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AS Biology > F212 3 Evolution > Flashcards

F212 3 Evolution Flashcards

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0
Q

Interspecific Variation

A

Variation between species

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1
Q

Variation

A

The differences between individuals

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2
Q

Intraspecific Variation

A

Variation within a species

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3
Q

Continuous Variation

Definition

A

A whole range of types between two extremes
Controlled by genes and the environment
Most individuals are close to the mean, few individuals at the extremes

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4
Q

Discontinuous Variation

Definition

A

Distinct categories with no intermediate values

This type if variation is determined by one gene

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5
Q

Continuous Variation

Examples

A

Height in humans
Length if leaves on an oak tree
Length of stalk of a toadstool

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6
Q

Discontinuous Variation

Examples

A

Gender, mammals are either male or female, plants can be male, female or hermaphrodite
Some bacteria have flagella and others don’t
Human blood groups, A, B, AB, O

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7
Q

What Causes Variation?

A

Genetics

Environment

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8
Q

Genetic Causes of Variation

A

Mutations - a random change in the DNA base sequence amuses genetic variation between individuals
The combination of alleles offspring inherit from their parents determines their visible characteristics

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9
Q

Environmental Causes of Variation

A

Environmental factors do not change the genes that a person has, they affect the visible characteristics
E.g. A persons skin will tan and become darker in the sun
A plant will grow towards a source of light

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10
Q

Behavioural Adaptations

Definition

A

An aspect of the behaviour of an organism that helps it to survive in the conditions it lives in

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11
Q

Physiological / Biochemical Adaptions

Definition

A

An adaptation that ensures the correct functioning of cell processes

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12
Q

Anatomical Adaptations

Definition

A

Any structure that enhances the survival if the organism is an adaptation

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13
Q

Behavioural Adaptations

Example

A

When you touch an earth worm it contracts and withdraws into its burrow
This helps to avoid it being eaten

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14
Q

Physiological / Biochemical Adaptions

Example

A

Yeast produces the correct enzymes to respire the sugars in their current environment

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15
Q

Anatomical Adaptions

Example

A

Many bacteria have flagella which allow them to move independently

16
Q

Darwin’s Observations

A

Variation between offspring
Offspring inherit features form parents
Organisms have the ability to produce large numbers of offspring
Populations of organisms remain relatively stable over time

17
Q

Darwin’s Conclusions

The Theory of Evolution

A

Genetic variation between individuals
Over reproduction
Struggle to survive
Only the best adapted survive
Survivors reproduce passing on the advantageous genes
Gradual changes in the population over many years

18
Q

Speciation

A

The formation of a new species

19
Q

Allopatric Speciation

A

Speciation as a result of a geographical cause, two parts of a population become separated and evolve differently

20
Q

Sympatric Speciation

A

Two species remain in the same geographical area but a reproductive barrier occurs e.g.

  • a biochemical change preventing fertilisation
  • behavioural change meaning a courtship dance is not recognised
  • physical change in sexual organs
21
Q

Selection Pressure

Definition

A

An environmental factor which determines which species survives

22
Q

Evidence for the Theory of Evolution

Fossils

A

General trend in the fossil record shows smaller more simple organisms in the distant past and more complex organisms today
Darwin found fossils of Brachiopods which had slowly changed over time

23
Q

Evidence for the Theory of Evolution

Problems with Fossils

A

Fossil evidence is incomplete
Usually on,y the hard parts of the organism survive to become a fossil
Fossils only form under certain conditions
Can be damaged or destroyed by the movements of rocks

24
Q

Evidence for the Theory of Evolution

Biological Molecules

A

Certain biological molecules are found throughout the living world, if one species gave ride to another you would expect them to have the same biological molecules
Two closely related species will have recently evolved into separate species so biological molecules will be identical or similar
In species that took separate evolutionary paths a long time ago biological molecules will differ

25
Q

Evidence for the Theory of Evolution

Protein Variation

A

Higher organisms have extra subunits as part of their DNA and RNA polymerase which improve the regulation of its action
The sequence of amino acids that make up cytochrome c is compared between species, the number of differences is greater for more distantly related species

26
Q

Evidence for the Theory of Evolution

DNA

A

The sequences of bases can be compared to see how closely related
Organisms that share common ancestors have more similar DNA than less closely related organisms

27
Q

Pesticide Resistance in Insects

How it works

A

Insects with resistance will survive to reproduce
Insects without resistance will die
The advantageous resistance will be inherited and the resistance will quickly spread through the population

28
Q

Pesticide Resistance in Insects

Causes

A

Insects may be able to break down the insecticide using enzymes
The target receptor protein of the pesticide on the cell membrane may be modified

29
Q

Pesticide Resistance in Insects

Impact on Humans

A

Mosquitos which become resistant to insecticide are dangerous as they carry the malaria parasite

Insects that survive may be eaten by predators and the insecticide will move up the food chain

30
Q

Drug Resistance in Microorganisms

How it Works

A

Most of the bacteria are killed by the drugs but those with resistance survive to reproduce

The resistance is inherited and quickly spreads through the population

31
Q

Drug Resistance in Microorganisms

Causes

A

Over and incorrect use of antibiotics leads to strains of bacteria resistant to virtually all antibiotics in use

32
Q

Drug Resistance in Microorganisms

Impact on Humans

A

Medical researches are struggling to develop new and effective drugs as the bacterial populations rapidly become resistant to them

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