Cells in blood, hair, finger nails and any other tissue in our body can be cultured to create a karyotype of the chromosomes. 

The chorion develops around the embryo early in a pregnancy. Later, as a fetus develops from the embryo, the chorion fuses with the amnion.

There will be a 50% chance (2 out of 4) of having a carrier (Aa) child. Similarly, each time there will be a 25% chance of having an offspring who will inherit the disease (aa) and die.

Since both parents are homozygous recessive (aa), all of their children will be as well. As a result, none of them will be free of this recessive trait in their phenotypes.

There is a 50% chance that the children will be heterozygous (Aa) and a 25% chance that they will be homozygous dominant (AA). Children with either of these genotypes will have this trait expressed in their phenotypes.

The source of these alien genes was mostly male American soldiers. Since they left Vietnam, they were only visitors. However, by successfully mating with Vietnamese women, they left copies of their genes in south-east Asia.

Both mutation and gene flow can cause new variations of genes to enter a population's gene pool. However, only mutation can introduce them into the gene pool of an entire species.

Population genetics carry out research about microevolution, which is slight change in gene pool frequencies over just a few generations.  However, such small changes over many generations can result in the evolution of new species, or macroevolution.

Supra means above, orbital refers to the eyes, and a torus is a projecting bony bar or ridge. A supraorbital torus is a ridge on the frontal bone above the eye socket.

Non-random mating of any sort can cause a change in population's gene pool frequencies, independent of any other evolutionary mechanism. Consanguineous mating (or inbreeding) is a form of non-random mating.

The frequency of heterozygotes will grow while the frequency of homozygotes will correspondingly shrink. This is because individuals who have the same genotype for a trait would not mate. As a result, heterozygotes, or crosses, are most commonly born.

These are standard diagnostic tools to determine whether or not an unborn child is at risk for a small range of very serious genetic disorders.

When amniocentesis is done after the 15^th week of pregnancy, there is 99+% accuracy in detecting Down syndrome and most other problems related to gross chromosomal abnormalities, including neural tube defects such as spina bifida.

If after repeated testing and peer review by other scientists in the same field, an hypothesis still holds up as a valid explanation for a group of facts, it becomes accepted as a theory.

This method is used to draw out a sample of chorion tissue for cell culturing. As with amniocentesis, ultrasound monitoring helps to prevent damage to the unborn child during the sampling procedure.

This is a definition of his principle of independent assortment. In other words, the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parents, are possible.

An allele is one of two or more alternate forms of a gene. If an individual is homozygous (YY or GG) for a trait, it has inherited the same allele from both parents. If it is heterozygous (YG), it has inherited different alleles for the trait.

Since the amount of AFP in a mother's blood varies with the stage of a pregnancy, a wrong date can mislead a doctor. Similarly, when it is unknown that there are twins, the resulting large amount of AFP will likely be misinterpreted as a problem.

The reason is that mating is between individuals with the same genotypes -- AA X AA, aa X aa, or Aa X Aa. The first 2 mating combinations only produce homozygous offsprings, while 50% of the offsprings of the latter are homozygous as well.

All of the children will be healthy since none of them can be homozygous recessive (aa). However, there will be a 50% chance at each birth that the children will be carriers (Aa). The remaining 50% will be homozygous dominant (AA).

They are regarded as genes. Each inherited trait is determined by at least one gene from each parent.

There is a 50% chance that the children will be heterozygous (Aa) and a 25% chance that they will be homozygous dominant (AA). Children with either of these genotypes will have this trait expressed in their phenotypes.

Since both parents are homozygous recessive (aa), all of their children will be as well. As a result, none of them will be free of this recessive trait in their phenotypes.

He gave us the concept of unit inheritance as the basis for understanding genetic inheritance in all living things, including humans.

Phenotype includes the observable characteristics, including physical appearance. It results from the genotype and environmental influences. A phenotype includes not only easily measured traits like hair colour but also less apparent ones such as blood type.