2.4: Variation & Inheritance Flashcards
What is variation?
The differences within a population
What causes variation?
Combining genes from two parents
What is a phenotype?
A particular characteristic description
What are phenotypes determined by?
The genes present in an organisms DNA
What are the types of variation?
Discrete & Continuous
What is discrete variation?
A result of single gene inheritance - the characteristics are only dependent on one gene - where the measurements fall into distinct groups
What is continuous variation?
A result of polygenic inheritance - characteristics caused by a number of genes - where there is a range of values between a minimum and a maximum
What chart can show discrete variation?
Bar Chart
What chart can show continuous variation?
Histogram
What are the different versions of a gene called?
Alleles
What are dominant alleles?
An allele that will automatically determine a phenotype
What is a recessive allele?
An allele that can be dominated by another when determining phenotype
What is a genotype?
The combination of alleles
What does homozygous mean?
When both alleles are the same
What does heterozygous mean?
When both alleles are different
How can biologists determine offspring’s phenotypes?
By carrying out a monohybrid cross in a punnett square
Why are predicted phenotype ratios not always achieved?
- Reproduction is random
- The number of offspring can be small
