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TLS Online TPP Program

#Question id: 17668

The most recent common ancestor of all land plants was probably similar to modern-day members of which group? 

#Unit 9. Diversity of Life Forms
  1. green algae 
  2. red algae 
  3. charophytes 
  4. brown algae 
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TLS Online TPP Program

#Question id: 15154

#Unit 8. Inheritance Biology

In this problem we will explore some of the many ways that mutations in two different genes can interact to produce different Mendelian ratios. Consider a hypothetical insect species that has red eyes. Imagine mutations in two different unlinked genes that can, in certain combinations, block the formation of red eye pigment yielding mutants with white eyes. In principle, there are two different possible arrangements for two biochemical steps responsible for the formation of red eye pigment. The two genes might act in series such that a mutation in either gene would block the formation of red pigment. Alternatively, the two genes could act in parallel such that mutations in both genes would be required to block the formation of red pigment.
Further complexity arises from the possibility that mutations in either gene that lead to a block in enzymatic activity could be either dominant or recessive. If the crosses between a wild type insect with red eyes and a true breeding white eyed strain with mutations in both genes. Such considerations yield the Pathways in parallel with a recessive mutation in one gene and a dominant mutation in the other, determine the phenotype of the F1 progeny and the expected phenotypic ratio of red to white eyed insects in the F2.
TLS Online TPP Program

#Question id: 15155

#Unit 8. Inheritance Biology

In this problem we will explore some of the many ways that mutations in two different genes can interact to produce different Mendelian ratios. Consider a hypothetical insect species that has red eyes. Imagine mutations in two different unlinked genes that can, in certain combinations, block the formation of red eye pigment yielding mutants with white eyes. In principle, there are two different possible arrangements for two biochemical steps responsible for the formation of red eye pigment. The two genes might act in series such that a mutation in either gene would block the formation of red pigment. Alternatively, the two genes could act in parallel such that mutations in both genes would be required to block the formation of red pigment.

Further complexity arises from the possibility that mutations in either gene that lead to a block in enzymatic activity could be either dominant or recessive. If the crosses between a wild type insect with red eyes and a true breeding white eyed strain with mutations in both genes. Such considerations yield the Pathways in parallel with dominant mutations in both genes, determine the phenotype of the F1 progeny and the expected phenotypic ratio of red to white eyed insects in the F2.
TLS Online TPP Program

#Question id: 15190

#Unit 8. Inheritance Biology

The recessive mutant allele that causes cystic fibrosis is much more frequent in Caucasians population than in other world populations. Some scientists believe heterozygotes must have had a survival advantage during plagues such as cholera that occasionally swept through this population. What concept does this illustrate?
TLS Online TPP Program

#Question id: 15191

#Unit 8. Inheritance Biology

Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, ck and ca. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.
Based on the concepts of dominance, determine whether ck and ca were dominant or recessive alleles by crossing the true-breeding sepia hamsters to true-breeding black hamsters. From the resulting F1 progeny phenotype, what would be the ratio of F2 phenotype
TLS Online TPP Program

#Question id: 15192

#Unit 8. Inheritance Biology

Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, ca and ck. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.
Based on the concepts of recessivity, determine whether ck and ca were dominant or recessive alleles by crossing the true-breeding albino hamsters  with the true-breeding sepia hamsters. From the resulting F1 progeny phenotype, what would be the ratio of F2 phenotype
TLS Online TPP Program

#Question id: 15193

#Unit 8. Inheritance Biology

Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, ca and ck. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.
would mate the true-breeding  ca ca  hamsters to the true-breeding ck ck  hamsters to produce heterozygous  ca and ck  F1 progeny. Crosses and their interpretation that would have allowed geneticists to come to the conclusion that ca and ck were likely to be alleles of the same using the concept that alleles of the same gene will be tightly linked. What will be the ratio of F2 hamster;