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Biology Paper 2 > Inheritance, variation and evolution. > Flashcards

Inheritance, variation and evolution. Flashcards

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1
Q

What is DNA?

A

It is the chemical that all genetic material in a cell is made up of.

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2
Q

What is the function of DNA?

A

It codes for all inherited characteristics in an organism.

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3
Q

Where is DNA found?

A

In the nucleus in long strands called chromosomes.

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4
Q

What is the structure of DNA?

A

It is a two-stranded polymer coiled into a double helix.

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5
Q

What is a gene and what is its function?

A

It is a small section of DNA in a chromosome and it codes for specific amino acids in a specific order for a specific protein.

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6
Q

What does DNA also determine?

A

What proteins the cell produces and therefore what kind of cell it is.

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7
Q

What is a genome?

A

It is the entire set of genetic material in an organism.

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8
Q

Why is it important to understand the human genome for scientists?

A

They can see if certain genes are linked to diseases. By understanding inherited diseases will allow making effective treatments.

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9
Q

How can scientists trace human migration with the genome?

A

All humans are descended from a common ancestor and we have mostly identical genomes but by looking at specific populations there will be differences and with this knowledge, scientists can figure out where they split off.

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10
Q

What is a nucleotide and what does it contain.?

A

It is a repeating unit of the DNA polymer and it contains a phosphate group, a sugar, and a base.

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11
Q

What do bases join onto?

A

They join onto the sugar but also to the other side of a helix; with another base.

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12
Q

Which bases pair with each other?

A

A with T and C with G.

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13
Q

What does the order of bases decide?

A

The order of amino acids within a protein.

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14
Q

How many bases code for amino acids?

A

3

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15
Q

Where are proteins made?

A

Cytoplasm on ribosomes.

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16
Q

How do ribosomes make proteins?

A

They use the code in the DNA.

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17
Q

How does the DNA reach the ribosomes?

A

A molecule called mRNA copies the code from the DNA and acts as a messenger between the two.

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18
Q

Why are proteins needed?

A

They are necessary for enzymes, hormones, and structural proteins (for strength).

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19
Q

What are mutations?

A

They are a random change in an organism’s DNA and they can be inherited.

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20
Q

What can increase the chance of a mutation?

A

Exposure to radiation.

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21
Q

What effect do mutations have?

A

They change the sequence of the DNA bases and can therefore affect which proteins are made.

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22
Q

What are the types of mutation?

A

Insertion, deletions and substitutions.

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23
Q

What can insertions and deletions do?

A

Create knock-on effects for the coding of amino acids.

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24
Q

What is sexual reproduction?

A

Where genetic information is combined to be genetically different to the parents - it involves the fusion of two gametes (and therefore chromosomes).

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25
Q

What is asexual reproduction?

A

Where there are only one parent and the offspring are genetically identical.

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26
Q

How are gametes made?

A

Meiosis.

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27
Q

What is the process of meiosis?

A

The process starts off with one cell and from there duplicates its genetic material (chromosomes). The cell is then split and the chromosomes are pulled apart. So each cell has one copy of each chromosome. There is then another division where the chromosomes are pulled apart and it results in 4 gametes with only 23 chromosomes.

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28
Q

What does the process of meiosis result in?

A

Genetically different gametes after the chromosomes have been shuffled up.

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29
Q

What are the advantages of sexual reproduction?

A

It allows for natural selection, variation increases the chance of surviving as a disease might only wipe out the vulnerable, selective breeding can be used to speed up natural selection and create desirable characteristics?

30
Q

What are the advantages of asexual reproduction?

A

Only one parent is needed so you don’t need to find a mate, it is much faster as well.

31
Q

What is the male chromosome represented by?

A

Y and the female is an X

32
Q

What are the chances that a child is a girl?

A

50%

33
Q

How do genes control your characteristics?

A

They have two alleles (versions) of every gene in your body and these are on each chromosome in your body.

34
Q

What is it called when both alleles are the same?

A

Homozygous.

35
Q

What happens if the alleles are heterozygous.

A

One will either be dominant or recessive and the dominant will overrule the other.

36
Q

What is polydactyly caused by?

A

A dominant allele.

37
Q

What is in vitro fertilisation (IVF)

A

When embryos are fertilized in a laboratory and implanted into the mother’s womb.

38
Q

How can embryos be screened for genetic disorders?

A

During IVF a cell can be removed and analyzed for genetic disorders.

39
Q

What are some issues with embryonic screening?

