Brainscape's Knowledge GenomeTM

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


See full index

Higher Biology > 1.7 Evolution > Flashcards

1.7 Evolution Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is inheritance?

A

the passing of genes from one organism to another

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

What is vertical inheritance?

A

describes the passage of genetic info from parents to offspring

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

Vertical inheritance - sexual reproduction?

A

vertical inheritance by sexual reproduction is a slow process as it involves stages of gamete production and fertilisation
It may be influenced by seasons and mating rituals
It results in variation by mixing up parental genotypes
Gametes show variation due to the random way that homologous chromosomes separate to form haploid gametes

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

TOP TIP

A

Sexual reproduction results in variation in genotype and phenotype

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

Vertical Inheritance - Asexual reproduction?

A

Vertical Inheritance by asexual reproduction is much faster process as it does not involve the production of gametes or fertilisation
It doesn’t produce variation as offspring only come from one parent and not the fusion of gametes
Asexual reproduction forms a clone (a group of genetically identical offspring)

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

Horizontal Inheritance Prokaryote

Prokaryote Transformation?

A

a fragment of DNA or a plasmid from one bacterium is taken up from the environment by another bacterium

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

Prokaryote Transduction?

A

a virus carries genetic material from one bacterium to another

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

Prokaryote Conjugation?

A

A bridge forms between two different bacteria and fragment of DNA or a plasmid is passed from one to another

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

TOP TIP

A

Horizontal transfer is the mechanism that introduces variation into prokaryotes

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

Rapid evolution in prokaryotes?

A

this means that bacterial genomes can be shared rapidly and they can undergo rapid evolution
consider that transgenic bacteria reproduce asexually and can double in number every 20 mins

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

MRSA

A

certain bacteria can exchange plasmids carrying the genes that confer resistance to antibiotics from one bacteria to another
this has resulted in the rapid emergence of strains of bacteria resistant to several antibiotics
MRSA causes infections which are extremely difficult to cure and which sometimes prove to be fatal

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

Horizontal Inheritance Prokaryote

eukaryote viruses?

A

some viruses can insert their genome into the host cell’s genome
many non-coding introns are thought to be the result of viral genetic integration
e.g. HIV retrovirus can be spliced into the DNA of the host white blood cell

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

eukaryote agrobacterium?

A

bacteria such as agrobacterium tumefaciens can transfer their DNA directly into eukaryotic plant cells
this is useful in genetic engineering

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

TOP TIP

A

Horizontal transfer is the mechanism that introduces variation into prokaryotes

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

TOP TIP

A

dont be tempted to identify vertical or horizontal inheritance patters according to how diagrams are laid out - a horizontal arrow on a diagram does not necessarily mean horizontal inheritance

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

What is natural selection?

A

non random increase in the frequency of those specific genes which increase an organisms chance of survival

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

What are the stages of natural selection?

A
  1. Organism produce more offspring than the environment can support
  2. Genetic variation occurs within individuals of a population
  3. Individuals compete for available resources such as food and mates
  4. Individuals with favourable genes which give them an advantage in the environment such as the ability to find prey and more likely to survive and pass genes onto the next generations
  5. Frequency of these favourable genes increases within the population. Individuals without these favourable genes gradually begin to die out.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Example evolution of resistant insects?

A

pest insects include mosquitoes which transmit diseases such as malaria and yellow fever and locusts which destroy crops
DDT is a poisonous chemical widely used against many insect pests
Resistance to DDT occurred due to a mutation
Resistant insects are able to make an enzyme that renders DDT harmless
These mutants were already in the population naturally in small numbers and were not produced as a result of DDT use
When DDT is first applied the vast majority of insects died as they were not resistant
the few resistant in the population survived, enjoying a selective advantage
resistant insects reproduced passing on the mutant advantageous gene for resistance to the next generation
resistant insects increase in frequency in the population
DDT is now ineffective in treating many species of insect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

IMPORTANT NOTE ON NATURAL SELECTION

A

change in environment does not cause mutation
the mutant allele is already present in the population in small numbers
the change in environment allow the mutation to have a selective advantage and increase in numbers in the population

20
Q

TOP TIP

A

Natural selection can affect gene frequencies in two ways
advantageous mutations - non random increases in alleles
deleterious mutations - non random decreases in alleles

21
Q

What is sexual selection?

