alleles for gcse aqa combined science Flashcards
What is an allele?
An allele is a variant form of a gene.
True or False: Alleles can be dominant or recessive.
True
What do we call the genetic makeup of an organism?
Genotype
What is the physical expression of a genotype called?
Phenotype
Fill in the blank: The allele that masks the effect of another allele is called __________.
dominant
Fill in the blank: The allele that is masked by a dominant allele is called __________.
recessive
What is the term for an organism with two identical alleles for a trait?
Homozygous
What is the term for an organism with two different alleles for a trait?
Heterozygous
What is the expected phenotype ratio in a monohybrid cross of two heterozygous parents?
3:1
True or False: An organism’s phenotype can be influenced by environmental factors.
True
What is a Punnett square used for?
To predict the genotypes and phenotypes of offspring from a genetic cross.
What are alleles located on chromosomes called?
Loci
True or False: All genes have only two alleles.
False
What type of allele is represented by a capital letter?
Dominant allele
What type of allele is represented by a lowercase letter?
Recessive allele
Fill in the blank: The observable characteristics of an organism are its __________.
phenotype
What is the ratio of phenotypes in a dihybrid cross of two heterozygous parents?
9:3:3:1
True or False: A person can have a recessive phenotype if they have one dominant allele.
False
What is the term for a trait that is controlled by multiple alleles?
Multiple alleles
Fill in the blank: The combination of alleles for a particular gene is called the __________.
genotype
What is the term for the different forms of a gene that can exist at a single locus?
Alleles
True or False: Genetic mutations can create new alleles.
True
What is the main difference between incomplete dominance and codominance?
In incomplete dominance, the phenotype is a blend, while in codominance, both alleles are fully expressed.
What type of inheritance pattern is demonstrated by blood types?
Codominance
Fill in the blank: The genetic makeup of an organism is referred to as its __________.
genotype
What is the purpose of a test cross?
To determine the genotype of an organism with a dominant phenotype.
True or False: A phenotype can only be influenced by genetics and not by the environment.
False
