Correct answer:
"<span>B- homologous chromosomes join together to form tetrads during prophase I"
</span>It is during prophase I that homologous chromosomes join together (<span>synapsis)</span> and form tetrads - four chromatids are together in the new structure of two chromosomes - and this is the reason why crossing-over occurs in this phase. It is in this tetrad that both arms of both chromosomes may crossover and matching regions exchange places. This process results in homologous chromosomes recombination leading to genetic variability.
Answer:
Meiosis is important because during sexual reproduction, it ensures that all produced organisms have the correct number of chromosomes. It is also responsible for producing genetic variations during the process of recombination, and it repairs some genetic defects.
The disadvantage from not having the trait normally arises only after the reproductive stage of the individual's lifecycle is mostly over. This is a special case of "no strong pressure", because evolution selects genes, not the organism. In other words the beneficial mutation does not alter the reproductive fitness.
Explanation:
Meiosis is important because during sexual reproduction, it ensures that all produced organisms have the correct number of chromosomes. It is also responsible for producing genetic variations during the process of recombination, and it repairs some genetic defects.
12C,13C,14C
these are all carbon Isotopes
Zygote implants itself in the uterus.
