrils and their strength.
* Secondary cell wall (between cell wall and membrane) contains more lignin and is thicker. Some structural plant cells grow it after finishing their growth - secondary thickening.
32
How can you measure the tensile strength of plant fibres?
1. Attach the fibre to a clamp stand and hang a weight from the other end.
2. Keep adding weights until the fibre breaks. Record the mass needed to break it.
3. Repeat the experiemnts with different samples of the same fibres and same length. Variables (temp, humidity) should be kept constant.
4. Calculate mean of results.
5. Safety: wear goggles, be careful with the masses.
33
What is sustainability?
Using the resources to meet the needs of the present without sacrificing the needs of future generations.
34
What are renewable resources?
Resources that can be used indefinetly without running out.
35
How can using plant fibres contribute to sustainability?
1. Substitutes plastic, which is made form oil, so not renewable.
2. Biodegradable
3. Plants are easier to grow and process than oil. They are cheaper and easier to do in developing countries. (less technology is needed).
36
How can using starch contributeto sustainability?
* Can make bioplastics.
* Can make biofuels i.e. bioethanol.
* This substitutes the use of fossil fuels such as oil and therefore increases sustainability.
37
For what do plants need water?
* Photosynthesis
* Transporting minerals
* Structural rigidity (turgor pressure)
* Regulate temperature (evaporating water helps plant cool down)
38
For what do plants need magnesium ions?
Production of chlorophyll - the pigment needed for photosynthesis.
39
For what do plants need nitrate ions?
Production of DNA, proteins and chlorophyll.
40
For what do plants need calcium ions?
Important in cell walls - they are required for plant growth.
(calcium pectate)
41
How could you investigate the effect of calcium ions in plants?
1. Make 3 nutrient broths of varying concentrations of calcium ions.
2. Use three test tubes for each broth.
3. Take 9 seedlings of the same plant and of the same age. Measure the initial mass of the seeds. Use a cotton wool to put the seedlings in the broth so that te roots are suspended.
4. Cover in aluminium foil so that no other organisms use light to develop in te nuttrient broth.
5. Place all tubes near a light source for a specific amount of time (2 weeks).
6. Remove the plant and blot it dry. Measure new mass. Calculate the change in mass. Note down visual differences too.
42
How can you investigate the antimicrobial properties of some plants using aseptic techniques?
1. Prepare and agar plate of bacteria. Use a sterile pippette to transfer bacteria from the broth (water+bacteria+nutrients) to the agar plate.
2. Prepare the extract of the plants. Dry, grind, and soak the plant in ethanol (which would extract the antimicrobial substances, which are soluble in ethanol). Filter.
3. Dip equally sized discs of sterile absorbent paper in the plant extract. The control will only be soaked in ethanol.
4. Place the paper discs on the agar plate away from each other. Place the lid and incubate at 25ºC for 24-48 hours. (temp. is high enough for bacteria to grow well but low to prevent growth of unwanted pathogens).
5. Keep all other variables constant.
6. There'll be a clear zone where bacteria can't grow.
7. The larger the clear zone, the more antimicrobial the plant is: work out the area (Pi.r2) or diameter.
43
What are examples of conditions needed for bacterial growth?
* Nutrients
* Oxygen (if aerobic respiration)
* Temperature and pH (would alter enzyme activity and therefore metabolic processes).
44
Why are aseptic techniques used?
To prevent contamination of unwanted organisms and human pathogens, since it can affect the growth of the microorganism of interest.
45
Which aseptic techniques should be used when testing the antimicrobial properties of plants?
* Close windows+doors.
* Regularly disinfect work surfaces to minimise contamination.
* Use sterile equipment and discard it safely. Galssware can be sterilised in an autoclave (steams equipment at high pressure).
* Work near a bunsen flame when transferring bacteria. Hot air rises so microbes in the air won't land in the plate. (ethanol is flammable so be careful).
* Flame the neck of the broth-containing container when opened and closed to cause air to move out, preventing unwanted organisms from falling in.
46
Who was William Withering and what did he discover?
* William Withering was a scientist in the 1700s that discovered of foxgloves could treat dropsy (swelling caused by heart failure). The extract contained the drug digitalis.
47
How did William withering test his digitalis soup?
* Chance observation: he observed that a patient recovered well from dropsy after being treated.
* He knew foxgloves were poisonous so he discovered by trial and error the right amount. (too little had no effect, too much poisoned).
48
How is a drug tested before clinical trials are carried out on humans?
1. Computer modelling for potential effects.
2. Tests carried out on human tissues in a lab.
3. Tested on live animals.
49
Modern drug testing in humans consist of 3 phases.
