What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci?
a. 3:1
b. 9:3:3:1
c. 1:1:1:1
d. 1:2:1
e. 9:4:2:1
Answer:
c. 1:1:1:1
Explanation:
When a heterozygous individual for two genes is test crossed with a double homozygous recessive individual, the progeny is obtained in 1:1:1:1 phenotypic ratio. This occurs as the heterozygous dominant individual forms four types of gametes in 1:1:1:1 ratio while the homozygous recessive individual would form only one type of gamete having one recessive allele for each gene.
For example, a test cross between TtRr (tall and red) and ttrr (short and white) would produce a progeny in following ratio=
1 tall, red: 1 tall, white: 1 short, red: 1 short, white
Here, T= tall, t= short, R= red, r= white
The correct answer is C. Mitosis produces 2 genetically identical diploid cells, while meiosis produces 4 genetically unique haploid cells.
Mitosis is where a parent cell duplicates its genetic information before dividing into 2, therefore, the daughter cells from mitosis are completely identical to their parent cell and the other daughter cell, and we call the cells which has complete genetic information as diploid. Mitosis is very useful in repairing, growth, asexual reproduction etc.
Meanwhile, meiosis involves 2 times of division. The parent cell first duplicates its genetic information, but then swapping them, and divide. 2 new cells are produced. Then these 2 cells are further divided but without duplicating the genetic material. Therefore, this results in 4 genetically different cells. We call them haploid, as they only have half of the chromosomes from their parent, which is the opposite of diploid. Meiosis is important in producing sex cells.
Answer:
The correct answer is "Redwood tree; human being; Paramecium; White Blood Cell; Escherichia coli; Chickenpox virus; Ribosome; Prion fibril; Water molecule; Sulfur atom".
Explanation:
Redwood trees are gigantic trees, and its size can reach up to 90 meters.
The average size of a human being is 1.7 meters for males and 1.6 meters for females.
Paramecium are members of the protozoa genus, among the largest unicellular algae. Its average size is among 50 to 330 micrometers.
White Blood Cell are up to 17 micrometers in diameter.
Escherichia coli is a type of bacteria, as a prokaryotic organism is much more smaller than a eukaryotic cell such asa the white blood cell. Escherichia coli is up to 2 micrometers in diameter.
Chickenpox virus are among the largest viruses, they are from 150 to 200 nanometers in diameter.
Ribosomes vary on size depending if they are Prokaryotic or Eukaryotic, where the first are up to 20 nanometers and the second are up to 30 nanometers.
Prion fibrils are aggregates comprised of several protein units. It size varies depending on the number of proteins, but the ones containing around 200 units can reach up to 27 nanometers.
Water molecule is comprised of two atoms of oxygen and one atom of hydrogen, its size is measured with picometers (1 picometer is equal to 1000 nanometers). A water molecule has a size of 275 picometers.
Sulfur atom is the smallest in the list. Its size is around 100 picometers.
Answer:
DNA binding domain and allosteric domain
Explanation:
Repressors are proteins that inhibit gene expression, They usually have DNA or RNA binding site which enables them to binde to the operator or associated silencers. Allosteric domain is the site for the binding of other molecules, such as corepressors and inducers that regulate repressor's activity.
Answer:
stomata are the openings in a leaf
