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.
The options to this question are:
A. The strength of Mama's children
B. The hope in Walter's dream
C. The sour feelings among the characters
D. The need to embrace
The best answer is:
the lack of nourishment for the surviving plant in a raisin in the sun most likely reflects "The strength of Mama's children".
<span>A plant in a raisin basically represents a mama's dream that there will a day when she will have her own house with a small garden in the backyard.</span>
Answer:
The correct answer is D. involves proteins in plasma membranes.
Explanation:
Animal cells have several types of proteins embedded in their cell membrane. These proteins play an important role in the transport of molecules, cell recognition, and cell communication.
Recognition proteins are a type of glycoproteins present in the plasma membrane that allow one cell of the body to recognize the other body cells by making contact with recognition proteins of other cells. Receptors proteins allow cell-cell communication by receiving extracellular proteins.
These proteins are important for proper growth and development of the cell. Therefore the correct answer is D. involves proteins in plasma membranes.
Answer:
c. Ductus venosus, vena cava, heart, ductus arteriosus, arteries
Explanation:
The circulatory system consists of the heart and blood vessels. In a fetus, the circulation of blood is different from circulation after delivery largely due to the fact that the lungs are not in use, rather, the fetus obtains oxygen and nutrients from the mother through the placenta and the umbilical cord.
Blood from the placenta is carried to the fetus by the umbilical vein. While some of this blood enters the fetal ductus venosus and is carried to the inferior vena cava, some others enter the liver. The blood from the inferior vena cava then moves into the right atrium of the heart. The foramen ovale, an opening between the right and left atrium in the fetus directs most of the blood flow from the right into the left atrium, thereby, bypassing pulmonary circulation. Most of the blood from the right atrium flows into the left ventricle and is pumped through the aorta to the rest of the body.
Some of the blood from the right atrium however, enters into the right ventricle and is pumped into the pulmonary artery. The ductus arteriosus which is a special connection between the pulmonary artery and the aorta in a fetus, directs most of this blood away from the lungs and into the arteries.
