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Genetic Diversity Flashcards

(43 cards)

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1
Q

Genetic diversity - definition

A

Genetic diversity is the number of different alleles of genes in a population.
A high genetic diversity is good.
It enables natural selection to occur.

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2
Q

Species - definition

A

Organisms with similar characteristics that can breed together to produce fertile offspring.

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3
Q

Genetic bottleneck

A

Events that cause a big reduction in the population.

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4
Q

Consequences of a Genetic Bottleneck

A

This reduces the number of different alleles in the gene pool and so reduces genetic diversity because survivors reproduce and a larger population is created from a few individuals.

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5
Q

The Founder Effect

A

When a few organisms from a population start a new colony (e.g. through migration, geographical separation, choice of religion, etc).
There is a chance that rare alleles in the original population are more frequent in the new colony, which could lead to more frequent incidents of genetic diseases.

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6
Q

What factor enables natural selection to occur?

A

Genetic diversity through mutations is a factor enabling natural selection to occur
Proposed by Charles Darwin

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7
Q

Natural Selection - Model Answer

A
  • Random mutation can result in new alleles of a gene
  • Many mutations are harmful but in certain environment the new alleles of a gene might benefit its possessor, leading to increased reproductive success.
  • The advantageous allele is inherited by members of the next generation
  • As a result, over many generations, the new allele increases in frequency in the population
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8
Q

What does natural selection result in?

A

It allows species to become better adapted to their environment.
Adaptations may be anatomical, physiological or behavioural

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9
Q

When do genotypes not result in reproductive success?

A

If…
- The organism is more likely to die before reproducing
- The organism is unable to grow sufficiently well to reproduce successfully
- the organism is unable to attract a mate

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10
Q

Types of selection

A
  • Directional selection - selection may favour individuals that vary in one direction from the mean of the population.
  • Stabilising selection - selection may favour average individuals, which may preserve the characteristics of a population.
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11
Q

Directional selection

A
  • favours individuals that differ from the mean of a population
  • an example of this is antibiotic resistance in bacteria
  • in the initial population, antibiotics is an extreme phenotype
  • in antibiotic rich environment, antibiotic resistance is selected for, changing the average phenotype of the population
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12
Q

Stabilising selection

A
  • favour the average phenotype of the population
  • an example is human birth weights
  • when a baby is born too small or too large, it has a higher mortality rate, so therefore the average phenotype is selected for and remain most frequent in the population
  • tends to eliminate the phenotypes at the extremes/the extreme phenotypes
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13
Q

Courtship behaviours allows individuals to…

A
  • successfully mate
  • recognise members of their species
  • identify a mate capable of breeding
  • form a pair bond in some cases, leading to successful mating and rearing of young
  • synchronise mating so they mate when ovulation is occurring
  • recognise fertility
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14
Q

Classification definition

A

The process of grouping organisms bases on their similarities

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15
Q

Why do we classify organisms?

A

Makes them easier to study and identify relationships between them

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16
Q

Binomial names

A

E.g Homo sapiens
First word (always capitalised) = genus
Second word = species

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17
Q

Types of classification - artificial classification

A

Divides organisms according to their current common features (e.g. colour, size, number of legs, etc)

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18
Q

Types of classification - phylogenetic classification

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A

Arranges species into groups based on their evolutionary origins, common ancestors and relationships. Shows points of divergence.

19
Q

Simple hierarchy

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A

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

20
Q

How can we clarify evolutionary relationships between species?

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A
  • fossils
  • advances in immunology and genome sequencing
  • behaviour (e.g. courtship)
  • location
  • DNA/proteins
  • biochemical processes
21
Q

Biodiversity definition

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A

The variety of living things within a habitat.

22
Q

Species diversity

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A

The number of different species and the number of individuals in each species within a community.

23
Q

Genetic diversity

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A

Refers to the variety of genes possessed by the individuals that make up a population of a species.

24
Q

Ecosystem diversity

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A

Refers to the range of different habitats.

