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BIOLOGY > INHERITANCE, VARIATION AND EVOLUTION > Flashcards

INHERITANCE, VARIATION AND EVOLUTION Flashcards

1
Q

What is DNA?

A

A chemical called deoxyribonucleic acid and is what all of the genetic material in a cell is made from
It contains coded information

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2
Q

Where is DNA found?

A

In the nucleus of a cell in chromosomes

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3
Q

What is the structure of DNA?

A

It is a polynucleotide and has a double helix structure

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4
Q

What is a gene?

A

A small section of DNA found on a chromosome
Each gene codes for a particular sequence of amino acids to make a specific protein (say in what order to put the AA)

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5
Q

What is a genome?

A

The entire set of genetic material in an organism

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6
Q

What are DNA strands?

A

They are polymers made up of lots of repeating units called nucleotides

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7
Q

What does a nucleotide contain?

A

Phosphate (circle)
Sugar (hexagon)
Base (square)

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8
Q

What are the different bases and which ones to they connect with?

A

A - T
C - G

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9
Q

How many bases codes one amino acid?

A

3

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10
Q

Where are proteins made?

A

In ribosomes (in the cytoplasm)

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11
Q

How are proteins made? - protien synthesis

A

A molecule called mRNA (copy of the DNA code) acts as a messenger between the nucleus and ribosomes carrying the correct amino acids in the correct order

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12
Q

What happens when a chain of amino acids have formed?

A

It folds into a unique shape which allows the protein to perform the task it is meant to do

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13
Q

What are some examples of proteins?

A

Hormones
Catalysts (enzymes)
Structural proteins

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14
Q

What is a mutation?

A

A random change in an organism’s DNA (can be inherited)

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15
Q

What do mutations do?

A

They change the sequence of DNA bases in a gene which produces a genetic variant
This leads to a change in protein made as there is not the correct amino acids to form it

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16
Q

What could happen if a mutation occurs and the proteins shape is changed (enzymes)?

A

The enzymes active site is changed so the substrate will no longer be able to bind to it

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17
Q

What is an insertion mutation?

A

When a new base is inserted into the DNA
Changes the way the group of 3 bases is read to code for an amino acid (can change more than one)

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18
Q

What is a deletion mutation?

A

When a random base is deleted from the DNA base sequence (like insertions)

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19
Q

What is a substitution mutation?

A

When a random base is changed to a different base in the DNA base sequence

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20
Q

What happens during sexual reproduction?

A

Mother and father produce gametes by meiosis (egg and sperm cells)
Each one contains 23 chromosomes
Egg and sperm cell then fuse together to form a zygote with the full number of chromosomes (46)

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21
Q

What happens during asexual reproduction?

A

The offspring is genetically identical to the parent
Happens by mitosis
Clone is produced

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22
Q

What are the steps of meiosis?

A

Cell duplicates its genetic information (chromosomes arrange themselves into pairs)
Cell divides into 2 and the two lines of chromosomes are split up
In the second division the 2 cells divide into 4 and the chromosomes are pulled apart
Four gametes are produced each with only a single set of chromosomes

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23
Q

How does sexual reproduction have an advantage over asexual reproduction?

A

In sexual reproduction the organism inherits genes from both its parents which produces variation
This increases the chance of a species survival (natural selection)

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24
Q

How does asexual reproduction have an advantage over sexual reproduction?

A

Only needs one parent so less energy and faster

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25
Q

What are the 23rd pair of chromosomes in the body?

A

XY (male) or XX (female)

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26
Q

What is an allele?

A

A different version of a gene/sequence of DNA

27
Q

What is homozygous recessive?

A

When the two alleles are the same and are both recessive
(bb)

28
Q

What is homozygous dominant?

A

When the two alleles are the same and are both dominant
(BB)

29
Q

What is heterozygous?

A

When the two alleles are different so one is recessive and one is dominant
(Bb)

30
Q

What is the only way an organism can display a recessive characteristic?

A

If both alleles are recessive

31
Q

What is your genotype?

A

The combination of alleles you have

32
Q

What is your phenotype?

