Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

13. Mendelian Genetics

Genotype vs. Phenotype

General Biology

13. Mendelian Genetics

Genotype vs. Phenotype

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1:20 minutes

Problem 2

Textbook Question

Whether an allele is dominant or recessive depends on
a. How common the allele is, relative to other alleles
b. Whether it is inherited from the mother or the father
c. Whether it or another allele determines the phenotype when both are present
d. Whether or not it is linked to other genes

Verified step by step guidance

Understand the concept of alleles: Alleles are different forms of a gene that can exist at a specific locus on a chromosome. They can be dominant or recessive, which affects how they influence the phenotype.

Review the definition of dominant and recessive alleles: A dominant allele is one that expresses its trait in the phenotype even when only one copy is present (heterozygous condition). A recessive allele requires two copies (homozygous condition) to express its trait in the phenotype.

Focus on the key factor that determines dominance or recessiveness: Dominance or recessiveness is determined by how the alleles interact to produce the phenotype when both are present. Specifically, a dominant allele will mask the effect of a recessive allele in a heterozygous individual.

Eliminate incorrect options: a) The frequency of an allele in a population does not determine whether it is dominant or recessive. b) Whether an allele is inherited from the mother or father does not affect its dominance or recessiveness. d) Linkage to other genes does not determine dominance or recessiveness.

Conclude with the correct answer: The correct answer is c) whether it or another allele determines the phenotype when both are present. This is the defining characteristic of dominant and recessive alleles.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Dominance in Alleles

Dominance refers to the relationship between alleles of a gene, where a dominant allele masks the effect of a recessive allele in a heterozygous individual. This means that if an individual has one dominant and one recessive allele, the dominant trait will be expressed in the phenotype, while the recessive trait will not.

Phenotype Expression

Phenotype is the observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental influences. The expression of a phenotype can be influenced by the dominance of alleles, where the presence of a dominant allele will dictate the visible traits, regardless of the recessive allele's presence.

Genetic Linkage

Genetic linkage refers to the tendency of alleles that are located close to each other on a chromosome to be inherited together during meiosis. While linkage can affect inheritance patterns, it does not directly determine whether an allele is dominant or recessive; rather, it influences the likelihood of allele combinations in offspring.