Selection And Evolution

Question 1

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Answer 1

Mutations that occur in body cells often have no effects at all on the organism

Question 2

Discontinuous variation and an example:

Answer 2

اختلاف گسسته
Differences between individuals of a species in which each one belongs to one of a small number of distinct categories with no intermediates.for example:
Blood group(qualitative differences)

Question 3

Continuous variation and an example:

Answer 3

اختلاف پیوسته
Difference between individuals of a species in which each one can lie at any point in the range between the highest and lowest values.for example:
Height and mass(quantitative differences)

Question 4

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Answer 4

Mutations in cells in the ovaries or testes of an animal or in ovaries or anthers of a plant may be inherited by offspring

Question 5

Discontinuous variation is caused entirely by….

Answer 5

Genes(with the environment having no effect)

Question 6

Continuous variation is also affected by genes but…………can also have an effect

Answer 6

Environment

Question 7

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Answer 7

In discontinuous variation different alleles at a single gene locus have large effect on the phenotype

Question 8

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Answer 8

in continuous variation different alleles at a single gene locus have small effect on the phenotype

Question 9

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Answer 9

In continuous variation different genes have the same, often additive effect on the phenotype

Question 10

Polygenes:

Answer 10

A number of different genes at different loci that all contribute to a particular aspect of phenotype(in continuous variation)

Question 11

Some other examples of discontinuous variation:

Answer 11

Inheritance of:
-sickle cell anemia (HBB)
-haemophilia(F8)
-flower color in salvia)
-stem color of tomato plants
-feather colors of chicken

Question 12

Biotic factors:
(Example)

Answer 12

An environmental factor that is caused by living organisms (predation,competition for food or infection by pathogens

Question 13

Abiotic factors:
Example

Answer 13

An environmental factor that is caused by non-living components.(water supply,nutrient levels of the soil,soil ph, light intensity)

Question 14

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Answer 14

Most genes have many more than two alleles that you consider

Question 15

Fitness:

Answer 15

The ability of an organism to survive and reproduce

Question 16

Selection pressure:

Answer 16

An environmental factor that affects the chance of survival of an organism.(organisms with one phenotype are more likely to survive and reproduce than those with a different phenotype

Question 17

Stabilizing selection:

Answer 17

Natural selection that tends to keep allele frequencies relatively constant over many generations

Question 18

Directional selection:

Answer 18

Natural selection that causes a gradual change in allele frequency over many generations

Question 19

Disruptive selection :

Answer 19

Natural selection that maintains relatively high frequencies of two different sets of alleles;individuals with intermediate features and allele sets are not selected for

Question 20

Polymorphism:
(happens when disruptive selection)

Answer 20

The continued existence of two or more different phenotypes in species

Question 21

Directional changes happen when

Answer 21

There’s a change in selection pressure or when a new allele arises by mutation

Question 22

Antibiotic resistance of bacteria is an example of ……

Answer 22

Directional selection

Question 23

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Answer 23

Plasmids are quite frequently transferred from one bacterium to another (even between different species)

Question 24

Genetic drift:

Answer 24

The gradual change in allele frequency in a small population,where some alleles are lost or favoured just by chance and not by natural selection

Question 25

Gene pool:

Answer 25

The complete range of DNA base sequences in all the organisms in a species or population

Question 26

Founder effect :

Answer 26

The reduction in a gene pool compared with the main populations of a species, resulting from only two or three individuals (with only a selection of the alleles in the gene pool) starting off a new population

Question 27

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Answer 27

Without genetic variation the species is unlikely to be able to adapt to changes in its environment such as climate change

Question 28

Evolutionary bottleneck :

Answer 28

A period when the numbers of a species fall to a very low level resulting in the loss of a large number of alleles and therefore a reduction in the gene pool of the species

Question 29

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Answer 29

If the differences are significant and migration and non random mating can be discounted,this suggests that DIRECTIONAL SELECTION is occurring in the population

Question 30

Artificial selection (selective breeding):

Answer 30

The selection by humans of organisms with desired traits to survive and reproduce

Question 31

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Answer 31

Unlike natural selection,artificial selection often concentrates on 1 or 2 characteristics

Question 32

Inbreeding depression:

Answer 32

A loss of the ability to survive and grow well due to breeding between close relatives; this increases the chance of harmful recessive alleles coming together in an individual and being expressed

Question 33

Inbreeding;

Answer 33

Breeding between organisms with similar genotypes or that are closely related.

Question 34

Outbreeding:

Answer 34

Breeding between individuals that are not closely related to

Question 35

Hybrid vigour:

Answer 35

An increase ability to survive and grow well, as a result of outbreeding and therefore increasing heterozygousity

Question 36

Evolution:

Answer 36

A process leading to the formation of new species from pre-existing species over time

Question 37

Morphological:

Answer 37

Relating to structural features

Question 38

Physicological:

Answer 38

Relating to metabolic and other processes in a living organism

Question 39

Reproductive isolation:

Answer 39

The ability of two groups of organisms to breed with one another;two populations of the same species may be geographically separated or two different species are unable to breed to produce fertile offspring

Question 40

Genetically isolated:

Answer 40

No longer able to breed together.there is no exchange of genes

Question 41

Speciation:

Answer 41

The production of new species

Question 42

Geographical isolation:

Answer 42

Separation by a geographical barrier such as stretch of water or a mountain range

Question 43

Allopatric speciation:

Answer 43

The development of new species following geographical isolation

Question 44

Sympatric speciation:

Answer 44

The development of new species without any geographical separation

Question 45

Ecological separation:

Answer 45

The separation of two populations because they live in different environments in the sane area and so can not breed together

Question 46

Behavioural separation:

Answer 46

The separation of two populations because they have different behaviors which prevent them breeding together

Question 47

About human mitochondrial DNA(mtDNA):

Answer 47

-is inherited through the female line(zygote contains the mitochondria of the egg but not for the sperm)

-since the mtDNA is circular and therefore cannot undergo any form of crossing over so changes in the sequence of nucleotides can only arise by mutation

-mtdna mutates faster then nuclear DNA acquiring one mutation every 25000 years