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GCSE Biology > B14 Variation and Evolution > Flashcards

B14 Variation and Evolution Flashcards

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1
Q

What is Variation?

A

The difference in the characteristics of an individual in a population

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2
Q

What are reasons for variation?

A
  • Genetic causes (differences in inherited genes: eye colour, sex)
  • Environmental causes (conditions an organism develops in: plants grown in light, deprived of co2 or mineral ions)
  • Combination of both (Environmental + Genetic causes: inherited hair and skin colour, get bleached or darker skin from sun)
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3
Q

What are the only type of genetically identical humans?

A

Identical twins- from the same fertilised egg

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4
Q

What is Natural Selection?

A

Organisms gaining an advantage over members of their own species through mutation, making them more likely to breed and survive

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5
Q

What is a phenotype?

A

the physical characteristics of an organism

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6
Q

What is the theory of evolution by natural selection?

A

All species of living things have evolved from simple life forms that first developed over 3 billion years ago

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7
Q

When do mutations occur?

A

Occur continuously, can take place when cells divide

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8
Q

What happens if a mutation takes place when gametes are formed?

A
  • Affect phenotype, introduce new variants into genes of species (important for survival)
  • Mutations can have no effect on phenotype, can also be fatal
  • Mutations RARELY produce adaptations making organisms better suited to their environments/ give advantages if there is an environmental change
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9
Q

How can evolution result in organisms well suited to their environments ?

A
  • individual organisms within a particular species may show a wide range of phenotype and genetic variation
  • those with characteristics best suited to the environment are more likely to survive + breed successfully
  • the alleles (variants) enabling the individuals to survive is passed onto offspring
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10
Q

When can a population of species evolving through natural selection be named a different species to another population of the same initial species?

A

If 2 populations of 1 species become so different they can no longer interbreed to produce fertile offspring, they have formed 2 new species

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11
Q

What is Selective Breeding?

A

The process where humans breed plants and animals for desired characteristics

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12
Q

What is the process of selective breeding?

A
  • Farmers + breeders select animals and plants from mixed populations that have useful or desirable traits- they are their breeding stock
  • then select offspring and only breed from the ones that show desired characteristics
  • continues over generations until all offspring show desired characteristic
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13
Q

What are examples of desired characteristics?

A
  • disease resistance (plant)
  • animals producing more meat, milk etc (food produce)
  • domestic dogs and farm animals with gentle nature
  • bright, large, unusual or heavily scented flowers
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14
Q

What are some problems with Selective breeding?

A
  • reduces number of alleles in population (only individuals with specific alleles are allowed to breed)-> reduces variation, can result in population dying out if the environment changes (new disease, climate change)
  • Can results in inbreeding-> little variation in population, prone to diseases + inherited defects
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15
Q

What is genetic engineering?

A

Modifying the genetic material of an organism to give it more desirable characteristics

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16
Q

What is the process of genetic engineering?

A
  • enzymes are used to isolate and take the required gene from an organism
  • gene is then inserted into a vector using more enzymes (ie bacterial plasmid or virus)
  • vector is then used to insert gene into required cell (bacteria, animal, fungi or plants)
  • genes transferred to cells at early stage of development (ie egg or early embryo in animals).

Organism grows, develops new desired characteristics from other organism

17
Q

How are plants usually genetically engineered?

A

Desired genes often inserted into meristem cells-> used to produce identical clones of genetically modified plant

18
Q

What are examples of transferring genes to animal and plant cells?

A
  • Genetically engineered bacteria can be cultured on a large scale-> make huge quantities of protein for other organisms (Ie human insulin, human growth hormone)
  • genes from jellyfish-> produce glow in the dark crops
  • animals make human proteins in their milk
  • modified mice to model human diseases (Alzheimer’s, cancer, diabetes)
19
Q

What are GM crops?

A

Crops that have had their genes modified by genetic engineering techniques
(genetically modified crops)

20
Q

What are characteristics of GM crops?

