Selective breeding
What is selective breeding?
Selective breeding is when humans choose plants or animals with desired traits to reproduce so those traits become more common in future generations.
What is an inherited trait?
An inherited trait is a characteristic that is passed from parents to offspring through genes.
What is a dominant trait?
A dominant trait is a trait that appears when at least one dominant allele is present.
What is a Punnett square used for?
A Punnett square is used to predict the possible genetic outcomes of a cross between two parents.
What is a genotype?
A genotype is the genetic makeup of an organism—the alleles it has for a trait.
Why do farmers use selective breeding?
Farmers use selective breeding to produce plants and animals with useful traits such as higher crop yield, disease resistance, faster growth, or better quality products.
Name two examples of inherited traits.
Eye color and hair type are examples of inherited traits. Answers vary
What is a recessive trait?
A recessive trait is a trait that only appears when two recessive alleles are present.
What do the letters in a Punnett square represent?
The letters represent alleles for a trait, usually with uppercase letters for dominant alleles and lowercase letters for recessive alleles.
What is a phenotype?
A phenotype is the physical expression of a trait that results from the genotype.
Give one example of selective breeding in animals or plants.
Dogs are selectively bred for traits like size, behavior, or strength (for example, herding dogs or guard dogs). Corn has been selectively bred to produce larger kernels.
How are inherited traits passed from parents to children?
Inherited traits are passed through genes in DNA, which children receive from both parents.
What happens when a dominant allele and a recessive allele are inherited together?
The dominant trait is expressed, and the recessive trait is hidden.
If one parent is AA and the other is aa, what are the possible genotypes of the offspring?
All offspring will have the genotype Aa.
Can two organisms have the same phenotype but different genotypes? Explain.
Yes. For example, AA and Aa can produce the same dominant phenotype.
What is one possible disadvantage of selective breeding?
Selective breeding can reduce genetic diversity, which may make a population more vulnerable to diseases or environmental changes.
What is the difference between inherited traits and acquired traits?
Inherited traits are passed down genetically, while acquired traits develop during a person’s lifetime due to environment or experience, such as learning a skill.
What does it mean if someone is a carrier of a recessive trait?
It means the person has one recessive allele and one dominant allele, does not show the recessive trait, but can pass it on to their children.
If two heterozygous parents (Aa × Aa) are crossed, what is the genotypic ratio?
The genotypic ratio is 1 AA : 2 Aa : 1 aa.
How does a dominant allele affect phenotype?
A dominant allele masks the effect of a recessive allele, so the dominant trait is expressed in the phenotype.
How can selective breeding lead to health problems in a species over time?
When only certain traits are selected repeatedly, harmful genes can also be passed along. This can cause inherited health problems because the gene pool becomes too limited.
Why can siblings have different inherited traits even though they have the same parents?
Siblings inherit different combinations of genes from their parents, which results in variation in traits.
If both parents are carriers of a recessive trait, what are the possible outcomes for their child?
There is a 25% chance the child will show the recessive trait, a 50% chance the child will be a carrier, and a 25% chance the child will show the dominant trait.
Using the same cross (Aa × Aa), what is the phenotypic ratio if A is dominant?
The phenotypic ratio is 3 dominant : 1 recessive.
In a cross between Aa × aa, what are the possible genotypes and phenotypes?
Genotypes: 50% Aa, 50% aa
Phenotypes: 50% dominant trait, 50% recessive trait