Topic 4 More On Genetics Flashcards
1
Q
What is evolution?
A
Evolution is the slow and continuous change of organisms from one generation to the next from natural selection.
2
Q
Outline the theory of natural selection.
A
- Mutations create different alleles and create genetic variation
- Environmental pressures, e.g., predators, disease, and competition, make survival harder
- Some mutations help an organism survive better
- Those with helpful alleles live longer and reproduce, passing on the advantage
- Others without the allele struggle and reproduce less
- Over time, helpful alleles become more common in the population.
3
Q
Describe how antibiotic resistance in bacteria can be used as an example to illustrate the process of evolution.
A
- Genetic variation exists due to mutations
- Antibiotics act as a selection pressure
- Mutations give a bacterium antibiotic-resistance
- If an antibiotic is countered, the bacterium survives, and others die
- Bacterium reproduces, passing on resistant allele
- The offspring of bacteria inherit the beneficial allele overtime
4
Q
Why is the development of antibiotic resistance in bacteria a good study for evolution?
A
- Bacteria reproduce very rapidly, allowing first-hand observation of evolution.
- Rats also are becoming resistant to the poision warfarin, which provides evidence of evolution.
5
Q
How can the observation of fossils provide evidence for evolution?
A
Older fossils are simpler, and newer fossils are complex. Fossils show chronological changes in organisms over time.
6
Q
Describe the role of Darwin in the development of the theory of evolution by natural selection.
A
- Spent 5 years around the world studying plants and animals on a ship called HMS Beagle
- He noticed variation to characteristics in similar species
- He noticed characteristics were passed on to offspring and wrote the theory of evolution by natural selection
7
Q
Describe the role of Wallace in the development of the theory of evolution by natural selection.
A
- He came up with natural selection independently of Darwin
- He observed lots of evidence, e.g., warning colours are used by some species like butterflies to deter predators from eating them
8
Q
How has the theory of evolution impacted modern biology and society?
A
- Classification of organisms from a common ancestor
- Antibiotic resistance has to be constantly developed to fight newly evolved resistant bacteria
- Conservation is important for organisms to adapt, creating conservation projects to protect species
9
Q
What fossils have provided evidence for human evolution? (3)
A
Hominid species fossils have been found:
- ‘Ardi’ 4.4m yrs
- ‘Lucy’ 3.2m yrs
- Leakey’s fossils 1.6m yrs
10
Q
What clues does ‘Ardi’ give about human evolution? (Ardipithecus ramidus)
A
- Found in Ethiopia, 4.4m yrs old
- Ape-like: Long arms, short legs, largetoes
- Human-like: Walked upright, didn’t use hands for walking
- Brain size was similar to a chimpanzee’s
11
Q
What clues does ‘Lucy’ give about human evolution? (Australopithecus afarensis)
A
- Found in Ethiopia, 3.2m yrs old
- Walked upright better than Ardi, with legs/feet more adapted to walking than climbing
- Brain slightly larger than Ardi’s, but still chimp-sized
- Limbs a mix of ape and human features, not fully like either
12
Q
How did Leakey’s findings provide evidence for human evolution?
(Homo species)
A
- Discovered in Kenya (1984) - Richard Leakey found many hominid species
- One a 1.6m yrs Homo erectus
- Turkana Boy was more human-like than Lucy
- Limbs and brain size closer to humans
- Walked more efficiently as feet + legs more adapted than Lucy’s
13
Q
How has the development of stone tools provided evidence for evolution?
A
Complex tools correlate with increased brain size.
14
Q
Describe the methods used by scientists to date tools.
A
- Structural features so simpler tools are older
- Carbon-14 dating, e.g., a wooden handle
- Stratigraphy by studying rock layers and the deeper the older
- Inaccurate as rock layers can move overtime
15
Q
What is a pentadactyl limb?
A
A limb with five digits, e.g., mammals, amphibians, reptiles.
16
Q
How does the pentadactyl limb provide evidence for evolution?
A
They have similar bone structures, but different functions which means that species have evolved from a common ancestry or it would be unlikely to have similar bone structures, e.g., a human hand and a bats wing.
17
Q
How did Woese split the 5 kingdoms into 3 domains?
A
- By studying RNA sequences, Woese discovered that some prokaryotes were very different from each other.
- So, he split them into two new groups archaea and bacteria.
- He also suggested organizing all life into three domains called archaea, bacteria, and eukarya.
- These domains are then broken down into smaller groups like kingdoms and species.
18
Q
What are the 5 kingdoms them divided into?
A
Smaller groups.
Kingdom, kyle
Phylum, play
Class, chess
Order, on
Family, fridays
Genus, good
Species, s***
19
Q
Name the five kingdoms.
A
- Animals
- Plants
- Fungi - mushrooms, toadstools, and yeasts.
- Protists - eukaryotic single-celled organisms without a nucleas.
- Prokaryotes - all single-celled organisms, e.g., algae.
20
Q
What happens to the number of organisms in each smaller group of kingdoms as you go down.
A
The number of organisms decreases.
21
Q
How has science improved over time to help with classification?
A
- With advances in technology, we can now study DNA and RNA sequences in different organisms.
- By comparing these sequences, we can see how similar they are-the more alike they are, the more closely related the organisms likely are.
- This helps us understand genetics and evolution better.
22
Q
Describe the three domains system.
A
Archaea,
Bacteria,
Eukarya,
23
Q
Describe the domain eukarya.
A
Includes a broad range of organisms, e.g., funig, plants, animals and protists
24
Q
Describe the domain bacteria.
A
True bacteria like E.coli and Staphylococcus.
25
Describe the domain archaea.
They look similar to bacteria but have different DNA and RNA sequences. They are found in extreme places like hot springs and salt lakes.
