12: Biodiversity Flashcards

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1
Q

Define Habitat & Community:

A

Habitat: place where an organism lives
Community: all the organisms in a habitat

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2
Q

What does Species Diversity consist of?
What is the Diversity Index formula?

A
  • number of different species present
  • number of individuals in each species

D = N(N-1) / sum of n(n-1)
N = Number of individuals of all species
n = number of individuals in a particular species

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3
Q

How can we avoid bias?
How can we get a representative sample?

A
  • Random Sampling
  • Use a very large number of quadrats (at least 20)
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4
Q

Describe Random Sampling:

A
  1. grid is laid out across the sample using tape measure
  2. random numbers are generated (i.e from random number generator) to provide coordinates for the grid
  3. these will be the sample points where frame quadrats are are placed
  4. within each quadrat, the number of species are counted + each organism in the quadrat is identified
  5. a very large number of randomly placed quadrats are required
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5
Q

Describe the Impact of Agriculture on Species Diversity:

A
  1. lower variety of habitats/niches (removal of grassland + hedgerows)
  2. fewer plant species, as only one crop is grown & weed removed/killed by herbicides
  3. few species of herbivores due to little variety of food
  4. lower types of carnivores, due to less herbivores
  5. lower diversity due to pesticides decreasing insect species
  6. low species diversity
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6
Q

How are Hedgerows a potential advantage for species diversity?

A
  • provides habitats for organisms
  • provides food + shelter for organisms
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7
Q

Define Gene:
Define Allele:
Define Genetic Diversity:

A
  1. short section of DNA that codes for a polypeptide
  2. different versions of a particular gene
  3. number of different alleles of genes in a population
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8
Q

What are the 3 causes of Genetic Variation?
What is the only way there can be variation in asexual organisms?

A
  1. mutation
  2. meiosis
  3. random fusion of gametes

Mutation

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9
Q

How can Gene Mutation lead to Non-Functioning Proteins?

A
  1. a gene is the sequence of bases in DNA that codes for the production of a protein
  2. if the sequence of DNA bases is altered in a gene, then this changes the sequence of bases in mRNA that is transcribed
  3. therefore this could change the sequence of amino acids translated for a protein
  4. this change in the primary structure of the protein causes a change in the tertiary structure, as hydrogen ionic and disulphide bonds form in different places
  5. this leads to a loss in function of protein
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10
Q

What is Meiosis 1?
What is Meiosis 2?

A
  1. homologous pairs separate, and the cells become haploid
  2. centromere breaks, and chromatids separate
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11
Q

How does Meiosis lead to Variation?

A
  1. it forms a new combination of alleles
    - independent segregation of homologous chromosomes (meiosis 1)
    - crossing over (meiosis 1)
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12
Q

Describe Independent Segregation (meiosis 1):

A
  • at the start, homologous chromosomes pair up, and line up at the equator of the spindle
  • this causes the orientation of the homologous chromosomes to be random
  • these homologous chromosomes will then separate into, different combinations of maternal + paternal chromosomes in the gametes formed
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13
Q

How do you work out the number of combinations of maternal + paternal chromosomes?

A

2^n
where n = number of pairs

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14
Q

Describe Crossing Over (Meiosis 1):

A
  • when homologous chromosomes associate, the form a bivalent and one of the chromatids of each homologous chromosome, get wrapped around each other at the chiasmata
  • this can cause sections of each chromatid to break off an re-join to the chromatid of the homologous partner (this is crossing over)
  • this is where alleles are exchanged between maternal + paternal chromosomes (genetic recombination)
  • when the new chromosomes move apart, there will be a new combination of alleles
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15
Q

Describe the Differences between Meiosis + Mitosis:

A
  1. meiosis contains 2 divisions forming 4 daughter cells, mitosis contains 1 division forming 2 daughter cells
  2. mitosis has genetically identical offspring, whilst meiosis has genetically variant offspring
  3. meiosis contains (independent segregation + crossing over), mitosis does not
  4. meiosis produced haploid offspring, mitosis produces diploid offspring
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