2016/2017
dichotomous_keys_ans.pdf | |
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2014/2015
Answers for Evolution package
1. Mutations randomly introduce new alleles into a population and change allele (trait) frequencies.
2. Microevolution is the small events that lead to evolution within a population - this occurs as one studies the number of copies of an allele(trait) compared to the total number of alleles in a population. Individual organisms do not evolve, populations do.
3. Non-random mating in sexually reproducing plants - inbreeding ( self-fertilization) will have an effect whereby homozygous genotypes become more common and harmful recessive alleles are more likely to be expressed.
Non-random mating in animals - a) inbreeding will increase the incidence of deformities and health problems compared to non-pure bred animals. b) choosing a particular phenotype as a partner will mean that only selected individuals ( traits) move on in the genetic pool and other less desirable traits are eliminated from the gene pool.
4.Types of Natural Selection
A. Stabilizing Selection: favours intermediate phenotypes ( middles of the way)... no extremes. Usual occurs when environmental conditions are constant
B. Directional Selection: favours phenotypes at one extreme over the other extreme or the middle ground. Usual occurs when environmental conditions are changing or the species is in a new habitat.
C. Disruptive Selection: favours both of the extreme phenotypes over the intermediate ( middle ground) phenotype. This can result in a complete elimination of the intermediate phenotype and develop 2 specialist species.
5. Genetic Drift
Founder Effect vs. Bottleneck Effect
Similarities: Population size decreases in both cases. The frequencies of alleles are changed by chance alone in both cases.
Differences:
Founder Effect - a few individuals ( who carry some but not all of the alleles of the original population's gene pool) start a new isolated population.
Bottleneck Effect - changes in gene distribution (alleles) that result from a rapid decrease in population size due to starvation, human activity and/or natural disaster.
6. a) the genes that make up skin must have a limited variation of the skin gene (limited alleles) therefore the skin of one individual is recognized by the next due to genetic similarity. There is a lack of genetic variation of skin alleles.
b) A sharp population decline indicates genetic drift, either founder effect or bottleneck.
Natural selection could also be applied, as the strongest individuals after a sharp population decline would survive.
7. genetic drift: the Bottleneck effect. Example: over hunting reduced the number of elephant seals to 20. Now, there are tens of thousands of elephant seals but with a low genetic diversity.
8. Gene flow would occur, new alleles will be brought into the gene pool. Genetic diversity will increase. ( see your sheet for the diagram)
9. The diversity would be lowered as the rare alleles would cease to exist in the population.
10. Mutation is a change that occurs in the DNA of an individual. This mutation can be passed on to offspring and over time has the potential to affect the entire gene pool of a population. The more genetic variation in the population, the greater the chance of natural selective advantage in some individuals when there is a change in the environment , thus influencing evolutionary changes in a population.
11. A genetic drift: bottleneck effect may occur due to the human activity of trapping green meeps. The percentage of green meeps would be reduced, leaving only the surviving grey meeps and the following generations would be mostly grey meeps.
1. Mutations randomly introduce new alleles into a population and change allele (trait) frequencies.
2. Microevolution is the small events that lead to evolution within a population - this occurs as one studies the number of copies of an allele(trait) compared to the total number of alleles in a population. Individual organisms do not evolve, populations do.
3. Non-random mating in sexually reproducing plants - inbreeding ( self-fertilization) will have an effect whereby homozygous genotypes become more common and harmful recessive alleles are more likely to be expressed.
Non-random mating in animals - a) inbreeding will increase the incidence of deformities and health problems compared to non-pure bred animals. b) choosing a particular phenotype as a partner will mean that only selected individuals ( traits) move on in the genetic pool and other less desirable traits are eliminated from the gene pool.
4.Types of Natural Selection
A. Stabilizing Selection: favours intermediate phenotypes ( middles of the way)... no extremes. Usual occurs when environmental conditions are constant
B. Directional Selection: favours phenotypes at one extreme over the other extreme or the middle ground. Usual occurs when environmental conditions are changing or the species is in a new habitat.
C. Disruptive Selection: favours both of the extreme phenotypes over the intermediate ( middle ground) phenotype. This can result in a complete elimination of the intermediate phenotype and develop 2 specialist species.
5. Genetic Drift
Founder Effect vs. Bottleneck Effect
Similarities: Population size decreases in both cases. The frequencies of alleles are changed by chance alone in both cases.
Differences:
Founder Effect - a few individuals ( who carry some but not all of the alleles of the original population's gene pool) start a new isolated population.
Bottleneck Effect - changes in gene distribution (alleles) that result from a rapid decrease in population size due to starvation, human activity and/or natural disaster.
