Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EDEXCEL BIOLOGY > TOPIC 4: Biodiversity > Flashcards

TOPIC 4: Biodiversity Flashcards

1
Q

What is a species?

A

a group of closely related organisms with similar morphology, physiology and behaviour, which can interbreed to produce fertile, viable offspring.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What problems are there with defining species?

A

asexual, extinct, rare, geographically isolated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define niche

A

the way an organism uses its environment & it’s role in the environment/ecosystem (predator? prey?)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens when two species occupy the same niche?

A

two species cannot occupy the same niche so there’s either splitting of the niche (one adapts to other niches) or extinction of one of the species.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is fundamental niche?

A

the largest niche an organism could occupy without competition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is realised niche?

A

the niche actually occupied due to competition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define ecosystem

A

A self-sustaining life-supporting environment with biotic and abiotic factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define community

A

All the populations of different species sharing an ecosystem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define population

A

total number of individual species within a community

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an adaptation?

A

behavioural, physiological & anatomical features of an organism that help it survive in its habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What’s a physiological adaptation?

A

features of cells, tissues & systems to help an organism survive in its habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What’s a behavioural adaptation?

A

actions by organisms that help an organism survive in its habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What’s an anatomical adaptation?

A

visible, physical features that help an organism survive in its habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What’s co-adaptation?

A

adaptation of 2 or more organisms resulting in mutual benefit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is directional selection?

A

selection pressure favoring one extreme trait, against the other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is stabilising selection?

A

favoring mean, selecting against both extremes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is disruptive selection?

A

favours both extremes, against mean

bimodal distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What causes allele frequencies to change?

A 
genetic drift,
non-random mating,
natural selection,
migration/emigration,
mutations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is genetic drift?

A

change in allele frequency due to chance (bottleneck - natural disaster/disease)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does speciation happen?

A
  1. some individuals migrate to nearby islands & are geographically isolated;
    different mutations and selection pressures;
  2. species adapt to each region for survival & breeding;
  3. change in allele frequencies over time & difference between gene pools;
    REPRODUCTIVE ISOLATION due to restricted gene flow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is meant by populations adapting?

A

change in allele frequency in population

22
Q

What factors increase the ability of a population to adapt?

A

strong selection pressure,
fast reproductive rate,
large gene pool

23
Q

Why is it unlikely a population can be perfectly adapted to their environment?

A

environments change; time lag to adapt,
selection pressure is always present,
mutations (new alleles)

24
Q

Why might it be a problem to be perfectly adapted?

A

dependence on other species makes them vulnerable if they die out,
less likely to survive environmental changes

25
Q

Define biodiversity

A

the number of different species and genetic variation between them

26
Q

What are endemics?

A

species unique to one geographic area

27
Q

What is species richness?

A

number of different species in a given habitat

28
Q

What is species evenness?

A

when species have similar abundances, no dominant species

29
Q

Where are biodiversity hotspots usually located?

A

equatorial,
islands - reproductive isolation,
coastal - immigration

30
Q

How is genetic variation measured?

A
  1. DNA sequenced to determine bases and alleles
  2. DNA copied using PCR and cut with restriction enzymes
  3. fragments separated by gel electrophoresis to create a banding pattern
31
Q

What does 2 bands in gel electrophoresis mean?

A

heterozygous as there’s a band for each allele

32
Q

What is the heterozygosity index?

A

number of heterozygotes / number of individuals in a population

33
Q

Why is a large heterozygosity index good?

A

more heterozygous a population, the larger the gene pool;

increased chance of survival

34
Q

Why is inbreeding bad?

A

heterozygosity lost, smaller gene pool;
decreased chance of survival;
recessive alleles have harmful effects (inbreeding depression)

35
Q

What’s the order of taxonomic heirarchy?

A

kingdom, phylum, class, order, family, genus, species

36
Q

What did Carl Woese discover?

A

new group of bacteria (methanogens) through RNA sequencing. They had no peptidoglycans in cell wall and membrane lipids differ from eukaryotes and bacteria.
proposed a new taxonomic structure (domains) - bacteria, eukaryota & archaea

37
Q

What is meant by molecular phylogeny?

A

molecular differences in DNA & proteins showing evolutionary relationships between organisms.
organisms with similar characteristics are placed in the same group.

38
Q

How is data critically evaluated by the scientific community?

A
  1. findings publish in a journal/presented at a scientific conference
  2. peer review to add weight to study
  3. other scientists repeat experiments to see if the findings can be replicated
39
Q

What are the main threats to species survival?

A

poaching;
habitat loss;
alien species introduced;
pollution

40
Q

What are the aims of captive breeding programmes?

A

increase no. of individuals of species;
maintain genetic diversity;
reintroduce into wild if possible

41
Q

What are studbooks?

A

breeding records of captives which allow planning of programme to retain alleles and genetic diversity

42
Q

How are seeds collected and conserved in a seedbank?

A
  1. viability checked with X-ray
  2. seeds surface sterilised & dried:
    stored at low temp to prevent germination
  3. germinating ability checked regularly - if below 75%, new seeds are collected
43
Q

What are the advantages of conserving seeds of different sizes?

A

maintain genetic diversity;
more chance of having beneficial alleles, increasing chance of future survival:
less chance of all of them being susceptible to disease

44
Q

Why are seeds conserved?

A

prevent species from becoming extinct;
conserves seeds with medicinal properties;
safeguarding useful genes;
allow for reintroduction of species in the future

45
Q

Suggest an explanation for variation in characteristics in species

A

mutations;
large gene pool;
polygenic inheritance

46
Q

How is change in phenotype brought about by natural selection?

A
  1. genetic variation w/in population due to mutations
  2. selection pressure - selection for better phenotype;
    individuals with worse phenotype selected against & die out
  3. individuals with advantageous alleles survive & breed, passing on the alleles to offspring
  4. over generations, there’s an increased frequency of the advantageous alleles/phenotype
47
Q

How does geographic isolation affect genetic diversity of each individual population?

A

genetic diversity decreases;
closely related individuals inbreed;
risk of inbreeding depression - more chance of homozygous recessive genotypes;
genetic drift (loss of alleles)

48
Q

How does transferring individuals from one population to another help endangered species survive?

A

increases gene pool;

increases potential for survival by better disease resistance/better physical characteristics for hunting

49
Q

Why are offspring of different species infertile?

A

genetic incompatibility due to different number of chromosomes

50
Q

Why don’t different species interbreed?

A

reproductive isolation;
don’t recognise courtship behaviour;
different breeding times;
physically incompatible (genitalia)

EDEXCEL BIOLOGY (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions