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Biology > B2.8 > Flashcards

B2.8 Flashcards

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1
Q

What are fossils?

A

The remains of animals from many years ago

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2
Q

Where are fossils found?

A

In rocks

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3
Q

What parts of an organism don’t decay easily?

A

Hard parts like teeth and bones

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4
Q

How do animal remains turn into fossils?

A

By stopping or slowing down decay by being kept in certain conditions such as having no oxygen or microbes

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5
Q

What are some other fossils?

A

~ Traces like footprints

~ Burrows

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6
Q

What sort of creatures are more likely to decay quickest?

A

Soft bodied ones (eg slugs)

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7
Q

Why is there no evidence of the creatures very early on?

A

~ They were mainly soft bodied so decayed away

~ Or their fossils have been lost due to geological activity (erosion, volcanic activity)

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8
Q

What can fossils show?

A

~ How new organisms arise
~ How new species are formed
~ How some species may have become extinct

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9
Q

Why is there uncertainty about the evolution of creatures over time?

A

Because of the lack of enough valid and reliable evidence

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10
Q

What can cause extinction?

A 
~ New competitors 
~ New disease 
~ New predators
~ Catastrophe
~ Environmental change
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11
Q

What has impacted the numbers of the Dutch elm tree?

A

It was infected with Dutch elm tree disease

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12
Q

What happened to the dodo bird?

A

~ Lived in Mauritius in 17th century

~ Humans hunted them and rats ate their eggs

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13
Q

Why did the numbers of red squirrel decrease?

A

New competitors (grey squirrels) evolved and took lots of the red squirrels food

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14
Q

How can catastrophes affect species?

A

They can destroy habitats and kill those animals

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15
Q

What is genetic variation caused by?

A

A range of alleles

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16
Q

What does isolation mean for species?

A

They are separated by a barrier (mountains, sea, river, stream)

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17
Q

How could the environment affect species?

A

~ Could be warmer
~ Could have different types of food
~ Could have different plants

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18
Q

What is natural selection?

A

~ Variation sped up by mutation
~ Survival of fittest
~ Advantaged individuals breed
~ Genes passed on

19
Q

What is speciation?

A

When species become too different to interbreed

20
Q

What mainly affects speciation?

A

Environmental change

21
Q

What did Darwin find when he was in the Galapagos Islands?

A

~ He found finches on the different islands

~ They all had different adaptations, particularly their beak shape, to help them eat the food on their island

22
Q

What can nerve cells be used to treat?

A

Parkinson’s disease

23
Q

What are some different types of stem cells?

A

~ Embryonic stem cells
~ Foetal stem cells
~ Adult stem cells

24
Q

What can genetic engineering be used for?

A

~ Hormone and medicine production

~ Genetically modified crops

25
Q

How are hormones and medicine produced from genetic engineering?

A

~ Genes are cut out using enzymes
~ Genes are transferred from one organism to another
~ These organisms are used

26
Q

How are genetically modified crops produced from genetic engineering?

A

~ Genes are transferred to another organism at the early stage of development
~ The organism develops desired characteristics

27
Q

Why can stem cells be used to treat disorders?

A

Because they are unspecialised

28
Q

How many parents does asexual reproduction require?

A

1

29
Q

How many parents does sexual reproduction require?

A

2

30
Q

What does asexual reproduction produce?

A

Identical individuals (clones) of the parent

31
Q

What does sexual reproduction require?

A

~ Mixing of genes

~ Fertilisation of gametes

32
Q

What happens with the modern cloning technique of tissue culture?

A

~ Cells taken from leaf/stem/roots
~ Cells encouraged to grow by being put in agar jelly
~ Cells then grow into plants which are then placed in soil

33
Q

What happens with the modern cloning technique of embryo transplants?

A

~ An embryo is split into balls of smaller cells

~ One of these small balls of cells are put in the womb of host mothers

34
Q

What happens with the modern cloning technique of adult cell cloning?

A 
~ Skin cell taken from animal 1
~ Egg cell taken from animal 2
~ Nucleus from skin cell is placed in egg cell
~ Electric shock is given to cell
~ Placed in a host mother
35
Q

What is a genetically modified crop?

A

A crop that has had its genes modified by having genes from another organism added to it to adapt its characteristics

36
Q

What are some examples of genetically modified crops?

A

~ Cotton crops
~ Tomato crops
~ Corn crops
~ Maize crops

37
Q

What are some advantages of genetically modified crops?

A

~ Improves strength of crops
~ Improves growth
~ Effective for several years

38
Q

What are some disadvantages of genetically modified crops?

A

~ Damage to the environment
~ Potential damage to humans
~ More expensive in some cases
~ Can reduce the number of species

39
Q

What is a species?

A

A group of organisms capable of interbreeding and producing fertile offspring

40
Q

What is Darwins theory of evolution by natural selection?

A

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

41
Q

What was Lamarcks theory?

A

~ That a change in environment over time led to more use of neck and legs
~ Led to increased size of characteristic acquired dying lifetime
~ This characteristic was passed to offspring

42
Q

Why may 2 species have evolved from 1 original species?

A

~ The species became isolated
~ This change of environment caused genetic variation
~ Natural selection
~ Over time new species evolved which were too different to interbreed

43
Q

Where does evidence for early life forms come from?

A

Fossils

Biology (21 decks)

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