12. (a) (i) Explain the following terms as used in genetics: species, variation - Leaving Cert Biology - Question 12 - 2006
Question 12
12.
(a) (i) Explain the following terms as used in genetics: species, variation.
(ii) Give one cause of genetic variation.
(b) The diagram shows some of the chromo... show full transcript
Worked Solution & Example Answer:12. (a) (i) Explain the following terms as used in genetics: species, variation - Leaving Cert Biology - Question 12 - 2006
Step 1
Explain the following terms as used in genetics: species, variation.
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Answer
Species: A species is a group of living organisms that can interbreed and produce fertile offspring. They are similar in many characteristics and share a genetic makeup.
Variation: Variation refers to the differences that exist between members of the same species or between populations. This can include physical traits, behaviors, or genetic makeup.
Step 2
Give one cause of genetic variation.
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Answer
One cause of genetic variation is sexual reproduction, where the combination of genetic material from two parents leads to offspring with unique genetic characteristics.
Step 3
What is the sex of this individual?
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The sex of this individual is female as indicated by the presence of XX chromosomes.
Step 4
How many loci are marked in the diagram?
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There are four loci marked in the diagram.
Step 5
"A is linked to B but not to C". Is this statement correct? Explain your answer.
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Answer
This statement is correct. A and B are located on the same chromosome, which indicates that they are linked. C is not linked to A and B since they are located on a different chromosome.
Step 6
Is D linked to D? Explain your answer.
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No, D is not linked to D as it refers to different genes that are on separate chromosomes and are therefore not genetically linked.
Step 7
What term is used to describe the allele pair Dd?
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Answer
The term used to describe the allele pair Dd is heterozygous, as it consists of two different alleles for a specific gene.
Step 8
Draw a diagram, similar to the one above, but in which A, B, and C are homozygous and the cell is taken from an individual of the opposite sex.
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To depict the opposite sex with homozygous alleles, the diagram would show the following:
Chromosome pairs would include AA (for A), BB (for B), and CC (for C).
The diagram would illustrate the individual inheriting one set of chromosomes from each parent, maintaining the homozygous nature (e.g., A, A; B, B; C, C).
Step 9
Give an account of the Theory of Natural Selection.
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The Theory of Natural Selection, proposed by Charles Darwin, describes the process through which organisms better adapted to their environment tend to survive and produce more offspring. This concept was further refined by Alfred Russel Wallace. Observations supporting this theory include the observation of large numbers of offspring being born, but the populations remaining constant due to low survival rates. Variations that provide an advantage in competition for resources lead to higher survival rates, while those without advantages tend to die out.
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