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Biology > 6- Inheritance, variation and evolution (2) > Flashcards

6- Inheritance, variation and evolution (2) Flashcards

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1
Q

What are chromosomes?

A

long strands of DNA

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2
Q

What are genes?

A

small section of DNA that codes for a sequence of amino acids which make a specific protein

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3
Q

What is the structure of DNA like?

A
  • sugar-phosphate back bone
  • base that joins to complimentary base
  • double helix structure
  • polymers made up of repeating nucleotides
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4
Q

What are mutations?

A
  • Changes to genetic codes
  • change sequence of DNA bases to produce a genetic variant
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5
Q

Describe sexual reproduction.

A
  • mother and father produce gametes by meiosis
  • egg and sperm each have 23 chromosomes, fuse to make 46
  • genetic information from mother and a father
  • produces genetically different cells
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6
Q

Describe asexual reproduction.

A
  • only one parent
  • offspring are genetically identical to parent - clone
  • ordinary cell makes a new cell by dividing
  • bacteria, some plants and some animals reproduce asexually
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7
Q

Explain the process of meiosis.

A
  • genetic information duplicated
  • chromosomes arranged into pairs
  • chromosome pairs line up in centre of the cell
  • pairs pulled apart so each new cell only has one copy of each chromosome
  • in the second division chromosomes line up again in centre of cell and arms of chromosomes pulled apart
  • four gametes produced, single set of each chromosome in it, each genetically different from the other
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8
Q

What are the advantages of sexual reproduction over asexual reproduction?

A
  • sexual produces variation
  • variation increases species chance of survival
  • better adapted to environment
  • selective breeding for desired characteristics and increased food production
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9
Q

What are the advantages of asexual reproduction?

A
  • only needs one parent
  • less energy - don’t have to find a mate
  • faster
  • offspring can be produced in favourable conditions
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10
Q

What organisms use both methods of reproduction and how?

A
  • malaria - reproduces sexually in the mosquito and asexually in the human host
  • strawberries produce seeds sexually and runners asexually
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11
Q

What did Mendel do?

A
  • genetic experiments on pea plants
  • concluded characteristics are determined by ‘hereditary units’
  • hereditary unitspassed on to offspring unchanged from both parents, one unit from each parent
  • wasn’t until after death people realised significance of his work
    -research massively helped understanding
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12
Q

Describe genetic variation.

A
  • caused by different genes
  • because characteristics are determined by genes inherited from parents
  • genes passed on in sex cells (gametes)
  • genes are combination of those from parents so never identical
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13
Q

Describe environemntal variation

A
  • characteristcs in an environment causing visible changes to a species
  • e.g weight is determined by environmental conditions rather than genetic
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14
Q

What was Darwin’s theory of evolution?

A
  • it was done by natural selection
  • had to compete for limited resources in an ecosystem
  • more suitable characteristics means more likely to survive - animals that survive reproduce and pass favourable genes to offspring
  • organisms less adapted less likely to reproduce and carry on favourable characteristics
  • beneficial characteristics become more common and species changes - evolves
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15
Q

What is speciation?

A
  • the development of an organism so much that a new species is formed
  • happens when populations of the same species can no longer interbreed
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16
Q

What is extinction?

A
  • no individuals of a species remain
  • caused by environment changes, new predators, new diseases, catastrophic event
17
Q

Why didn’t people Darwin’s theory of evolution?

A
  • went against common religious beliefs
  • Darwin couldn’t explain how these new characterists appeared or were passed on
  • didn’t know anything about gene’s or mutations
  • wasn’t enough evidence to convince other scientists
18
Q

What were Lamarck’s idea’s on evolution?

A
  • argued changes organism acquires during lifetime passed on - e.g if characteristic used a lot the offspring would inherit it
19
Q

What is selective breeding?

A
  • selecting an organism with the most favourable characteristic to produce the most favourable offspring - e.g disease resistant crops
20
Q

What are the drawback’s of selective breeding?

A
  • reduced gene pool and variation
  • can cause health problem’s and disease
  • hard to survive if new disease introduced as less chance of resistant alleles
21
Q

What is genetic engineering?