26
What is selective breeding?
Artificially selecting organisms with desirable characteristics.
Selective breeding is also known as artificial selection.
27
Outline the main steps in selective breeding.
1. Identify desired characteristics
2. Select the best and bread
3. Select offspring with the best characteristics and breed them
4. Repeat for several generations until all offspring have the desired characteristics
28
Why is selective breeding important in agriculture?
If farmers use selective breeding on bulls and cows with high meat, they can improve meat yield if they repeat over generation's.
29
Why is selective breeding important in medical research?
Research of alcoholism was done where rats would be bred with a strong or weak preference of alcohol which allowed comparison of differences like behaviour and brain function.
30
What are the four negatives of selective breeding?
- Reduced gene pool if different alleles
- Inbreeding disorders of inheriting harmful alleles. E.g. heart disease in boxer dogs
- Disease outbreak as there is not much genetic variation. Only a few will survive
- Ethical concerns as animals may be bred to have negative traits for medical research
31
How can plants be cloned? (2)
- Plant cuttings
- Tissue culture
32
What is tissue culture?
Growing cells on an artificial growth medium. The plants produced are genetically identical clones, so they have the same beneficial features, e.g., pesticide resistance, tasty fruit, etc.
33
How are plants grown using tissue culture?
1. Select plant
2. Take meristem samples, root or shoot tips
3. Grow in growth medium
4. Transfer to compost
34
What must be ensured in tissue culture?
Aseptic conditions to prevent the growth of microbes that harm plants.
35
What does the growth medium contain?
Nutrients and growth hormones.
36
Advantages of tissue culture. (4)
- Easy
- Fast
- Takes little space
- Grown all year
37
Disadvantages of tissue culture. (3)
- Reduced gene pool
- Low survival rate
- Harmful recessive alleles
38
Why is animal tissue culturing useful?
- Medical research
- Study tissue without harming animals
39
How are animal tissue cultures prepared?
1. Extract tissue
2. Separate cells with enzymes
3. Placed in a culture vessel and grown in a growth medium
4. After several cell divisions, they can be split up and grown in a culture vessel again
5. Stored for future use
40
What is genetic engineering?
Modifying an organism’s genome to introduce desirable characteristics.
41
What is the process of genetic engineering?
- Restriction enzymes cut DNA and vector to be left with sticky ends
- Ligase enzyme join two pieces of DNA from where they were cut
- The recombinant DNA is inserted into other cells, e.g., bacteria.
- These cells now use the gene to make proteins you want
42
What is a vector?
Something that is used to transfer DNA into a cell. They are plasmids and viruses.
43
What are the benefits of genetic engineering? (3)
- Modified crops survive herbicides. Farmers can spray weeds without harming the crops, so higher crop yields.
- Bacteria are modified to produce insulin for diabetes.
- Animals like goats+cows can be engineered to make medicinal proteins in their milk, which treat diseases like arthritis, cancer, and multiple sclerosis.
44
What are the risks of genetic engineering? (5)
- Unknown long-term effects
- Biodiversity loss
- Health issues in GM animals
- Affect food chains and human health
- A herbicide resistance gene may be picked up
45
What is Bacillus thuringiensis (Bt)?
Bacterium producing toxins killing insect larvae.
46
How is Bt used to protect crops such as corn and cotton?
Insert Bt toxin gene into crops so larvae die when feeding.
47
What are the benefits of Bt crops? (3)
- Higher yields
- Less use of chemicals
- Toxin-specific to pests
48
What are the risks of Bt crops? (3)
- Unknown consumption effects
- Pest resistance, so farmers use other insecticides
- Biodiversity loss
49
What are agricultural methods to increase food production? (2)
- Intensive farming using fertilizers to provide nutrients that help plant growth
- Biological control
50
What is the advantage of intensive farming?
Increases crop yields.
51
What are the disadvantages of intensive farming? (3)
- Eutrophication
- Reduced biodiversity
- Unethical practices
52
What is biological control?
Introducing predators to control pests.
53
What are the advantages of biological control?
- Long-lasting results
- Less environmental harm
E.g. cane codes were introduced to Australia to eat beetles that were damaging crops.
54
What is the risk of biological control?
Control organism becomes a pest.
E.g cane todes that were introduced to Australia now poision the native species that eat them.
55
What are some examples of nutrients that help plant growth?
Nitrates and phosphates.
56
What did Darwin and Wallace both do together? 🌹
They published their papers on evolution together, although they didn't always agree on the same thoughts of natural selection.
57
Why is Darwin more acknowledged than Wallace?
Darwin wrote a famous book, "On the Origin of Species," published in 1859 that gave lots of evidence of his theory's and expanded on them.
58
How do you measure brain size?
By working out the cranial capacity, which is the space taken up by the brain in the skull.
59
How did tools evolve over time?
Homo habilis (2M yrs): Simple sharp flakes for cutting.
Homo erectus (1M yrs): Hand axes for hunting/digging.
Neanderthals (300K yrs): Flint blades & spears.
Homo sapiens (50K yrs): Arrowheads, hooks, needles.
60
What is recombinant DNA?
Two different bits of DNA stuck together.
61
How can genetic engineering be used to help people with diabetes?
Bacteria containing the gene human insulin can be grown in huge numbers of fermenter to produce insulin for people with diabetes.
62
How can GM crops help food security?
Crops that are engineered to be resistant to pests grow better in drought conditions, improving yeild.
63
What is an example of a GM crop that combats deficiency diseases?
Golden rice has been engineered to produce a chemical that's converted in the body to vitamin A.
64
Why do people disagree with GM crops? (3)
1. People argue that the main problem is poverty
2. Some countries may become dependent on companies who sell GM seeds
3. Poor soil may be the main reason, so even GM seeds won't survive