A

the chances of successful reproduction are increased if a sexual partner is selected on the recognition and non random selection of strong genetic traits

  1. male/male rivalry
  2. female choice
22
Q

male/male rivalry?

A

males compete with physical aggression to access for females

e.g. stags

23
Q

female choice?

A

selection of a male based on a high quality visual display of genetic traits, his ability to outcompete other males, protect territory, his skills at nest building or performing mating rituals
e.g. eye spots on feathers of male peacock, lrger the more attractive

24
Q

What are quantitative traits?

A

quantitative traits are continuous variables due to polygenic inheritancee
when you plot data for continuous variables in a large population you should get a normal distribution curve

25
Q

What is continuous variation?

A

characteristic changes gradually from one extreme to another

26
Q

What is polygenic inheritance?

A

characteristic determined by the interaction of more than one gene

27
Q

What are the three ways that natural selection can affect the frequency of a measurable trait within a large population?

A

stabilising selection
disruptive selection
directional selection

28
Q

What is stabilising selection?

A

stabilising selection occurs within a stable environment and selects for the mean value/range of a genetic trait within a population, avoiding the more extreme versions of the trait

29
Q

What is directional selection?

A

direction selection occurs within a changing environment and selects for a lesson common version of a genetic trait within a population resulting in an increase in frequency

30
Q

what is disruptive selection?

A

disruptive selection occurs when two different environments or resources become available and selection is for the: most extreme versions of a genetic trait, resulting in the population splitting into: two distinct groups

31
Q

What is a gene pool?

A

The total of all the different alleles in a population is called the gene pool
If a species is under no selection pressure frequencies of individual alleles will stay the same from generation to generation

32
Q

REMEMBER!

A

An allele is a form of a gene

33
Q

What is genetic drift?

A

is a random increase or decrease in the frequency of DNA sequences within the gene pool of a population
As a result of chance events, neutral mutations and by colonisation and the founder effect.
It is most prevalent in small populations

34
Q

What is the founder effect?

A

specific alleles of genes may have different frequencies or may be lost when some organisms becomes isolated from the main population and ‘found’ a new separate population (splinter group)
The new population contains a random selection of alleles from the parent population.

35
Q

Genetic drift and neutral mutation?

A

the combined effect of more than one neutral mutation could result in a selective advantage or disadvantage
this is rare in large populations and it is very rare for two individuals with neutral mutations to meet and breed
in a splinter group the neutral mutations may represent a higher percentage, increasing the chances of two individuals meeting and producing offspring who passes both mutations
selection pressures then work to change the frequency of the neutral mutation

36
Q

What is the bottleneck effect?

A

the majority of a population may die out due to a natural disaster and a large number of genes are lost
survivors may carry a small random selection of genes from the original population
this results in a change in frequency of alleles in a population and significant loss of genetic variation

37
Q

What is a species?

A

a group of organisms that can interbreed to produce fertile offspring

38
Q

REMEMBER!

A

remember that different species do not produce fertile young when they interbreed. Only fertile young can be produced with members of the same species

39
Q

What is speciation?

A

speciation is the evolution of two or more species from a common ancestor

40
Q

Explain process of speciation?

A

Large population with common gene pool
isolation - two populations separated by a barrier
Mutation - mutation gives rise to new alleles
natural selection - selection pressures are different for each population: temperature, predation
this gives different characteristics a selective advantage allowing them to accumulate in the population
time - after a long period of time if the barrier is removed there is no interbreeding

41
Q

What are the two types of speciation?

A

allopatric

sympatric

42
Q

What is allopatric speciation?

A

occurs when isolation of subpopulations is by a geographical barrier such as a river, desert, mountain or sea

43
Q

What is sympatric speciation?

A

occurs when isolation of subpopulations is given by a behavioural or ecological barrier or due to polyploidy occurring within a population

44
Q

TOP TIP

A

isolation barriers prevent interbreeding and gene flow between subpopulations

45
Q

What are hybrid zones?

A

exist where interbreeding is possible and as a result genes are able to flow between subpopulations (overlaps)
they form where the ranges of two closely related species overlap
within these hybrid zones members of the two species can interbreed but the hybrids formed are less fit or sterile and are eliminated by natural selection
members of each species continue to colonise the hybrid zone and undergo hybridisation to populate

46
Q

Size of hybrid zone?

A

hybrid zone - narrow
indicates two overlap populations are genetically distinct species

wide
greater genetic variation within overlapping population

Higher Biology (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions