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Science biology > Natural Selection > Flashcards

Natural Selection Flashcards

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1
Q

What are fossils?

A

The ‘remains’ of organisms from millions of years ago, which are found in rocks

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2
Q

What are the 3 main ways that fossils are formed?

A

1 ) Gradual replacement by minerals

  • Decay really slowly
  • Replaced by minerals
  • Form rock-like substances
  • Dig them up
  • Separate from rock

2) Casts and impressions
Casts:
- Organism buried in soft material (clay)
- As the clay hardens (organism decays)
- Left with gap same size and shape as the organism
Impressions:
- Footprint that stays there for a very long time

3) Preservation (no decay)

  • Organisms stuck in amber or tar pits
  • No oxygen or moisture, no decay takes place and organism remains completely in-tact
  • Can happen in glaciers (too cold) or in peat bog (too acidic)
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3
Q

What are some reasons why a species might go extinct?

A
  • Environment changes too quickly
  • Habitat cut down
  • New predator
  • New disease
  • new species outcompetes them
  • Catastrophic event
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4
Q

Why are fossils used to as evidence for evolution?

A

Fossils show us how species have changed over millions of years

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5
Q

Why is the fossil record incomplete?

A
  • Some organisms are soft-bodied so do not fossilise well

- Some fossils formed long ago may have been destroyed since

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6
Q

What is the Linnean system?

A

New type of classification system created in the 1700’s by Carl Linneus, based on characteristics and bone structure

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7
Q

What are the groups of the Linnean system?

A
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
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8
Q

What is the Binominal system?

A

Where you name species based on their genus and species name

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9
Q

What is the Three Domain System?

A

Introduced by Carl Woese

  • Eukaryota
  • Bacteria
  • Archaea
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10
Q

What are evolutionary trees?

A

Evolutionary relationships between different species or groups ‘common ancestors’

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11
Q

What do the branch points show on an evolutionary tree (circled red in the above diagram)?

A

The divergence of a single population/species into two separate populations/species

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12
Q

What is selective breeding?

A

Take the best plants or animals and breed them together, in the hope of getting even better offspring

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13
Q

What is the process of selective breeding?

A
  • Select the thing you want to breed that has the characteristics you’re after
  • Breed them together
  • Then again, out of the offspring, choose the most desirable characteristics
  • Breed again

You do these steps for all generations, to get the characteristics that you desire

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14
Q

What are some drawbacks of selective breeding?

A
  • Reduces the gene pool of the population
  • Can sometimes lead to inbreeding (makes offspring particularly prone to diseases and defects)
  • Less variation within a population
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15
Q

What is a gene pool?

A

Collections of all the alleles of an entire population

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16
Q

What is genetic engineering?

A
  • Find one organism that has the desired characteristic
  • Pick the gene responsible for that trait
  • Transfer that gene to another organism, so that organism will develop the same trait

This is modifying the organism’s genome
You can call this organism genetically modified

17
Q

What is gene therapy?

A

To use genetic engineering to treat inherited disorders

  • You give a person a healthy version of the gene in hope that it will fix the problem
18
Q

What are some problems of gene therapy?

A
  • The faulty gene will be in all cells - would have to transfer the new gene into every cell of the body
19
Q

What are pros and cons of genetic engineering using crops as an example?

A

Pros:

  • Crops with more desirable characteristics
  • More fruits
  • Resistant to disease
  • More food for less money
  • Important in developing countries

Cons:

  • Don’t know how genetically modified plants might affect our health
  • Plants might make themselves into the wild, and outcompete other plants and change the whole ecosystem
20
Q

What are the steps for genetically engineering?

A
  • Find gene that you want
  • Cut that section of DNA out to isolated, done with enzymes
  • Insert gene into a vector (could either be a virus or a bacterial plasmid)
  • Introduce vector to whichever organism we want to have the gene
  • Organism cells will take up the vector and the genes it contains
  • Start producing the protein that the gene codes for

Science biology (12 decks)

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