B7: Inheritance, variation & Evolution Flashcards
(83 cards)
1
Q
When are mutations able to happen?
A
When cells divide
2
Q
What happens when a mutation happens at meiosis?
A
It completely changes changes the genetics of the gametes
3
Q
What are the 4 genetically different gametes produced during sexual reproduction called?
A
Haploid cells
4
Q
Which is the processes that results in the formation of two genetically identical daughter cells?
A
Mitosis
5
Q
Sexual reproduction [definition]:
A
The process of reproduction where the nuclei of two gametes (sex cells) fuse to form a zygote
6
Q
How many parents are involved in sexual reproduction?
A
2
7
Q
Asexual Reproduction [definition]:
A
Asexual reproduction is the process of reproduction that forms genetically identical offspring from only one parent
8
Q
Genome [definition]:
A
The genome is the entire (all) genetic material of an organism
9
Q
What are the 3 levels of organisation in a genome?
A
- DNA
- Genes
- Chromosomes
10
Q
Asexual reproduction in fungi [7]:
A
- Spores germinate form new fungus
- Hyphae from two different fungi join
- Zygote formed when nuclei has 2 sets of chromosomes
- Meiosis happens
- Spores w/ single set of chromosomes germinate to form new fungus
- Fungal hyphae contain nuclei with one set of chromosomes
- Mitosis
11
Q
Hyphae [definition]:
A
A mass of thin threads that make up fungi
12
Q
Where are the organs for sexual reproduction in plants and what are they? [2]:
A
- The flower
- The pollen and egg cells
13
Q
Sexual Reproduction in plants [3]:
A
- The pollen from one flower must reach the female parts of another flower
- This is called pollination, it is the plant equivalent of mating
- Once the pollen has fused with the egg cell, seeds are formed
14
Q
How are flowers adapted for pollination?
A
They are adapted to attract animal pollinators such as insects, birds, or bats
15
Q
What does sexual reproduction bring about?
A
It introduces variation and enables plants to survive as conditions change through natural selection
16
Q
What is the main disadvantage of asexual reproduction in plants?
A
The new plants are identical to their parent and so no variation is introduced
17
Q
Reproduction in malaria inside the parasites
A
-
18
Q
Where do malarial parasites reproduce asexually?
A
They reproduce asexually in the human liver and blood cells
19
Q
What triggers the sexual reproduction of the malaria parasites?
A
The drop in temperature between the human body and the mosquito
20
Q
What does the fast changing variation in malaria parasites cause?
A
The fast changing variation in malaria parasites results from a life cycle that includes mitosis alone in humans and a combination of meiosis and mitosis in the body of the female mosquito
21
Q
Why does one always inherit their mitochondria DNA from their mother?
A
Because it comes from the mitochondria in the egg cell
22
Q
What is the aim of the 100,000 genomes project?
A
To find out as much as possible about human DNA
23
Q
What is a mutation unable to cause?
A
The destruction of an organism
24
Q
What happens when mutations take place non-coding DNA? [2]:
A
- It does not directly affect the phenotype
- However, variants in the non-coding DNA can affect which genes are switched on and switched off
25
How does inheritance work? [4]:
- The chromosomes you inherit carry genetic information in the form of genes
- Many of these genes have different forms or alleles
- Each allele codes for a different protein
- The combination of alleles you inherit will determine your characteristics
26
Variation [definition]:
Within a population, variation describes differences in the characteristics of individuals
27
What differences can variation be a result of? [3]:
- A combination of genetic and environmental causes
- The conditions in which the organism developed (environment)
- Genetics (inherited genes)
28
Evolution [definition]:
The gradual change of inherited characteristics of biological populations over time
29
When does speciation happen? [2]:
- When the average phenotypes of two populations have diverged so much that the two populations can no longer breed to produce fertile offspring
- Two different species have been formed
30
Speciation [definition]:
The process by which two species evolve from a single original species by natural selection
31
Why does speciation happen? [2]:
- It can happen as a result of evolution
| - Natural mutations can create new alleles and two populations can begin to diverge
32
Natural selection [2]:
- Natural selection was proposed by Charles Darwin in 1859
- He theorised that all species evolved from simple life forms that first appeared on Earth more than three billion years ago
33
How does natural selection happen? [3]:
- Individuals possessing genes that make them better adapted to the environment will have a greater chance of survival.