A

They fear that it might lead to a point where people pick and choose their children, or that they totally disregard undesirable people and it is expensive.

40
Q

What are the arguments for embryonic screening?

A

It will stop suffering, it will save money in the long run and there are laws against it going too far.

41
Q

Who was Gregor Mendel and what did he discover?

A

He was a monk that studied pea plants and saw that the height was determined by ‘hereditary units’ (GENES) which were passed down. He saw that the unit for tall plants -T - was dominant over the unit for small plants - t .

42
Q

Why did it take a long time for people to accept Mendel’s work?

A

Nobody knew about genes, DNA, or chromosomes. He was only a monk. It was only when similarities were seen by scientists who were starting to understand chromosomes.

43
Q

What are the two types of variation?

A

Genetic and environmental.

44
Q

What are examples of genetic variation?

A

Eye colour, blood group, inherited disorders.

45
Q

What are examples of enironmental variation?

A

Sunlight can affect the height of plants.

46
Q

What introduces variation?

A

Mutations.

47
Q

What is the theory of evolution?

A

All of the species of today are descendants of the very first simple life forms and they have evolved from that.

48
Q

What is the “survival of the fittest?”

A

Darwin knew there can be wide variation in a species and that these organisms have to compete for resources. He concluded that those with the best characteristics were more likely to survive and therefore were more likely to reproduce and to pass down their characteristics.

49
Q

What is a phenotype?

A

An organisms’ observable characteristics determined by the genotype.

50
Q

What is speciation and how can it occur?

A

When a new species is created and it cannot breed the old one. This can come from geographical separation.

51
Q

How can extinction occur?

A

New predator, environmental change, disease, competition, catastrophic event.

52
Q

Why did people disagree with Darwin?

A

It went against religion, there was not much explanation on Darwin’s part; just a lot of statements. There was not enough evidence.

53
Q

Why was Lamarck so dumb?

A

He thought that the changes in an organism during its lifetime were passed on. But after enough observations and hypotheses, he was rejected.

54
Q

What is selective breeding?

A

It is when humans select which animals or plants will be bred together for certain purposes.

55
Q

What are the reasons for selective breeding?

A

Crops with disease resistance, dogs with good temperament, animals with more meat or milk, and plants that look nice.

56
Q

What is the process for selective breeding?

A

Choose to desirable organisms - breed them together and then breed those offspring and so on for a few generations until the desired characteristics

57
Q

What is the main drawback of selective breeding?

A

Reduction in the gene pool as the number of different alleles goes down with selection. This causes health problems and defects. Also if a new disease comes there is not a lot of variation all could die.

58
Q

What is genetic engineering?

A

Transferring genes that have the desirable traits from one organism to another.

59
Q

How is genetic engineering carried out?

A

The useful gene is cut out by enzymes and put into a vector. A vector can then be put onto a virus or bacterial plasmid. The vector is then inserted into the cell.

60
Q

For what reasons might scientists use genetic engineering?

A

Bacteria have been modified to make insulin, crops can be improved for yield, quality, and the ability to withstand disease, to prevent inherited disease and treat it.

61
Q

What are the pros of genetically modified crops?

A

Increased yield, withstand disease, can help people who lack nutrients to include more in their diets as well as being able to be grown in more hostile environments.

62
Q

What are the cons of genetically modified crops?

A

It can affect biodiversity levels, people are worried about whether it is safe for humans.

63
Q

What are the different ways of cloning?

A

Using tissue culture, plant cuttings. Embryo transplants. Adult cell cloning.

64
Q

What is tissue culture cloning?

A

When plants are grown in a medium that is very beneficial for their growth (hormones are used etc.) and can be used to preserve species or to improve the stock.

65
Q

What is plant cutting cloning?

A

Taking a cutting of a good parent plant and planting it to produce copies and can be done cheaper and quicker.

66
Q

How do embryo transplants work?

A

Sperm and egg cells are taken out of the good parents and fertilized. This embryo then splits many times and the clones are implanted into mothers.

67
Q

What is adult cell cloning?

A

Taking an unfertilized egg cell - removing its nucleus. A nucleus from an adult body cell is put into the egg cell. which is then electrically shocked into division and then put into an adult female.

68
Q

What are the issues surrounding cloning?

A

Could be unhealthy, reduced gene pool, worry for human cloning in the future.

69
Q

What are fossils?

A

The remains of organisms in rocks.

70
Q

What are the three ways of fossil formation?

A

Gradual replacement by minerals, From casts and impressions. From preservation where no decay happens.

Biology Paper 2 (3 decks)

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