Answer:
External fertilization usually occurs in aquatic environments where both eggs and sperm are released into the water. After the sperm reaches the egg, fertilization can then take place.External fertilization is most common in amphibians and fish.
Explanation:
Some animals produce offspring through asexual reproduction while other animals produce offspring through sexual reproduction.
Sexual reproduction starts with the combination of a sperm and an egg in a process called fertilization. This can occur either outside the bodies or inside the female.There are two types of fertilization in sexual reproduction. Internal fertilization and external fertilization.External fertilization is a common and widespread in aquatic environments where both eggs and sperm are released into the water. After the sperm reaches the egg, fertilization takes place. Most external fertilization happens during the process of spawning where one or several females release their eggs and the male(s) release sperm in the same area, at the same time. The spawning may be triggered by environmental signals, such as water temperature or the length of daylight. Nearly all fish spawn, as do crustaceans (such as crabs and shrimp), mollusks (such as oysters), squid, and echinoderms (such as sea urchins and sea cucumbers). Frogs, corals, mayflies, and mosquitoes also spawn
Answer:
The answer is D) Another biopsy from a distinct site may show a different result.
Explanation:
In molecular biology southern blot is used to detect a specific sequence of DNA. Mitochondria are energy producing organelles in the cell and they possess DNA that is inherited only from the mother. Although Southern blot is the classic method used to detect large deletions in mitochondrial DNA, it is not always sensitive enough to detect heteroplasmic deletions at low levels leading to results that are not always reliable. Heteroplasmy refers to the presence of more than one mitochondrial DNA in an individual. The presence of a mutation in the mitochondrial DNA can create an intracellular heteroplasmic mix of mutant and normal mitochondrial DNA. Cells with a higher rate of cell division like blood can yield inconclusive results in southern analysis because heteroplasmy favors wild type mitochondrial DNA. Thus, non-dividing cells such as muscle cells are preferred for the analysis.
Answer:
Explanation:
The most common disease-causing mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is the out-of-frame deletion of 3 nucleotides (CTT). ... CFTR cDNA, mRNA, and protein sequences in the vicinity of the ... synthesis of a protein product with the same amino acid sequence .
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