- Individuals with the best chances of survival are the most likely to breed successfully (because they survive).
- The characteristics responsible for the increase in the likelihood of survival are more likely to be passed on to the next generation.
34
Who came up with natural selection?
Charles Darwin
35
Selective breeding [2]:
- Speeds up natural selection by selecting animals that have a required characteristic
- Humans have done this in farming for thousands of years (with both crops and animals) to promote the genetic characteristics that we view as desirable.
36
What is getting strong, fast racehorses an example of?
Selective breeding
37
Steps in selective breeding [5]:
- Choose parents who most strongly display the desired characteristic.
- Breed the chosen parents
- From the resultant offspring (children), choose the offspring that best display the desired characteristic.
- Breed these chosen offspring.
- Repeat this process of breeding and re-selection over many generations until all the offspring show the desired characteristic
38
What type of selection is selective breeding?
Artificial selection
39
Uses of Selective Breeding [4]:
- In farming, animals that produce more milk or meat are also useful for yield-related reasons.
- Gentle-natured domestic dogs are useful as these animals must co-exist (live with) with humans.
- Flowers can be selected based on visual criteria, such as size or colour.
- Disease resistance in food crops is a useful characteristic because it improves yield (food production productivity).
40
Disadvantages of selective breeding [2]:
- Selective breeding can reduce variation (differences in characteristics) within a population, making it harder for a species to adapt to environmental change.
- Selective breeding can lead to inbreeding.
41
What is a problem caused by inbreeding?
Some breeds become particularly susceptible to disease or inherited defects
42
What are some examples of organisms that are selectively bred? [4]:
- Dogs
- Crops
- Farm animals
- Flowers
43
What is the desired characteristic in dogs when selective breeding?
Docile-nature
44
What is the desired characteristic in farm animals when selective breeding?
Produce more meat or dairy to increase yield
45
What is the desired characteristic in crops when selective breeding?
Disease resistance
46
What is the desired characteristic in flowers when selective breeding?
Visual features, such as colour and size
47
What agricultural term is used to describe food production productivity?
Yield
48
Genetic engineering [definition]:
The process by which scientists can manipulate and change the genotype of an organism
49
Examples of genetic engineering [2]:
- Insulin-producing gene
| - Vitamin A rice
50
How is the insulin-producing gene genetically modified?
The gene that produces insulin can be inserted into bacteria. Those bacteria can then mass-produce insulin to treat people with diabetes.
51
How is Vitamin A rice genetically modified?
- A lack of vitamin A can lead to blindness.
- A lot of communities that were lacking in vitamin A were found to use rice as the core of their diet.
- Therefore, a gene that produced vitamin A was taken from bacteria and added to rice, producing rice (golden rice) that was rich in Vitamin A.
52
What does genetic engineering involve? [2]:
- Modifying an organism's genome
| - Introducing a gene from another organism
53
Genetic engineering process [4]:
- Enzymes are used to “cut” the desired gene out of a chromosome.
- The same enzyme is used to “cut” a vector. The Vector is usually a bacterial plasmid (loop of DNA) or virus.
- The vector is used to insert the gene into the required cells.
- If the gene is delivered into cells before they have differentiated (at the egg or embryo stage), all cells in the developed organism will have the gene and show the characteristic.
54
What are used to "cut" genes out of DNA during genetic engineering?
Enzymes
55
What can a lack of vitamin A lead to?
Blindness
56
Uses of genetic engineering [3]:
- Transferring genes into animals
- Transferring genes into plants
- Transferring genes into bacteria
57
How are sheep genetically modified?
Sheep have had their genomes modified so that their milk contains drugs that can be used to treat human diseases.
58
Advantages of GM crops [5]:
- Preventing inherited diseases.
- Improving food production efficiency.
- GM crops generally show increased yields.
- They could help to provide the nutrients that are often missing from the diets of those living in developing nations
- GM crops are popular in some parts of the world and no complications have been experienced so far.
59
Disadvantages of Genetic Engineering [5]:
- Because it is a relatively recent development, it is uncertain what the long-term effects may be.
- Some consider it unethical to create new life forms or move genes between species.
- Some people expect GM crops to negatively impact wildflower and insect populations, thus reducing biodiversity.
- Some people think that there will be long-term effects of consumption on human health.
- If transplanted genes managed to escape into the natural environment, we could accidentally create a ‘superweed’ that is resistant to herbicides.
60
Clone [definition]:
Clones are genetically identical individuals (copies), produced naturally by asexual reproduction
61
What are the 2 methods of producing artificial clones?
- Tissue culture
| - cuttings
62
Monoculture [definition]:
When the individuals in a species are all the same
63
How can animals be cloned? [2]:
- Embryo transplants
| - Adult cell cloning
64
Tissue culture [4]:
- Small groups of cells are extracted (taken) from a plant and placed in a growth medium (such as a petri dish with plant food in).
- Division of these cells will eventually result in the formation of a clone of the parent plant.
- The advantages of this technique are that it is quick, space-efficient and time-independent.
- This technique is important for commercial use in nurseries and the preservation of rare species.
65
Cuttings [5]:
- Good parent plants are used by gardeners as a source of cuttings.
- To take a cutting, a branch is cut off from the parent plant.
- Hormones are then used to encourage the roots to grow and the cutting is then planted.
- Planting cuttings produce clones of the parent plant.
- This allows a large number of plants with favourable characteristics to be produced quickly and cheaply.
66
Adult cell cloning process [5]:
- Take an unfertilised egg cell and remove the nucleus.
- The egg cell is then injected with the nucleus from an adult body cell, belonging to the animal which is to be cloned.
- An electric shock is given to the egg cell to stimulate it to divide.
- Once the embryo has grown into a larger ball of cells, it is implanted into a surrogate mother.
- The embryo (a clone of the original adult body cell) will continue to develop in the womb of the surrogate.
67
Embryo transplants
Developing embryos can be split into smaller groups of cells before differentiation (cell specialisation) to give many smaller and identical embryos, which can then be put into host mothers
68
In the first step of adult cell cloning, what is removed from the unfertilised egg cell?
The Nucleus
69
A farmer fertilised egg cells with sperm from his best bull before splitting the embryo. We call this process:
Embryo transplantation
70
How was Dolly the sheep cloned?
Adult cell cloning
71
A new species is made when 2 populations have diverged so much that they cannot do what?
Breed
72
Dairy cows and wheat are well suited to their purpose due to what?
Selective breeding
73
Golden rice is supplemented with which of the following vitamins?
Vitamin A
74
What is the name given to the loop of bacterial DNA often used as a vector in genetic engineering?
Plasmid
75
According to Alfred Wallace's proposal, which of the following is the first stage in speciation?
Geographical isolation
76
Natural selection process [4]:
- Variation
- Survival of the fittest
- Successful breeding
- The best characteristics survive
77
The controversy around natural selection [3]:
- Natural selection challenged the common belief that God created the natural world.
- At the time, genes had not been discovered and Darwin was unable to suggest a method for the passing of characteristics between generations
- There were scientists that regarded the evidence presented by Darwin as inconclusive.
78
Theory of Inheritance of Acquired Characteristics [2]:
- Other theories of evolution proposed that changes in an organism over its lifetime could be passed on to its children.
- The most famous of these theories was Lamarck's theory of inheritance of acquired characteristics
79
Lamarck's observations about giraffes [4]:
- Giraffes have very long necks, which allow them to reach the upper branches of trees to feed
- Earlier giraffes had shorter necks and so would have to stretch to reach their food.
- Continual stretching resulted in the elongation of giraffe necks within a lifetime.
- Lamarck believed that this newly-acquired characteristic would then be passed on to the next generation
80
The credibility of Lamarck's theory:
Lamarck's theory has since been disproven. Changes that happen in an animal's lifetime are NOT passed on to future generations.
81
Who came up with the theory of inheritance of acquired characteristics?
Lamarck
82
How did Alfred Wallace explain speciation? [4]:
- Two populations of the same species become geographically isolated
- The population's exhibit (show) genetic variation.
- Due to differing environments and selection pressures, natural selection (survival of the fittest) operates differently on the populations.
- This eventually leads to genetic divergence until the populations are unable to interbreed to produce fertile offspring.
At this point, they have become two different species.
83
The joint writings of Alfred Russel Wallace and Charles Darwin [3]:
- Both had spent a significant amount of time on islands.
This decision helped their research on evolution because the isolation of island populations leads to enhanced speciation rates.
- In 1858, the two combined their great minds to produce joint writings.
- After the two had produced joint writings, Darwin accelerated the publication of ‘On The Origin of Species’ to be the first of the two to publish.
