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Biology A level > Unit 7 - Genetics, populations, evolution and ecosystems > Flashcards

Unit 7 - Genetics, populations, evolution and ecosystems Flashcards

(60 cards)

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1
Q

What is a Gene?

A

A squence of bases on a DNA molecule that codes for a protein

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2
Q

What is an allele?

A

A different version of a gene

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3
Q

What is genotype?

A

The genetic constitution of an organism - the alleles an orgaism has, e.g. BB, Bb or bb for eye colour

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4
Q

What is phenotype?

A

The expression of the genetic constitution and its interaction with the environment. - an organisms charcteristic, e.g. blue eyes

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5
Q

What is the dominant characteristic?

A

An allele whose characteristic apperas in the phenotype when there is only one copy present.

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6
Q

What is the recessive characteristic?

A

An allele whose characteristic only appears in the phenotype if two copies are present.

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7
Q

What is a codominant characteristic?

A

Alleles that are both expressed in the phenotype

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8
Q

What is the locus?

A

The fixed position of a gene on a chromosome

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9
Q

What is a homozygote?

A

An organism that carries two copies of the same allele, e.g. BB or bb

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10
Q

What is a heterozygote?

A

An organism that carries two different alleles, e.g. Bb

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11
Q

What is a carrier?

A

A person carrying an allele which is not expressed in the phenotype but that can be pased on to offspring.

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12
Q

Habitat definition

A

The place where an organism lives

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13
Q

Population definition

A

All the organisms of one species in a habitat

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14
Q

Community

A

Populations of different species in a habitat

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15
Q

Ecosystem

A

A community plus all of the non-living conditions in the area which it lives

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16
Q

Abiotic conditions

A

The non-living features of the ecosystem

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17
Q

Biotic conditions meaning

A

The living features of the ecosystem

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18
Q

Niche

A

The role of a species within its habitat

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19
Q

Adaptation

A

A feature that all members of a species have that increases their chance of survival and reproduction

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20
Q

What does a niche contain

A

The organisms biotic interactions
The organisms abiotic interactions

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21
Q

Carrying capacity

A

The maximum stable population size of an organism that an ecosystem can support.

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22
Q

Interspecific competition

A

When organisms of different species compete with each other

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23
Q

Taking a random sample of an area

A

1- Choose an area to sample
2-Use random sampling to avoid bias
3- Use the appropriate process (Quadrat/ Transect)
4-Repeat with as many samples as possible, reducing the likleyhood that the results are due to chance.

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24
Q

Taking a random sample of an area

A

1- Choose an area to sample
2-Use random sampling to avoid bias
3- Use the appropriate process (Quadrat/ Transect)
4-Repeat with as many samples as possible, reducing the likleyhood that the results are due to chance.

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25
Mark release recapture
Capture organism using an appropriate capture tecnique Mark the organism in a harmless way which doesn't increase any likleyhood of predation Release them, allowing them to integrate into the populatio Use the equationto estimate population size
26
Equation mark release recapture
(num in 1st sample * num in second) / num marked in second
27
REQUIRED prac- Investigating percentage cover of marram grass on a shorline
1- Place a tape measure in a straight line from shore, heading inland 2- Take 1m squared quadrat divided into 100 squares 3- Staering from the shore, place the quadrat next to the tape measure 4-Count the squares containing marram grass and record the result in a table as a percentage cover 5-At each sample point, you should also measure the PH and record results in the table 6-Repeat the observations every 10m along the transect.
28
Safety risks with field work
- Make sure you know local tide times -Wear suitable clothing and footwear for weather and terrain -Wash hands before eating
29
Ethical issues with fieldwork
-Could cause soil/ sand erosion - Investigations should be planned to have the smallest impact possible -Avoid walking on plants themselves
30
Stages of primary succession
1-Abiotic conditions are hostile- no soil to retain water- only pioneer species like like lichens grow 2-Pioneer species die and bacteria decompose them producing a basic soil 3- Conditions become less hostile - basic soil retains water- more organisms move in then grow and die- soil becomes deeper and richer 4-Larger plants which need more water and nutriens are able to grow in deeper soil 5-One organism /type of organism can profit from the deep rich soil (dominant species) and can outcompete all other species + climax community is formed.
31
Climate climaxes of different biomes
Temperate climate have lots of avaliable water + deep soil so trees are contained in their climate climax Polar climate these factors arent present so it is only herbs and shrubs
32
Gene
A sequence of bases on a DNA molecule that codes for a protein
33
Allele
Two different versions of the same gene
34
Genotype
The genetic constitution of an organism
35
Phenotype
The expression of the genetic constitution and its interaction with the environment
36
Dominant
An allele whose characteristics appear in the phenotype even when there's one copy
37
Recessive
An allele whose characteristics are only expressed in the phenotype if two copies are present
38
Codominant
Alleles that are both expressed in the phenotype
39
Locus
The fixed position of a gene on a chromosome
40
Homozygote
An organism that carries two copies of the same allele
41
Heterozygote
An organism that carries two different alleles
42
Carrier
A person carrying an allele which is not expressed in the phenotype but can be passed onto offspring
43
Expected ratio dihybrid inheritance F2
9:3:3:1
44
Expected ratio monohybrid inheritance F2
3:1
45
Expected ratio codominant F2
1:2:1
46
Gene pool
The complete set/ range of alleles present in a population
47
Hardy weinberg equations
p+q=1 Psquared +2pq+ qsquared = 1
48
Conditions for hardy weinberg equation
Large population No immigration/ emigration No mutations Random mating No selection
49
What is speciation
When two species develop from one original population
50
Things that cause variation in phenotypes
Random occurences in fertilisation Environmental conditions
51
Evolution
Induviduals of the same species vary due to differing alleles Predation disease and competition creates struggle for survival (Selection pressure) Some alleles better than others for survival Some organisms more likely to survive and reproduce and pass on alleles A greater proportion of next generation inherit beneficial alleles So frequency of beneficial allele increases in gene pool.
52
Types of natural selection
Directional Stabilising Disruptive
53
Types of speciation
Allopatric Sympatric
54
Behaviours that can cause reproductive isolation
Seasonal- Sexually active at different times Mechanical- Different genatalia Behavioural- Different courtship rituals
55
Description of how genetic drift can lead to evolution
- Induviduals within a population show variation - By chance one allele is selected over another - Number of induviduals of that allele increases - Changes is allele frequency could lead to reproductive isolation and speciation
56
Why manage succession?
At climax community there may be lower diversity Some plants may be needed for the ecosystem to thrive
57
Two methods of managing succession
Grazing animals Managed burning
58
Features of a climax community
- Same population present for a long period of time - Abiotic factors constant
59
Three features of climax community
Same species present over a long time Abiotic factors more or less constant Populations stable around carrying capacity
59
Three features of climax community
Same species present over a long time Abiotic factors more or less constant Populations stable around carrying capacity

Biology A level (13 decks)

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