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 independent variable is the type of food available.<span>The dependent variable is the frequency of each type of beak (or number of birds with each beak type)</span>
Answer is A. restriction enzyme
In biology ,Restriction enzyme is known as a scissor.
Answer:
The tail of the sperm, the flagellum
Explanation:
We find cilia in the human body. They coat the epithelial cells of the upper respiratory tract and play a role in keeping dust particles, smog, and potentially harmful microorganisms from entering the lungs.
Their movements enable the movement of mucus or other substances across the surface of various epithelial cells. The cilia also cover parts of the male and female reproductive tract.
Flagella are found in sperm, whose tail represents the flagellum in its structure. The body wall of the sponge, among others, contains cells with whips that create and maintain the flow of water through the body.
<h2>540 million years ago
</h2>
Paleozoic.
Era immediately follows Precambrian It lasted about 4.5 billion years.
When did abundant fossil evidence first appear in the geologic record.
540 million years ago.