25
Species richness
- a measure of species diversity - the number of different species in a particular area at a given time (community) - this allows us to gain a good idea of the area but it isn’t good for comparisons as it doesn’t tell use how many individuals of each species there are
26
Simpson’s species diversity index
- used to compare the species diversity of different areas - takes into account the number of species present as well as the abundance of each species - when the calculation is carried out, we can use the result to compare species diversity in different habitats - larger result = greater species diversity
27
Write out the formula of the calculation for diversity
28
How does deforestation happen and what is the problem?
**Problem** Hugely reduced biodiversity, as it removes habitats and food sources which organisms rely on **Why does it happen?** - To clear land for agriculture/development - For wood resources
29
How does deforestation affect species diversity?
- Fewer plant species - Smaller range of habitats - Smaller range of food sources - Insects killed by machinery or pesticides
30
FARMING - woodland clearance
**Definition** - cutting down trees to clear land for agricultural use **Affect** - reduction in number of tree species. Destroys habitats and food sources.
31
FARMING - Pesticides
**Definition** - chemicals that kill organisms that feed in crops **Affect** - directly kills pests. Could be loss of food sources for other organisms
32
FARMING - Herbicides
**Definition** - chemicals that kill weeds **Affect** - reduces plant diversity. Destroys habitats and food sources.
33
FARMING - Hedgerow removal
**Definition** - hedgerows around agricultural land removed to make more land for crop growth (lots of small fields into large fields) **Affect** - reduction in number of plant species. Destroys habitats and food sources.
34
FARMING - Monoculture
**Definition** - Farmers plant fields of only one crop. **Affect** - reduces number of plant species. No longer supports a range of habitats and food sources.
35
Conversation techniques (name at least 5)
- maintain existing hedgerows - plant hedges instead of using fences - maintain/create ponds - leave wet corners of fields (do not drain them) - plant native tree species - reduce use of pesticides - use organic fertilisers - use crop-rotation and which includes nitrogen-fixing plant (to improve soil quality) - create natural meadows and use hay for silage - avoid cutting verges/field edges until after flowering and seed dispersal - introduces conservation headlands (areas where pesticides are used restrictively so that wild flowers and insects can breed)
36
Why does using observable characteristic to measure genetic diversity have limitations?
A number of phenotypes are polygenic, which means they are coded for by more than one gene.
37
What do we do to investigate genetic diversity now?
- We now directly observe DNA sequences - DNA can be sequenced and scanned by lasers to compare order of bases - the more closely related species show more similarities in their DNA sequences - we can also compare base sequences of mRNA (as they are complementary to the DNA - however it is hard to get the whole sequence through this - we can also compare amino acid sequences
38
Immunological comparison of proteins
SIMILAR TO MONOCLONAL ANTIBODIES 1) Inject the protein from the human into a rabbit for example 2) The rabbit will reproduce antibodies specific to all the antigen sites of the human protein 3) These antibodies are then extracted from the rabbit. 4) The antibodies are mixed with blood from a third species such as a chimpanzee 5) These antibodies respond to antigen of chimpanzees. 6) This response is the formation of a precipitate. 7) The more similar the antigens, the more precipitate formed and therefore the more closely related the species
39
Quantitative investigation of variation within a species involve
- collecting data from random species - calculating a mean value of collected data and the standard deviation of that mean - interpreting the means values and their standard deviation - when doing repeats for a mean must be AT LEAST 5
40
Sampling
- easier to sample than count all individuals - important that samples are representative of the population, so therefore a large number of samples is needed - sampling should avoid bias, so it must be random. This can be done by marking out a number grid or coordinates using a tape measure and the using a random number generator to get coordinates - chance can’t be removed from the sampling process, but the effect can be minimised by using a large sample size and analysing the data we collect in order to determine the extent chance may have been involved
41
Standard deviation
42
Selective pressure
The pressure from the environment or other organisms that causes organisms to adapt.
43
Selective advantage
When an organisms adapts to overcome the selective pressure.

Biology (10 decks)

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