4.1.1 a - The DNA of prokaryotes as well as that found in chloroplasts and mitochondria is best described as:

• a single-stranded, finger like molecule found in the cytosol.

• a circular, double-stranded molecule bound around a set of eight histone proteins.

• a circular, double-stranded molecule not bound by histone proteins or a double membrane

• a double-stranded molecule bound by histone proteins and a double membrane

4.1.1 a - PAST EXAM 2020 MC 12 - In the structure of DNA, adenine pairs with which other base?

• uracil

• guanine

• cytosine

• thymine

4.1.1 b - Recall the subunits that compose a nucleotide.

• a ribose sugar, a phosphate group and one of four nitrogenous bases.

• deoxyribose sugar, a phosphate group and one of four nitrogenous bases.

• deoxyribose sugar, a phosphate group and one of four nucleic acids.

• deoxyribose sugar, phosphorus and one of four nitrogenous bases.

4.1.1 b - What is the correct complementary strand for the following strand of DNA:

AATCATGGA

• AATCATGGA

• TTAGTACCT

• UUAGUACCU

• GGATAUCUA

4.1.1 b - The hydrogen bonds between nitrogenous bases that connect the two strands in a double helix are considered?

• weak and base specific

• weak and non-base specific

• strong and base specific

• strong and non-base specific

4.1.1 c - The following sentence describes the function of which enzyme in the process of DNA replication. 'This enzyme unwinds the DNA double helix and separates the strands to prepare for replication'.

• synthase

• replicase

• polymerase

• helicase

4.1.1 c - The following sentence describes the function of which enzyme in the process of DNA replication. 'This enzyme is responsible for assembling nucleotides to generate new DNA strand that is complementary to the original template strand'.

4.1.2 a - PA MOCKEXAM 2020 MC 13 - During meiosis II, what is the role of homologous chromosomes?

• pairing

• separation

• duplication

• recombination

4.1.2 a - Identify which of the following paragraphs best demonstrates how crossing over and recombination contributes to genetic variation?

• When a male gamete and a female gamete finally meet, each is the result of an immense number of genetic possibilities created during independent assortment and crossing over. The random nature of this process occurring in the development of both gametes results in almost infinite potential variation in the resulting progeny. The random meeting of these two diverse groups of genes further diversifies the resulting gametes

• Chromosome segments are exchanged between nonsister chromatids of homologous chromosomes during the prophase of meiosis I. This exchange between chromosomes from different parents, creates new combinations of alleles in the gametes that are not found in either parent that had previously been on opposing homologous chromosomes. This recombination contributes to genetic diversity in the gametes.

• When cells divide during meiosis, homologous chromosomes are randomly distributed during anaphase I, separating and segregating independent of each other. This results in gametes that have unique combinations of chromosomes that may come from different parents. This means that while all gametes will carry one of each homologous chromosome pair these will be a mix of chromosomes providing new groups of alleles not found in the parent.

4.1.2 a - Identify which of the following best compares the processes of spermatogenesis and oogenessis (with reference to haploid and diploid cells).

• Both processes involve meiosis in the formation of two haploid daughter cells. Significantly this results in eggs and sperm with half the genetic material of the parents diploid somatic cells.

  While in spermatogenesis, 4 functioning gametes are produced in oogenesis, only 1 gamete and 3 non-gamete polar bodies are produced. Therefore 4 times as many sperm are produced as eggs for each stem cell resulting less reproductive opportunities for successful fertilisation of eggs. In spermatogenesis, sperm are continuously produced whilst in oogenesis, eggs are generated before birth. Significantly this means that sperm are produced throughout a male lifespan whilst egg maturation often does not continue into menopause.

• Both processes involve meiosis in the formation of two haploid daughter cells. While in spermatogenesis, 4 functioning gametes are produced in oogenesis, 1 only one gamete and 3 non-gamete polar bodies are produced. In spermatogenesis, spermatocytes are continuously produced whilst in oogenesis, oocytes are generated before birth.

• Both processes involve meiosis in the formation of two haploid daughter cells. Significantly this results in eggs and sperm with half the genetic material of the parents diploid somatic cells.

  While in spermatogenesis, only 1 gamete and 3 non-gamete polar bodies are produced, in oogenesis, 4 functioning gametes are produced. Therefore 4 times as many eggs are produced as sperm for each stem cell resulting less reproductive opportunities for successful fertilisation of eggs.

  In spermatogenesis, sperm are generated before birth, while in oogenesis, eggs are continuously produced. Significantly this means that sperm are produced throughout a male lifespan whilst egg maturation often does not continue into menopause.

• Both processes involve meiosis in the formation of two haploid daughter cells. While in spermatogenesis, only 1 gamete and 3 non-gamete polar bodies are produced, in oogenesis, 4 functioning gametes are produced. In spermatogenesis, sperm are generated before birth, while in oogenesis, eggs are continuously produced.