Answer:
Crossing over and random alignment are the events of meiosis-I that add new gene combinations to the gametes. Random fusion of male and female gametes is called random fertilization.
Explanation:
During the pachytene stage of meiosis-I, part of the chromatids of each of the homologous chromosomes of a bivalent is broken apart and exchanged. This exchange of the genetic material between the members of a bivalent is called crossing over. The recombinant chromatids formed by crossing over have new allele combinations that were otherwise not present in the parental chromatids.
During metaphase I, the homologous pairs are aligned at the cell's equator in a random manner. This means that either the paternal or maternal chromosome of a pair may face one or the other pole of the cell. The arrangement of chromosomes during metaphase-I determines whether the paternal or maternal chromosome of each pair would be distributed to one or the other pole of the cell. This random segregation creates new gene combinations in gametes.
All the gametes have equal chances of getting fused with a gamete from the opposite gender. This is called random fertilization and further adds variations.
Answer:
<em>Exceptions to Mendel's principles:
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Does exceptions mean that Mendel was "wrong"? The answer is "NO". It means that we know more today about diseases, genes, and heredity than compared to what he expalined 150 years ago. Here I have summerized the exceptions with examples:
<em>Incomplete dominance</em>: When an organism is heterozygous for a trait and both genes are expressed but not completely.
<em>Example</em><em>:</em> SnapDragon Flowers
<em>Codominance</em>: When 2 different alleles are present and both alleles are expressed.
<em>Example</em>: Black Feathers + Whites feathers --> Black and white speckled feathers
<em>Multiple alleles</em>: Three or more alternative forms of a gene (alleles) that can occupy the same locus.
Example: Bloodtype
<em>Polygenic traits</em>: more than one gene controls a particular phenotype
Example: human height, Hair color, weight, and eye, hair and skin color.
The reproductive system is different from other body systems in that the reproductive system functions in the survival of a species while all other body systems function to ensure the survival of the individual.
Light aka the sun I know for a fact