A

What characteristics you have as a result of your genotype

33
Q

What allele is cystic fibrosis caused by?

A

A recessive allele

34
Q

What allele is polydactyly caused by?

A

A dominant allele

35
Q

What is cystic fibrosis?

A

Genetic disorder which results in the body producing a lot of thick sticky mucus in air passages and pancreas

36
Q

What is poldactyly?

A

When a baby is born with extra fingers or toes

37
Q

What are the benefits of embryo screening?

A

Helps stop people suffering
Treating disorders costs the government a lot of money
Laws in place (cannot select gender of baby)

38
Q

What are the problems of embryo screening?

A

Implies people with genetic disorders are ‘undesirable’
Expensive
People can pick the most desirable qualities that they want

39
Q

What is embryo screening?

A

Embryos are fertilised in a lab and then implanted in a woman’s womb
A cell can be removed from the embryo and its genes can be analysed which can detect any genetic disorders

40
Q

What did Mendel discover by observing pea plants?

A

Characteristics in plants are determined by hereditary units
(one unit from each parents passed onto offspring which can be dominant or recessive)

41
Q

What are gametes?

A

Reproductive/sex cells

42
Q

What causes genetic variation?

A

Combining of genes from two parents so no two of the species are genetically identical

43
Q

What are mutations?

A

Changes to the sequences of bases in DNA

44
Q

How can mutations create variation?

A

Change to base so change to protein therefore can result in a new phenotype which could be better suited to the environment then natural selection

45
Q

What is the idea of ‘survival of the fittest’?

A

Organisms with more suitable characteristics for the environment would be more successful competitors and would be more likely to survive to reproduce and pass on those genes

46
Q

When does speciation happen?

A

When the same species change enough to become reproductively isolated (can’t interbreed to produce fertile offspring)

47
Q

What is speciation?

A

When the phenotype of an organism changes so much because of natural selection that a completely new species is formed

48
Q

What are reasons for extinction?

A

Environment changes too quickly
New predator kills them all
New diseases kill them all
Can’t compete with another (new) species for food
Catastrophic event kills them (volcano)

49
Q

What did Lamarck believe?

A

That changes that an organism acquires during its lifetime will be passed on to its offspring

50
Q

What is selective breeding?

A

When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population

51
Q

What is a disadvantage of selective breeding?

A

Reduces the gene pool (number of different alleles) which is inbreeding

52
Q

What are the dangers of inbreeding?

A

Can cause health problems as there is more chance of e organism inheriting harmful genetic defects

53
Q

How is genetic engineering carried out?

A

Useful gene isolated from organism using enzymes and put inside a vector which is introduced to an organism and the gene is inserted into its cells

54
Q

What are the cons of genetically modified crops?

A

Affect number of wildflowers (and population of insects) which reduces farmland biodiversity
Might not be safe
Weeds may pick up the herbicide resistant gene

55
Q

What are the pros of genetically modified crops?

A

Increase yield
Engineered to contain nutrients that developing nations are missing

56
Q

What is isolation?

A

Where populations of the same species are separated (geographically due to physical barriers)

57
Q

What happens when species are isolated?

A

Environments are different (climate etc) therefore different characteristics will become more common in each population due to natural selection

58
Q

How can bacteria become antibiotic resistant?

A

Random mutations lead to changes in characteristics which can be resistant to particular antibiotic therefore antibiotic-resistant strains form
Bacteria reproduces rapidly so evolve quickly

59
Q

Why should you take the full course of antibiotics?

A

So all of the bacteria is destroyed so there are none left to mutate and develop into antibiotic-resistant strains

60
Q

What is the order of the Linnaean system (Carl Linnaeus 1700’s)?

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

61
Q

What is the three-domain system (Carl Woese 1990)?

A

Archaea (primitive bacteria)
Bacteria (true bacteria)
Eukaryota (fungi, plants, animals and protists)

62
Q

How do you figure out a species two-part Latin name?

A

Genus + species

63
Q

What do evolutionary trees show?

A

Show how scientists think different species are related to each other (common ancestors)

BIOLOGY (8 decks)

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