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A Level Biology Edexcel A > Biodiversity & Natural Resources Year 2 > Flashcards

Biodiversity & Natural Resources Year 2 Flashcards

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1
Q

Define Biodiversity.

A

The variety of species and the range of taxa (species diversity), the variety of alleles within a species (genetic diversity) and the variety of ecosystems (ecosystem diversity) of which organisms are a part.

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2
Q

Define biodiversity hotspot.

A

An area with very high biodiversity.

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3
Q

Define species.

A

A group of organisms with homologous features (similar anatomy, physiology and behaviour), which can interbreed to produce fertile offspring and are reproductively isolated from other species in time, place or behaviour (geographical isolation results in reproductive isolation).

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4
Q

Define species richness.

A

The number of different species present in a habitat at any one time.

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5
Q

Define species evenness.

A

The number of organisms (population size) of each species in a habitat.

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6
Q

What is the equation for calculating biodiversity index?

A

D = N(N-1)/ sum of n(n-1)

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7
Q

Define endemic species.

A

A species which is only found in one geographical location.

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8
Q

Define niche.

A

The role of an organism/ species within its habitat/ ecosystem.

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9
Q

Define competition.

A

The struggle between two organisms for the same limited resource within the environment.

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10
Q

List the possible niches of an organism.

A

• be a producer
• be a decomposer
• be a food source for another organism
• provide shelter for other organisms
• be a pollinator

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11
Q

What is adaptation?

A

Adaptation is when organisms have specialised features that increase their chance of survival and reproduction in the environment in which they live. This means they can then pass alleles /genes for these advantageous characteristics on to their offspring in the next generation.

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12
Q

What are the 3 types of adaptations?

A

• Behavioural
•Phsyiological
• Anatomical

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13
Q

Define behavioural adaptation.

A

How an organism behaves to increase its chance of survival. e.g birds mating dance

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14
Q

Define physiological adaptation.

A

Processes inside an organism that increase its chance of survival or reproduction. e.g venom produced by snake

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15
Q

Define anatomical adaptation?

A

Structural features of an organism that increase its chance of survival or reproduction.

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16
Q

Define co-adaptation.

A

When two different species evolve together in tandem and become dependent on each other, making them more closely adapated.

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17
Q

Define evolution.

A

A change in allele frequency in a population over time.

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18
Q

Define allele frequency

A

The relative frequency with which an allele is found in a population.

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19
Q

Define selection pressure.

A

A change in the environment that can affect the organsims’s ability to survive in a given environment e.g. new predator, use of antibiotics.

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20
Q

What is meant by struggle for existence?

A

Competition between members of a species for resources for survival and reproduction.

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21
Q

Describe the process of natural selection.

A
  • There is genetic variation in the population due to a random mutation which can be an advantageous allele which aids survival in the environment which has a specific selection pressure (e.g. allele for disease resistance)
  • This increases the chance of survival and reproduction passing on the advantageous allele to the offspring.
  • Therefore evolution has occurred as the allele frequency for the advantageous alleles has increased over time.
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22
Q

The ability of a population to adapt quickly will depend on:

A

• strength of selection pressure
• the reproductive rate of the organism
• the size of the gene pool

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23
Q

How do you calculate allele frequencies?

A

p + q = 1

where p = frequency of dominant allele
q = frequency of recessive allele

24
Q

State the Hardy-Weinberg equation.

A

p² + 2pq + q² = 1

Frequency of homozygous dominant individuals + frequency of heterozygous individuals + frequency of homozygous recessive individuals = 1

25
Q

What is the Hardy-Weinberg equation used for?

A

Used to see whether there has been a change in allele frequencies over time. (if evolution has occurred). This can be done by comparing allele frequencies at two points in time, if the frequency has changed this indicates evolution has occurred.

26
Q

What does the Hardy-weinberg principle state in terms of the conditions for evolution not to occur.

A
  • The population size is large enough for genetic drift not to occur.
  • Mating is random
  • There is no gene flow
  • No mutations/ are rare
  • No natural selection

If any of these conditions are not met, a change in allele frequencies can occur.

27
Q

Define gene pool.

A

All the alleles of all the genes present in a population of a species.

28
Q

Define genetic diversity.

A

The number of different alleles in a population/ gene pool, and the frequency of different alleles in a particular species.

29
Q

How can genetic diversity be measured?

A
  • Can be observed in the external phenotype
  • DNA sequencing
  • Gel electrophoresis
  • Heterozygosity index can be calculated.
30
Q

Give the equation used to calculate the heterozygosity index.

A

H = number of heterozygotes/ number of individuals in the population.

31
Q

Why is genetic diversity important?

A

It increases the gene pool which increases the chance of a mutation which may be an advantageous allele so gives the organsim a selective advantage which aids the survival and reproduction in the environment with a specific selection pressure.

32
Q

Give the two types of speciation.

A
  1. Allopatric
  2. Sympatric
33
Q

What is allopatric speciation?

A

Speciation that occurs as a result of geographical isolation between populations.

34
Q

What is sympatric speciation?

A

When populations become reproductively isolated without a geographical barrier. They become isolated in the same habitat due to another isolating mechanism. This results in reproductive isolation and there is no gene flow.

35
Q

Give some methods of isolation.

