Science - Chapter 3: Grade 7

good luck :D

Heredity

The passing of traits from parent to offspring

Trait

specific characteristics of an individual

genetics

The scientific study of heredity

Gene

A segment of DNA on a chromosome that codes for a specific trait

allele

Different forms of a gene

Dominant allele

one whose trait always shows up in the organism when the allele is present

Recessive allele

An allele that is hidden whenever the dominant allele is present

Punnett square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Phenotype

An organism's physical appearance, or visible traits.

Genotype

genetic makeup of an organism

homozygous

An organism that has two identical alleles for a trait

Heterozygous

having two different alleles for a trait

incomplete dominance

occurs when one allele is only partially dominant

codominance

occurs when both alleles for a gene are expressed equally

meiosis

the process by which the number of chromosomes is reduced by half to form sex cells

polygenic inheritance

occurs when more than one gene affects a trait

what does polygenic inheritance result in?

A broad range of phenotypes

What is an example of codominance?

AB blood type

What is an example of incomplete dominance?

red flower + white flower \= pink flower

What is the percentage of heterozygous genotypes if Both parents are heterozygous? (Use Punnett Square)

50%

What is the difference between incomplete dominance and codominance?

In codominance, both alleles in the genotype are seen in the phenotype. In incomplete dominance, a mixture of the alleles in the genotype is seen in the phenotype.

Why would a pea plant be tall when it's a hybrid for stem height?

Hybrid pea plant is stem height tall because it has one dominant and one recessive allele. In a situation like this, the dominant allele covers up the recessive allele for short stems.

what happens during meiosis

During meiosis, the chromosome pairs separate into two different cells. The sex cells that form later have only half as many chromosomes as the other cells in the organism.

What is probability?

the likelihood that an event will occur