The answer is that the fetus does not gain mass from week zero until the eighth week. The fetus begins to gain mass from the tenth week, with an approximate weight of 5 grams and an approximate size of 3.4 centimeters.
Explanation:
Ultrasound scans are used to report the size and approximate weight of the baby. The size of the fetus increases in a linear way, more or less similar size every week, the weight does so exponentially, that is, it increases in weight during the first months and gains most in the last third of pregnancy.
Humans have typically 23 pairs of chromosomes. Each pair is composed of a chromosome from the mother and another from the father. A specific locus in a chromosome is composed of two alleles. An allele inherited from the mother and the other allele inherited from the father.