What does phase 1 consist on?
Testing the drug on a small group of healthy individuals to find safe dosage, side effects and body reaction to the drug.
50
Modern drug testing in humans consist of 3 phases.
What does phase 2 consist on?
Once the drug passes phase 1, it will be tested on a larger group of people (this time PATIENTS) to see how well the drug works.
51
Modern drug testing in humans consist of 3 phases.
What does phase 3 consist on?
Once the drug has passed phases 1 and 2, the drug is compared to existing treatments. It is tested on hundreds or thousands of patients (to increase reliability). Some patients recieve the existing drug while others recieve the new drug. This is to see if the new drug is actually better than the existing ones.
52
What are two methods that increase validity in modern drug testing?
* The use of placebos (phase 2).
* Double blind study design (phase 2 and 3).
53
What does the use of placebos consist on?
* Patients are split in two groups in phase 2.
* One group is given a placebo - an inactive sbstance that looks like the drug.
* Patients often show a placebo effect - they show improvement because they believe that they're recieving the treatment.
* This shows if the drug actually work (if it is any better than the placebo).
54
What does blind study design consist on?
* Phase 2 and 3 clinical trials are often double blind - neither the patients nor the doctors who's been given the new drug and who's been given the placebo (or old drug in phase 3).
* This reduces bias because the attitudes of the patients and doctors can't affect the result. *(doctors may overestimate the improvement of a patient if they know he has recieved the drug).*
55
What is Biodiversity?
The variety of living organisms in an area.
56
What is species diversity?
The number of different species and the abundance of each species in an area.
57
What is genetic diversity?
The variation of alleles within a species (or population of a species).
58
What is endemism?
When a species is unique to a single place (isn't naturally found in other areas).
59
What human activities can reduce biodiversity?
* Farming (monocultures).
* Deforestation (destructon of habitats).
60
What is an habitat?
The place where an organism lives.
61
What is species richness?
A measure of species diversity that counts the number of species. The higher, the more species diversity.
62
What is the diversity index?
A measure of species diversity that takes into account the number of different species (calculated by an equation). The higher, the greater the species diversity.
63
Why are samples taken when measuring biodiversity?
It's usually too time consuming to count every individual in a habitat.
64
Why are the measures of biodiversity usually an estimate?
They are based on samples.
65
How is a sample taken?
1. Choose an area to sample within an habitat.
2. Choose random sample sites (random number generator for coordinates).
3. Count the number of individuals of each species. (use a quadrat for plants, a sweepnet for flies, a pitfall trap tfor insects and a net for aquatic animals).
4. Repeat. Take as many samples as possible.
5. Use the results to esimate the total number of individuals and total number of species.
66
What should be taken into account when taking samples to compare different species?
The same sampling technique should be used.
67
What is the gene pool of a species?
The complete set of alleles in a species (or population).
68
What two things can you look at when measuring genetic diversity?
Phenotype and Genotype.
69
How would you measure genetic diversity by observing phenotypes?
The greater the number of different phenotypes, the greater the genetic diversity.
70
Give an example where genetic diversity is observed through the phenotype.
Humans in northern europe show a variety of blue, grey, green and brown eyes while outside this area eyes are usually brown.
There's greater genetic diversity in eye colour in northern europe.
71
How can genetic diversity be measured by observing the genotype?
* Samples of DNA from an organism's are taken and the base pair sequence is analysed.
* The order of bases in each allele is slightly different.
* Therefore, you can look at similarities and differences in the alleles within a species.
* You can also look at the number od different alleles a species has (humans have 3 for blood groups while gorillas only have 1)
72
What is the heterozygosity index?
An index that measures genetic diversity by taking into account the proportion heterozygotes. The greater, the higher the genetic diversity.
73
What is the formula for the heterozygosity index?
H = number of heterozygotes / number of individuals in the population.
74
What can you do to estimate the genetic diversity in the whole genome of a population?
Find the average of H (heterozygosity index) for many loci.
75
What is the equation for the index of diversity (D)?
D = N(N-1) / ((sigma)n(n-1))
N = Total number of organisms
n =Total number of organisms of one species
76
The higher the index of diversity...
...the more diverse the area is (more species diversity)
77
What does it mean if the index of diversity is 1?
All the individuals are of the same species.
78
What is a niche?
The role of a species within its habitat, including interactions with living organisms and non-living environment.
79
Can more than one species occupy the same niche?
No. It may seem like it, but there will be slight differences in each species' niche.
80
What happens if two species try to occupy the same niche?
One species will be more successful than the other, until only one species is left in that niche.
