2.1 The diagrams below represent the distribution of chromosome pair 21 as it appears in gametes at the end of meiosis II in a human male - NSC Life Sciences - Question 2 - 2018 - Paper 2

If gamete A (which has 24 chromosomes, including an extra chromosome 21) fuses with a normal gamete containing 23 chromosomes, the resulting zygote will have 47 chromosomes total. This condition, known as trisomy 21 or Down syndrome, occurs when there are three copies of chromosome 21 instead of the usual two, leading to developmental and physical features associated with the syndrome.

The phenotype of individual 2 is female without SCID.

The phenotype of individual 1 is male with SCID.

The genotype of individual 3 is XᶺXᶺ.

Individual 5 inherited the disorder by receiving one copy of the Xᶺ allele from the mother, who is a carrier or affected, and the Y chromosome from the father.

An advantage of cloning is that it allows for the production of organisms with desired characteristics, such as high milk yield.

A disadvantage of cloning is that it reduces genetic variation in the offspring, which may lead to vulnerabilities in populations.

The donor cell was taken from LMJC 865 because this cow had a high average milk production yield, ensuring the desired trait was preserved in the clone.

An ear cell was used instead of an ovum because somatic cells can undergo cloning through a process called nuclear transfer, allowing for the entire genetic information to be retained.

The cloning process involves removing the nucleus from an ovum and replacing it with the nucleus from a somatic cell. The resulting zygote is then stimulated to undergo mitosis and is placed into the uterus of an adult female for development.

The dominant flower colour is purple.

Cross 1 demonstrated that when a purple-flowering plant is crossed with a white-flowering plant, all offspring produced (40 in total) displayed the purple phenotype. This indicates that the allele for purple flowers is dominant over the allele for white flowers.

Mendel's Law of Segregation states that during meiosis, the two alleles for a characteristic separate so that each gamete receives only one allele for that characteristic.

In cross 2, the genotypes of the parents can be shown as follows: Parent 1 (purple) genotype: Dd; Parent 2 (white) genotype: dd. The Punnett square for this cross would show the following potential offspring genotypes: 50% Dd (purple) and 50% dd (white).