1. The correct answer is: c. Sister chromatids fail to separate during meiosis.
There are three ways for nondisjunction to occur:
• a pair of homologous chromosomes fail to separate in meiosis I
• sister chromatids fail to separate during meiosis II
• failure of sister chromatids to separate during mitosis.
If a pair of sister chromatids fail to separate properly during anaphase II the possible outcome is one daughter cell with an extra chromosome (one daughter cell with missing chromosome). Consequently, anomalies occurs.
2. The correct answer is: c. It inhabits reverse transcriptase
Zidovudine is a antiretroviral medication (thymidine analogue) with the function to inhibit the activity of the enzyme-reverse transcriptase. Reverse transcriptase is an enzyme used by HIV virus to produce double-stranded DNA (from its RNA) which will be inserted in the host’s DNA. By inhibiting it, zidovudine decreases replication of the HIV virus.
3. The correct answer is: b. fragmentation
Fragmentation is a form of reproduction, asexual, in which an organism is split into fragments and each of these develop into new organism. In the case of plant this type of reproduction is often and it is called vegetative reproduction. So, aloe vera can grow from cuttings or offsets. As a result, new plants (offspring) will be genetically identical to parent plant (there is no genetic variation as in sexual reproduction).
4. The correct answer is: c. flower color
When Mendel crossed pure-bred green-seeded and pure-bred yellow-seeded he expected offspring with blended traits (intermediate green-yellow color). Surprisingly, he found that this cross produced offspring with only one color. This occurs because of the different alleles (variants) of the same gene that determinate the color of the flower. If allele for the yellow is dominant, the yellow flowers will be produced.