81
What are adaptations?
Features that increase an organism's chance of survival and reproduction.
82
What three types of adaptations are there?
Behavioural, physiological and anatomical.
83
What are behavioural adaptations?
Ways an organism acts that increase its chance of survival and reproduction.
(i.e. some species 'play dead' when they feel threatened by a predator)
84
What are physiological adaptations?
Processes inside an organism's body that increase its chance of survival and reproduction.
(i.e. bears slow down their metabolism when hibernating; some bacteria produce antibiotics to reduce competition)
85
What are anatomical adaptations?
Structural features of an organism's body that increase its chance of survival and reproduction.
(i.e. whales have a thick layer of fat)
86
How does evolution by natural selection makes useful adaptations more common inside a species?
1. Random mutations can introduce new alleles, so variation in phenotype is shown.
2. Some of this characteristics are useful for survival and reproduction.
3. Selection pressures like predatin, disease or competition create a struggle for survival.
4. Individuals with the avantageous alleles survive and are more likely to pass on the allele while individuals without it are more likely to die and therefore not reproduce.
5. Over time, the number of individuals with advantageous alleles increases. This leads to evolution as there's a change in allele frequency.
87
How did natural selection lead to evolution with peppered moths?
1. Peppered moths show variation: some have alleles for light colour and others have allele for dark colours (which arose from random mutations).
2. Before the 1800s, there were more light moths than dark ones.
3. During the 1800s, pollution darkened the trees.
4. Dark colour moths were now more able to camouflage from predators while the light coloured moths stood out and were more susceptible to predation (selection pressure).
5. Dark moths were more likely to survive, reproduce and pass on the alleles for black colours to their offspring.
6. Over time, the frequency of the alleles for black colour increased.
88
What is a species?
A group of similar organisms that can reproduce to give fertile offspring.
89
What ways are there for a population to become reproductively isolated?
* Seasonal changes in flowering or mating.
* Mechanical changes in genitalia.
* Behavioural changes - courtship rituals may not be attractive to the main population.
* Geographical isolation.
90
How can geographical isolation lead to speciation?
1. A physical barrier divides a population of a species (floods, volcanic eruptions, earthquakes can cause barriers)
2. Conditions on either side of the barrier may be different (i.e. different climate).
3. Different characteristics become more common in each population due to natural selections (different random mutations will arise + different selection pressures)
4. Eventually the two groups will become so genetically distinct that they won't be able to breed to give fertile offspring. They will become reproductively isolated.
5. the 2 groups will become separate species.
91
What is evolution?
A change in allele frequency
92
Does the Hardy-Weinberg principle predict a change in allele frequency?
No
93
Under which conditions would there be no change in allele frequency?
* large population
* No immigration
* no emigration
* no mutations
* no natural selection
* random mating
(if there's a change in allele frequency we can see the opposite is happening)
94
Write the two Hardy-Weinberg equations
p + q = 1
p^2 + 2pq + q^2 = 1
p = dominant allele frequency
q = recessive allele frequency
95
Which phenotype is often given in hardy-weinberg questions? Why?
The recessive phenotype.
It's the only phenotype from which the genotype can be worked out.
(if phenotype is recessive, genotype is homozygous recessive)
96
What is taxonomy?
The science that studies classification.
97
What are the 8 taxonomic groups in order from biggest to smallest?
1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
98
What happens to the number of groups and the number of individuals in each group as you go down the taxonomic group hierarchy?
Each time there are more groups and less individuals in each group.
99
Some species of the same genus can be very similar.
Why are they classified into different species?
They can't breed together to produce fertile offspring.
100
How does the binomial system work?
First word is the genus and the second name is the species name.
Names are in Latin.
Written in italics and first name starts with upper case, but second name doesn't.
101
What are the advantages of using a binomial system?
It enables scientists to communicate about organisms in a standard way that minimises confusion. All species are called the same in all countries.
102
What evidence were old classification based on?
Only observable phenotypes.
However, scientists can't agree on the relative importance of different characteristics and sometimes physical similitude doesn't mean that they are closely related.
103
What evidence are new classifications based on?
New technologies such as DNA sequencing has allowed clarification about relationships between different species by taking into account the organism's genotype as well as its phenotype.
104
What are the 5 kindoms that exist?
1. Prokaryotae (Monera)
2. Protocista
3. Fungi
4. Plantae
5. Animalia
105
What are the general features of organims in the Prokaryotae (Monera) kingdom?
* Prokaryotic (so no nucleus)
* Unicellular
* Less than 5 um
i.e. Bacteria
106
What are the general features of organims in the Protocista kingdom?
