Concept explainers
Videos
_________is the original source of new alleles.
| a. Mutation | c. Gene flow |
| b. Natural selection | d. Genetic drift |
Introduction:
Genes control the phenotypic expression of an organism. For a single character, different organisms can show different variations for a single character. These variations arise due to different alleles for a single gene. Alleles are different forms of a single gene. During sexual reproduction, offsprings get alleles for a gene both the parents
Answer to Problem 1SA
Correct answer:
Mutation is the original source of new alleles. Hence, the correct answer is option a.
Explanation of Solution
Reason for correct answer:
Option a. is given as “Mutation”.
Mutations cause a change in the amino acid sequence of a gene. These changes result in new phenotypic expressions of that gene in the organism. Mutations cause the formation of alleles that cause various phenotypic expressions of the same character in the mutated organism. Therefore, it can be said that the source of new alleles are mutations in the genes of organisms.
Reason for incorrect answer:
Option b. is given as, “Natural selection”.
Natural selection occurs due to the accumulation of variations over generations. These traits are inherited and are different due to crossing over during reproduction. New alleles are not formed by this process. Hence, option b. is incorrect.
Option c. is given as, “Gene flow”.
Gene flow refers to the process by which new genes enter a population or some genes exit a population. There is no creation of new alleles. Hence, option c. is incorrect.
Option d. is given as, “Genetic drift”.
Genetic drift allows the change of allele frequency in a population. Inherited traits accumulate over generations leading to the gradual drift of population. The changes are random events and there is no formation of new alleles. Hence, option d. is incorrect.
Hence, the options b., c., and d. are incorrect.
The original source of new alleles is a mutation. Thus, the correct option is a.
Want to see more full solutions like this?
Chapter 17 Solutions
BIOLOGY:CONCEPTS+APPL.(LOOSELEAF)
- What are intrinsically disordered proteins, and how might they be useful for a living system?arrow_forwardWhat are Amyloid Fibrils? What biological functions are these known to perform?arrow_forwardHow do histamine and prostaglandins help in the mobilization of leukocytes to an injury site? What are chemotactic factors? How do they affect inflammation process?arrow_forward
- Compare and contrast neutrophils and macrophages. Describe two ways they are different and two ways they are similar.arrow_forwardDescribe the effects of three cytokines (not involved in the initial inflammation response). What cells release them?arrow_forwardDescribe activation of helper T cells or cytotoxic T cellsarrow_forward
- Compare and contrast MHC 1 and MHC 2. Describe two way they are different and two ways they similar including how they are used in antigen presentation.arrow_forwardDescribe two antimicrobial properties of the skin.arrow_forwardDescribe how the inflammation response starts including the sentinel cells and the chemicals involved. How do pathogens trigger the response particularly in the skin?arrow_forward
- How does complement promote the immune response? Describe three waysarrow_forwardWhich of the following is not a possible mechanism for autoimmunity? Select one: A. Abnormal expression of MHC II molecules in non-antigen-presenting cells B. Activation of polyclonal B cells C. Polymorphism of HLA alleles D. Molecular mimicry E. Release of sequestered antigensarrow_forwardWRITTEN WORK 3: NON-MENDELIAN GENETICS Part A: Complete the Punnett square and calculate for the probability of genotype and phenotype. i i Genotype: Phenotype: 08:55arrow_forward
Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College