A
  • transfering genes responsible for more favourable characteristics from one organism to another so it also has desirable characteristics
  • usefulgene isolated from one organisms genome using genome’s and is inserted into a vector
  • vector usually virus or bacterial plasmid
  • when vector introduced to target organism, useful gene inserted
  • used for genetically modifying crops and making animals resistant to disease
  • -
22
Q
  • Why is genetic engineering contraversial?
A

-worries about long term effects for future generations

23
Q

What are the adavantages of Gm CROPS?

A
  • Increase yield
  • add missing nutrients
  • already being grown in placed and not caused problems
24
Q

What are the disadvantages of GM crops?

A
  • some people believe will affect number of wild flowers growing and reduce biodiversity
  • not everyone convinced it’s safe as we don’t fully understand effects on human health
25
Q

How can plants be cloned by tissue culture?

A
  • few plant cells put in growth medium with hormones and grow into clones of parent plant
  • plants can be grown very quickly in little space and grown all year round
  • can be used to preserve plants that are rare and hard to produce naturally
26
Q

How are plant clones produce by cuttings?

A
  • gardeners take cuttings from parent plants to produce genetically identical clones
  • can be produced quickly and cheaply
  • more simple method than tissue culturing
27
Q

How can you make animal clones with embryo transplants?

A
  • sperm cells taken from a prize bull and egg cells from a prize cow using embryo transplants
  • sperm used to artificially fertilise egg
  • embryo developed and split multiple times
  • cloned embryo’s implanted into lots of other cows where they grow into baby calves
  • hundreds of ideal offspring can be produced every year
28
Q

How is adult cell cloning used to make clones?

A
  • unfertilised egg, nucleus removed and inserted into ‘empty egg cell
  • egg cell stimulated by electric shock to divide
  • implanted into woman womb with genetically identical copy of original adult body cells
29
Q

What are the issues surrounding cloning?

A
  • reduced gene pool - less variation
  • might not be as healthy as normal animal
  • people worry humans might be cloned
30
Q

How are most fossils made?

A
  • reptile dies and falls to the ground
  • flesh rots, leaving skeletons to be covered in sand or soil and clay
  • skeleton protected by sand or soil for millions of years
  • skeleton becomes mineralised and turns to rock
  • eventually, fossil emerges as rocks move and erosion takes place
31
Q

How can casts and impresion fossils be made?

A
  • when an organism burried in soft material clay
  • clay hardens and organism decays, leaving a cast of itself - footprints can also be preserved as casts
32
Q

How can preservation take place in other forms?

A
  • in amber and tar pits - no oxygen or moisture so decay microbials cannot survive
  • in glaciers where it’s too cold for decay microbes to work - Peat bogs are too acidic for decay microbials
33
Q

How can Isolation cause speciation?

A
  • populations of a species seperated
  • conditions on either side of barrier slightly different e.g different climates
  • populations adapt to new climates
  • pass on favourable adaptations to offspring
  • new species is formed
34
Q

What is antibiotic resistant bacteria?

A
  • random mutations that cause bacteria’s characteristics to change e.g more resistant to antibiotic, causing it to become unaffected by antibiotics
  • bacteria reproduce rapidly so adaptations happen quickly - resistant bacteria reproduce and increase population size - MRSA antibiotic superbug that affects people in hospitals and can be fatal
35
Q

What is the Linnaean system 1700’s?

A
  • system in organising animals introduced by Carl Linnaeus - divided into Kingdom, Phylum, Class, Order, Family, Genus, Species
36
Q

What is the Woese system?

A
  • 3 domain system
  • Archaea - prokaryotic cells first found in hot springs and salt lakes
  • Bacteria - true bacteria e.g E.Coli
  • Eukaryota - wide range of organisms including fungi, plants, animals and protists
  • these are then subdivided into Linnaeus sytem
37
Q

What is the binomial system?

A
  • how organisms are named
  • first part is genus, second part is species
  • used worldwide, same in all countries

Biology (17 decks)

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