The person should be a male.
Only male carries XY chromosomes, meanwhile female carries XX chromosomes. "Heterozygous for the X and Y chromosomes" means that the person have both X and Y chromosomes in their cells, therefore only males fits the description.
This is also why the birth rate of girl or a boy is always 50%, it is because the sex of a person is only determined by the sperm from a male. Each sperm either carries a X or a Y chromosome, never the both. Therefore, the chances of a X or a Y sperm fertilising an X egg is always 50%, also explains why both female or male must have at least one X chromosome because an egg always carry an X.
I had to look for the options and here is my answer: When transcription of a protein-coding gene occurs in a bacterial RNA polymerase, what happens is that, it produces pre-mRNA. Pre-mRNA is also an RNA strand that is not yet matured and it is still to be synthesized.
Answer:
B. High temperatures
Explanation:
the canopy of the forest cover the rest of the forest, so it is cooler
