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Biology GCSE AQA (OH) > B-6 Inheritance, DNA and evolution > Flashcards

B-6 Inheritance, DNA and evolution Flashcards

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1
Q
  • What is DNA
A
  • DNA is the chemical that that genetic material is made up of
  • Coded information- act as instructions
  • ## Inherited characteristics
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2
Q
  • What is DNA’s structure
A
  • Two strands twisted together in double helix
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3
Q
  • What are chromosomes
A
  • Long molecules of DNA

- Come in paris

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4
Q
  • What are genes
A
  • Small sections of DNA on chromosomes
  • ## Each gene codes for sequence of amino acids that make a specific protein
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5
Q
  • What is a genome
A
  • Entire genetic material in an organism

- Scientists have worked out the human genome

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6
Q
  • What is the significance of working out the human genome
A
  • Working out common ancestors and migration patterns
  • Inherited disease gene cause
  • Disease and genes linked to it
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7
Q
  • What is sexual reproduction
A
  • Joining- fusing- of male and female gametes
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8
Q
  • What forms of sexual reproduction is seen in animals and plants
A
  • Animals- Sperm and egg cells

- Plants- Pollen and egg cells

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9
Q
  • Why are offering in sexual reproduction not identical
A
  • There is a mixing of genetic material which leads to a variety of offspring
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10
Q
  • What is the difference between mitosis and meiosis
A
  • Mitosis leads to identical cells forming

- Meiosis leads to non-indeoitcal cells

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11
Q

Why do gametes have half the number of chromosomes

A
  • Gametes are produced by meiosis and only have one cope of each chromosome
  • So when gamut fusion takes place the full fusion takes place
  • Ceel devisor takes place to make them have half the number of chromosomes
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12
Q
  • What is a gamete
A

-Sex cells with half the number of cells than the original

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13
Q
  • What are the stages in meiosis - extra knowledge
A
  • Copies the genetic material are made
  • Cell divides once after alining along centre
  • The cell is pulled apart and each new cell has a different combination of cells
  • In the second devising the chromosomes are pulled apart to the poles
  • They split again and four different cells are made
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14
Q
  • What happens when a cell divides to form gametes
A
  • Copies of gametes are made
  • Cell divides twice to form gametes - 4- each with single set of chromosomes
  • All gametes are genetically different
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15
Q
  • What is an allele
A
  • Different form os a gene
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16
Q
  • What is a dominant allele
A
  • If a dominant gene is present it will express itself regardless of other allele
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17
Q
  • What is a receive allele
A
  • Requires two receive alleles to be present to be expressed
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18
Q
  • What is meant by homozygous
A
  • An organism or gene that has two of the same alleles
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19
Q
  • What is meant by heterozygous
A
  • If two alleles are different
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20
Q

What is a genotype

A
  • Combination of alleles you have
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21
Q
  • What is a phenotype
A
  • Your expressed characteristics- determined by your genotype
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22
Q
  • What characteristics are controlled by a single gene
A
  • Fur in mice

- Red-green colour blindness

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23
Q
  • How do alleles work
A
  • Alleles work at a molecular level to develop expressive phenotype
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24
Q
  • Explain the genetics of a Tt gene combinations
A
  • TT- homozygous dominant- T expressed
  • tt- homozygous recessive
  • Tt or tT- Heterozygous dominate- T expressed
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25
Q

What are genetic disorders

A
  • Some disorders are inserted this is caused by inheritance of certain alleles
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26
Q
  • What is polydactyl disease
A
  • Inherited disorder
  • Having extra fingers or toes
  • Caused by dominant alleles
27
Q
  • What is the likelihood of getting polydactyl disease
A
  • With one parent having allele- 50%

- With two parents having allele- 75%

28
Q
  • What is cystic fibrosis
A
  • Disorder of cell membrane
  • Caused by recessive allele
  • Inherited disorder
29
Q
  • What is the likelihood of getting cystic fibrosis
A
  • Both parents have to be carriers- 25%
30
Q
  • What are arguments for genetic screening
A
  • Help stops suffering
  • Money saved- less treatment
  • Laws are in place to stop it going to far
31
Q
  • What are arguments against embryonic screening
A
  • Prejudice against “unwanted”
  • Everyone will want it to get perfect baby
  • Expensive
32
Q
  • How is sex decided
A
  • Ordinary human body has 23 sets of chromosomes
  • one pair determine sex

Male- XY Female- YY

  • 50% chance of either
33
Q
  • What is variation
A
  • Different characteristics within a population