6. a) the genes that make up skin must have a limited variation of the skin gene (limited alleles) therefore the skin of one individual is recognized by the next due to genetic similarity. There is a lack of genetic variation of skin alleles.
b) A sharp population decline indicates genetic drift, either founder effect or bottleneck.
Natural selection could also be applied, as the strongest individuals after a sharp population decline would survive.
7. genetic drift: the Bottleneck effect. Example: over hunting reduced the number of elephant seals to 20. Now, there are tens of thousands of elephant seals but with a low genetic diversity.
8. Gene flow would occur, new alleles will be brought into the gene pool. Genetic diversity will increase. ( see your sheet for the diagram)
9. The diversity would be lowered as the rare alleles would cease to exist in the population.
10. Mutation is a change that occurs in the DNA of an individual. This mutation can be passed on to offspring and over time has the potential to affect the entire gene pool of a population. The more genetic variation in the population, the greater the chance of natural selective advantage in some individuals when there is a change in the environment , thus influencing evolutionary changes in a population.
11. A genetic drift: bottleneck effect may occur due to the human activity of trapping green meeps. The percentage of green meeps would be reduced, leaving only the surviving grey meeps and the following generations would be mostly grey meeps.
complex_punnett_squares.pdf | |
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easy_punnett_squares_ans.pdf | |
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Answers:
1- Dominant is the form of a trait that always appears when an individual has an allele for it whereas recessive is a form of a trait that only appears if an individual has 2 alleles for it. Example would be that a the dominant yellow seed colour (Yy or YY) versus the recessive green seed colour (yy).
2- The grandmother's hair colour allele was recessive in the father’s genotype and was given to the child. We can presume that the mother also was carrying the same recessive allele for the grandmother’s hair colour and as such the child ( F2 generation) obtained the 2 recessive alleles which were then expressed.
3- Yes. F1 generation, only the dominant allele is expressed. In the F2 generation, there is a ratio of 2.8:1 tall vs. short ratio, this is very close to the 3:1 Mendelian ratio.
4- a. F1 generation - only yellow peas will be produced
5 - Use each plant as a true breeding plant, then produce an F1 generation and determine which flower colour is only expressed in the offspring. this colour would then be the dominant allele.
6- Genotype is the genetic makeup of an individual ( combination of alleles)
Phenotype is the physical and physiological traits of an individual ( what gets shown)
7 - Heterozygous can be used on its own because there is is only one genotype option with a dominant allele with a recessive allele ( ex: Yy). Homozygous there are two options: 2 dominant alleles or 2 recessive alleles , therefore we need to distinguish by prefacing with dominant or recessive. (ex; homozygous dominant YY versus homozygous recessive yy).
8 - come show me and I will let you know….
9 - a. F : freckles and f : no freckles.
11. a. RR b.rr c.Rr
a. Tall plant b. Tall plant c. short plant
1- Dominant is the form of a trait that always appears when an individual has an allele for it whereas recessive is a form of a trait that only appears if an individual has 2 alleles for it. Example would be that a the dominant yellow seed colour (Yy or YY) versus the recessive green seed colour (yy).
2- The grandmother's hair colour allele was recessive in the father’s genotype and was given to the child. We can presume that the mother also was carrying the same recessive allele for the grandmother’s hair colour and as such the child ( F2 generation) obtained the 2 recessive alleles which were then expressed.
3- Yes. F1 generation, only the dominant allele is expressed. In the F2 generation, there is a ratio of 2.8:1 tall vs. short ratio, this is very close to the 3:1 Mendelian ratio.
4- a. F1 generation - only yellow peas will be produced
- They did not use true-breeding plants as their parental or P generation. They must have used instead an F1 generation plant by mistake that had some recessive alleles.
5 - Use each plant as a true breeding plant, then produce an F1 generation and determine which flower colour is only expressed in the offspring. this colour would then be the dominant allele.
6- Genotype is the genetic makeup of an individual ( combination of alleles)
Phenotype is the physical and physiological traits of an individual ( what gets shown)
7 - Heterozygous can be used on its own because there is is only one genotype option with a dominant allele with a recessive allele ( ex: Yy). Homozygous there are two options: 2 dominant alleles or 2 recessive alleles , therefore we need to distinguish by prefacing with dominant or recessive. (ex; homozygous dominant YY versus homozygous recessive yy).
8 - come show me and I will let you know….
9 - a. F : freckles and f : no freckles.
- ff
- Ff or FF. You would have to do a special cross test with a recessive individual to be sure of the genotype since there are two possibilities.
- a. Black fur allele is dominant , white fur allele is recessive.
- Genotype of the parents has to be heterozygous (Bb). The offspring has to be homozygous recessive ( bb).
11. a. RR b.rr c.Rr
a. Tall plant b. Tall plant c. short plant