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Earth’s orbital speed around the Sun is closest to OC) 850 mi/h
These are the two domains Archaea & Bacteria.
The Experiment name is 'swan neck flask'.
Since only one of his two treatments employed the same type of nutritious broth and flask, only one of his two treatments was exposed to preexisting cells.
Nutrient Broth- A common culture medium for undemanding microorganisms is nutrient broth. Numerous standardized techniques for analyzing meals, dairy products, water, and other items advocate it.
Pre-existing Cell- All cells originate from previously existing cells, according to the third component of the cell theory definition. This implies that cells are not created spontaneously, as the term "spontaneous genesis" implies. Current cells are constantly used to create new ones.
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Answer:
AaBb × aabb
Explanation:
A test cross is a cross between an unknown genotype (dominant phenotype) with a homozygous recessive genotype in order to discover the actual genotype of the species exhibiting dominant phenotype.
This is because one allele of a gene is capable of masking the expression of another, the allele masking is called DOMINANT allele while the allele being masked is called RECESSIVE allele. The combination of these two alleles is termed heterozygosity.
An organism that is phenotypically dominant for a specific trait may either be heterozygous or homozygous for that gene. For example, a plant gene for tallness with an dominant allele T, and recessive allele t. This plant will need tall if the genotype is TT (homozygous dominant) or Tt (heterozygous dominant). In order to know which of these genotypes the plant actually has, a test cross is conducted.
In this example, two genes A and B are involved. For the first gene, A represents dominant allele while a represents recessive allele. For the second gene, B represents dominant allele while b represents recessive allele.
In a cross involving parents AABB (homozygous dominant for both genes) and aabb (homozygous recessive for both genes), the F1 progeny will all exhibit phenotypic dominance (AaBb).
However, we cannot know the genotype by merely looking at the phenotype. We cannot ascertain yet whether the dominance is heterozygous or homozygous, hence the need for a test cross.
The test cross is between the dominant F1 progeny and a homozygous recessive i.e. AaBb × aabb. Some of the F2 generation will show recessive traits if the unknown genotype is heterozygous.
