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A Level Biology Revision > Genetic information, variation and relationships between organisms- Joseph Felton > Flashcards

Genetic information, variation and relationships between organisms- Joseph Felton Flashcards

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1
Q

State three differences between the DNA of eukaryotes and prokaryotes?

A

Eukaryotes have a nucleus and their DNA is long, linear and associated with histone proteins. Prokaryotic cells have circular DNA called plasmids found in the cytoplasm of their cell.

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2
Q

What is a gene?

A

A base sequence of DNA that codes for an amino acid sequence of a polypeptide.

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3
Q

What is the name of the fixed position a gene occupies on a DNA molecule?

A

The locus.

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4
Q

What is a triplet?

A

A sequence of three DNA bases.

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5
Q

The genetic code is degenerate. What does this mean?

A

There are four DNA bases that can only code for a possible 64 triplet codes.

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6
Q

What is the difference between an intron and an exon?

A

An exon is a base sequence that codes for an amino acid. An intron is a non-coding sequence.

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7
Q

What is the difference between a genome and a proteome?

A

The genome is the complete set of genes within a cell and the proteome is the proteins they code for.

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8
Q

Name the three different types of RNA found within a cell?

A

Ribosomal RNA, mRNA and tRNA.

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9
Q

Where does transcription take place?

A

In the nucleus.

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10
Q

What is the role of RNA polymerase?

A

To add the RNA nucleotides to complete the mRNA strand.

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11
Q

What is the difference between pre-mRNA and RNA?

A

Pre-mRNA still contains both introns and exons where mRNA has had its introns removed through splicing.

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12
Q

What is the precise site of protein synthesis?

A

The ribosome.

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13
Q

What is a codon?

A

three DNA bases.

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14
Q

What is the role of tRNA?

A

Transfers an amino acid to the binding site of the ribosome.

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15
Q

Where does meiosis occur?

A

In the gonads of sexually reproductive eukaryotic organisms.

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16
Q

How many daughter cells are produced in meiosis?

A

4

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17
Q

Distinguish between the terms haploid and diploid?

A

Haploid is half the number of chromosomes whereas diploid is the full set of chromosomes.

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18
Q

State two processes which occur during meiosis that increase genetic variation?

A

Independent segregation and crossing over.

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19
Q

State two types of gene mutation?

A

Base deletion and base substitution.

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20
Q

Name two ways mutation can occur?

A

Affects from UV radiation and X-rays.

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21
Q

What is the name of the process that involves a mutation in the number of chromosomes during meiosis?

A

Chromosome non-disjunction.

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22
Q

What is genetic diversity?

A

The number of different alleles within a population.

23
Q

How can new alleles of a gene appear in a population?

A

Random mutation.

24
Q

State three types of adaption that organisms might have?

A

Anatomically, behaviourally, physiologically.

25
Q

What is a phenotype?

A

A phenotype is a physical characteristic of an organism.

26
Q

Give one example of directional selection?

A

Antibiotic resistance.

27
Q

Give on example of stabilising selection?

A

Weight of babies.

28
Q

What is a species?

A

A group of organism that can produce fertile offspring.

29
Q

Why is courtship behaviour important?

A

To allow successful mating

30
Q

What is a taxon?

A

A class of organism.

31
Q

What is the correct order?

Class, domain, phylum, species, genus, kingdom, order, family,

A

Domain, Kingdom, phylum, class, order, family, genus, species.

32
Q

What is a phylogenetic classification system?

A

Shows relationship between members in the same taxon.

33
Q

Name two modern techniques which have allowed evolutionary relationships between organisms to be discovered?

A

Genome sequencing, immunological comparisons

34
Q

What is species richness?

A

Number of different species in a community.

35
Q

Why is an index of diversity a better measure of biodiversity than species richness?

A

Takes into account both the number of species and the number of individuals of each species.

36
Q

What does the symbol mean?

A

‘sum of’

37
Q

State two ways intensive farming has reduced biodiversity?

A

Trees are felled and hedgerows are pulled up

38
Q

Why do farmers need to produce more food?

A

To cope with the growing population.

39
Q

Why is it important to use random sampling when collecting data?

A

To not be biased.

40
Q

How would you find the mean value of six values?

A

Total the six values then divide them by how many values there are.

41
Q

What is standard deviation?

A

How much the data varies from the mean.

42
Q

What is the name of the distribution shown by the graph?

A

Normal distribution.

43
Q

Where would the mean value be on the graph?

A

Where the values vary.

44
Q

What is the structure of RNA?

A

Pentose sugar, a nitrogen-containing organic base, a phosphate group.

45
Q

Describe the process of transcription?

A

Enzyme acts on specific region of DNA causing two strands to separate exposing nucleotides, the template strand pairs with complementary nucleotides from the pool present in the nucleus, RNA polymerase joins nucleotides to the strand. when a ‘stop’ triplet code is reached RNA polymerase detaches.

46
Q

Describe the process of translation?

A

A ribosome becomes attached to the starting codon, tRNA molecule with a complementary anticodon sequence moves to the codon and pairs up with the codon on the mRNA. A tRNA molecule with a complementary anticodon pairs with the next codon on the mRNA. Both tRNA molecules carry a specific amino acid. This process continues as the two amino acids are joined by a peptide bond using an enzyme and ATP which is hydrolysed to provide energy. This process continues until the ribosome reaches a stop codon and polypeptide chain is complete.

47
Q

What is chromosome non-disjunction?

A

When a gamete has one more or fewer chromosomes.

48
Q

What is directional selection?

A

When the phenotype that are best suited to the new conditions are most likely to survive.

49
Q

What is stabilising selection?

A

The individuals with the phenotype closest to the mean will survive. Individuals with phenotypes at the extremes will not survive.

50
Q

What is the difference between interspecific variation and intraspecific variation?

A

Interspecific variation is where one species differs from another, intraspecific variation is where members of the same species differ from another.

51
Q

What happens during base substitution?

A

A nucleotide in a DNA molecule is replaced by another nucleotide that has different base.

52
Q

What happens during base deletion?

A

When a nucleotide is lost from the normal DNA sequence.

53
Q

What is an allele?

A

One of the particular forms of a different gene.

54
Q

What happens during crossing over?

A

Chromatids of each pair becomes twisted round each other, tension is created and portions of the chromosome break off. broken portions may re-join with homologous partners, new combinations of paternal and maternal alleles are produced.

A Level Biology Revision (10 decks)

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