A
  • Ecological isolation - individuals occupy different parts of the same habitat.
  • Temporal isolation - individuals reproduce at different times
  • Behavioural isolation - individuals do not recognise each others courtship behaviours
  • Physical incompatibility - there are physical reasons to prevent mating e.g. incompatible genitalia
  • Hybrid inviability - offspring are produced but do not survive to reproductive age
  • Hybrid sterility - offspring survive to reproductive age but are infertile
36
Q

Describe the system for naming species.

A

Carl Linnaeus came up with the binomial system of nomenclature, which gives every species a unique two part Latin name. First part of the name indicates the genus (upper-case letter) and second part indicates species (lowe-case letter).

37
Q

What is taxonomy?

A

Taxonomy is the science of classifying living organisms.

38
Q

Define taxonomic heirarchy.

A

A taxonomic heirarchy is a series of taxa where organisms share one or more common features and a common ancestor. Organisms are first divided into large groups, then subdivided into increasingly smaller groups.

39
Q

Give the taxonomic heirarchy.

A
  1. Kingdom
  2. Phylum
  3. Class
  4. Order
  5. Family
  6. Genus
  7. Species
40
Q

How do taxonomists classify living organisms?

A

Organisms are placed into groups (taxonomic groups) based on similarities in phenotype and genotype. Molecular phylogeny is used to identify similarities in DNA base sequences. Organisms that have features in common will be placed in the same taxonomic group.

41
Q

Classification is built around the species concept - what is this?

A

Organisms which have similar characteristics and DNA and can interbreed to produce fertile offspring are placed in the same species.

42
Q

State the 5 kingdoms.

A
  • Animalia
  • Plantae
  • Fungi
  • Protists
  • Prokaryotae
43
Q

Define molecular phylogeny.

A

Using the sequence of DNA or RNA bases, sequence of amino acids in a protein, or structure of cell membranes to analyse evolutionary relationships and group organisms together based on shared/ similar features.

44
Q

Define phylogenetic tree.

A

A diagram that shows the evolutionary relationship between organisms based on molecular differences. They show where species shared and branched off from common ancestors.

45
Q

State the 3 domains.

A
  1. Prokaryotes
  2. Eukaryotes
  3. Archaea
46
Q

How did Woese come up with these domains?

A

Woese used molecular phylogeny (sequenced the RNA of bacteria) and found that there were differences between the bacteria and methanogens such as different RNA sequences, methanogens had no peptidoglycans in their cell walls, methanogens had different membrane lipids. Therefore, the methanogens were placed in a different group - archaea.

47
Q

Describe the process of critical evaluation.

A
  • Scientists communicate their research to the scientific community by publishing their findings in scientific journals and conferences.
  • Other scientists will then critically evaluate the evidence to ensure that is valid through peer review.
  • Other scientists repeat the experiments to check their reliability and validity. The theory may or may not be accepted by the scientific community.
48
Q

Define in-situ conservation.

A

When species are protected on the site of the threatened species and also includes protecting ecosystems and maintaining habitats.

49
Q

Define ex-situ conservation.

A

When species are protected away from the site of the threatened species. Populations can be supported in zoos + conservation centres.

50
Q

How do zoos use captive breeding programs to conserve rare species?

A
  • increasing population numbers of species at risk of extinction
  • protecting animals from predators/ poachers
  • Move animals between zoos and use studbooks to keep records of breeding and to maintain/ increase genetic diversity.
  • DNA profiling/ sequencing to monitor genetic diversity
  • Breeding can involve use of IVF, artificial insemination or surrogates.
51
Q

How do zoos use reintroduction programmes to conserve rare species.

A
  • Carefully select habitats/ reserves to release animals into
  • Preparing animals for reintroduction - need to reinforce wild behaviour
  • Raise awareness and educate local population to protect animals
52
Q

What is genetic drift?

A

Occurs in small populations and some alleles may not be passed onto offspring/ future generations and can be lost from a population. Allele frequency changes over time.

53
Q

What is inbreeding?

A

When closely related individuals interbreed/ reproduce. The offspring are likely to become homozygous recessive for more harmful recessive alleles and and can show inbreeding depression e.g. less fertile. Inbreeding depression affects small populations.

54
Q

What are the roles of a seedbank?

A
  • Storage of many seeds from each plant species to help conserve endangered species, conserve genetic diversity, protect plants from drought etc. Seeds may also contain alleles with medicinal properties
  • To conduct scientific research into seed storage, germination conditions
  • To work with governments to safeguard threatened species, they rely on local knowledge to identify seeds.
  • Educate people about importance of conserving plants.
55
Q

How are seeds prepared for storage and stored?

A

Seeds are:
* cleaned and dried
* sterilised to kill microorganisms which can cause decay
* x-rayed to make sure they are viable
* stored at -20 cold and dry conditions to prevent germination
* subjected to germination checks every 10 years.

56
Q

Describe the adavantages of storing seeds rather than plants.

A
  • seeds are more likely to survive for a longer time
  • seeds can be frozen but plants cannot
  • seeds are small so take up less space and more can be stored so greater genetic diversity
  • seeds need less maintenance so it is cheaper to store them than plants

A Level Biology Edexcel A (9 decks)

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