A
  • often show increased yields-> improved resistance to insect attacks
  • more resistant to herbicides-> farmers can spray + kill more weeds without damaging plants (increase crop yield)
  • increase size of fruit or nutritional value of the crop
21
Q

Why is increasing crop yield important? + examples

A

provides food security for world’s human population

  • modified potatoes to make more starch + be more resistant to several common pests
  • modified soy beans-> produce healthier balance of fatty acids
  • Golden rice filled with nutrients
  • resistant to common diseases (ie mosaic virus)
22
Q

What is a clone?

A

an individual that has been produced asexually and is genetically identical to the parent

23
Q

Why are certain animals and plants chosen to be cloned?

A

High quality characteristics
- resistance or high milk yield etc

24
Q

What do clones have identical genetic information to?

A
  • to each other
  • to the single parent nucleus
25
Q

What is Tissue culture? + process

A

a modern technique for cloning plants

  • take a small meristem tissue sample from a cutting of the parent plant
  • grow the tissue in the agar with a mixture of nutrients and plant hormones-> starts as a small group of cells from the plant to a callus (big mass of identical plant cells)
  • use a different mixture of hormones and nutrients, stimulating each cell to form a new plant
  • the whole process must be aseptic
26
Q

Why is tissue culture popular for as a commercial cloning technique?

A
  • this process guarantees produces many offspring identical to the parent plant
27
Q

What is the process of taking cuttings?

A

Cut a section of leaf, stem or root
Add rooting powder containing auxins
Plant cutting into soil, leave to grow

28
Q

What is the process of Embryo transplants?

A
  • an early embryo produced from parents with desired characteristics
  • divide each embryo into individual cells
  • transfer embryo into host mothers, who have been given hormones to prepare for pregnancy
  • identically cloned calves are born, not biologically related to host mother, genetically identical to one another
29
Q

What are uses of cloning embryos?

A
  • transport high-quality embryos all over the world-> to places where cows with high milk/meat yield are badly needed for breeding with poor quality local stock
  • make identical copied of embryos, genetically modified to be medically useful compounds
30
Q

What is the process of Adult cell cloning?

A
  • the nucleus is removed from an unfertilised egg cell
  • nucleus is taken from an adult body cell (ie skin cell) of the same species
  • empty egg cell is fused together with the DNA in the nucleus
  • cell is given electric shock, stimulating division into embryo cells
  • when the embryo is developed enough it is placed into the uterus of an individual of that species
  • the embryo is a clone of the parent’s DNA in the nucleus
31
Q

Who is Dolly the Sheep?

A

the first large mammal ever to be cloned from the cell of another adult

32
Q

What are the benefits and risks of adult cell cloning?

A
  • can be cloned to produce useful proteins in milk etc
  • save animals from extinction
  • clone pets/prized animals after they die (CAN BE SEEN AS UNETHICAL)
  • could lead to the cloning of human babies-> unethical, could be an abused solution
  • reduced variety in populations (identical genes), less likely to survive with changes in the environment
33
Q

What is a benefit of genetic engineering regarding human disorders?

A

It has potential to cure inherited human disorders

34
Q

What are benefits of genetic engineering for humans?

A
  • genetically engineered microorganisms can make proteins humans need (ie human insulin)
  • genetically modify mice to mimic human diseases-> useful in developing cures (ie cancers, diabetes)
  • improved growth rates of plants and animals
  • increased g
35
Q

What are benefits of genetic engineering for agriculture?

A
  • improved growth rates of plants and animals
  • increased food values of crops, GM crops = larger yields
  • crops can be designed to grow in hot, dry or cold areas in the world
  • crops can be engineered to produce plants that make their own pesticide or resistant to herbicide
  • GM crops (ie golden rice) beginning to solve world hunger issues
36
Q

What are concerns about Genetic engineering?

A
  • new technology, lack of understanding of long term effects
  • concerns of effect on human health of eating GM food
  • genes from GM plants spreading into wildlife-> might spread infertility genes
  • fears of human engineering-> ethical concern. (manipulate genes of future children or ‘designer children’ with desirable characteristics like looks or intelligence)

GCSE Biology (20 decks)

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