* Eukaryotic
* Usually live in water
* Single celled or multicellular (simple)
i.e. Algae, protozoa
107
What are the general features of organims in the Fungi kingdom?
* Eukaryotic
* Chitin cell wall
* Saprotrophic (absorb nutrients from dead or decaying organisms)
i.e. Moulds, yeasts, mushrooms
108
What are the general features of organims in the Plantae kingdom?
* Eukaryotic
* Multicellular
* Cellulose cell walls
* Photosynthetic (contain chlorophyll)
* Autotrophs (produce their own food)
i.e. Mosses, ferns, plants
109
What are the general features of organims in the Animalia kingdom?
* Eukaryotic
* Multicellular
* No cell wall
* Heterotrophs (feed on other organisms)
i.e. fish, reptiles, birds, mammals
110
Where can scientists share their new discoveries?
In meetings and scientific journals.
Perhaps also the internet.
111
From which area did evidence for the new three domain system come?
Molecular Phylogeny: which looks at molecules (such as DNA and proteins) to see how closely related they are.
112
What is phylogeny?
The study of the evolutionary history of groups of organisms.
113
What does the new three domain system consist on?
All organisms are placed into one of the three domains: Bacteria, Archaea and Eukaryota.
The organisms that were in the prokaryotae kingdom are split between the Bacteria and Archaea domains.
All other four kingdoms (Protocista, Fungi, Plantae and Animalia) go into the Eukaryota domain.
114
Why was the prokaryotae kingdom split into the two domains (Archaea and Bacteria) in the new three domain system?
Molecular phylogeny suggested that archaea and bacteria are more distantly related than originally thought.
115
What are endangered species?
Species that are at risk of extinction because of a low population or a threatened habitat.
116
What is conservation?
The protection and management of endangered species.
117
What is a seedbank?
A store of ots of seeds from lots of different species of plants.
118
How can seedbanks help conserve biodiversity?
* If a plant species becomes extinct in the wild, the stored seeds can be used to reintroduce the species to the wild.
* Can also conserve genetic diversity, by conserving seeds of the same species but with different characteristics (so different alleles).
119
How does a seedbank store seeds?
* They create cool, dry conditions needed for long time storage.
* Seeds are tested for viability - they are planted, grown and new seeds are harvested.
120
What are the advantages of using seedbanks?
1. It's cheaper to store seeds than plants.
2. Larger numbers of seeds can be conserved.
3. Less labour is required to look after seeds than plants.
4. Plants would need their specific conditions for growth in each habitat, while seeds can be stored anywhere that's cool and dry.
5. Seeds are less likely to be damaged by disease or natural disease.
121
What are the disadvantages of using seedbanks?
1. Testing all the seeds for viability can be expensive and time consuming.
2. It may be difficult to collect seeds from some plants.
122
How can captive breeding programmes in zoos help preserve biodiversity?
Species that are endangered (or already extinct in the wild) can be bred together in zoos to help increase their numbers.
123
What problems can there be with captive breeding?
* Animals can have problems breeding outside their natural habitat, which can be hard to recreate in a zoo.
* There can be quite a lot of inbreeding.
* Many people think it's cruel to keep animals in captivity
124
Why are species reintroduced in the wild?
* Can increase number of organisms of a species in the wild, preventing the species from becoming extinct.
* This could help other species which relied on the endangered species for food.
* It can help restore habitats that have been lost.
125
What problems may there be when reintroducing a species to the wild?
* Reintroduced organisms could bring new diseases to habitats, harming other organisms.
* Reintroduced animals my not behave as they would if they were raised in the wild (i.e. may have trouble finding food and communicating with other members of the species)
*
126
How do seedbanks contribute to scientific research?
* Scientists can study how plant species can be successfully grown from seeds.
* They can be used to grow endangered plants for medical research, crops or materials. (therefore protecting species in the wild).
127
What disadvantage may there be when carrying out research with seedbanks?
Only studying plants from a seedbank may not be representative of wild plants since the data comes from a small, interbred populations.
128
How can zoos contribute to scientific knowledge?
* Increases knowledge about behaviour, physiology and nutrition of animals, which can contribute to improve conservation efforts.
* Research that is not possible in the wild can be available in zoos i.e. nutritional or reproductive studies.
129
What disadvantage is there when studying behaviour of organisms in a zoo?
Animals grown in captivity may act differently than those grown in the wild.
130
How can zoos and seedbanks help raise public awareness?
Allows people to get closer to organisms, increasing their interest in conservation work.
Can also provide training and education about conservation and biodiversity.
131