- Caused by both environment and genetics

34
Q
  • How can environment impact organisms
A
  • An example is a plant- one with lots of light will grow luscious and green. One in a dark room will grow tall and spindly
35
Q
  • What are mutations
A
  • Change in genetic information
  • Occur continuously- very rarely will they lead to change in phenotype
  • Little effect on genetic code
36
Q
  • How can environmental change lead to new phenotypes
A
  • IF a new phenotype makes an organism more suited to an environment it will happen more rapidly by natural selection
37
Q
  • What is evaluation
A
  • Evolution is the change in inherited characteristics in a population over time through a process of natural selection
  • May result in new species
38
Q

_ What is the theory of evolution

A
  • All species living have developed from simple life forms over 3 million years ago
39
Q
  • What are the steps in natural selection
A
  • Organisms with desirable characteristics are more likely to survive
  • MORe likely to reproduce
  • Those without desired characteristic die off
  • Over time desirable characteristic becomes more and more prominent
40
Q

How do two species form from one

A
  • IF one species becomes so different that they can no longer reproduce to produce fertile offspring they are 2 species
41
Q
  • What is selective breeding
A
  • Process which humans breed animals and plants for particular genetic characteristics
  • Humans have been doing it for thousands of years
42
Q

-What are examples of selective breeding

A
  • Animals that have more meet or milk
  • Crops with disease resistance
  • Dogs with gentle nature
  • Decretive plants- large flowers
43
Q

What are the steps in selective breeding

A
  • Choose parents with desired characteristic
  • Breed
  • Breed offspring with desired characteristic
  • Reproduce
44
Q

What is the drawback to genetic engineering

A
  • Reduction in gene pool- inbreeding- genetic disease
45
Q

What is genetic engineering

A
  • A process that involves the genome of an organism and introducing the gene of an organism with the desired characteristic
46
Q
  • What are examples of GE
A
  • Plant crops have been GEd to make GMOs to produce higher yield and be resistant to disease
  • Bacteria have been Ged to produce insulin
47
Q
  • What are the pros of GE
A
  • Increased crop yield
  • Nutrient engineering- Golden rice- blindness - Beta carotene
  • Already ahppening- no bad effects yet
48
Q

What are the cons to GE

A
  • Gm crops reduce the population of wild flowers around it- in turn biodiversity reduced
49
Q
  • What are the steps in GE
A
  • Enzyme used to isolate required gene
  • Isolated into vector usually a virus or plasmid
  • Vector then used to insert it into required cell
  • Genes transfered to cells of animals, plants or micro-organisms in early stages- allow to develop with it
50
Q
  • What are fossils
A
  • Remains of organisms from millions of years ago found in rocks
  • We can earn about the extent of change
51
Q
  • How are fossils formed
A
  • Parts of organisms not decaying as not all conditions were present
  • Parts of organisms replaced by minerals
  • Preserved remains from organisms
52
Q
  • What issues with fossils
A
  • Uncertainty about starts earth as most organisms were soft bodied and left little remains
53
Q

-What is extension

A
  • No living individual of a species is left
54
Q
  • What are the causes of extinction
A
  • Environmental changes
  • New predator
  • New disease
    _ Can’t compete for food
  • Catastrophic event
55
Q

What is resistant bacteria

A
  • Bacteria that is now resistant to Antibiotics

- Bacteria as it can evolve at faster rate as it reproduces rapidly

56
Q
  • What are the steps in forming resistant bacteria
A
  • Mutation occurs
  • Strain is resistant when rest are killed off
  • Reproduce and become dominant form
  • No treatment and now immune
57
Q
  • What is MMRA
A
  • Resistant form of bacteria
58
Q
  • How can resistant bacteria be reduced
A
  • Only prescribed when needed
  • Finnish full course of antibiotics
  • Agricultural use limited
59
Q
  • Why can new medication not be made for resistant bacteria
A
  • Development of antibiotics is expensive and cannot be done at the same rate as the development of resistant strains
60
Q
  • What was the original form of classification
A
  • Linnaeus system

- Kingdoms- phylum-class-order-family-spices

61
Q

How does classification change

A
  • With more knowledge
62
Q
  • What was the system found in the 1990s
A
  • Woes’ system,
  • Archaea- Extremophiles-primitive
  • Bacteria- True bacteria
  • Eukyrots- Fungi, plants and animals- with a true nucleus
63
Q

What are evolutionary trees

A
  • Used to show how they believe organisms are related

- Fossil data is used to map extinct organisms

Biology GCSE AQA (OH) (9 decks)

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