Answer:
B. It is done by humans to select certain traits useful to us.
Explanation:
There are two main types of selection: natural and artificial. Natural selection is all of the other answers, it is seen over generations and allows the fittest to survive. It also occurs with no human intervention. However, artificial selection is done by humans. It occurs when humans breed animals to best fit their needs. This is best seen in dog breeding.
Answer:
The correct option is <em>B. Crossing- over </em>
Explanation:
In biology, crossing over can be described as a phenomenon by which homologous chromosomes exchange segments during the process of meiosis.
The unexpected results came because the DNA segment between the homologous chromosomes was exchanged during meiosis. The alleles got shuffled by this process and hence showed the unexpected results.
Crossing over and independent assortment are phenomenon which occurs only during the process of meiosis. These phenomenons cannot be observed during mitosis.
Answer:
The plasma membrane is made up by a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment. Only relatively small, non- polar materials can easily move through the lipid bilayer of the plasma membrane.
Explanation:
Answer:
See the answer below
Explanation:
The stock solution of Gentamycin has a concentration of 5 mg/ml while each plate needs to contain 50 micrograms/ml of Gentamycin.
5 mg/ml = 5000 micrograms/ml
There is a need to dilute the stock antibiotic solution in order to arrive at 50 micrograms/ml. Using the dilution principle;
m1v1 = m2v2
5000 x 1 = 50 x v2
v2 = 5000/50 = 1000 ml
<em>Hence, in order to prepare 50 micrograms/ml, 1 ml of the stock Gentamycin should be taken and diluted with 999 ml of distilled sterilized water. 1 ml of the diluted Gentamycin will then be added to each agar plate while they are still in the molten form at a warm temperature.</em>
Answer:
Prenatal.
Explanation:
The sexual reproduction may be defined the process of fusion of the male sperm and female ovum that leads to the formation of the zygote. Zygote is diploid in nature.
The prenatal development includes all the stages that are involved in the development of the single cell till the completion of the nine months of the fetus. The development of all organs and the process of the cell specification all occurs in the prenatal development stage.
Thus, the answer is prenatal.
