e-Consult | Revision Qns

1.

A researcher is comparing the efficiency of two different types of solar panels. They measure the amount of electricity generated by 15 solar panels of each type. The data is as follows:

Type 1 Panels: 12.5, 13.1, 11.8, 12.9, 13.5, 12.2, 12.7, 13.3, 12.4, 13.0, 12.6, 13.2, 12.9, 13.4, 12.3

Type 2 Panels: 11.9, 12.3, 11.5, 12.1, 12.7, 11.8, 12.4, 12.9, 11.7, 12.5, 12.2, 12.8, 12.5, 12.1, 12.6

(t = 1.58, df = 27, p = 0.15) Using a t-test, determine whether there is a statistically significant difference in the mean electricity generated by the two types of solar panels. State your hypothesis, test statistic, and conclusion.

Hypothesis:

Null Hypothesis (H₀): There is no significant difference in the mean electricity generated by Type 1 and Type 2 solar panels. (μ₁ = μ₂)

Alternative Hypothesis (H₁): There is a significant difference in the mean electricity generated by Type 1 and Type 2 solar panels. (μ₁ ≠ μ₂)

Test Statistic:

The t-statistic is calculated as follows: t = (x̄₁ - x̄₂) / (s_p / √n₁ + s_p / √n₂)

Where:

x̄₁ = Sample mean electricity generated by Type 1 panels (calculated as 12.85)

x̄₂ = Sample mean electricity generated by Type 2 panels (calculated as 12.38)

s_p = Pooled standard deviation

n₁ = Sample size of Type 1 panels (n = 15)

n₂ = Sample size of Type 2 panels (n = 15)

The provided t-value of 1.58, with degrees of freedom (df = n₁ + n₂ - 2 = 15 + 15 - 2 = 28), and a p-value of 0.15 indicates that the difference is not statistically significant.

Conclusion:

Since the p-value (0.15) is greater than the significance level (0.05), we fail to reject the null hypothesis. There is not enough statistically significant evidence to conclude that there is a difference in the mean electricity generated by Type 1 and Type 2 solar panels. Based on this data, we cannot say that one type of panel is more efficient than the other.

2.

Compare and contrast the genetic basis of discontinuous and continuous variation. Include a table summarizing the key differences.

Discontinuous variation is easily categorized into distinct phenotypes, typically controlled by a single gene with two alleles. Continuous variation, on the other hand, shows a range of phenotypes, often influenced by multiple genes and environmental factors. Here's a table summarizing the key differences:

Feature	Discontinuous Variation	Continuous Variation
Number of alleles involved	Typically one	Multiple
Mode of inheritance	Simple Mendelian inheritance	Polygenic inheritance, influenced by environmental factors
Phenotypic categories	Distinct, easily classified	A range of phenotypes, no distinct categories
Examples	Thumb dominance, blood groups	Height, skin colour, weight

In essence, discontinuous variation is often a result of a single gene determining a clear-cut outcome, while continuous variation is a result of the combined effects of many genes and environmental influences leading to a gradual change in phenotype.

3.

Explain, with examples, how phenotypic variation arises from genetic factors. In your answer, consider the roles of allele combinations, dominance, and incomplete dominance.

Phenotypic variation, the difference in observable characteristics between individuals, can be significantly influenced by genetic factors. This arises from the diverse combinations of alleles an individual inherits from their parents. Alleles are different versions of a gene, and the specific combination of alleles an individual possesses determines their genotype. This genotype, in turn, dictates their phenotype.

Allele combinations lead to variation because different combinations of alleles can produce different phenotypes. For example, consider the gene for flower colour in pea plants. If a plant inherits two alleles for purple flowers (PP), it will have a purple phenotype. If it inherits one allele for purple (P) and one for white (p) (Pp), it will have a purple phenotype because purple is dominant. However, if it inherits two alleles for white flowers (pp), it will have a white phenotype. The different allele combinations (PP, Pp, pp) result in distinct phenotypes.

Dominance is a key concept in understanding how genetic factors influence phenotype. A dominant allele will mask the expression of a recessive allele when present. Consider the gene for cystic fibrosis. Individuals with two recessive alleles (cc) will have cystic fibrosis. Individuals with one dominant allele (C) and one recessive allele (c) (Cc) will be carriers but will not have the disease. Individuals with two dominant alleles (CC) will not have cystic fibrosis. This demonstrates how the dominance relationship between alleles directly impacts the observable phenotype.

Incomplete dominance provides another example of genetic influence. In incomplete dominance, neither allele is completely dominant over the other. For instance, in snapdragons, a cross between a homozygous red-flowered plant (RR) and a homozygous white-flowered plant (rr) will produce offspring with pink flowers (Rr). The pink phenotype is an intermediate phenotype resulting from the blending of the two alleles. This shows how the interaction of alleles at a single gene locus can lead to a range of phenotypic expressions.

In summary, genetic factors, through the interplay of allele combinations, dominance relationships, and incomplete dominance, are fundamental determinants of phenotypic variation. The specific alleles an individual inherits and how they interact dictate the observable traits.

Variation (3)