Answer the following questions:
1.What does it mean to say that DNA is the genetic material?
2.What is the difference between a 'gene" and an allele? Give an example of multiple alleles for a gene.
3.What is the principle of segregation and how is this principle demonstrated in the results of Mendel's dihybrid crosses?
brid crosses?
4.What is the “principle of independent assorment'and how is this principle demonstrated in the results of Mendel's dihybrid crosses?
5. Explain why random union of male and female gametes is necessary for Mendelian
segregation and independent assortment to occur.
6. What is the difference between inbreeding depression and heterosis?
7.Which of the following genotype frequencies of AA, Aa, and aa, respectively, satisfy the
Hardy-Weinberg principle?
(a) 0.25, 0.50, 0.25
(b) 0.36, 0.55, 0.09
(c) 0.49, 0.42, 0.09
(d) 0.64, 0.27, 0.09
(e) 0.29, 0.42, 0.29
8. The following blood-type data were collected in a sample of 700 Native Americans from South Dakota:
Blood Type
A
B
AB
O
Number of Individuals
326
20
16
338
* Estimate the frequencies of the A, B, and O alleles from the sample data.
9. Why animal breeders Estimate Heritability?
10. What are the three methods of selection that have been generally used and discovered by
Hazel and Lush.? Explain.
within introduction, conclusion and reference.
1. To say that DNA is the genetic material means that it is the molecule responsible for carrying and transmitting hereditary information in living organisms. DNA contains the instructions for building and maintaining an organism, and it is passed on from parents to offspring during reproduction.
2. A gene is a specific segment of DNA that carries the instructions for building a particular protein or RNA molecule. An allele, on the other hand, is a specific form or variant of a gene. Genes may have multiple alleles, which are different versions of the same gene that can lead to variations in traits. For example, the gene for blood type in humans has three alleles: A, B, and O.
3. The principle of segregation, also known as Mendel's first law, states that during gamete formation, the alleles for each gene segregate or separate from each other so that each gamete receives only one allele for each gene. This principle is demonstrated in the results of Mendel's dihybrid crosses, where he crossed plants that differed in two traits controlled by two different genes. Mendel observed that the traits were inherited independently, with each trait segregating independently from the other.
4. The principle of independent assortment, also known as Mendel's second law, states that during gamete formation, the alleles of different genes segregate independently of one another. This principle is demonstrated in the results of Mendel's dihybrid crosses, where he observed that the inheritance of one trait did not influence the inheritance of the other trait. This suggests that the inheritance of one gene is not dependent on the inheritance of another gene.
5. The random union of male and female gametes is necessary for Mendelian segregation and independent assortment to occur because it introduces genetic variation. If the union of gametes was not random, and certain gametes were consistently favored, then the segregation and assortment of alleles would not be random either. Random union allows for the mixing and shuffling of alleles, leading to new combinations in the offspring.
6. Inbreeding depression refers to the decline in fitness or vitality that can occur in offspring from mating closely related individuals. It can lead to reduced fertility, increased susceptibility to diseases, and decreased overall survival. Heterosis, on the other hand, also known as hybrid vigor, refers to the increased fitness or vitality observed in offspring from mating unrelated individuals. It can lead to enhanced growth, fertility, and overall health.
7. The genotype frequencies that satisfy the Hardy-Weinberg principle are those that follow the equation p^2 + 2pq + q^2 = 1, where p represents the frequency of the dominant allele and q represents the frequency of the recessive allele. Option (c) 0.49, 0.42, 0.09 satisfies the equation and thus satisfies the Hardy-Weinberg principle.
8. To estimate the frequencies of the A, B, and O alleles from the sample data, we can calculate the allele frequencies by dividing the number of individuals with a certain blood type by the total number of individuals. The estimated frequencies would be: A allele = (326 + 0.5 x 20) / (2 x 700) = 0.470, B allele = (20 + 0.5 x 16) / (2 x 700) = 0.043, O allele = (338 + 0.5 x 16) / (2 x 700) = 0.487.
9. Animal breeders estimate heritability to understand the extent to which the variation in a particular trait is due to genetics. By estimating heritability, breeders can determine how much improvement in a trait can be achieved through selective breeding. It helps them make informed decisions about which individuals to breed and which traits to focus on in order to achieve desired characteristics in future generations of animals.
10. The three methods of selection discovered by Hazel and Lush are selection based on individual phenotype, selection based on family performance, and selection based on progeny testing.
- Selection based on individual phenotype involves choosing individuals for breeding based on their observable physical or performance traits. This method is commonly used in animal breeding programs to improve traits such as milk production, meat quality, or disease resistance.
- Selection based on family performance involves evaluating and selecting individuals based on the performance of their relatives. This method takes into account the performance of an individual's relatives, such as parents, siblings, or offspring, to estimate the genetic potential of that individual.
- Selection based on progeny testing involves evaluating and selecting individuals based on the performance of their offspring. This method requires breeding individuals and evaluating the performance of their offspring to determine their genetic potential and select for desirable traits.
Overall, these selection methods aim to improve the genetic quality of a population by selecting individuals with superior traits and incorporating their genetics into future generations.
Reference:
No external references were used for this response.