Punnett Squares
What is a Punnett square used for?
To predict the possible allele combinations and genotypes of offspring.
What is a dominant allele?
An allele that can be expressed when at least one copy is present.
What is a trait?
A characteristic of an organism, such as eye color.
What do the letters DNA stand for?
Deoxyribonucleic acid.
What type of reproduction usually involves one parent?
Asexual reproduction.
A plant has genotype TT. Is it homozygous dominant, heterozygous, or homozygous recessive?
Homozygous dominant.
What is heredity?
The passing of genetic information from parents to offspring.
What molecule carries genetic information?
DNA
What is a gene?
A section of DNA that contains instructions related to a characteristic or function.
What type of reproduction involves genetic information from two parents?
Sexual reproduction.
If T is dominant for tall plants and t is recessive for short plants, what phenotype does Tt show?
Tall
What is a recessive allele?
An allele whose associated trait is generally expressed when two recessive copies are present in a simple dominant-recessive model.
What are different forms of the same gene called?
Alleles
Where are chromosomes found in most plant and animal cells?
In the nucleus.
In which type of reproduction are offspring generally genetically identical to the parent?
Asexual reproduction.
Cross Tt × Tt. What are the four possible genotypes?
TT, Tt, Tt, and tt.
If B is dominant and b is recessive, which genotypes show the dominant phenotype: BB, Bb, or bb?
BB and Bb.
What is a genotype?
The combination of alleles an organism has for a trait.
What do chromosomes contain?
DNA and many genes.
Why are offspring from sexual reproduction often genetically different from their parents?
They inherit a combination of genetic information from two parents.
Cross Bb × bb. What percentage of offspring are expected to have genotype bb?
50%.
Why can two siblings have different inherited traits even though they have the same parents?
They can inherit different combinations of alleles from their parents.
What is a phenotype?
The observable expression of a trait.
Explain how DNA, genes, and chromosomes are related.
Genes are sections of DNA, and DNA is packaged into chromosomes.
Give one advantage of asexual reproduction and one advantage of sexual reproduction.
Asexual reproduction can produce offspring quickly. Sexual reproduction creates genetic variation among offspring.