Back to Course

JSS3: BASIC SCIENCE - 1ST TERM

0% Complete
0/0 Steps
  1. Family Traits | Week 1
    6Topics
    |
    1 Quiz
  2. Environmental Hazards I - Soil Erosion | Week 2
    3Topics
  3. Environmental Hazards I - Flooding | Week 3
    5Topics
    |
    1 Quiz
  4. Environmental Hazards II - Bush Burning | Week 4
    4Topics
  5. Environmental Hazards II - Deforestation | Week 5
    4Topics
    |
    1 Quiz
  6. Environmental Hazards III - Desertification | Week 6
    4Topics
    |
    1 Quiz
  7. Environmental Hazards III - Description of the Ozone Layer and its Location in the Atmosphere | Week 7
    3Topics
    |
    1 Quiz
  8. Drug and Substance Abuse | Week 8
    4Topics
    |
    1 Quiz
  9. Resources from Living Things | Week 9
    4Topics
  10. Resources from Non-Living Things | Week 10
    2Topics
    |
    1 Quiz
Lesson 1, Topic 4
In Progress

Dominant and Recessive Traits

Lesson Progress
0% Complete

A trait is said to be dominant when it keeps appearing in each generation, while a trait is said to be recessive when they are present in an individual, yet they do not appear physically.

Dominant Traits: If a dominant tall man, TT, marries a tall woman, who has a recessive trait for shortness, Tt, and they produce four children, all of them will be tall, meaning that tallness is dominant over the gene for shortness. 

This is demonstrated below:

Basic Science Jss3 - Traits

∴ they are all tall.

Genotypic Ratio   =  2:2.

Phenotypic Ratio  = 4:0.

Recessive Traits:  If a tall man, TT, marries a short woman, tt, they may not produce any short child or children, but the children having the recessive traits, may produce short children by the second generation. 

This is illustrated below:

Recessive trait

Genotypic Ratio = 4:0.

Phenotypic Ratio = 4:0.

However, in the second generation, short children can be produced. 

This is illustrated below:

secong gen e1605122945278

Genotypic Ratio = 1:2:1.

Phenotypic Ratio = 3:1.

back-to-top
error: